Circuit board assembly and communication equipment

Abstract

The invention relates to the technical field of communication, in particular to a circuit board assembly and communication equipment. The circuit board assembly comprises a substrate; a gap is formed between the substrate and the circuit board; the welding structure is located in the gap and conducts the substrate and the circuit board; wherein the welding structure comprises a plurality of first welding structures and a plurality of second welding structures, the plurality of first welding structures and the plurality of second welding structures are in one-to-one correspondence, and partition pieces are arranged between the first welding structures and the second welding structures which correspond to each other, so that the first welding structures and the second welding structures which correspond to each other are separated; and the plurality of connecting pieces can be supported between the substrate and the separator and / or between the circuit board and the separator. According to the circuit board assembly, the welding defects of tin connection and open welding in the welding process can be overcome.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a circuit board assembly and communication equipment. Background Art

[0002] At present, surface mount technology (SMT) packaging has become a packaging form with great development potential. SMT type packaging can be grid array (GA) packaging. GA packaging includes pin grid array (PGA) packaging and ball grid array (BGA) packaging. Among them, BGA packaging is the main chip packaging form in the current ICT industry, and the package and the circuit board (such as printed circuit board, Printed circuitboard, PCB) are usually soldered by ball planting and tin printing. The ball planting method between the package and the circuit board adopts a single solder ball structure, that is, a solder point on the package is welded to a solder point on the circuit board to form a solder ball structure.

[0003] Due to the complexity of the package structure and the materials used, the difference in the coefficient of thermal expansion (CTE) between different materials will affect the allowable combined deformation range of the package body and the circuit board, that is, the tolerance of the solder balls between the package and the circuit board. Solder joints that exceed the solder ball tolerance will result in bridging and open soldering.

[0004] With the development of ICT industry equipment specifications, the chip package size has increased significantly in recent years, and a single package in the industry has shown a trend of exceeding the target size of 100mm×100mm. As the chip size becomes larger and larger, the die, fan-out package (FoP) and package body size inside a single package are rapidly expanding, resulting in a significant increase in the deformation of the die, fan-out package and package at different temperatures. In particular, large-size and dense-pitch area array packages are prone to insufficient tolerance when using conventional ball planting (single solder ball structure) and tin printing welding methods, which increases the risk of quality defects in the assembly process at all levels, such as tinning or open soldering.

[0005] Therefore, the conventional soldering method of ball implantation and tin printing can no longer meet the welding requirements of large deformation. How to improve the tolerance of the solder balls between the package and the circuit board to achieve large-size and fine-pitch area array packages and circuit boards with large tolerance assembly has become an urgent problem to be solved. Summary of the invention

[0006] The embodiments of the present application provide a circuit board assembly and a communication device, which can solve the problem of bridging and open soldering of the soldering structure between the package and the circuit board caused by the increasing degree of thermal deformation of the chip as the chip size increases. The present application is introduced from multiple aspects below, and the implementation methods and beneficial effects of the following multiple aspects can be referenced to each other.

[0007] In the first aspect of the present application, a circuit board assembly is provided. The specific circuit board assembly includes: a substrate; a circuit board, wherein a gap is provided between the substrate and the circuit board; a welding structure, wherein the welding structure is located in the gap and conducts the substrate and the circuit board; wherein the welding structure includes a plurality of first welding structures and a plurality of second welding structures, wherein the plurality of first welding structures and the plurality of second welding structures correspond to each other one by one, and a separator is provided between each corresponding first welding structure and second welding structure to separate the corresponding first welding structure and second welding structure; and a plurality of connectors, wherein the plurality of connectors can be supported between the substrate and the separator and / or between the circuit board and the separator.

[0008] The above-mentioned circuit board assembly introduces a new welding structure in the gap between the substrate (for example, including a BGA package) and the circuit board (for example, a printed circuit board, Printed circuit board, PCB), improves the traditional single-ball structure into a double-sided welding module (including a first welding structure and a second welding structure), and introduces a separator separating the first welding structure and the second welding structure in the first welding structure and the second welding structure of the double-sided welding module; the comprehensive thermal deformation of the substrate (for example, including a BGA package) and the circuit board (for example, a printed circuit board, Printed circuit board, PCB) can be decomposed into two parts, reducing the welding process capability required for the single-sided solder joint, improving the overall welding tolerance capability of the overall welding structure, preventing the problems of bridging and open soldering caused by the increase in the degree of thermal deformation of the chip as the chip size increases during the welding process, and realizing large-tolerance assembly of large-size and dense-pitch area array packages (i.e., substrates) and circuit boards.

[0009] In addition, the circuit board assembly of the embodiment of the present application further includes a connector (also referred to as a gasket) supported between the substrate and the separator and / or between the circuit board and the separator. For example, a connector is supported between the substrate and the separator; or, a connector is supported between the circuit board and the separator; or, a connector is supported between the substrate and the separator, and a connector is also supported between the circuit board and the separator. Exemplarily, the connector is a metal column.

[0010] The functions of the connector include the following two: one is to control the minimum weld height, that is, to control the minimum weld height between the separator and the substrate (for example, the height of the welds at the two side edges and the middle position of the circuit board assembly), and the minimum weld height between the separator and the circuit board (for example, the height of the welds at the two side edges and the middle position of the circuit board assembly) to ensure that there will be no bridging during the welding process; the other is to adjust the shape of the double-sided solder ball module by adjusting the thickness of the connector at the two side edges and the center of the circuit board assembly, so that the deformation trend of the separator matches the deformation trend of the substrate (for example, the substrate), so that the separator is located in the center of the substrate and the circuit board, and the solder ball tolerance capability is higher.

[0011] In a possible implementation of the first aspect, the number of separators is one, the plurality of first welding structures and the plurality of second welding structures share one separator, and the separator is deformable under the welding temperature environment.

[0012] It can be understood that by setting a separator between the first welding structure and the second welding structure, the comprehensive large thermal deformation of the substrate and the circuit board can be decomposed into two parts: the thermal deformation of the first part is the thermal deformation between the separator and the substrate, and the thermal deformation of the second part is the thermal deformation between the separator and the circuit board, so as to reduce the welding process capability required for the welding structure of any one of the two parts, improve the tolerance capability of the solder balls of the first welding structure or the second welding structure, and thus improve the tolerance capability of the solder balls of the overall welding structure. In addition, the separator of the embodiment of the present application can be a rigid material or a flexible material, and the separator can be deformed in a welding temperature environment (for example, 200°C to 245°C). Thus, the separator has a certain flexibility at high temperature, and the comprehensive thermal deformation of the substrate and the circuit board is matched by connecting parts of different thicknesses. Exemplarily, the thermal expansion coefficient of the separator needs to be between the substrate and the circuit board, so as to have the effect of centering the gap between the separator and the circuit board, decomposing the comprehensive large thermal deformation of the coupling of the substrate and the circuit board into small thermal deformations of the upper and lower parts, and realizing the effect of large deformation welding.

[0013] In a possible implementation of the first aspect above, the number of the separators is at least two, and at least two first welding structures and two second welding structures are respectively provided on two sides of each separator.

[0014] It can be understood that the partition is divided, and each divided partition corresponds to a partition area. There are multiple first welding structures and multiple second welding structures in each partition area. After cutting, each partition area has a higher degree of freedom, and the thermal expansion coefficient of the partition itself has less influence on the comprehensive thermal deformation of the substrate and the circuit board, which is beneficial to improving the tolerance capability of the solder balls of the overall welding structure.

[0015] The embodiments of the present application do not limit the number of separators and the number of welding structures corresponding to each separator. By way of example, the number of separators includes four, or sixteen, and each separator area includes sixteen first welding structures and second welding structures, or four first welding structures and second welding structures.

[0016] In a possible implementation of the first aspect above, a plurality of connecting members are supported between the substrate and the partition and between the circuit board and the partition.

[0017] In a possible implementation of the first aspect, the connectors are distributed in the central area and / or the edge area of ​​the separator. That is, the connectors are distributed in the central area and the edge area of ​​the separator; or, the connectors are distributed in the central area of ​​the separator; or, the connectors are distributed in the edge area of ​​the separator.

[0018] In a possible implementation of the first aspect above, two ends of the connector supported between the substrate and the separator are respectively connected to the separator and the substrate; two ends of the connector supported between the circuit board and the separator are respectively connected to the separator and the circuit board.

[0019] In a possible implementation of the first aspect, there are multiple separators, two adjacent separators are arranged at intervals, and one separator is provided between each corresponding first welding structure and second welding structure.

[0020] In a possible implementation of the first aspect, the first welding structure and the second welding structure are respectively provided with connecting pieces. Exemplarily, the connecting piece is integrated with the first welding structure and the second welding structure.

[0021] In a possible implementation of the first aspect, two ends of the connector in the first welding structure are respectively connected to the separator and the substrate, and two ends of the connector in the second welding structure are respectively connected to the separator and the circuit board.

[0022] In a possible implementation of the first aspect described above, a plurality of connectors are supported between the substrate and the separator; wherein each connector is supported between the first welding structure and the separator, and the heights of at least some of the connectors between the substrate and the separator are unequal so as to conform to the lower surface of the substrate. By constructing connectors with a certain gradient difference on the separator plate, conformation to the lower surface of the substrate is achieved. That is, the embodiment of the present application constructs a corrective module (a connector with a certain gradient difference) on the separator to convert a large-scale deformation of the substrate (for example, including a chip) into a small-scale deformation or no deformation, thereby ensuring welding on a substrate with large thermal deformation. Exemplarily, the gradient difference of the connector in the embodiment of the present application is designed according to the deformation of the substrate.

[0023] In a possible implementation of the first aspect, the side of the separator close to the substrate is shaped like the lower surface of the substrate. Exemplarily, the upper surface of the separator is ground and preformed to construct the same deformation as the substrate. That is, the embodiment of the present application constructs an orthopedic module by processing the separator. Exemplarily, the lower side of the orthopedic module is a plane. That is, the lower side of the separator (the surface facing the circuit board) is a plane.

[0024] In a possible implementation of the first aspect above, a plurality of connectors are supported between the circuit board and the separator; wherein the connectors are distributed in an edge region of the separator, and two ends of the connectors are respectively connected to the separator and the circuit board.

[0025] In a possible implementation of the first aspect above, the first welding structure includes a first welding pad and a first solder ball provided on the substrate, and the second welding structure includes a second welding pad and a second solder ball provided on the circuit board; wherein the first welding pad is located on the substrate, the first solder ball is electrically connected to the first welding pad, and the second welding pad is located on the circuit board, and the second solder ball is electrically connected to the second welding pad.

[0026] In a possible implementation of the first aspect, the pitch of the plurality of first welding structures is less than 0.5 mm, and the pitch of the plurality of second welding structures is less than 0.5 mm. That is, the circuit board assembly of the embodiment of the present application is a close-pitch structure. However, the specific value of the pitch of the welding structure of the present application is not limited, and can also be other values, for example, greater than or equal to 0.5 mm.

[0027] In a possible implementation of the first aspect, the separator is provided with a plurality of through holes, an inner wall of each through hole is provided with a conductive medium, and each corresponding first welding structure is connected to the second welding structure through the conductive medium.

[0028] In a possible implementation of the first aspect, the substrate includes a package, and the package is a ball grid array (BGA) package.

[0029] In a possible implementation of the first aspect, the size of the package is 40 mm × 40 mm or larger. That is, the circuit board assembly of the embodiment of the present application is a large-size package structure. However, the size of the package of the present application is not limited, for example, it can be other sizes, such as 50 mm × 50 mm, or less than 40 mm × 40 mm.

[0030] A second aspect of the present application provides another circuit board assembly, which includes a substrate; a circuit board, with a gap between the substrate and the circuit board; a welding structure, which is located in the gap and conducts electricity between the substrate and the circuit board; wherein the welding structure includes a plurality of first welding structures and a plurality of second welding structures, the plurality of first welding structures and the plurality of second welding structures correspond one to one, and each corresponding first welding structure and second welding structure share a connecting member, and the connecting member connects the first welding structure and the second welding structure.

[0031] The embodiment of the present application uses a connector (e.g., a metal needle) to connect a first welding structure (e.g., a liquid solder ball, which becomes a solid solder ball after welding) and a second welding structure (e.g., a liquid solder ball, which becomes a solid solder ball after welding) to achieve the connection between the substrate and the circuit board, and improve the welding tolerance capability through the wetting force of the connector and the liquid solder ball. During the welding process, as the temperature rises, the substrate (e.g., with a chip) will undergo thermal deformation. When the solder ball reaches the liquidus and melts, the concave area of ​​the substrate will penetrate the liquid solder ball and support it on the circuit board. The upturned area of ​​the substrate will form an elongated solder joint due to the wettability of the liquid solder ball and the metal needle, which also prevents the welding structure from bridging and opening during the welding process.

[0032] In a possible implementation of the second aspect, the connecting member includes a metal needle.

[0033] In a possible implementation of the second aspect above, the first welding structure includes a first welding pad and a first solder ball provided on the substrate, and the second welding structure includes a second welding pad and a second solder ball provided on the circuit board; wherein the first welding pad is located on the substrate, the first solder ball is electrically connected to the first welding pad, and the second welding pad is located on the circuit board, and the second solder ball is electrically connected to the second welding pad.

[0034] In a possible implementation of the second aspect, the substrate includes a package, and the package is a ball grid array (BGA) package.

[0035] In a possible implementation of the second aspect, a size of the package is 40 mm×40 mm or larger.

[0036] The third aspect of the present application provides another circuit board assembly, which includes a substrate; a circuit board, a gap between the substrate and the circuit board; a welding structure, the welding structure is located in the gap and conducts the substrate and the circuit board; wherein the welding structure includes at least two layers of electroplating layers stacked. The embodiment of the present application uses the electroplating structure to perform multiple electroplating on the upper basic side to form a multi-layer electroplating layer, which can increase the amount of tin in the solder joint, increase the welding tolerance, achieve large tolerance welding, and prevent the welding structure from generating bridging tin and open welding problems during the welding process.

[0037] In a possible implementation of the third aspect above, the electroplating layer includes a first electroplating layer and a second electroplating layer, and the first electroplating layer and the second electroplating layer are spaced apart along the height direction; wherein, the outermost electroplating layer away from the substrate among the at least two stacked electroplating layers is the second electroplating layer, and the height direction is a direction perpendicular to the plane where the surface of the substrate is located.

[0038] In a possible implementation of the third aspect above, the welding structure further includes a barrier layer, and the barrier layer is disposed between the first electroplating layer and the second electroplating layer.

[0039] In a possible implementation of the third aspect, the material of the first electroplating layer includes Cu, the material of the second electroplating layer includes Sn / SnAg, and the material of the barrier layer includes Ni. The electroplated Cu acts as a gasket to control the minimum weld height and avoid bridging during the welding process.

[0040] In a possible implementation of the third aspect, the substrate includes a package, and the package is a ball grid array (BGA) package.

[0041] In a possible implementation of the third aspect above, a size of the package is 40 mm×40 mm or larger.

[0042] The fourth aspect of the present application provides another communication device, which includes the first aspect, the second aspect and the third aspect, and any one of the possible implementations of the first aspect, the second aspect and the third aspect, and the circuit board assembly is installed in the housing of the communication device. Exemplarily, a slot is provided in the housing of the communication device, and the circuit board in the circuit board assembly is plugged into the slot in the housing to achieve electrical connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic structural diagram of a welding structure of a circuit board assembly in some embodiments;

[0044] Figure 2 is a schematic diagram of the tolerance capability of the soldering structure of the circuit board assembly in some embodiments, wherein: Figure 2 (a) shows the tolerance capability of a single solder ball contact boundary. Figure 2 (b) is a schematic diagram showing the tolerance capability of the open solder boundary of a single solder ball;

[0045] Figure 3 The structure diagram of the welding structure of the circuit board assembly provided in the first embodiment of the present application is Figure 1 ;

[0046] Figure 4 is a schematic diagram showing the tolerance capability of the welding structure of the circuit board assembly provided in the first embodiment of the present application;

[0047] Figure 5 The structure diagram of the welding structure of the circuit board assembly provided in the first embodiment of the present application is Figure 2 ;

[0048] Figure 6 (a) to (c) are the process flow of the welding structure of the circuit board assembly provided in the first embodiment of the present application. Figure 1 ;

[0049] Figure 7 (a) to (c) are the process flow of the welding structure of the circuit board assembly provided in the first embodiment of the present application. Figure 2 ;

[0050] Figure 8 (a) and (b) are the process flow of the welding structure of the circuit board assembly provided in the first embodiment of the present application. Figure 3 ;

[0051] Fig. 9 The structure diagram of the welding structure of the circuit board assembly provided in the second embodiment of the present application is Figure 2 ;

[0052] Fig.10a The structure diagram of multiple separators of the welding structure of the circuit board assembly provided in the second embodiment of the present application is Figure 1 ;

[0053] Fig.10b The structure diagram of multiple separators of the welding structure of the circuit board assembly provided in the second embodiment of the present application is Figure 2 ;

[0054] Fig.11 The structure diagram of the welding structure of the circuit board assembly provided in the second embodiment of the present application is Figure 3 ;

[0055] Fig.12 The structure diagram of multiple separators of the welding structure of the circuit board assembly provided in the second embodiment of the present application is Figure 3 ;

[0056] Fig.13 (a) to (g) are process flow charts of the welding structure of the circuit board assembly provided in the second embodiment of the present application;

[0057] Fig.14 The structure diagram of the welding structure of the circuit board assembly provided in the third embodiment of the present application is Figure 1 ;

[0058] Fig.15 (a) to (d) are the process flow of the welding structure of the circuit board assembly provided in the third embodiment of the present application. Figure 1 ;

[0059] Fig.16 The structure diagram of the welding structure of the circuit board assembly provided in the third embodiment of the present application is Figure 2 ;

[0060] Fig.17 (a) to (d) are the process flow of the welding structure of the circuit board assembly provided in the third embodiment of the present application. Figure 2 ;

[0061] Fig.18 is a structural schematic diagram of a welding structure of a circuit board assembly provided in a fourth embodiment of the present application;

[0062] Fig.19 (a) to (h) are process flow charts of the welding structure of the circuit board assembly provided in the fourth embodiment of the present application;

[0063] Fig. 20 is a structural schematic diagram of a welding structure of a circuit board assembly provided in a fifth embodiment of the present application;

[0064] Fig.21 (a) to (i) are process flow charts of the welding structure of the circuit board assembly provided in the fifth embodiment of the present application. DETAILED DESCRIPTION

[0065] An embodiment of the present application provides a circuit board assembly including a substrate, a circuit board, and a welding structure, wherein the welding structure between the substrate and the circuit board is a double-sided solder ball structure, which replaces the traditional single solder ball welding structure between the substrate and the circuit board. The double-sided solder ball structure improves the welding tolerance capability of the welding structure and solves the problems of bridging and open welding caused by the combined large thermal deformation of the coupling of the substrate and the circuit board during the welding process of the circuit board assembly.

[0066] The circuit board assembly provided in the embodiment of the present application is applied to communication equipment, which may be, but is not limited to, ICT (Information Communication Technology, abbreviated as ICT) such as base stations, servers, routers, switches, supercomputers, AI devices, and data centers. The circuit board assembly can be understood as a board-level assembly architecture formed by assembling the packaging structure to a carrier.

[0067] Among them, the circuit board assembly of the embodiment of the present application includes an assembly structure formed by assembling any package or structural part in the form of BGA (Bail Grid Array, BGA) to a carrier (such as the circuit board described later). For example, the package and structural part in the form of BGA can also be a BGA socket. Among them, the size of the package includes 14mm×14mm, or large size (40mm×40mm and above, such as 40mm×40mm, 50mm×50mm) large deformation surface array package. The circuit board assembly of the embodiment of the present application can also be applied to the assembly of other large deformation welding devices, such as large size connectors, large deformation castle boards and LGA (LandGrid Array, grid array package) and other scenarios.

[0068] The present application embodiment takes a BGA package or structural member as an example for explanation. Figure 1 , Figure 1 A schematic diagram of the structure of a circuit board assembly is shown. Figure 1 As shown, the circuit board assembly includes a substrate 10 and a circuit board 20. Exemplarily, the substrate 10 and the circuit board 20 are arranged opposite to each other along the thickness direction of the circuit board assembly.

[0069] The substrate 10 can be understood as the package substrate in the above-mentioned package structure. The package substrate is a carrier for semiconductor chip packaging, which can provide electrical connection, protection, support, heat dissipation, assembly and other functions for the chip. The package structure can be formed by, for example, setting I / O (IN / OUT) output pins for electrical connection with the circuit board 20 on the back of the substrate 10 and packaging electronic devices such as chips on the front of the substrate 10.

[0070] In the embodiment of the present application, a packaging structure in the form of BGA packaging is used as an example for explanation. It can be understood that BGA is a surface mount package for multi-pin LSI (Large-scale integrated circuit) in which ball contacts are made in an array on the back of the substrate 10 as lead pins and components such as chips are assembled on the front of the substrate 10.

[0071] The circuit board 20 can be understood as the carrier mentioned above, which can carry the substrate 10 and be assembled with the substrate 10, thereby realizing electrical interconnection with the substrate 10. Exemplarily, the circuit board 20 is a printed circuit board (PCB).

[0072] Exemplarily, the substrate 10 and the circuit board 20 are assembled by welding. Figure 1As shown, a plurality of first solder balls 101 are arranged on the surface of the substrate 10 facing the circuit board 20, and a plurality of second solder balls 102 are arranged on the surface of the circuit board 20 facing the substrate 10, and the plurality of first solder balls 101 and the plurality of second solder balls 102 are arranged one by one. Exemplarily, the first solder balls 101 are the spherical contacts that can be used as lead pins as mentioned above.

[0073] Generally, when the substrate 10 and the circuit board 20 are welded and assembled, a first solder ball 101 and a second solder ball 102 are welded to form a solder ball structure (i.e., a single solder ball structure). However, at room temperature, the substrate 10 and the circuit board 20 may have a certain degree of warpage, and during the welding process of the substrate 10 and the circuit board 20, the warpage will change with the change of temperature. Figure 1 A schematic diagram of welding defects of a single solder ball structure during welding of a substrate 10 and a circuit board 20 is shown.

[0074] like Figure 1 As shown, it can be understood that due to the complexity of the packaging structure and the materials used, there are differences in thermal expansion coefficients between different materials. When the thermal expansion coefficients of different materials are mismatched, the substrate 10 and the circuit board 20 will produce thermal deformation.

[0075] For example, reference Figure 1 , the two side edges of the substrate 10 are along the height direction (such as Figure 1 The two side edges of the circuit board 20 are tilted upward along the height direction (as shown in the X direction) Figure 1 The X direction in the middle is shown) bent downward, so that the gap between the substrate 10 and the circuit board 20 is shown from the central area (as shown in the X direction) to the bottom. Figure 1 The dashed line C area) to the edge area (as shown Figure 1 The vertical height of the gap between the substrate 10 and the circuit board 20 (as shown by the middle dotted line D area) tends to gradually increase, that is, the vertical distance of the central area of ​​the gap between the substrate 10 and the circuit board 20 is the smallest, and the vertical distance of the edge area is the largest.

[0076] It should be noted that Figure 1 The thermal deformation structures of the substrate 10 and the circuit board 20 shown are not unique. For example, the edges of both sides of the substrate 10 are deformed along the height direction (eg Figure 1 The two side edges of the circuit board 10 are bent downward along the height direction (as shown in the X direction) Figure 1 Alternatively, the edges of the substrate 10 and the circuit board 20 are warped upward along the height direction (as shown in the X direction). Figure 1 The X direction in the figure shows the shape of the steel bar.

[0077] During the welding process of the substrate 10 and the circuit board 20, when the tolerance capacity of a single solder ball structure is insufficient, the quality risk of welding the substrate 10 and the circuit board 20 will increase sharply, and the difficulty of assembly will increase, especially in the welding defects of bridging and open soldering will occur at the same time. Among them, the tolerance capacity refers to the comprehensive deformation range of the substrate 10 and the circuit board 20 that the solder ball can allow in a single solder ball structure, and the value corresponds to the difference between the maximum weld height and the minimum weld height. If the solder ball tolerance capacity is exceeded, the welding structure will have bridging and open soldering.

[0078] Solder bridging can be understood as a welding defect in which two adjacent solder joints between the substrate 10 and the circuit board 20 are bridged together during the welding process, which is manifested as a short circuit in electrical function. Open soldering can be understood as a welding defect in which no effective solder joint is formed between the substrate 10 and the circuit board 20, which is manifested as an open circuit in electrical function. Figure 1 As shown, the central area of ​​the substrate 10 and the circuit board 20 (eg Figure 1 There is a tinning phenomenon in the edge area of ​​the substrate 10 and the circuit board 20 (as shown in the dotted line C area). Figure 1 There is open welding phenomenon (as shown in the dotted line D area).

[0079] The tolerance capability of the solder balls of a single solder ball structure between the substrate 10 and the circuit board 20 during the soldering process will be analyzed below.

[0080] Figure 2 A schematic diagram showing the tolerance capability analysis of a single solder ball structure is shown. Figure 2 (a) shows that the solder ball of a single solder ball structure is at the solder joint boundary. Figure 2 (b) shows that the solder ball of a single solder ball structure is at the open solder boundary. Figure 2 The middle dotted line G represents the upper surface of the circuit board 20, the dotted line F represents the lower surface of the substrate 10 when adjacent solder balls are at the soldering boundary, and the dotted line E represents the lower surface of the substrate 10 when the solder balls are at the soldering opening boundary.

[0081] like Figure 2 As shown in (a), when two adjacent solder balls of a single solder ball structure between the substrate 10 and the circuit board 20 are at the soldering boundary, the vertical height of the solder joint between the substrate 10 and the circuit board 20 reaches a minimum value (e.g. Figure 2 (as shown in the height Hmin in (a), that is, the minimum weld height is Hmin1.

[0082] like Figure 2 As shown in (b), when the solder ball of the single solder ball structure between the substrate 10 and the circuit board 20 is at the open soldering boundary, the vertical height of the solder joint between the substrate 10 and the circuit board 20 reaches a maximum value (as shown in FIG. Figure 2 (b) shows the height Hmax), that is, the maximum weld height is Hmax1.

[0083] Then, the tolerance capability of the solder ball of the single solder ball structure is ΔH1=Hmax1-Hmin1.

[0084] It can be seen that the tolerance capacity ΔH1 of the solder ball of a single solder ball structure is limited. As the chip size becomes larger and larger, the thermal deformation degree of the substrate is also increasing. The tolerance capacity ΔH1 of the solder ball of a single solder ball structure cannot meet the assembly requirements and welding quality of the circuit board assembly of the large deformation substrate.

[0085] Therefore, the embodiment of the present application introduces a new solder joint structure (the double-sided solder ball module, the correction module, the pin structure and the stacked solder joint structure described later) between the substrate and the circuit board, which improves the overall welding tolerance capability, can solve the welding defect problem (such as bridging and open soldering problems) caused by the mismatch of thermal expansion coefficients of the substrate 10 and the circuit board 20, meet the assembly requirements and welding quality of the circuit board assembly of the large deformation substrate, and ensure the high reliability of the circuit system of the circuit board assembly 100 during normal operation.

[0086] Double-sided solder ball module solution:

[0087] The specific structure of the circuit board assembly 100 including the double-sided solder ball module will be described below with reference to the accompanying drawings.

[0088] refer to Figure 3 , Figure 3 A schematic structural diagram of a circuit board assembly 100 using a double-sided solder ball module as a soldering structure provided in an embodiment of the present application is shown.

[0089] like Figure 3 As shown, the circuit board assembly 100 provided in the embodiment of the present application includes a substrate 10, a circuit board 20 and a welding structure. There is a gap between the substrate 10 and the circuit board 20, and the welding structure is located in the gap, and the welding structure is used to conduct the substrate 10 and the circuit board 20. The welding structure of the embodiment of the present application includes a plurality of first welding structures 1 and a plurality of second welding structures 2, and the plurality of first welding structures 1 and the plurality of second welding structures 2 correspond to each other one by one, that is, one first welding structure 1 and one second welding structure 2 are welded.

[0090] Exemplarily, the substrate 10 includes a package. In the embodiment of the present application, the package is a large-size, fine-pitch ball grid array (BGA) package, wherein the pitch of the plurality of first welding structures 1 is less than 0.5 mm, the pitch of the plurality of second welding structures 2 is less than 0.5 mm, and the size of the package is 40 mm×40 mm and above, for example, 40 mm×40 mm, 50 mm×50 mm.

[0091] For example, continue to refer to Figure 3Each first soldering structure 1 includes a first soldering pad 11 and a first soldering ball 12 provided on the substrate 10, and each second soldering structure 2 includes a second soldering pad 21 and a second soldering ball 22 provided on the circuit board 20. Each first soldering pad 11 is located on the back side of the substrate 10, and the plurality of first soldering pads 11 are arranged along the extension direction of the substrate 10 (such as Figure 3 Each first solder pad 11 is provided with a first solder ball 12, and the first solder ball 12 is electrically connected to the first solder pad 11. Each second solder pad 21 is located on the front side of the circuit board 20, and the plurality of second solder pads 21 are arranged along the extension direction of the circuit board 20 (as shown in the Y direction). Figure 3 The first solder balls 12 and the second solder balls 22 are arranged at intervals (as shown in the Y direction), and each second solder pad 21 may be provided with a second solder ball 22, and the second solder ball 22 is electrically connected to the second solder pad 21. It can be understood that the first solder ball 12 or the second solder ball 22 can be understood as a spherical contact distributed in the gap between the substrate 10 and the circuit board 20 when the substrate 10 and the circuit board 20 are assembled, that is, a welding material that can constitute the first welding structure 1 or the second welding structure 2.

[0092] Continue to refer Figure 3 ,, a separator 30 is provided between each corresponding first welding structure 1 and second welding structure 2 to separate the corresponding first welding structure 1 and second welding structure 2. For example, the separator 30 is formed by a PCB board. The separator 30 is provided with a plurality of through holes 31, and a conductive medium is provided on the inner wall of each through hole 31, and each corresponding first welding structure 1 and second welding structure 2 are connected through the conductive medium. Thus, the first welding structure 1, the second welding structure 2 and the separator 30 therebetween of the embodiment of the present application constitute a double-sided solder ball module of the circuit board assembly 100. It can also be understood that two solder ball structures are formed after the first welding structure 1 and the second welding structure 2 are welded, and the two solder ball structures are separated by the separator 30.

[0093] refer to Figure 3 , Figure 3 The number of separators 30 is shown to be one, and the plurality of first welding structures 1 and the plurality of second welding structures 2 share one separator 30. One separator 30 separates the gap between the substrate 10 and the circuit board 20 into a first gap A, and separates the gap between the substrate 10 and the circuit board 20 into a second gap B. The first gap A is provided with a plurality of first welding structures 1 distributed at intervals, and the second gap B is provided with a plurality of second welding structures 2 distributed at intervals, and the plurality of first welding structures 1 correspond to the plurality of second welding structures 2 one by one.

[0094] The embodiment of the present application constructs a double-sided solder ball module (including a first soldering structure 1, a second soldering structure 2, and a separator 30 therebetween) to separate the combined large thermal deformation of the substrate 10 (including a chip, for example) and the circuit board 20 (for example, a printed circuit board) into two small deformations, the upper and lower parts, thereby reducing the soldering process capability required for the single-sided solder joints, improving the overall soldering tolerance capability, and preventing the soldering and solder bridging phenomena in the soldering structure between the substrate 10 and the circuit board 20 during the soldering process, thereby realizing large-size and fine-pitch surface array BGA packages (i.e., substrates) and circuit boards. Large tolerance assembly.

[0095] Exemplarily, the separator 30 is deformable under a welding temperature environment, and the welding temperature includes 200°C to 245°C, that is, the separator 30 of the embodiment of the present application can be rigid or flexible, and the separator 30 has a certain flexibility at high temperature, and the thermal expansion coefficient of the separator 30 needs to be between the substrate 10 and the circuit board 20, so as to achieve the effect of centering the separator 30 in the gap between the substrate 10 and the circuit board 20, and decomposing the comprehensive large thermal deformation of the coupling between the substrate 10 and the circuit board 20 into small thermal deformations of the upper and lower parts (that is, the first part is the thermal deformation between the separator 30 and the substrate 10, and the second part is the thermal deformation between the separator 30 and the circuit board 20), thereby achieving the effect of large deformation welding.

[0096] Continue to refer Figure 3 The double-sided solder ball module provided in the embodiment of the present application further includes a plurality of connectors 40, such as Figure 3 As shown in the figure, a plurality of connectors 40 are supported between the substrate 10 and the separator 30 and between the circuit board 20 and the separator 30. In some possible implementations, the connector 40 is supported between the substrate 10 and the separator 30; or, the connector 40 is supported between the circuit board 20 and the separator 30. Exemplarily, the connector 40 is fixed between the substrate 10 and the separator 30 and between the circuit board 20 and the separator 30 by welding or electroplating.

[0097] The connecting member 40 provided in the embodiment of the present application mainly has the following two functions:

[0098] First, it is understandable that Figure 1 As shown in the dotted line C area, when the vertical distance between the substrate 10 and the circuit board 20 is too small, adjacent solder joints may be bridging under normal circumstances. Therefore, by providing a connector 40 between the substrate 10 and the separator 30 and between the circuit board 20 and the separator 30, the minimum support height at which soldering defects such as bridging do not occur between the substrate 10 and the circuit board 20 can be effectively guaranteed through the supporting effect of the connector 40, and the comprehensive large thermal deformation of the substrate 10 and the circuit board 20 during the soldering process can be prevented from being aggravated with the change of temperature, resulting in bridging between two adjacent solder joints.

[0099] In other words, the connector 40 can control the minimum weld height between the substrate 10 and the circuit board 20, that is, control the minimum weld height between the separator 30 and the substrate 10 (for example, the height of the weld at the two side edges and the middle position of the circuit board assembly), and the minimum weld height between the separator 30 and the circuit board 20 (for example, the height of the weld at the two side edges and the middle position of the circuit board assembly), to ensure that bridging does not occur during the welding process.

[0100] Second, if Figure 1 As shown in the dotted line D area, when the vertical distance between the substrate 10 and the circuit board 20 is too large, the adjacent solder joints may open under normal circumstances. Therefore, in addition to setting the separator 30 between the first welding structure 1 and the second welding structure 2 on the substrate 10 and the circuit board 20, the embodiment of the present application also adjusts the vertical height of the connector 40 in different areas (such as the central area or the edge area) of the substrate 10 and the circuit board 20, and adjusts the shape of the separator 30 so that the deformation trend of the separator 30 that is aggravated by temperature changes during the welding process matches the deformation trend of the substrate 10, so that the separator 30 can be located in the middle of the gap between the substrate 10 and the circuit board 20, thereby improving the tolerance of the solder ball.

[0101] In other words, by adjusting the thickness of the connectors at the edges and center of both sides of the circuit board assembly 100 to adjust the shape of the double-sided solder ball module, the deformation trend of the separator 30 is matched with the deformation trend of the substrate (such as the substrate 10), so that the separator 30 is located in the exact center of the substrate 10 and the circuit board 20, and the solder ball tolerance capability is higher.

[0102] In this embodiment, the shape of the connecting member 40 has various possibilities. Figure 3 The cross-sectional shape of the connector 40 (shown in the X direction) includes a combination of one or more of a U-shape, a rectangle, and an arc. The height direction of the connector 40 is perpendicular to the plane where the surface of the circuit board 20 is located. For example, the connector 40 can be cylindrical (such as Figure 3 As shown in FIG. 1 ), or the connecting member 40 may be U-shaped, or the connecting member 40 may be truncated cone-shaped, or the connecting member 40 may be spherical. It should be understood that the shape of the connecting member 40 is not limited to the aforementioned shapes, and any geometric shape that can play a supporting role and can be manufactured within the processable range can be used as the connecting member 40, and the embodiments of the present application do not limit this.

[0103] In some possible embodiments, the type of the connector 40 may be an electronic component. For example, the electronic component may be a resistor or a capacitor. Alternatively, in some possible embodiments, the type of the connector 40 may be a gasket. For example, the gasket may be made of one or more metal materials, such as a copper alloy. Alternatively, the gasket may also be made of materials such as ceramics and plastics.

[0104] It should be noted that the possible types of the connector 40 are not limited to the above description, and it can be any object with a high melting point that will not melt during the welding process and a supporting function, and the embodiments of the present application do not limit this.

[0105] In addition, the height of each connector 40 has various possibilities for variation, and the actual height of the connector 40 is selected to ensure that adjacent solder joints do not become bridging and to avoid the problem of open solder joints that fail to form effective solder joints. The height of each connector 40 can be designed according to actual conditions under the aforementioned conditions, which has strong flexibility and a wide range of applications.

[0106] The following will be combined with the attached Figure 4 and Figure 5 The tolerance capability of the solder balls of the soldering structure of the double-sided solder ball module provided in the embodiment of the present application is described.

[0107] Please refer to Figure 4 , Figure 4 The figure shows the tolerance analysis diagram of the double solder balls in the double-sided solder ball module. The dotted line G represents the plane where the circuit board 20 is located, the dotted line F represents the upper surface of the substrate 10 when the adjacent solder balls of the first soldering structure 1 and the second soldering structure 2 are at the soldering boundary, and the dotted line E represents the upper surface of the substrate 10 when the solder balls of the first soldering structure 1 and the second soldering structure 2 are at the soldering boundary.

[0108] like Figure 4 As shown in (a), when the adjacent first solder ball 12 and the second solder ball 22 of the double solder ball welding structure between the substrate 10 and the circuit board 20 are at the soldering boundary, the vertical height of the solder joint between the substrate 10 and the circuit board 20 reaches the minimum value (as shown in FIG. Figure 4 (a) shows the height Hmin2), that is, the minimum weld height is Hmin2.

[0109] like Figure 4 As shown in (b), when the first solder ball 12 and the second solder ball 22 of the double solder ball welding structure between the substrate 10 and the circuit board 20 are at the open soldering boundary, the vertical height of the weld between the substrate 10 and the circuit board 20 reaches a maximum value (e.g. Figure 4 The height Hmax in (b) is shown), that is, the maximum weld height is Hmax. Then, the tolerance capability of the double solder balls in the double-sided solder ball module is ΔH2=Hmax2-Hmin2.

[0110] Combination Figure 4 As can be seen from (a) and (b), the tolerance capability ΔH2 of the double solder balls in the double-sided solder ball module provided in the embodiment of the present application has been greatly improved, which is approximately twice the tolerance capability ΔH1 of the single solder ball, that is, ΔH2≈2ΔH1.

[0111] Please refer to Figure 5 , Figure 5 The schematic diagram of the M-shaped welding structure of the thermal deformation structure of the substrate 10 and the circuit board 20 is shown. The central area of ​​the substrate 10 is concave downward, and the edge area shows a trend of first bending upward and then bending downward, with the largest deformation degree. The central area of ​​the circuit board 20 is also concave downward, and the edge area is warped upward, and the deformation degree of the circuit board 20 is smaller than that of the substrate 10. As a result, the vertical height of the gap between the substrate 10 and the circuit board 20 shows an M-shaped change trend, that is, the spacing in the central area is small, and the spacing in the edge area is first large and then small.

[0112] It should be noted that the deformation of the substrate 10 and the circuit board 20 is not limited to Figure 5 The types shown in the figure may also be other types of deformation, such as W-shaped deformation, twisted deformation, etc. Figure 5 The M-shaped deformation shown is for illustration purposes only.

[0113] Based on the above description and combined Figure 5 It can be seen that the double-sided solder ball module provided in the embodiment of the present application is provided with a separator 30 for separating the substrate 10 and the circuit board 20 between the substrate 10 and the circuit board 20 for comprehensive thermal deformation, so as to separate the large deformation into small deformation between the substrate 10 and the separator 30 and small deformation between the circuit board 20 and the separator 30.

[0114] At the same time, the double-sided solder ball module provided in the embodiment of the present application also sets connectors 40 of different vertical heights between the substrate 10 and the separator 30 and between the circuit board 20 and the separator 30 according to the different deformation trends of the substrate 10 and the substrate 20, so that the deformation trend of the separator 30 aggravated by temperature changes during the welding process matches the deformation trend of the substrate 10, so that the separator can be located in the middle position of the gap between the substrate 10 and the circuit board 20, thereby improving the tolerance capability of the solder ball and preventing the problem of tin connection and open soldering caused by the increase in the degree of thermal deformation of the chip as the chip size increases during the welding process, thereby realizing the large tolerance assembly of large-size and dense-pitch surface array BGA package (i.e., substrate) and circuit board.

[0115] Exemplarily, the connecting members 40 are respectively distributed in the central area and the edge area of ​​the separator 30, but the present application is not limited to this. The connecting members 40 can also be arranged in other areas of the separator 30. For example, the connecting members 40 can also be arranged separately in the central area or the edge area of ​​the separator 30, or in the first welding structure 1 and the second welding structure 2.

[0116] In the embodiment of the present application, before the substrate 10 and the circuit board 20 are welded, the position of the first solder ball 12 or the second solder ball 22 may include the following four situations:

[0117] (1) The first solder ball 12 and the second solder ball 22 are disposed on the upper and lower sides of the separator 30;

[0118] (2) The first solder ball 12 is disposed on the back side of the substrate 10, and the second solder ball 22 is disposed on the lower side of the separator 30;

[0119] (3) The first solder ball 12 is disposed on the upper side of the separator 30 , and the second solder ball 22 is disposed on the front side of the circuit board 20 ;

[0120] (3) The first solder balls 12 are disposed on the back side of the substrate 10 , and the second solder balls 22 are disposed on the front side of the circuit board 20 .

[0121] In this embodiment, the soldering process of the circuit board assembly 100 is described by taking the case where the first solder ball 12 and the second solder ball 22 are disposed on the upper and lower sides of the separator 30 as an example.

[0122] The following will be combined Figures 6 to 8 , the welding process flow of the circuit board assembly 100 when the number of the separator 30 in the embodiment of the present application is one is illustrated as follows:

[0123] Example 1:

[0124] like Figure 6 As shown, the manufacturing method of the circuit board assembly 100 provided in the embodiment of the present application specifically includes the following steps:

[0125] S1: Provide welding structure.

[0126] refer to Figure 6 In (a), a double-sided solder ball module in which the first solder ball 12 and the second solder ball 22 are disposed on the upper and lower sides of the separator 30 is prepared and waits for soldering. Connectors 40 are disposed on both sides of the substrate 10 .

[0127] S2: welding the welding structure to the substrate 10 .

[0128] refer to Figure 6 In (b), the double-sided solder ball module (ie, the soldering structure) is then soldered to the substrate 10 side, and the vertical height of the first gap A (ie, the height of the solder joint) is adjusted through the connector 40 on the substrate 10 side.

[0129] S3: welding the welding structure to the circuit board 20 .

[0130] refer to Figure 6 In (c), the soldered substrate 10 and the double-sided solder ball module are invertedly soldered to the side of the circuit board 20 provided with the connector 40, and the substrate 10 and the circuit board 20 are soldered and assembled to form a circuit board assembly 100 with a double-sided solder ball module.

[0131] Example 2:

[0132] In Example 1, the double-sided solder ball module is first soldered to the substrate 10 side, while in Example 2, the double-sided solder ball module is first soldered to the circuit board 20 side. Figure 7 In (a), connectors 40 are provided on both sides of the circuit board 20; Figure 7 In (b), the double-sided solder ball module (ie, the soldering structure) is then soldered to the side of the circuit board 20, and the vertical height of the second gap B (ie, the height of the weld) is adjusted by the connector 40 on the side of the circuit board 20; Figure 7 In (c), the soldered circuit board 20 and the double-sided solder ball module are then invertedly soldered to the side of the substrate 20 provided with the connector 40, and the substrate 10 and the circuit board 20 are soldered and assembled to form a circuit board assembly 100 with a double-sided solder ball module.

[0133] Example 3:

[0134] The difference between the welding process flow of Example 1 and Example 2 is that Example 3 first mounts the substrate 10, the double-sided solder ball module and the circuit board 20 together. Figure 8 In (a), connectors 40 are provided on both sides of the substrate 10, and connectors 40 are provided on both sides of the circuit board 20; Figure 8 In (b), the double-sided solder ball module (i.e., the welding structure), the substrate 10 provided with the connector 40, and the circuit board 20 provided with the connector 40 are mounted together; then the mounted double-sided solder ball module, the substrate 10, and the circuit board 20 are furnace-welded at one time, and the substrate 10 and the circuit board 20 are welded and assembled to form a circuit board assembly 100 with a double-sided solder ball module.

[0135] In the above embodiment, the number of the separator 30 is one (eg Figure 3 As shown), but the present application does not limit the number of separators 30. In some possible implementations, refer to Fig. 9 , the number of separators 30 of the welding structure provided in the embodiment of the present application is at least two. This is equivalent to, Fig. 9 The embodiment shown is to Figure 3 In the embodiment shown, the double-sided solder ball module is divided by a separator, and the size and number of the divisions are not limited.

[0136] in, Fig. 9 Two separators are shown in the figure as an example. Accordingly, the circuit board assembly 100 has two welding areas. Fig. 9 The separator 30 on the left side corresponds to a welding area. Fig. 9 The separator 30 on the middle right side corresponds to another welding area.

[0137] like Fig. 9As shown, three first welding structures 1 and three second welding structures 2 are respectively provided on both sides of each separator 30. In addition, a plurality of connectors 40 are supported between the substrate 10 and the separator 30, and a plurality of connectors 40 are supported between the circuit board 20 and the separator 30. After the segmentation is completed, the minimum weld height of each welding area of ​​the circuit board assembly is controlled by the connector 40 to avoid solder joint caused by too low weld height.

[0138] For example, Fig. 9 As shown in the figure, two separators 30 are symmetrically arranged, and a connector 40 is distributed in the edge area of ​​each separator 30. The two ends of the connector 40 supported between the substrate 10 and the separator 30 are connected to the separator 30 and the substrate 10 respectively, and the two ends of the connector 40 supported between the circuit board 20 and the separator 30 are connected to the separator 30 and the circuit board 20 respectively, so that the deformation trend of the separator 30 aggravated by temperature change during welding matches the deformation trend of the substrate 10, so that the separator 30 can be located in the middle of the gap between the substrate 10 and the circuit board 20, improve the tolerance of the solder ball, prevent the soldering structure from causing the problem of bridging and desoldering due to the increase in the degree of thermal deformation of the chip as the chip size increases during welding, and realize the large tolerance assembly of the large-size and fine-pitch surface array BGA package (i.e., the substrate 10) and the circuit board 20.

[0139] In some possible implementations, a connector (not shown) is distributed in the central area of ​​the separator 30, so that the gap between the substrate 10 and the circuit board 20 always maintains a certain vertical distance, which can prevent the comprehensive thermal deformation of the substrate 10 and the circuit board 20 from increasing with the change of temperature during welding, resulting in the phenomenon of bridging between two adjacent solder joints. That is, the distribution of the connector in the central area of ​​the separator 30 can control the minimum weld height and avoid bridging caused by too low weld height.

[0140] It should be noted that the number of separators 30 in the embodiment of the present application is not limited to two. In other embodiments, the number of separators 30 may be three or more. Accordingly, the circuit board assembly 100 has three or more welding areas. In other words, the number of welding areas of the circuit board assembly 100 corresponds to the number of separators 30.

[0141] For example, refer to Fig.10a The number of the separators 30 is four, and sixteen first welding structures 1 and second welding structures 2 are arranged on both sides of each separator 30. Fig.10a FIG. 1 shows that the first solder ball 12 of the first solder structure 1 is provided on one side of the separator 30 corresponding to the substrate 10.

[0142] For example, refer to Fig.10bThe number of the separators 30 may also be sixteen, and four first welding structures 1 and second welding structures 2 are provided on both sides of each separator 30 . Fig.10b It is also shown in FIG. 1 that the first solder ball 12 of the first solder structure 1 is provided on one side of the separator 30 corresponding to the substrate 10 .

[0143] It is understandable that the above Figures 9 to 10b The numbers of the first welding structures 1 and the second welding structures 2 on both sides of each separator 30 shown are not limited thereto, and may be other numbers, such as four, five, six, eight, etc.

[0144] It can be understood that the size of the separator 30 in the embodiment of the present application only needs to be reasonably distributed between the substrate 10 and the circuit board 20. In other words, the sizes of the multiple separators 30 can be the same or different, and can be selected according to actual conditions, and the embodiment of the present application does not impose strict restrictions on this.

[0145] In some possible implementations, reference Fig.11 and Fig.12 The welding structure provided in the embodiment of the present application has a plurality of separators 30 , and two adjacent separators 30 are arranged at intervals, and a separator 30 is provided between each corresponding first welding structure 1 and second welding structure 2 .

[0146] For example, Fig.11 and Fig.12 As shown in FIG. 1 , a first welding structure 1 and a second welding structure 2 are provided on the upper and lower sides of each separator 30. That is, Fig.11 and Fig.12 Shown is the smallest segmentation unit.

[0147] In the smallest division unit of the circuit board assembly 100, a connector 40 is respectively provided in the first welding structure 1 and the second welding structure 2. The two ends of the connector 40 in the first welding structure 1 are respectively connected to the separator 30 and the substrate 10, and the two ends of the connector 40 in the second welding structure 2 are respectively connected to the separator 30 and the circuit board 20. That is, in this embodiment, the connector 40 is located in the first solder ball 12 and the second solder ball 22.

[0148] It can be understood that when the number of the partitions 30 is small (eg Fig. 9 10), or when the partition size of the partition 30 is large (eg Fig. 9 ), the separator 30 needs to be connected to the substrate 10 and the circuit board 20 through the connector 40 to adjust the comprehensive thermal deformation of the substrate 10 and the circuit board 20. Fig.10b , Fig.11 , Fig.12As shown), or when the partition size of the partition 30 is small (for example Fig.11 and Fig.12 As shown in the figure, the connector 40 is only used to ensure that the spacing between the substrate 10 and the circuit board 20 and the separator 30 is not too small to cause the bridging phenomenon. The comprehensive thermal deformation of the substrate 10 and the circuit board 20 is matched by the solder ball buoyancy of the first solder ball 12 and the second solder ball 22 to achieve large tolerance welding.

[0149] In other words, when the partition size of the partition 30 is smaller, the degree of freedom of each partition 30 is higher after the segmentation is completed, and the thermal expansion coefficient of the partition 30 itself has a smaller impact on the combined thermal deformation of the substrate 10 and the circuit board 20, which is beneficial to improving the tolerance capability of the solder balls of the overall welding structure and ensuring the welding quality of the substrate 10 and the circuit board 20.

[0150] The following will be combined Fig.13 , the welding process of the circuit board assembly 100 is described as follows when the size of the separator 30 of the embodiment of the present application is the smallest separator unit, that is, each separator 30 has a first welding structure 1 and a second welding structure 2 on the upper and lower sides:

[0151] refer to Fig.13 In (a), a whole undivided separator 30 is first provided, and a plurality of through holes 31 are formed in the separator 30. A conductive medium is formed on the inner wall of each through hole 31 for conducting with the corresponding first welding structure 1 and the second welding structure 2 through the conductive medium.

[0152] refer to Fig.13 In (b), balls are then planted on both sides of the entire separator 30, that is, a plurality of first solder balls 12 and a plurality of second solder balls 22 are respectively arranged on the upper and lower sides of the entire separator 30, one first solder ball 12 corresponds to one second solder ball 22, and each first welding structure 1 and each corresponding second welding structure 2 are connected through the conductive medium in the through hole 31 on the separator 30.

[0153] refer to Fig.13 In (c), the entire separator 30 after ball implantation is then composited onto the intermediate member 50 , that is, the intermediate member 50 and the entire separator 30 are composited via the second solder ball 22 .

[0154] refer to Fig.13 In (d), the entire separator 30 is then divided into a plurality of separators 30, so that a first welding structure 1 and a second welding structure 2 are provided on the upper and lower sides of each of the divided separators 30. Exemplarily, the entire separator 30 is divided into a plurality of separators 30 using a laser cutting process.

[0155] refer to Fig.13In (e), one side of the uncompounded intermediate member 50 of the plurality of separators 30 with double-sided ball planting (eg Fig.13 The first solder ball 12 is located on the side (e) and then inverted and soldered to the substrate 10. The substrate 10 is provided with a first solder pad 11 ( Fig.13 (not shown), the first solder ball 12 is soldered to the first solder pad 11 on the substrate 10 .

[0156] refer to Fig.13 In (f), the intermediate member 50 combined with the plurality of separators 30 via the second solder balls 22 is removed.

[0157] refer to Fig.13 In step (g), the substrate 10 and the plurality of separators 30 welded on the back are finally inverted and welded to the circuit board 20. The circuit board 20 is provided with a second soldering pad 21 ( Fig.13 (not shown), the second solder ball 22 is soldered to the second solder pad 2 on the circuit board 20. Thus, the substrate 10 and the circuit board 20 are soldered and assembled to form a circuit board assembly 100 with a double-sided solder ball module.

[0158] It should be noted that Fig.13 There is no connecting part 40 set in the first solder ball 12 and the second solder ball 22 on the upper and lower sides of each separator 30 shown. Since the freedom of each separator 30 under the minimum separation unit is higher, the thermal expansion coefficient of the separator 30 itself has a smaller impact on the combined thermal deformation of the substrate 10 and the circuit board 20. Therefore, a connecting part 40 is not set for each solder ball, which can reduce costs.

[0159] For example, in some embodiments, the connector 40 is provided in part of the first solder ball 12, and the connector 40 is not provided in part of the first solder ball 12; or, in some embodiments, the connector 40 is provided in part of the second solder ball 22, and the connector 40 is not provided in part of the second solder ball 22; or, in some embodiments, the connector 40 is provided in part of the first solder ball 12, and the connector 40 is not provided in part of the first solder ball 12, the connector 40 is provided in part of the second solder ball 22, and the connector 40 is not provided in part of the second solder ball 22.

[0160] Exemplarily, during the soldering process, a plurality of spacers 30 may be disposed in the middle of the gap between the substrate 10 and the circuit board 20 to improve the tolerance of the solder balls and prevent the soldering structure from causing solder joints to open due to the increase in thermal deformation of the chip as the chip size increases during the soldering process, thereby achieving a large-tolerance assembly of a large-size, fine-pitch surface array BGA package (i.e., the substrate 10) and the circuit board 20.

[0161] In summary, by adopting the double-sided solder ball module welding structure solution, during the welding process of the circuit board assembly 100, the high-temperature deformation of the double-sided solder ball module divides the large comprehensive deformation into two small deformations in the upper and lower parts, and the large tolerance welding is achieved through the tolerance capacity of the upper and lower solder balls (the first solder ball 12 and the second solder ball 22), thereby solving the problems of bridging and open soldering caused by deformation during the welding process.

[0162] Orthopedic module solution:

[0163] The specific structure of the circuit board assembly 100 including the orthopedic module will be described below with reference to the accompanying drawings.

[0164] This implementation case transforms the large-scale deformation of the chip into small-scale deformation or no deformation by constructing a correction module, thereby ensuring the welding of the large thermal deformation BGA on the board.

[0165] refer to Fig.14 , Fig.14 The structure of the circuit board assembly 100 provided in the embodiment of the present application with the orthopedic module as the welding structure is shown. Figure 1 .

[0166] like Fig.14 As shown, a circuit board assembly 10 provided in an embodiment of the present application includes a substrate 10, a circuit board 20, a separator 30, a first welding structure 1 and a second welding structure 2 located on the upper and lower sides of the separator 30, and a plurality of connectors 40 supported between the substrate 10 and the separator 30.

[0167] Specifically, each of the multiple connectors 40 located in the gap (i.e., the first gap A) between the substrate 10 and the separator 30 is supported between the first solder ball 12 of the first solder structure 1 and the separator 30, and each connector 40 is connected to the second solder ball 22 of the second solder structure 2 through the conductive medium in the through hole 31 on the separator 30. The heights of at least some of the connectors 40 located between the substrate 10 and the separator 30 are unequal to conform to the lower surface of the substrate 10 (i.e., the back of the substrate 10 described above). Thus, the orthopedic module of the circuit board assembly 100 of the embodiment of the present application includes the first solder ball 12, the second solder ball 11, multiple connectors 40 of unequal heights, and the separator 30.

[0168] By constructing a correction module, the thermal deformation of the substrate 10 side is absorbed, and the large-scale deformation of the substrate 10 (for example, including the chip) is converted into a small-scale deformation or no deformation, thereby ensuring the welding of the BGA with large thermal deformation on the board.

[0169] For example, Fig.14As shown, the number of the separator 30 is one, the substrate 10 has a deformation trend of a concave center area and an upward warping edge area, and the height change trend of the connecting member 40 located between the substrate 10 and the separator 30 ( Fig.14 The deformation trend of the substrate 10 is similar to that of the middle curve C. That is, the plurality of connectors 40 as a whole also have a tendency that the central region is concave downward and the edge region is warped upward.

[0170] Understandable, reference Fig.14 The circuit board assembly 100 of the embodiment of the present application is to construct a connector 40 on the separator 30 with the same height change trend as the deformation trend of the substrate 10, so as to transform the large-scale deformation of the chip (i.e., the substrate 10) into a small-scale deformation or no deformation on the back side of the separator 30 (i.e., the side close to the circuit board 20). For example, Fig.14 As shown in FIG. 1 , the back side of the separator 30 is not deformed, thereby preventing the solder joint from opening due to the increase in chip thermal deformation as the chip size increases during the soldering process.

[0171] It should be noted that the deformation trend of the substrate 10 is not limited, and other types of deformation trends may also be possible, such as the substrate 10 being Figure 5 The M-shaped deformation trend shown, or the deformation trend of the substrate 10 with the center area warping upward and the edge area concave downward. Before welding, the deformation trend of the substrate 10 can be obtained by simulation, so that the height deformation trend of the connecting member 40 located between the substrate 10 and the separator 30 is set accordingly to imitate the lower surface of the substrate 10.

[0172] Continue to refer Fig.14 A plurality of connectors 40 are distributed between the circuit board 20 and the partition 30 (ie, the second gap B). Fig.14 It is shown that two connectors 40 are spaced apart and distributed in the edge area of ​​the separator 30, and the two ends of each connector 40 are respectively connected to the separator 30 and the circuit board 20. In this embodiment, the function of the connector 40 between the circuit board 20 and the separator 30 is the same as that of the connector 40 at the corresponding position in the above-mentioned double-sided solder ball module solution, and the above description can be referred to, and no further description is given here.

[0173] In addition, the number of the separators 30 in the embodiment of the present application is not limited to one, and may also be the arrangement form of the separators 30 in the above-mentioned double-sided solder ball module solution, that is, dividing the entire separator into multiple separators.

[0174] The following will be combined Fig.15 ,right Fig.14 The soldering process of the circuit board assembly 100 is illustrated as an example:

[0175] refer to Fig.15In (a), first, a side of the entire separator 30 close to the substrate 10 is provided with a deformation trend (such as Fig.15 A plurality of connectors 40 of different heights are provided in a similar shape to that shown in (b) in the figure, and tin is sprayed on one end of the connector 40 facing the substrate 10. As described above, the deformation trend of the substrate 10 can be obtained by simulation, so that the height deformation trend of the connector 40 located between the substrate 10 and the separator 30 is set accordingly. A substrate 10 provided with a first welding structure (including a first solder ball 12 and a first solder pad 11) is provided. Then, the separator 30 is mounted on the back side of the substrate 10. Among them, the connector 40 in the edge area of ​​the separator 30 is mounted on the first solder ball 12 on the substrate 10.

[0176] refer to Fig.15 In (b), the mounted separator 30 is then furnace-welded together with the substrate 10. The substrate 10 deforms as the welding temperature changes. The multiple connectors 40 on the separator 30 are welded to the multiple first solder balls 12 on the back of the substrate 10 in a one-to-one correspondence.

[0177] refer to Fig.15 In (c), balls are then planted on a side of the separator 30 away from the substrate 10 , that is, a plurality of second solder balls 22 corresponding to the plurality of first solder balls 12 are arranged one by one.

[0178] refer to Fig.15 In (d), the spacer 30 after ball implantation is inverted and welded to the circuit board 20 to make the substrate 10 and the circuit board 20 conductive. Thus, the substrate 10 and the circuit board 20 are welded and assembled to form a circuit board assembly 100 with a correction module.

[0179] For example, the plurality of connectors 40 with different heights on the separator 30 include metal pillars, which can be implemented by electroplating, mounting or pillar planting technology. In addition, the present application does not specifically limit the height variation trend (or gradient) of the plurality of connectors 40. The height variation trend of the plurality of connectors 40 can be one, two or more. The arrangement of the plurality of connectors 40 can be to cover the entire separator 30 area (such as Fig.14 ), it can also be arranged selectively.

[0180] The orthopedic module of the embodiment of the present application is not limited to being realized by constructing a connector 40 with a certain gradient difference on the separator 30, but can also be realized by processing the separator 30 to construct the same deformation as the substrate.

[0181] refer to Fig.16 , Fig.16 A schematic structural diagram of a circuit board assembly 100 in which the orthopedic module (formed by processing the separator 30 ) provided in an embodiment of the present application is used as a welding structure is shown.

[0182] like Fig.16 As shown, a circuit board assembly 10 provided in an embodiment of the present application includes a substrate 10, a circuit board 20, a separator 30, and a first welding structure 1 and a second welding structure 2 located at the upper and lower sides of the separator 30. In the embodiment of the present application, the specific structure and connection form of the first welding structure 1 and the second welding structure 2 are the same as the specific structure and connection form of the first welding structure 1 and the second welding structure 2 in the double-sided solder ball module, which will not be repeated here.

[0183] The side of the separator 30 close to the substrate 10 is shaped similarly to the lower surface of the substrate 10 (ie, the back surface of the substrate 10 mentioned above).

[0184] For example, Fig.16 As shown, there is one separator 30, and the substrate 10 has a deformation trend of being concave in the central area and warping in the edge area. The change trend of the outer surface of the separator 30 on the side close to the substrate 10 is similar to the deformation trend of the substrate 10, that is, the outer surface of the separator 30 on the side close to the substrate 10 also shows a deformation trend of being concave in the central area and warping in the edge area.

[0185] Understandable, reference Fig.16 The circuit board assembly 100 of the embodiment of the present application is to construct the same change trend as the substrate 10 on the side of the separator 30 close to the substrate 10, so as to transform the large-scale deformation of the chip (i.e., the substrate 10) into a small-scale deformation or no deformation on the back side of the separator 30 (i.e., the side close to the circuit board 20). For example, Fig.16 As shown in FIG. 1 , the back side of the separator 30 is not deformed, thereby preventing the solder joint from opening due to the increase in chip thermal deformation as the chip size increases during the soldering process.

[0186] It should also be noted that the deformation trend of the substrate 10 is not limited, and other types of deformation trends may also be possible, such as the substrate 10 being Figure 5 The M-shaped deformation trend shown, or the deformation trend of the substrate 10 with the center area warping upward and the edge area concave downward. Before welding, the deformation trend of the substrate 10 can be obtained by simulation, so that the side of the separator 30 close to the substrate 10 is processed accordingly to imitate the lower surface of the substrate 10.

[0187] The following will be combined Fig.17 ,right Fig.16 The soldering process of the circuit board assembly 100 is illustrated as an example:

[0188] refer to Fig.17 In (a), a whole separator 30 is first provided, and the outer surface of the separator 30 close to the substrate 10 is in a state of deformation tendency (such as Fig.17The separator 30 is shaped like the one shown in (b) in FIG. 1 , and tin is sprayed on the shaped surface of the separator 30. A substrate 10 having a first solder structure (including a first solder ball 12 and a first solder pad 11) is provided. Then, the separator 30 is attached to the back side of the substrate 10.

[0189] Test Fig.17 In (b), the mounted separator 30 is then soldered together with the substrate 10 in a furnace. The substrate 10 deforms as the soldering temperature changes, and the separator 30 is soldered to the plurality of first solder balls 12 on the back of the substrate 10 .

[0190] refer to Fig.17 In (c), balls are then planted on a side of the separator 30 away from the substrate 10 , that is, a plurality of first solder balls 1 corresponding to the plurality of first solder balls 12 are arranged one by one.

[0191] refer to Fig.17 In (d), the spacer 30 after ball implantation is inverted and welded to the circuit board 20 to make the substrate 10 and the circuit board 20 conductive. Thus, the substrate 10 and the circuit board 20 are welded and assembled to form a circuit board assembly 100 with a correction module.

[0192] For example, the pre-molding can be achieved by grinding the outer surface of the separator 30 close to the substrate 10 to construct the same deformation as the substrate 10. Alternatively, a micro-concave or micro-convex model (determined according to the deformation of the substrate 10) is first obtained through an integrated molding process, and then drilling and electroplating are performed.

[0193] In summary, this implementation case transforms the large-scale deformation of the chip into small-scale deformation or no deformation by constructing a correction module, thereby ensuring the welding of the large thermal deformation BGA on the board and solving the problems of bridging and open welding caused by deformation during the welding process.

[0194] Pin structure scheme:

[0195] The specific structure of the circuit board assembly 100 including the pin structure will be described below with reference to the accompanying drawings.

[0196] This embodiment improves the soldering tolerance capability through the wetting force of the metal needle and the liquid solder ball.

[0197] refer to Fig.18 , Fig.18 The structure of the circuit board assembly 100 using the pin structure as the welding structure provided in the embodiment of the present application is shown. Figure 1 .

[0198] refer to Figure 18 to Figure 19 The embodiment of the present application also provides a circuit board assembly 100 whose welding structure is a pin structure (ie, a connecting member is used to connect the first welding structure 1 and the second welding structure 2).

[0199] like Fig.18 As shown, the circuit board assembly 100 provided in the embodiment of the present application includes a substrate 10, a circuit board 20 and a welding structure. There is a gap between the substrate 10 and the circuit board 20, and the welding structure is located in the gap, and the welding structure is used to conduct the substrate 10 and the circuit board 20. The welding structure includes a plurality of first welding structures 1 and a plurality of second welding structures 2, and the plurality of first welding structures 1 and the plurality of second welding structures 2 correspond to each other one by one.

[0200] For example, continue to refer to Fig.18 The first welding structure 1 includes a first welding pad 11 and a first welding ball 12 provided on the substrate 10, and the second welding structure 2 includes a second welding pad 21 and a second welding ball 22 provided on the circuit board 20. The first welding pad 11 is located on the back side of the substrate 10, and a plurality of first welding pads 11 are distributed at intervals, and each first welding pad 11 may be provided with a first welding ball 12, and the first welding ball 12 is electrically connected to the first welding pad 11. The second welding pad 21 is located on the front side of the circuit board 20, and a plurality of second welding pads 21 are distributed at intervals, and each second welding pad 21 may be provided with a second welding ball 22, and the second welding ball 22 is electrically connected to the second welding pad 21.

[0201] Continue to refer Fig.18 A connecting member 40 is shared in each corresponding first welding structure 1 and second welding structure 2. The connecting member 40 connects the first solder ball 12 of the first welding structure 1 and the second solder ball 22 of the second welding structure 2. The welding tolerance of the first solder ball 12 and the second solder ball 22 is improved by the wetting force of the connecting member 40 and the liquid solder ball during the welding process, that is, the wettability of the liquid solder ball and the connecting member 40 causes the first solder ball 12 and the second solder ball 22 to form a slender solder joint together, thereby preventing the welding structure between the substrate 10 and the circuit board 20 from opening during the welding process.

[0202] It can be understood that during the welding process, as the temperature rises, the chip (ie, substrate 10) undergoes thermal deformation. When the first solder ball 12 and the second solder ball 22 reach the liquidus and melt, as shown in FIG. Fig.18 As shown in the figure, the central area of ​​the substrate 10 is concave downward, so that the connector 40 can penetrate the liquid solder ball and support the circuit board 20 on the side close to the substrate 10, thereby preventing the soldering structure between the substrate 10 and the circuit board 20 from having a bridging phenomenon during the soldering process.

[0203] The following will be combined Fig.19 , the welding process flow of the circuit board assembly 100 with a welding structure having a pin structure according to an embodiment of the present application is described by way of example:

[0204] like Fig.19 As shown, the manufacturing method of the circuit board assembly 100 provided in the embodiment of the present application specifically includes the following steps:

[0205] refer to Fig.19 In (a), tin is printed on the back side of the substrate 10 (ie, the side close to the soldering structure). Exemplarily, the material of the first solder ball 12 of the substrate 10 includes a tin ball or a tin column.

[0206] refer to Fig.19 In (b), a needle (ie, connector 40) is implanted in the first solder ball 12 of the substrate 10 through a mold 60 so that one end of the connector 40 is connected to the first solder ball 12. Exemplarily, the mold 60 is a graphite mold.

[0207] refer to Fig.19 In (c), the substrate 10 with implanted needles is put into a furnace for welding, and then the mold 60 is removed.

[0208] refer to Fig.19 In (d), tin is printed on the front side of the circuit board 20 (ie, the side close to the soldering structure).

[0209] refer to Fig.19 In (e), a ball is planted on the front side of the circuit board 20 (ie, the second solder ball 22). Exemplarily, the material of the second solder ball 22 of the circuit board 20 includes a tin ball or a tin column.

[0210] refer to Fig.19 In (f), the end of the second solder ball 22 of the circuit board 20 away from the circuit board 20 is leveled to facilitate the insertion of the other end of the connector 40 into the second solder ball 22 in the subsequent process.

[0211] refer to Fig.19 In (g), the substrate 10 and the circuit board 20 are mounted so that the other end of the connector 40 on the substrate 10 is connected to the second solder ball 22 on the circuit board 20 .

[0212] refer to Fig.19 In (h), the mounted substrate 10, circuit board 20 and welding structure are furnace-welded, so that each corresponding first welding structure 1 and second welding structure 2 share a connecting member 40, so that the connecting member 40 connects the first welding structure 1 and the second welding structure 2. Thus, the substrate 10 and the circuit board 20 are welded and assembled to form a circuit board assembly 100 with a pin structure.

[0213] It can be understood that in the above process, Fig.19 The process steps (a), (b), and (c) can be Fig.19 The process steps (d), (e) and (f) are carried out simultaneously to improve production efficiency.

[0214] For example, the connector 40 in the embodiment of the present application includes a metal pin, and the material of the metal pin is not specifically limited in the embodiment of the present application, for example, it is any one or more of good electrical conductor materials such as copper pin, silver pin or gold pin. The embodiment of the present application does not specifically limit the connection method between the connector 40 and the substrate 10, for example, it is soldering, welding or wire bonding.

[0215] In summary, the embodiment of the present application connects the substrate 10 and the circuit board 20 through a metal needle (connector 40), improves the welding tolerance capability through the wetting force of the metal needle and the liquid solder ball (the first solder ball 12 and the second solder ball 22), and solves the problems of bridging and open soldering caused by deformation during the welding process.

[0216] Laminated solder joint structure scheme:

[0217] The specific structure of the circuit board assembly 100 including the laminated solder joint structure will be described below with reference to the accompanying drawings.

[0218] This implementation case uses the electroplating industry chain to perform multiple electroplating of Cu and Sn / SnAg on the substrate side to increase the tin content of the solder joints and achieve large tolerance welding.

[0219] refer to Fig. 20 , Fig. 20 The structure of the circuit board assembly 100 provided in the embodiment of the present application using the laminated solder joint structure as the soldering structure is shown. Figure 1 .

[0220] like Fig. 20 As shown, the circuit board assembly 100 provided in the embodiment of the present application includes a substrate 10, a circuit board 20 and a welding structure. There is a gap between the substrate 10 and the circuit board 20, and the welding structure is located in the gap. The welding structure is used to conduct the substrate 10 and the circuit board 20. The welding structure includes at least two layers of electroplating layers stacked. For example, Fig. 20 As shown in , the number of electroplating layers includes four layers. The embodiment of the present application does not impose any specific limitation on the number of electroplating layers, which can be selected according to actual conditions.

[0221] By providing at least two stacked electroplating layers, the volume of the solder joints can be increased to increase the soldering tolerance of the soldering structure between the substrate 10 and the circuit board 20, thereby preventing the soldering structure between the substrate 10 and the circuit board 20 from opening during the soldering process.

[0222] In some possible implementations, continue to refer to Fig. 20 The electroplating layer includes a first electroplating layer 71 and a second electroplating layer 72. The first electroplating layer 71 and the second electroplating layer 72 are arranged along a height direction (eg Fig. 20 The interval setting is shown in the X direction.

[0223] Specifically, Fig. 20 As shown in FIG. 1 , the outermost electroplating layer away from the substrate 10 of the at least two stacked electroplating layers is the second electroplating layer 72. Fig. 20 The X direction is perpendicular to the plane where the surface of the substrate 10 is located. The second electroplating layer 72 is connected to the circuit board 20, and the first electroplating layer 71 is connected to the substrate 10.

[0224] In addition, reference Fig.21 In some possible implementations, the welding structure of the circuit board assembly 100 provided in the embodiment of the present application further includes a barrier layer 73, and the barrier layer 73 is disposed between the first electroplating layer 71 and the second electroplating layer 72. The barrier layer 73 can prevent the first electroplating layer 71 and the second electroplating layer 72 of two materials from reacting during welding. Exemplarily, the material of the first electroplating layer 71 includes Cu, the material of the second electroplating layer 72 includes Sn / SnAg, and the material of the barrier layer 73 includes Ni.

[0225] It can be understood that the present embodiment does not impose any specific restrictions on the materials of the first electroplating layer 71 and the second electroplating layer 72, as long as one of the two electroplating materials is involved in welding and the other plays a supporting role to prevent the soldering structure between the substrate 10 and the circuit board 20 from bridging during welding. For example, in the present embodiment, the Cu electroplating layer plays a role in controlling the minimum spacing between the substrate 10 and the circuit board 20.

[0226] The following will be combined Fig.21 , the welding process flow of the circuit board assembly 100 with a welding structure having a four-layer stacked solder joint structure according to the embodiment of the present application is described by way of example:

[0227] like Fig.21 As shown, the manufacturing method of the circuit board assembly 100 provided in the embodiment of the present application specifically includes the following steps:

[0228] refer to Fig.21 (a), receiving the substrate 10; Fig.21 In (b), Cu is plated on the back side of the substrate 10 (i.e., the side close to the welding structure), i.e., the first electroplating layer 71. Exemplarily, the material of the first electroplating layer 71 of the substrate 10 includes Cu or Sn / SnAg, etc.; Fig.21 In (c), the surface of the first electroplating layer 71 is Ni, that is, the barrier layer 73; Fig.21 In (d), the surface Sn / SnAg of the barrier layer 73, i.e., the first second electroplating layer 72; Fig.21 In (e), Ni is continuously plated on the surface of the second electroplating layer 72, i.e., the second barrier layer 73; Fig.21 In (f), Cu is continuously plated on the surface of the second barrier layer 73, i.e., the second first electroplating layer 71; Fig.21 In (g), Ni is continuously plated on the surface of the second first electroplating layer 71, i.e., the third barrier layer 73; Fig.21 In (h), Sn / SnAg is continuously plated on the surface of the third barrier layer 73, i.e., the second second electroplating layer 72, i.e., the outermost electroplating layer; Fig.21 In (i), the substrate 10 is subjected to a reflow process to form a four-layer stacked electroplating layer structure.

[0229] In summary, the laminated solder joint structure of the embodiment of the present application mainly consists of electroplated Cu and electroplated Sn / SnAg, and the number of electroplated layers is not limited ( Fig.21 Four layers are shown), the starting electroplating layer can be Cu or Sn / SnAg, and the electroplating end layer is the Sn / SnAg layer involved in welding. The electroplating materials are not limited to Cu and Sn / SnAg. It is required that one of the two electroplating materials participate in welding and the other plays a supporting role. In order to avoid the reaction of the two materials during welding, an intermediate barrier layer can be added. For Cu and Sn / SnAg electroplating materials, Ni is selected as the barrier layer. By using the electroplating industry chain, the first electroplating layer 71 and the second electroplating layer 72 are electroplated multiple times on the side of the substrate 10 to increase the amount of solder joint tin in the solder joint structure, achieve large tolerance welding, and solve the problems of tin connection and open welding caused by deformation during welding.

[0230] In summary, the application embodiments improve the overall welding tolerance capability group by introducing a new solder joint structure (double-sided solder ball module, correction module, pin structure and stacked solder joint structure) between the substrate and the circuit board, which can solve the welding defect problem (such as bridging and open soldering problems) caused by the mismatch of thermal expansion coefficients between the substrate and the circuit board, meet the assembly requirements and welding quality of the circuit board assembly of the large deformation substrate, and ensure the high reliability and temperature resistance of the circuit board assembly during normal operation.

Claims

1. A circuit board assembly, characterized in that: include: substrate; A circuit board, wherein a gap is provided between the substrate and the circuit board; A welding structure, the welding structure is located in the gap and conducts the substrate and the circuit board; wherein, The welding structure includes a plurality of first welding structures and a plurality of second welding structures, the plurality of first welding structures correspond to the plurality of second welding structures one by one, and a separator is provided between each corresponding first welding structure and second welding structure to separate the corresponding first welding structure from the second welding structure; A plurality of connectors can be supported between the substrate and the separator and / or between the circuit board and the separator.

2. The circuit board assembly according to claim 1, wherein: The number of the separator is one, the plurality of first welding structures and the plurality of second welding structures share one separator, and the separator is deformable under a welding temperature environment.

3. The circuit board assembly according to claim 1, wherein: The number of the separators is at least two, and at least two of the first welding structures and two of the second welding structures are respectively disposed on two sides of each separator.

4. The circuit board assembly according to claim 2 or 3, characterized in that: The plurality of connection members are supported between the substrate and the partition and between the circuit board and the partition.

5. The circuit board assembly according to claim 4, wherein: The connecting elements are respectively distributed in the central area and / or the edge area of ​​the partition.

6. The circuit board assembly according to claim 4 or 5, characterized in that: Two ends of the connecting member supported between the substrate and the separator are respectively connected to the separator and the substrate; two ends of the connecting member supported between the circuit board and the separator are respectively connected to the separator and the circuit board.

7. The circuit board assembly according to claim 1, wherein: There are a plurality of separators, and two adjacent separators are arranged at intervals, and one separator is provided between each corresponding first welding structure and second welding structure.

8. The circuit board assembly according to claim 7, wherein: The connecting members are respectively disposed in the first welding structure and the second welding structure.

9. The circuit board assembly according to claim 8, wherein: Two ends of the connecting member in the first welding structure are respectively connected to the separator and the substrate, and two ends of the connecting member in the second welding structure are respectively connected to the separator and the circuit board.

10. The circuit board assembly according to claim 2, wherein: The multiple connectors are supported between the substrate and the separator; wherein each connector is supported between the first welding structure and the separator, and at least part of the connectors between the substrate and the separator have unequal heights to conform to the shape of the lower surface of the substrate.

11. The circuit board assembly according to claim 2, wherein: The side of the partition close to the substrate is shaped like the lower surface of the substrate.

12. The circuit board assembly according to claim 10 or 11, characterized in that: The plurality of connectors are supported between the circuit board and the separator; wherein the connectors are distributed in the edge area of ​​the separator, and two ends of the connectors are respectively connected to the separator and the circuit board.

13. The circuit board assembly according to any one of claims 1 to 12, characterized in that: The first welding structure includes a first welding pad and a first welding ball provided on the substrate, and the second welding structure includes a second welding pad and a second welding ball provided on the circuit board; wherein, the first welding pad is located on the substrate, the first welding ball is electrically connected to the first welding pad, the second welding pad is located on the circuit board, and the second welding ball is electrically connected to the second welding pad.

14. The circuit board assembly according to any one of claims 1 to 13, characterized in that: The separator is provided with a plurality of through holes, and a conductive medium is provided on the inner wall of each through hole, and the corresponding first welding structure and the second welding structure are connected to each other through the conductive medium.

15. The circuit board assembly according to any one of claims 1 to 14, characterized in that: The substrate includes a package, and the package is a ball grid array (BGA) package.

16. A communication device, characterized in that: The communication device comprises a housing and a circuit board assembly according to any one of claims 1 to 15, wherein the circuit board assembly is installed in the housing.

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