Ceramic ball column grid array packaging structure and process implementation method thereof

Abstract

The invention belongs to the technical field of electrical interconnection structures, and particularly relates to a ceramic ball column grid array packaging structure and a process implementation method thereof. According to the technical scheme, the ceramic ball column grid array packaging structure comprises a ceramic substrate, a printed circuit board and a ball column pin array composed of a plurality of ball column pin structures, each ball column pin structure comprises a necking section and spherical contact sections arranged at the two ends of the necking section, the ceramic substrate and the printed circuit board are each provided with a plurality of bonding pads, and the bonding pads are arranged on the ceramic substrate and the printed circuit board. One spherical contact section of the ball column pin structure is connected with a bonding pad of the ceramic substrate, and the other spherical contact section of the ball column pin structure is connected with a bonding pad of the printed circuit board. According to the ceramic ball column grid array packaging structure and the process implementation method thereof, the large-scale and high-density array packaging requirement is met, and the ceramic ball column grid array packaging structure has excellent thermal fatigue resistance, mechanical vibration resistance and heat dissipation performance and good welding spot mechanical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical interconnection structures, and in particular relates to a ceramic ball column grid array packaging structure and a process implementation method thereof. Background Art

[0002] As innovative research and development in the aviation and aerospace fields continue to advance, the service environment of electronic products equipped therein will become increasingly harsh, and they will need to withstand multi-physical field loads such as force, heat, high humidity, and electricity. The probability of failure will gradually increase, and urgent demands such as high reliability and long life are put forward for electronic products serving in complex environments. Studies have shown that 70% of electronic product failures are caused by the packaging process. Therefore, how to achieve high-reliability packaging is the key and foundation for the long service life of electronic products in complex environments.

[0003] Array packaging technology is gradually replacing traditional wire bonding and surface mounting technologies, becoming the mainstream packaging technology in the electronics industry, and is gradually being widely used in cutting-edge fields such as aviation and aerospace. Ceramic ball grid array (CBGA) packaging connects the ceramic substrate and the corresponding pads of the printed circuit board through solder balls. It has a high interconnection density and excellent electrical performance (small signal transmission delay, small parasitic parameters, and strong anti-interference ability, etc.), and is currently the most commonly used array packaging form in electronic products. However, due to the large difference in thermal expansion coefficients between ceramic substrates and printed circuit boards, it is easy to generate large thermal stress inside the solder joints, and fatigue damage is continuously accumulated during the work / stop cycle, causing cracks to initiate and expand inside the solder joints, which in turn leads to failure of electronic products.

[0004] Ceramic column grid array (CCGA) packaging is a derivative technology of CBGA packaging. It uses solder columns instead of solder balls. It can use the creep of slender solder columns to release thermal stress, effectively solve the thermal fatigue problem caused by the mismatch of thermal expansion coefficients of ceramic substrates and printed circuit boards, and significantly improve the thermal fatigue life and reliability of electronic products. At the same time, CCGA packaging increases the distance between the ceramic substrate and the printed circuit board, making it have better heat dissipation performance. In this regard, a number of public patents have been applied for: a high-precision CCGA device board-level assembly method (CN202311691033.0), a CCGA package device rapid column planting method (CN202111242846.2) and a CCGA-microwave device mixed printed circuit board assembly reflow soldering method and tooling (CN202111341564.8). However, the traditional solder column type CCGA has poor resistance to physical shocks such as mechanical vibration, and the solder column is prone to deformation, causing electronic products to fail and be scrapped. In his doctoral dissertation “Failure Analysis and Optimization Strategy Research of High-Density Ceramic Column Grid Array Packaging”, Wang Xiaoqiang analyzed in detail the stress failure of CCGA solder columns under vibration and thermal vibration coupling environment and the corresponding mechanism.

[0005] From the above, we can see that the current CBGA and CCGA packaging technologies may fail under complex load environments such as heat and vibration. Summary of the invention

[0006] In order to solve the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a ceramic ball column grid array packaging structure and a process implementation method thereof, which meet the requirements of large-scale and high-density array packaging and have excellent thermal fatigue resistance, mechanical vibration resistance, heat dissipation performance and good solder joint mechanical properties.

[0007] The technical solution adopted by the present invention is:

[0008] A ceramic ball-post grid array packaging structure comprises a ceramic substrate, a printed circuit board and a ball-post pin array composed of a plurality of ball-post pin structures, wherein the ball-post pin structure comprises a necking section and spherical contact sections arranged at both ends of the necking section, and a plurality of pads are arranged on both the ceramic substrate and the printed circuit board, wherein one of the spherical contact sections of the ball-post pin structure is connected to the pad of the ceramic substrate, and the other spherical contact section of the ball-post pin structure is connected to the pad of the printed circuit board.

[0009] The ball-pillar pin structure is integrated by using precision metal 3D printing technology (such as laser melting deposition, etc.), and after printing, nickel and tin plating are performed to make the pins solderable. Next, Sn63Pb37 solder paste is printed on the pad of the ceramic substrate using a steel mesh, and then the ball-pillar pin structure is placed on the surface of the pad through the through hole on the tooling, and the ceramic substrate, tooling, and ball-pillar pin array are placed in a reflow oven together. After cooling and curing, a ceramic substrate with a ball-pillar pin array can be obtained. Finally, Sn63Pb37 solder paste is printed on the pad of the printed circuit board using a steel mesh, and then the ball-pillar pin array on the ceramic substrate is aligned with the pad on the surface of the printed circuit board, and they are placed in a reflow oven together. After cooling and curing, the tooling is removed to obtain the new ceramic ball-pillar grid array packaging structure proposed in the present invention.

[0010] As a preferred solution of the present invention, the size of the pad is 10% to 15% larger than the ball diameter of the spherical contact segment to meet the needs of ball-pillar pin array packaging.

[0011] As a preferred solution of the present invention, the ball-post pin structure is integrally formed, and the surface of the ball-post pin structure is electroplated with nickel and tin.

[0012] As a preferred solution of the present invention, the pad is coated with Sn63Pb37 solder paste.

[0013] As a preferred solution of the present invention, the thickness of the Sn63Pb37 solder paste coated on the pad is 0.12 mm.

[0014] As a preferred solution of the present invention, it also includes a cover plate and a base plate, the cover plate is provided with an array of through holes, and the base plate is provided with a positioning cavity. Before connecting the ceramic substrate and the ball-column pin array, a plurality of ball-column pin structures are placed in the through holes of the cover plate array, and the ceramic substrate is placed in the positioning cavity of the base plate. The cover plate and the base plate press the ceramic substrate and the ball-column pin array.

[0015] As a preferred solution of the present invention, a positioning hole is provided on the cover plate, and a positioning column is provided on the bottom plate, and the positioning column is inserted into the positioning hole.

[0016] As a preferred embodiment of the present invention, the height of the ball-column pin structure is 1.5-2.5 mm, the ball diameter of the spherical contact section is 0.6-0.8 mm, and the minimum diameter of the necking section is 2 / 3-3 / 4 of the ball diameter of the spherical contact section.

[0017] As a preferred solution of the present invention, the necking section of the ball-column pin structure includes a columnar section and transition sections on both sides of the columnar section, and the diameter of the transition section gradually decreases in the direction from the ball contact section to the columnar section.

[0018] A ceramic ball post grid array packaging process implementation method comprises the following steps:

[0019] S1: The designed ball-column pin structure is integrated by using precision metal 3D printing technology, and nickel and tin plating are performed after printing;

[0020] S2: Install the ceramic substrate into the positioning cavity of the base plate, and apply Sn63Pb37 solder paste on the surface pads of the ceramic substrate;

[0021] S3: Install the cover plate, and use the positioning holes and positioning columns to position and limit, and then place the ball column pin structure on the surface pad of the ceramic substrate through the through hole on the cover plate;

[0022] S4: placing the base plate on which the ceramic substrate is placed, the ceramic substrate, and the cover plate together into a reflow furnace, removing the cover plate after cooling and solidification, and obtaining a ceramic substrate with a ball column pin array;

[0023] S5: Apply Sn63Pb37 solder paste on the surface pad of the printed circuit board, and align the ball-column pin structure on the ceramic substrate with the surface pad of the printed circuit board;

[0024] S6: Put the ceramic substrate with the ball post pin array and the printed circuit board into a reflow oven together, with the welding temperature being 200-210° C. After cooling and solidification, a ceramic ball post grid array packaging structure can be obtained.

[0025] The high consistency manufacturing technology of the ball-pillar pin structure and the high reliability reflow soldering interconnection process method provided by the present invention can effectively ensure the reliability of the array package and meet the high reliability and long life service requirements of electronic products under complex working conditions.

[0026] The beneficial effects of the present invention are:

[0027] 1. Excellent anti-thermal fatigue properties: The ball-column pin structure proposed in the present invention is composed of a spherical contact section and a necking section, and is integrally formed. The two spherical contact sections are welded to the corresponding pads of the ceramic substrate and the printed circuit board respectively. The ball-column pin structure can release the thermal stress of the solder joint through the creep of the necking section, effectively solve the thermal fatigue failure problem caused by the mismatch of the thermal expansion coefficients of the ceramic substrate and the printed circuit board, and significantly improve the thermal fatigue life of the package.

[0028] 2. Good mechanical properties of solder joints: In the traditional ceramic column grid array packaging process, the coplanarity of the bottom surface of the solder column is difficult to ensure, and the solder flux on the welding interface is not easy to discharge, which may lead to large-area void defects during the reflow process. The new ceramic ball column grid array packaging structure proposed in the present invention uses the spherical contact segments at both ends to interconnect with the ceramic substrate and the printed circuit board respectively, and the solder paste can climb along the side wall of the pin, so that the solder paste wraps a larger area around the pin, which can effectively disperse the stress of the solder joint. Therefore, the solder joint of the ball column pin structure of the present invention has good mechanical properties.

[0029] 3. Excellent resistance to mechanical vibration: Compared with the high-lead solder columns used in the current ceramic column grid array packaging, the ball-column pin structure proposed in the present invention uses metal materials with higher strength and higher melting point, which improves its ability to resist physical shocks such as mechanical vibration, and can effectively avoid failure and scrapping of the array packaging structure due to bending and deformation.

[0030] 4. Excellent heat dissipation performance: Compared with the current ceramic ball grid array package, the distance between the ceramic substrate and the printed circuit board of the new ceramic ball column grid array package structure proposed in the present invention is larger. At the same time, the ball column structure design increases the space occupied by the air between the solder column arrays, which is conducive to air circulation and greatly improves the convective heat transfer efficiency. Therefore, this packaging form has excellent heat dissipation performance.

[0031] 5. Effective feasibility of ball-column pin process: The ball-column pin structure proposed in the present invention is integrated by precision metal 3D printing technology (such as laser melting deposition, etc.). After printing, nickel and tin plating are required to make the pins solderable. At the same time, laser or plasma activation is performed before electroplating the pin structure to increase the adhesion of the electroplated metal.

[0032] 6. Effective vertical interconnection process feasibility: The new ball-post pin array structure proposed in the present invention is interconnected with the ceramic substrate and the printed circuit board using a step reflow soldering process. The specific process flow is as follows: first, the ball-post pin array is interconnected with the pads on the surface of the ceramic substrate, and then the ceramic substrate with the ball-post pin array is interconnected with the printed circuit board. Sn63Pb37 solder paste is used in both welding processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a ball-column pin structure;

[0034] Figure 2 is a schematic diagram of a ball post grid array package structure;

[0035] Figure 3 It is a schematic diagram of the structure of the cover plate and the base plate;

[0036] Figure 4 It is a schematic diagram of the structure of capsule-shaped pins;

[0037] Figure 5 It is a schematic diagram of the structure of a spindle-shaped pin;

[0038] Figure 6 It is a flow chart of the ball post grid array packaging process implementation.

[0039] In the figure: 1-spherical contact section; 2-columnar section; 3-transition section; 4-ceramic substrate; 5-ball-column pin array; 6-printed circuit board; 7-cover plate; 8-bottom plate; 71-positioning hole; 81-positioning column; 72-through hole; 82-positioning cavity. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0042] like Figure 1 and Figure 2As shown, the ceramic ball column grid array packaging structure of this embodiment includes a ceramic substrate 4, a printed circuit board 6 and a ball column pin array 5 composed of a plurality of ball column pin structures, the ball column pin structure includes a necking section and a spherical contact section 1 arranged at both ends of the necking section, and a plurality of pads are arranged on the ceramic substrate 4 and the printed circuit board 6, one of the spherical contact sections 1 of the ball column pin structure is connected to the pad of the ceramic substrate 4, and the other spherical contact section 1 of the ball column pin structure is connected to the pad of the printed circuit board 6.

[0043] The ball-column pin structure is integrated by using precision metal 3D printing technology (such as laser melting deposition, etc.), and after printing, nickel and tin plating are performed to make the pins solderable. Next, Sn63Pb37 solder paste is printed on the pad of the ceramic substrate 4 using a steel mesh, and then the ball-column pin structure is placed on the surface of the pad through the through hole 72 on the tooling, and the ceramic substrate 4, the tooling, and the ball-column pin array 5 are placed in a reflow furnace together. After cooling and curing, the ceramic substrate 4 with the ball-column pin array 5 can be obtained. Finally, Sn63Pb37 solder paste is printed on the pad of the printed circuit board 6 using a steel mesh, and then the ball-column pin array 5 on the ceramic substrate 4 is aligned with the surface pad of the printed circuit board 6, and they are placed in a reflow furnace together. After cooling and curing, the tooling is removed to obtain the new ceramic ball-column grid array packaging structure proposed in the present invention.

[0044] The corresponding pads are designed on the surface according to the electrical input / output interface layout of the ceramic substrate 4 and the printed circuit board 6. The size of the pad is 10% to 15% larger than the ball diameter of the spherical contact section 1 to meet the packaging requirements of the ball column pin array 5.

[0045] The material of the ball-pillar pin structure is copper, which has a melting point of about 1083°C, which can ensure that the ball-pillar pin array 5 structure itself will not remelt during the subsequent welding process. The metal material of the ball-pillar pin structure has the characteristics of high melting point, high conductivity, high stability, etc., which can prevent the interconnect pins from remelting during the subsequent reflow soldering process and improve its ability to resist physical shocks such as mechanical vibration. At the same time, laser or plasma activation is performed before electroplating the 3D printed pin structure to increase the adhesion of the electroplated metal.

[0046] The ball-column pin structure is integrated using precision metal 3D printing technology (such as laser molten deposition, etc.). After printing, chemical nickel plating and chemical tin plating are required to make the pins solderable.

[0047] The pad is coated with Sn63Pb37 solder paste. The thickness of the Sn63Pb37 solder paste printed during the two reflow soldering processes is 0.12 mm. The soldering temperature is about 200-210°C.

[0048] like Figure 3As shown, when welding the ceramic substrate 4 and the ball-column pin array 5, a tool is used. The tool includes a cover plate 7 and a base plate 8. The cover plate 7 is provided with an array of through holes 72, and the base plate 8 is provided with a positioning cavity 82. Before connecting the ceramic substrate 4 and the ball-column pin array 5, a number of ball-column pin structures are placed in the through holes 72 of the cover plate 7 array, and the ceramic substrate 4 is placed in the positioning cavity 82 of the base plate 8. The cover plate 7 and the base plate 8 press the ceramic substrate 4 and the ball-column pin array 5. Among them, the cover plate 7 is provided with a positioning hole 71, and the base plate 8 is provided with a positioning column 81, and the positioning column 81 is inserted into the positioning hole 71. The ball-column pin array 5 is regularly arranged, and there is a preset spacing between adjacent pins, and the spacing can effectively prevent adjacent pins from generating electromagnetic interference during operation.

[0049] The height of the ball-column pin structure is 1.5-2.5 mm, the ball diameter of the spherical contact section 1 is 0.6-0.8 mm, the diameter of the cylindrical section is 0.4-0.6 mm, and the diameter of the cylindrical section is 2 / 3-3 / 4 of the ball diameter of the spherical contact section 1. The ball diameters of the spherical contact sections 1 at both ends can be the same or different.

[0050] The necking section of the ball-column pin structure includes a columnar section 2 and transition sections 3 on both sides of the columnar section 2 , and the diameter of the transition section 3 gradually decreases in the direction from the ball contact section 1 to the columnar section 2 .

[0051] like Figure 4 and Figure 5 As shown, the ball-column pin structure can also be designed into two special forms, namely, a capsule-shaped pin and a spindle-shaped pin, which have no transition section 3 and no columnar section 2 respectively.

[0052] like Figure 6 As shown, the ceramic ball post grid array packaging process implementation method of this embodiment includes the following steps:

[0053] S1: The designed ball-column pin structure is integrated by using precision metal 3D printing technology. After printing, nickel and tin plating are performed to make the pin structure weldable.

[0054] S2: Install the ceramic substrate 4 into the positioning cavity 82 of the bottom plate 8, and apply Sn63Pb37 solder paste on the surface pads of the ceramic substrate 4;

[0055] S3: Install the cover plate 7, and use the positioning holes 71 and the positioning posts 81 for positioning and limiting, and then place the ball post pin structure on the surface pad of the ceramic substrate 4 through the through hole 72 on the cover plate 7;

[0056] S4: placing the base plate 8 on which the ceramic substrate 4 is placed, the ceramic substrate 4 and the cover plate 7 together into a reflow furnace, removing the cover plate 7 after cooling and solidification, and obtaining the ceramic substrate 4 with the ball-pillar pin array 5;

[0057] S5: applying Sn63Pb37 solder paste on the surface pads of the printed circuit board 6, and aligning the ball-column pin structure on the ceramic substrate 4 with the surface pads of the printed circuit board 6;

[0058] S6: Put the ceramic substrate 4 with the ball post pin array 5 and the printed circuit board 6 into a reflow furnace at a welding temperature of 200-210° C. After cooling and solidification, a ceramic ball post grid array packaging structure can be obtained.

[0059] When the ball-post pin array 5 structure is interconnected with the ceramic substrate 4 and the printed circuit board 6, a reflow soldering process is used. The ball-post pin structure high consistency manufacturing technology and high reliability reflow soldering interconnection process method provided by the present invention can effectively ensure the reliability of the array package and meet the high reliability and long service life requirements of electronic products under complex working conditions.

[0060] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A ceramic ball post grid array packaging structure, characterized in that: The invention comprises a ceramic substrate (4), a printed circuit board (6) and a ball-column pin array (5) composed of a plurality of ball-column pin structures, wherein the ball-column pin structure comprises a necking section and spherical contact sections (1) arranged at both ends of the necking section, and a plurality of soldering pads are arranged on the ceramic substrate (4) and the printed circuit board (6), wherein one of the spherical contact sections (1) of the ball-column pin structure is connected to the soldering pad of the ceramic substrate (4), and another of the spherical contact sections (1) of the ball-column pin structure is connected to the soldering pad of the printed circuit board (6).

2. The ceramic ball post grid array packaging structure according to claim 1, characterized in that: The size of the pad is 10% to 15% larger than the ball diameter of the spherical contact section (1).

3. The ceramic ball post grid array packaging structure according to claim 1, characterized in that: The ball-column pin structure is integrally formed, and the surface of the ball-column pin structure is electroplated with nickel and tin.

4. The ceramic ball post grid array packaging structure according to claim 1, characterized in that: The pad is coated with Sn63Pb37 solder paste.

5. The ceramic ball post grid array packaging structure according to claim 4, characterized in that: The thickness of the Sn63Pb37 solder paste coated on the pad is 0.12 mm.

6. The ceramic ball post grid array packaging structure according to claim 4, characterized in that: The invention also comprises a cover plate (7) and a base plate (8); the cover plate (7) is provided with an array of through holes (72); the base plate (8) is provided with a positioning cavity (82); before connecting the ceramic substrate (4) and the ball-column pin array (5), a plurality of ball-column pin structures are placed in the through holes (72) of the cover plate (7); the ceramic substrate (4) is placed in the positioning cavity (82) of the base plate (8); the cover plate (7) and the base plate (8) press the ceramic substrate (4) and the ball-column pin array (5) together.

7. The ceramic ball post grid array packaging structure according to claim 6, characterized in that: The cover plate (7) is provided with a positioning hole (71), the bottom plate (8) is provided with a positioning column (81), and the positioning column (81) is inserted into the positioning hole (71).

8. The ceramic ball post grid array packaging structure according to claim 1, characterized in that: The height of the ball-column pin structure is 1.5-2.5 mm, the ball diameter of the spherical contact section (1) is 0.6-0.8 mm, and the minimum diameter of the necking section is 2 / 3-3 / 4 of the ball diameter of the spherical contact section (1).

9. The ceramic ball post grid array packaging structure according to claim 1, characterized in that: The necking section of the ball-column pin structure comprises a columnar section (2) and transition sections (3) on both sides of the columnar section (2), and the diameter of the transition section (3) gradually decreases in the direction from the ball contact section (1) to the columnar section (2).

10. A method for implementing a ceramic ball post grid array packaging process, using a ceramic ball post grid array packaging structure according to claim 7, characterized in that: The following steps are involved: S1: The designed ball-column pin structure is integrated by using precision metal 3D printing technology, and nickel and tin plating are performed after printing; S2: installing the ceramic substrate (4) in the positioning cavity (82) of the base plate (8), and coating Sn63Pb37 solder paste on the surface pads of the ceramic substrate (4); S3: installing the cover plate (7), and using the positioning holes (71) and the positioning posts (81) for positioning and limiting, and then placing the ball post pin structure on the surface pad of the ceramic substrate (4) through the through holes (72) on the cover plate (7); S4: placing the base plate (8) on which the ceramic substrate (4) is placed, the ceramic substrate (4), and the cover plate (7) together into a reflow furnace, and removing the cover plate (7) after cooling and solidification, thereby obtaining a ceramic substrate (4) with a ball-column pin array (5); S5: coating Sn63Pb37 solder paste on the surface pads of the printed circuit board (6), and aligning the ball-column pin structure on the ceramic substrate (4) with the surface pads of the printed circuit board (6); S6: placing the ceramic substrate (4) with the ball-post pin array (5) and the printed circuit board (6) together into a reflow furnace at a soldering temperature of 200 to 210° C., and after cooling and solidification, a ceramic ball-post grid array packaging structure can be obtained.

Images