Miniaturized surface-mounted backflow transformer and manufacturing method thereof

Abstract

The invention discloses a miniaturized surface-mounted backflow transformer which comprises a main magnet formed by bonding an upper magnet and a lower magnet in an aligned mode, a winding groove is formed in the main magnet, and a coil assembly formed by winding a cable is embedded in the winding groove; a ceramic base plate is fixedly bonded to the bottom of the main magnet and provided with a wiring assembly connected with a leading-out wire of the coil assembly. The assembly structure of the miniaturized surface-mounted backflow transformer is exquisite and compact, the assembly space required by the whole equipment is small, and the utilization rate of the coil arrangement space is high. The invention further discloses a manufacturing method for the miniaturized surface-mounted backflow transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid integrated circuit packaging, and in particular to a miniaturized surface-mount return transformer. The present invention also relates to a manufacturing method for the miniaturized surface-mount return transformer. Background Art

[0002] In traditional hybrid integrated circuit power products, the miniaturized surface-mount return transformer used usually has a skeleton structure.

[0003] like Figure 1 As shown, in the existing surface-mount transformer structure, the frame 10 is fixed to the surface of the lower magnetic material 102 by a fastener adhesive, and the upper magnetic material 101 and the lower magnetic material 102 are also fixed together by bonding. The wire winding 103 is wound on the wire slot of the frame 10, and the lead wire on the wire winding 103 is connected to the frame lead pin 104, which extends from both sides of the frame 10 for surface-mount welding of the transformer.

[0004] In practical applications, such as Figure 1 In the surface-mount transformer of the prior art shown in the figure, due to the presence of the skeleton 10, the winding space of the coil winding 103 is occupied, resulting in that the achievable winding density of the surface-mount transformer is limited and the utilization rate of the coil arrangement space is low; and the presence of the lead pins 104 in the skeleton 10 also leads to a larger overall structural size of the miniaturized surface-mount return transformer after assembly. Among all the components inside the hybrid integrated circuit power supply product, the layout space occupied by the surface-mount transformer is also the largest, causing many adverse effects on the arrangement and adaptation of related components.

[0005] Therefore, how to optimize the component structure of the surface-mount transformer to make its overall structure more sophisticated, occupy a smaller assembly space, and improve the space utilization of its wire package layout is an important technical problem that technical personnel in this field currently need to solve. Summary of the invention

[0006] The object of the present invention is to provide a miniaturized surface mount return transformer, the component structure of the miniaturized surface mount return transformer is relatively delicate and compact, the assembly space required for the whole device is small, and the space utilization rate of the coil arrangement is high. Another object of the present invention is to provide a miniaturized surface mount return transformer manufacturing method for the miniaturized surface mount return transformer.

[0007] In order to solve the above technical problems, the present invention provides a miniaturized surface-mount return transformer, comprising a main magnet formed by aligning and bonding an upper magnet and a lower magnet, wherein the main magnet has a winding groove inside, and a wire package component formed by winding a cable is embedded in the winding groove;

[0008] A ceramic pad is bonded and fixed to the bottom of the main magnet, and a wiring assembly connected to the lead-out wire of the wire package assembly is arranged on the ceramic pad.

[0009] Preferably, the wiring assembly includes a metal pad and a wiring pin, the metal pad is welded at high temperature to the bottom of the ceramic pad, the assembly end of the wiring pin is connected to the metal pad, and the free end of the wiring pin extends out of the side of the main magnet and is connected to the lead wire of the wire package assembly.

[0010] Preferably, the lead wire of the wire package assembly is an enameled wire, and the free end of the wiring pin is protrudingly provided with a wiring terminal for winding the enameled wire.

[0011] Preferably, there are two wiring terminals, and the two wiring terminals are symmetrically arranged on the end surface of the free end of the wiring pin, and the two wiring terminals are gap-fitted to form a U-shaped groove that is welded and fixed to the lead wire of the wire package assembly.

[0012] Preferably, the lead wire of the wire package assembly is an enameled copper strip with a positioning hole at the end, and the free end of the wiring pin is protrudingly provided with a wiring boss that is plug-fitted into the positioning hole and fixed by welding.

[0013] Preferably, the exterior of the wiring assembly is coated with a nickel plating layer.

[0014] Preferably, the exterior of the nickel plated layer is coated with a gold plated layer.

[0015] Preferably, the metal pad and the connection pin are fixed by welding with high melting point solder.

[0016] The present invention also provides a method for manufacturing a miniaturized surface mount return transformer, which is used to manufacture the miniaturized surface mount return transformer as described above, comprising the steps of:

[0017] Prepare the substrate, process the ceramic pad into shape using a high-temperature sintering process or a high-temperature welding process, and arrange the wiring components in place;

[0018] Substrate assembly: Use tooling to position the ceramic pad and wiring assembly reliably;

[0019] Main body assembly, using tooling to wind the cable into a wire package assembly, then assemble the wire package assembly on the lower magnet, and then align and bond the upper magnet and the lower magnet to form the main magnet, and ensure that the wire package assembly is located in the winding groove of the main magnet, and remove the paint and tin the lead wire of the wire package assembly;

[0020] The overall assembly is to reliably bond and fix the ceramic pad to the bottom of the main magnet, and reliably connect the lead wires of the wire package assembly to the wiring assembly to complete the overall assembly of the miniaturized surface mount return transformer.

[0021] Preferably, the step of assembling the substrate further includes the following subdivision steps which are implemented in sequence:

[0022] Initial forming, using a forming process, to obtain a blank plate frame with a plurality of tube pin blanks arranged inside, each tube pin blank being connected to the inner side of the blank plate frame through a connecting rib;

[0023] Initial assembly: align the blank sheet frame at the metal pad, use high melting point solder to weld each pin blank to the metal pad, and bond the metal pad to the bottom of the ceramic pad;

[0024] Plating protection: electroplating nickel on the surface of metal pads, high melting point solder layers and pin blanks. After the nickel plating is formed by electroplating, gold is electroplated on the surface of the nickel layer.

[0025] Pin forming, separating the pin blank from the connecting rib, and then using a tool to bend the pin blank into a connection pin with a desired shape;

[0026] In the main body assembly of the step, the lead wires on the wire package assembly that have been depainted and tinned are welded to the free ends of the connection pins.

[0027] Compared with the above-mentioned background technology, the miniaturized surface-mount return transformer provided by the present invention, when assembled and used, forms a main magnet by aligning and bonding the upper magnet and the lower magnet, and uses this in combination with the winding groove as the winding assembly structure basis of the wire package assembly, arranges the wire package assembly formed by winding the cable in the winding groove, and on this basis, combines with the ceramic pad fixed by bonding to the bottom of the main magnet, so as to realize the assembly of the main basic structure of the miniaturized surface-mount return transformer, and at the same time, utilizes the wiring assembly installed on the ceramic pad to be reliably connected to the lead wire of the wire package assembly, as the wire package connection structure of the miniaturized surface-mount return transformer, thereby eliminating the need for structural components such as the skeleton and skeleton lead pins in the prior art, and can complete the miniaturized surface-mount return transformer. The overall assembly and corresponding installation and operation of the miniaturized surface-mount return transformer have greatly optimized the internal component structure and layout space of the miniaturized surface-mount return transformer, so that a large amount of assembly space occupied by the main magnet due to the layout of the skeleton can be reused, thereby providing sufficient structural space for the cable layout of the wire package assembly, and greatly improving the utilization rate of the wire package layout space; in addition, due to the streamlining of structural components such as the skeleton lead-out pins, the overall structure of the miniaturized surface-mount return transformer is more regular and sophisticated, the occupied assembly space is smaller, and the space utilization rate is higher, thereby realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power products and other equipment can also be optimized accordingly.

[0028] In the manufacturing method of the miniaturized surface-mount return transformer provided by the present invention, through the steps of substrate preparation, substrate assembly, main body assembly, overall assembly and the like, the upper magnet and the lower magnet are aligned and bonded to form a main magnet, and this is combined with a winding groove as the winding assembly structure basis of the wire package assembly, the wire package assembly formed by winding the cable is arranged in the winding groove, and then combined with a ceramic pad bonded and fixed to the bottom of the main magnet, the main basic structure of the miniaturized surface-mount return transformer can be assembled, and on this basis, the wiring assembly installed on the ceramic pad is reliably connected to the lead-out wire of the wire package assembly, and the wiring assembly can be assembled. The overall assembly and corresponding installation and operation of the miniaturized surface-mount return transformer are completed without the need to install and arrange components such as the frame and frame lead-out pins, which greatly optimizes the internal component structure and layout space of the miniaturized surface-mount return transformer, provides sufficient structural space for the cable layout of the wire package assembly, and improves the utilization rate of the wire package layout space. At the same time, the overall structure of the miniaturized surface-mount return transformer is more regular and sophisticated, the assembly space occupied is smaller, and the space utilization rate is higher, thus realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power products and other equipment is also optimized accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a structural front cross-sectional view of a surface-mount transformer in the prior art;

[0031] Figure 2 A front cross-sectional view of the structure of a miniaturized surface-mount return current transformer having a wire package assembly wound by enameled wire provided by a specific embodiment of the present invention;

[0032] Figure 3 for Figure 2 Schematic diagram of the assembly structure of the lead wires and the connection pins of the center line package assembly;

[0033] Figure 4 A front cross-sectional view of the structure of a miniaturized surface-mount return current transformer having a wire package assembly wound by enameled copper tape provided by a specific embodiment of the present invention;

[0034] Figure 5 for Figure 4 Schematic diagram of the assembly structure of the lead wires and the connection pins of the center line package assembly;

[0035] Figure 6A flowchart of a method for manufacturing a miniaturized surface-mount return transformer provided by a specific embodiment of the present invention;

[0036] Figure 7 A flow chart of a method for manufacturing a miniaturized surface-mount return transformer provided by another specific embodiment of the present invention;

[0037] Figure 8 for Figure 7 The schematic diagram of the structure of the blank sheet frame in the manufacturing method of the miniaturized surface mount return transformer is shown.

[0038] in,

[0039] 10-frame; 101-upper magnetic material; 102-lower magnetic material; 103-wire winding; 104-frame lead pin;

[0040] 11-main magnet; 111-upper magnet; 112-lower magnet; 113-winding groove;

[0041] 12-wire package assembly; 121-lead wire; 122-positioning hole;

[0042] 13- Ceramic pad;

[0043] 14-wiring assembly; 141-metal pad; 142-wiring pin; 143-wiring terminal; 144-U-shaped groove; 145-wiring boss; 146-nickel plating; 147-gold plating; 148-high melting point solder layer; 15-blank sheet frame; 151-pin blank; 152-connecting rib. DETAILED DESCRIPTION

[0044] The core of the present invention is to provide a miniaturized surface-mount return transformer, the component structure of which is relatively delicate and compact, the assembly space required for the entire device is small, and the space utilization rate of the wire package layout is high; at the same time, a miniaturized surface-mount return transformer manufacturing method for the miniaturized surface-mount return transformer is provided.

[0045] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0046] Please refer to Figures 2 to 5 .

[0047] In a specific embodiment, the miniaturized surface-mount return transformer provided by the present invention includes a main magnet 11 formed by aligning and bonding an upper magnet 111 and a lower magnet 112, the main magnet 11 has a winding groove 113 inside, and a wire package component 12 formed by winding a cable is embedded in the winding groove 113;

[0048] A ceramic backing plate 13 is bonded and fixed to the bottom of the main magnet 11 , and a wiring assembly 14 connected to the lead-out wire 121 of the wire package assembly 12 is arranged on the ceramic backing plate 13 .

[0049] During assembly and use, the main magnet 11 is formed by aligning and bonding the upper magnet 111 and the lower magnet 112, and this is combined with the winding groove 113 as the winding assembly structure basis of the wire package assembly 12, and the wire package assembly 12 formed by winding the cable is arranged in the winding groove 113. On this basis, combined with the ceramic pad 13 bonded and fixed to the bottom of the main magnet 11, the assembly of the main basic structure of the miniaturized surface-mounted return transformer can be achieved. At the same time, the wiring assembly 14 installed on the ceramic pad 13 is reliably connected to the lead wire 121 of the wire package assembly 12 as the wire package connection structure of the miniaturized surface-mounted return transformer, thereby eliminating the need for structural components such as the skeleton and skeleton lead pins in the prior art, and the miniaturized surface-mounted return transformer can be completed. The overall assembly and corresponding installation and operation of the miniaturized surface-mount return transformer have greatly optimized the internal component structure and layout space of the miniaturized surface-mount return transformer, so that a large amount of assembly space occupied by the main magnet 11 due to the arrangement of the skeleton can be reused, thereby providing sufficient structural space for the cable arrangement of the wire package assembly 12, and greatly improving the utilization rate of the wire package arrangement space; in addition, due to the streamlining of structural components such as the skeleton lead-out pins, the overall structure of the miniaturized surface-mount return transformer is more regular and sophisticated, the assembly space occupied is smaller, and the space utilization rate is higher, thereby realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power supply products and other equipment can also be optimized accordingly.

[0050] It should be noted that, in actual applications, compared with the structure of the traditional miniaturized surface-mount return transformer equipped with a skeleton in the prior art, the skeleton inside the traditional miniaturized surface-mount return transformer and the magnetic materials such as the upper magnet 111 and the lower magnet 112 are assembled with a micro-gap. Since the thermal expansion coefficients of the skeleton and the magnetic materials are quite different, when the operating temperature changes rapidly within a large gradient range, since the thermal expansion coefficient of the skeleton is much larger than that of the magnetic material, the magnetic material is easily squeezed due to the deformation of the skeleton, resulting in the phenomenon of bursting of the magnetic material. The structure of the miniaturized surface-mount return transformer in the present scheme is a frameless assembly structure, and the wire package component 12 is wound by multiple strands of cable. Since the frame as an assembly component is omitted, the winding arrangement space of the wire package component 12 is relatively ample, and its cable winding structure is relatively loose, so it has a certain structural elasticity and will not cause a large degree of squeezing on magnetic materials such as the main magnet 11, thereby effectively avoiding the phenomenon of expanding and cracking magnetic materials; and, the miniaturized surface-mount return transformer in the present scheme can meet the rapid temperature change requirements of hybrid integrated circuits in a wide temperature range (such as rapid temperature change conditions between -65°C and 150°C), significantly improving the working condition tolerance and application convenience of the miniaturized surface-mount return transformer.

[0051] Furthermore, the wiring assembly 14 includes a metal pad 141 and a wiring pin 142. The metal pad 141 is sintered at high temperature and connected to the bottom of the ceramic pad 13. The assembly end of the wiring pin 142 is connected to the metal pad 141. The free end of the wiring pin 142 extends out of the side of the main magnet 11 and is connected to the lead wire 121 of the wire package assembly 12. Generally, considering the conventional application requirements under most working conditions, the wiring pin 142 can be an L-shaped pin, so that the extended end of the L-shaped pin can be kept extending along the axial direction of the main magnet 11, so that the external structure of the miniaturized surface mount return transformer is more regular and compact, the assembly space utilization rate is higher, and the alignment connection adaptation effect of the wiring pin 142 and the lead wire 121 of the wire package assembly 12 is better.

[0052] In actual operation, the wire package assembly 12 can be bonded and fixed to the inner wall of the winding groove 113, and preferably bonded and fixed to the lower magnet 112. In addition, the upper magnet 111 and the lower magnet 112, and the lower magnet 112 and the ceramic pad 13 are respectively bonded and fixed. Specifically, the above-mentioned bonding structures and the bonding structures mentioned in the rest of the present solution can all be bonded and fixed using epoxy adhesive.

[0053] In the surface-mount transformer structure of this solution, a small amount of epoxy adhesive is used only in local areas to bond the upper magnet 111 and the lower magnet 112, and the wire package assembly 12 and the lower magnet 112, respectively. The adhesive thickness is relatively thin, and the typical adhesive thickness is not more than 0.1 mm. This can avoid the stress matching problem between the epoxy adhesive and each adhesive connector, and meet the reliability requirements of the transformer in terms of high-speed temperature change. At the same time, the epoxy adhesive has a large bonding strength, which can meet the product's requirements in terms of high-reliability mechanical environmental stress. Generally, the intermittent working temperature of epoxy adhesive is as high as 300°C, and the continuous working temperature can reach 200°C. The solder selected in the product packaging process is generally low-temperature lead solder (such as 63Sn37Pb) or lead-free solder (such as Sn96.5Ag3.0Cu0.5), with melting points of 183°C and 217°C respectively. The maximum peak temperature of reflow soldering does not exceed 260°C. Therefore, the epoxy adhesive and the corresponding bonding structure in this application meet the requirements of product reflow soldering during the packaging process.

[0054] On this basis, the epoxy adhesive used in the miniaturized surface mount reflow transformer structure of this solution can be compatible with the cleaning solvent and cleaning process after reflow soldering, meeting the cleaning requirements of the product after reflow soldering during the packaging process.

[0055] Of course, the adhesive used in the above scheme can also be made of hard silicone rubber, especially for the bonding between the lower magnet 112 and the ceramic pad 13, it is advisable to use an epoxy adhesive film or hard silicone rubber with a certain elasticity to complete the bonding, and the selected epoxy adhesive or adhesive film should meet the requirements of reflow soldering during the product packaging process (the peak welding temperature is 240°C to 260°C). In addition, the elastic epoxy adhesive film or hard silicone rubber selected in this scheme can be compatible with the cleaning solvent and cleaning process after reflow soldering to meet the cleaning requirements of the product after reflow soldering during the packaging process. In actual applications, staff can flexibly select and adjust the specific type of colloid according to the specific working conditions to achieve the welding assembly of the corresponding components. In principle, as long as it can meet the component assembly process requirements of the miniaturized surface-mount reflow transformer, it can be used.

[0056] On the other hand, the ceramic material of the ceramic pad 13 itself can give it good insulation properties, which can meet the insulation performance requirements between the metal pad 141 located at the bottom and the main magnet 11 located on its upper surface; at the same time, the ceramic pad 13 has excellent mechanical strength. As a mechanical support structure for the miniaturized surface-mount return transformer, its strength meets the product's requirements for high-reliability mechanical environmental stress.

[0057] Compared with the transformer in the prior art that uses a traditional skeleton as a mechanical support structure, in this solution, the metal pad 141 is arranged at the bottom of the ceramic pad 13, and its components occupy a small space, so that its overall size is much smaller than the existing conventional miniaturized surface-mount return transformer, which helps to optimize the corresponding line connection and layout.

[0058] It should be further pointed out that the ceramic pad 13 in the present embodiment can be manufactured by a variety of processes. Different manufacturing processes of the ceramic pad 13 have different preferred materials for the matching wiring pins 142, high melting point solder and metal pad 141. The structural design of the ceramic pad 13 and its supporting components are explained below with two specific implementation schemes.

[0059] In the first set of embodiments, the ceramic backing plate 13 is manufactured by using the HTCC (high temperature co-fired ceramic) process.

[0060] In this embodiment, the ceramic pad 13 is preferably made of alumina, and the connection pin 142 is preferably made of kovar material. The thermal expansion coefficients of the kovar material and the alumina material match each other, meeting the reliability requirements of the miniaturized surface-mounted return transformer in terms of high-speed temperature change.

[0061] Accordingly, the metal pad 141 in this embodiment is made of tungsten-molybdenum alloy, and the connection pin 142 is welded to the metal pad 141 using a high melting point silver-copper solder, the melting point of which is about 700° C., or a high lead solder (such as 92.5Pb5Sn2.5Ag), the melting point of which is 280° C. to 290° C. After welding, a solder resist is applied to the surface of the metal pad 141, the high melting point solder, and the connection pin 142 using an electroplated nickel layer 146.

[0062] In the second set of embodiments, the ceramic backing plate 13 is manufactured by using the AMB (active brazing) process.

[0063] In this embodiment, the ceramic pad 13 is preferably made of silicon nitride, the metal pad 141 is made of metallic copper, and the wiring pin 142 is also made of copper. The metal pad 141 and the wiring pin 142 are made of the same material, thereby ensuring that their thermal expansion coefficients are the same, thereby meeting the reliability requirements of the miniaturized surface-mount reflow transformer in terms of high-speed temperature change.

[0064] In this embodiment, high melting point silver-copper solder (solder melting point is about 700°C) is used for welding between the wiring pin 142 and the metal pad 141, or high lead solder (such as 92.5Pb5Sn2.5Ag) is used for welding (its melting point is 280°C~290°C). After welding is completed, the nickel plating layer 146 on the surface of the metal pad 141, the high melting point solder and the wiring pin 142 is used for solder resistance.

[0065] In the above two sets of specific implementation schemes, the welding structure of the ceramic pad 13 and its supporting components are both high-temperature welding systems. The melting point of the solder is higher than the peak temperature of the product during reflow soldering (240°C~260°C), and a solder resist layer is set on the surface of the metal pad 141, the high melting point solder and the wiring pin 142 to prevent the low-temperature solder from corroding the high melting point solder during the melting process.

[0066] Furthermore, the surface of the metal pad 141, the high melting point solder and the connecting pin 142 is coated with a nickel plating 146. The nickel plating 146 serves as a solder resist layer to prevent the low temperature solder from corroding the high melting point solder during the melting process. At the same time, the surface of the nickel plating 146 is coated with a gold plating 147, which can effectively prevent the nickel plating 146 from being oxidized due to exposure to the air, resulting in a decrease in solderability.

[0067] Please pay attention to Figure 2 and Figure 3 .

[0068] Specifically, the lead wire 121 of the wire package assembly 12 is an enameled wire, and the free end of the wiring pin 142 is protruding with a wiring terminal 143 for winding the enameled wire. The wiring terminal 143 can fully adapt to the enameled wire to ensure reliable connection between the lead wire 121 of the wire package assembly 12 and the free end of the wiring pin 142.

[0069] More specifically, there are two terminal heads 143, and the two terminal heads 143 are symmetrically arranged on the end surface of the free end of the wiring pin 142, and the gap between the two terminal heads 143 is matched to form a U-shaped groove 144 that is welded and fixed to the lead wire 121 of the wire package assembly 12. The lead wire 121 of the wire package assembly 12 is fully adapted to the U-shaped groove 144 and the terminal head 143, and then cooperates with the welding process to form a wrapping welding connection structure. In a specific application, the wrapping welding angle is not less than 270°, and the width of the U-shaped groove 144 is 0.2mm to 0.4mm larger than the diameter of the lead wire 121 of the wire package assembly 12.

[0070] Please pay attention to Figure 4 and Figure 5 .

[0071] In addition, the lead wire 121 of the wire package assembly 12 can also be an enameled copper strip with a positioning hole 122 at the end, and the free end of the wiring pin 142 is protrudingly provided with a wiring boss 145 that is inserted and adapted to the positioning hole 122 and fixed by welding. The wiring boss 145 is inserted into the positioning hole 122 to form an insertion adaptation structure, and then cooperates with the welding process to form a perforated welding structure to ensure a reliable connection between the lead wire 121 of the wire package assembly 12 and the free end of the wiring pin 142. Generally, the inner diameter of the positioning hole 122 is 0.2mm to 0.3mm larger than the width of the wiring boss 145.

[0072] It should be noted that when the lead wire 121 of the wire package assembly 12 is welded to the terminal pin 142, the main structure assembly of the miniaturized surface mount return transformer has been basically completed, including the bonding between the upper magnet 111 and the lower magnet 112, the bonding between the wire package assembly 12 and the lower magnet 112, the bonding between the lower magnet 112 and the ceramic pad 13, the bonding between the ceramic pad 13 and the metal pad 141, and the welding between the terminal pin 142 and the metal pad 141. Therefore, the welding of the connection between the lead wire 121 of the wire package assembly 12 and the terminal pin 142 cannot be performed by heating the whole with high-temperature solder (operating temperature not less than 280°C), so as to avoid the problem of the adhesive being subjected to excessive temperature and secondary melting at the solder joint between the terminal pin 142 and the ceramic pad 13. At the same time, if high-temperature solder is used for local welding, the simpler way is to perform manual welding in an air environment. However, when welding at high temperatures, the solder is prone to oxidation, and the wettability becomes poor. In addition, the temperature gradient between the solder joint temperature and the surrounding air is too large during high-temperature welding, which can easily cause poor solder joints. Therefore, this solution uses low-melting-point solder commonly used in the industry for local welding. Generally, lead solder (such as 63Sn37Pb) and lead-free solder (such as Sn96.5Ag3.0Cu0.5) can be used.

[0073] It should be further explained that since the lead wire 121 of the wire package assembly 12 is welded to the connection pin 142 with a low melting point solder, secondary melting will occur during the product reflow soldering. In order to ensure that the solder joint between the lead wire 121 of the wire package assembly 12 and the connection pin 142 will not be cold or disconnected during the product reflow soldering, the present solution adopts a wrap-around soldering structure and a perforated soldering structure. Figure 3 As shown, when the wire package assembly 12 is made of enameled wire, the lead wire 121 of the wire package assembly 12 is wound around the U-shaped groove 144 and the terminal 143 of the connection pin 142, and is welded and fixed to the connection pin 142 by a wrapping welding structure. Since the enameled wire is wound around the U-shaped groove 144, when the solder joint is melted for the second time, the phenomenon of cold solder joint or disconnection will not occur. Figure 5 As shown, when the wire package assembly 12 is wound by enameled copper tape, a positioning hole 122 is designed at the end of the lead wire 121 of the enameled copper tape, and a wiring boss 145 structure is designed at the free end of the wiring pin 142. The lead wire 121 of the wire package assembly 12 is welded and fixed to the wiring pin 142 by adopting a perforated welding structure formed by the wiring boss 145 and the positioning hole 122. Since the wiring boss 145 is inserted into the positioning hole 122 for welding, it can be ensured that no cold solder joint or disconnection will occur during the secondary melting of the solder joint.

[0074] On the other hand, it should be pointed out that in practical applications, the width of the connection pin 142 is 0.8 mm to 1.2 mm, and the thickness is 0.15 mm to 0.35 mm. The ceramic pad 13 can be processed by a ceramic film forming process, and the thickness of the ceramic pad 13 after processing is 0.3 mm to 1 mm, and the thickness of the metal pad 141 is 20 μm to 200 μm.

[0075] During the specific process implementation, after the connection pin 142 is welded and fixed to the metal pad 141, the connection pin 142 can be bent 90 degrees, and a bending angle or chamfer structure with a certain appropriate curvature is designed, and the connection pin 142 is welded to the lead wire 121 of the wire package component 12 in the air. The connection pin 142 needs to select a suitable thickness and width accordingly to meet the requirements of flow capacity and stress release, and ensure that it has a certain support strength after welding to prevent structural deformation during subsequent assembly and mechanical testing. After the connection pin 142 is welded to the lead wire 121 of the wire package component 12, there will be a small amount of stress at this place. When the thickness of the connection pin 142 is too large, the stress cannot be effectively released. In the subsequent environmental test or product application process, cracks may occur at the welding point, affecting product reliability; when the thickness of the connection pin 142 is too thin, it is easy to deform and collapse during the subsequent assembly and mechanical testing process. Therefore, in this solution, the width of the connection pin 142 is preferably 0.8 mm to 1.2 mm, and the thickness is preferably 0.15 mm to 0.35 mm, which can meet the performance requirements such as flow capacity, stress release, and support strength after welding.

[0076] In order to meet the high reliability requirements of hybrid integrated circuits, especially the rapid temperature change environmental stress requirements within a wide temperature range, the ceramic base plate in this application is preferably manufactured using the HTCC process or the AMB process. When the HTCC process is used, the thickness of the formed ceramic pad 13 is 0.5mm to 1mm, and the thickness of the metal pad 141 adapted thereto is 20μm to 50μm; when the AMB process is used, the thickness of the formed ceramic pad 13 is 0.3mm to 0.5mm, and the thickness of the metal pad 141 adapted thereto is 50μm to 200μm.

[0077] Please pay attention to Figure 2 .

[0078] In a specific embodiment, a method for manufacturing a miniaturized surface-mount return transformer provided in a specific embodiment of the present invention is used to manufacture the miniaturized surface-mount return transformer as described above, comprising:

[0079] Step S101, preparing substrate.

[0080] The ceramic backing plate 13 is processed and formed by a high temperature sintering process or a high temperature welding process, and the wiring assembly 14 is arranged in place.

[0081] Step S102: assembling the substrate.

[0082] By using the tooling positioning, the ceramic pad 13 and the wiring assembly 14 are reliably assembled.

[0083] Step S103, main body assembly.

[0084] The cable is wound into a wire package assembly 12 using tooling, and then the wire package assembly 12 is assembled on the lower magnet 112. The upper magnet 111 and the lower magnet 112 are then aligned and bonded to form the main magnet 11. The wire package assembly 12 is ensured to be located in the winding groove 113 of the main magnet 11, and the lead wires 121 of the wire package assembly 12 are depainted and tinned.

[0085] Step S104, overall assembly.

[0086] The ceramic backing plate 13 is reliably bonded and fixed to the bottom of the main magnet 11 , and the lead wire 121 of the wire package assembly 12 is reliably connected to the wiring assembly 14 , thereby completing the overall assembly of the miniaturized surface mount return transformer.

[0087] The manufacturing method of the miniaturized surface-mount return transformer comprises the following steps: substrate preparation, substrate assembly, main body assembly, and overall assembly. The upper magnet 111 and the lower magnet 112 are aligned and bonded to form the main magnet 11, and the winding groove 113 is used as the winding assembly structure basis of the wire package component 12. The wire package component 12 wound by the cable is arranged in the winding groove 113, and then combined with the ceramic pad 13 bonded and fixed to the bottom of the main magnet 11, the main basic structure of the miniaturized surface-mount return transformer can be assembled. On this basis, the wiring assembly 14 installed on the ceramic pad 13 is connected to the lead-out of the wire package component 12. The wire 121 is reliably connected to complete the overall assembly and corresponding installation and operation of the miniaturized surface-mount return transformer. There is no need to install and arrange components such as the frame and the frame lead-out pins, which greatly optimizes the internal component structure and layout space of the miniaturized surface-mount return transformer, and provides sufficient structural space for the cable layout of the wire package component 12, thereby improving the utilization rate of the wire package layout space. At the same time, the overall structure of the miniaturized surface-mount return transformer is more regular and sophisticated, the assembly space occupied is smaller, and the space utilization rate is higher, thereby realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power products and other equipment is also optimized accordingly.

[0088] Please pay attention to Figure 2 .

[0089] In a specific embodiment, a method for manufacturing a miniaturized surface mount return transformer provided in another specific embodiment of the present invention is used to manufacture the miniaturized surface mount return transformer as described above, comprising:

[0090] Step S201, preparing substrate.

[0091] The ceramic backing plate 13 is processed and formed by using the HTCC process or the AMB process, and the wiring assembly 14 is arranged in place.

[0092] Step S202: assembling the substrate.

[0093] By using the tooling positioning, the ceramic pad 13 and the wiring assembly 14 are reliably assembled.

[0094] Specifically, in step S202, substrate assembly, further includes the following subdivision steps to be implemented in sequence:

[0095] Step S2021, initial forming.

[0096] By means of stamping and cutting processes, a blank plate frame 15 with a plurality of pin blanks 151 arranged therein is obtained. Each pin blank 151 is connected to the inner side of the blank plate frame 15 via a connecting rib 152 .

[0097] Step S2022, initial assembly.

[0098] The metal pad 141 is fixed to the bottom of the ceramic pad 13 by high temperature sintering, and then the blank plate frame 15 is aligned and arranged at the metal pad 141, and each pin blank 151 is correspondingly welded to the metal pad 141 using high melting point solder.

[0099] It should be noted that the surface of the metal pad 141 does not contain a coating at this time. The structure of the miniaturized surface-mounted return transformer after assembly in this solution contains multiple connection pins 142 (no less than 4). When the connection pins 142 are welded to the metal pad 141, the consistency of the welding position needs to be ensured to avoid the winding or perforation accuracy between the lead wire 121 of the wire package assembly 12 and the connection pins 142 being affected by the large position offset of the connection pins 142 during the assembly process at the rear end. The connection pins 142 provided in this step are connected to the connection ribs 152, which can ensure that the relative positions between the connection pins 142 are fixed, and will not be offset during the welding process, thereby ensuring the welding assembly accuracy.

[0100] Step S2023, coating protection.

[0101] A nickel plating layer 146 is electroplated on the surface of the metal pad 141 , the high melting point solder layer 148 and the lead blank 151 . After the nickel plating layer 146 is formed by electroplating, a gold plating layer 147 is electroplated on the surface of the nickel layer.

[0102] Step S2024, pin forming.

[0103] The pin blank 151 is separated from the connecting rib 152 , and then the pin blank 151 is bent and formed into a connection pin 142 having a desired shape using a tool.

[0104] Step S203: main body assembly.

[0105] The cable is wound into a wire package assembly 12 using tooling, and then the wire package assembly 12 is assembled on the lower magnet 112. The upper magnet 111 and the lower magnet 112 are then aligned and bonded to form the main magnet 11. The wire package assembly 12 is ensured to be located in the winding groove 113 of the main magnet 11, and the lead wires 121 of the wire package assembly 12 are depainted and tinned.

[0106] More specifically, in the above-mentioned steps of main body assembly, the lead wire 121 on the wire package assembly 12 that has been depainted and tinned is welded to the free end of the connection pin 142 .

[0107] Step S204, overall assembly.

[0108] The ceramic backing plate 13 is reliably bonded and fixed to the bottom of the main magnet 11 , and the lead wire 121 of the wire package assembly 12 is reliably connected to the wiring assembly 14 , thereby completing the overall assembly of the miniaturized surface mount return transformer.

[0109] The manufacturing method of the miniaturized surface-mount return transformer comprises the following steps: substrate preparation, substrate assembly, main body assembly, and overall assembly. The upper magnet 111 and the lower magnet 112 are aligned and bonded to form the main magnet 11, and the winding groove 113 is used as the winding assembly structure basis of the wire package component 12. The wire package component 12 wound by the cable is arranged in the winding groove 113, and then combined with the ceramic pad 13 bonded and fixed to the bottom of the main magnet 11, the main basic structure of the miniaturized surface-mount return transformer can be assembled. On this basis, the wiring assembly 14 installed on the ceramic pad 13 is connected to the lead-out of the wire package component 12. The wire 121 is reliably connected to complete the overall assembly and corresponding installation and operation of the miniaturized surface-mount return transformer. There is no need to install and arrange components such as the frame and the frame lead-out pins, which greatly optimizes the internal component structure and layout space of the miniaturized surface-mount return transformer, and provides sufficient structural space for the cable layout of the wire package component 12, thereby improving the utilization rate of the wire package layout space. At the same time, the overall structure of the miniaturized surface-mount return transformer is more regular and sophisticated, the assembly space occupied is smaller, and the space utilization rate is higher, thereby realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power products and other equipment is also optimized accordingly.

[0110] In summary, the miniaturized surface-mount return transformer provided in the present invention, when assembled and used, is formed by aligning and bonding the upper magnet and the lower magnet to form a main magnet, and this is combined with the winding groove as the winding assembly structure basis of the wire package assembly, and the wire package assembly formed by winding the cable is arranged in the winding groove. On this basis, combined with the ceramic pad fixed by bonding to the bottom of the main magnet, the assembly of the main basic structure of the miniaturized surface-mount return transformer can be realized. At the same time, the wiring assembly installed on the ceramic pad is reliably connected to the lead wire of the wire package assembly as the wire package connection structure of the miniaturized surface-mount return transformer, thereby eliminating the need for structural components such as the skeleton and skeleton lead pins in the prior art, and the miniaturized surface can be completed. The overall assembly and corresponding installation and operation of the surface-mount return transformer greatly optimize the internal component structure and layout space of the miniaturized surface-mount return transformer, so that a large amount of assembly space occupied by the main magnet due to the layout of the skeleton can be reused, thereby providing sufficient structural space for the cable layout of the wire package assembly, and greatly improving the utilization rate of the wire package layout space; in addition, due to the streamlining of structural components such as the skeleton lead-out pins, the overall structure of the miniaturized surface-mount return transformer is more regular and sophisticated, the occupied assembly space is smaller, and the space utilization rate is higher, thereby realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power supply products and other equipment can also be optimized accordingly.

[0111] In addition, the present invention provides a method for manufacturing a miniaturized surface-mount return transformer using the miniaturized surface-mount return transformer. The method sequentially performs the steps of substrate preparation, substrate assembly, main body assembly, and overall assembly. The upper magnet and the lower magnet are aligned and bonded to form a main magnet. The main magnet is combined with a winding groove as the winding assembly structure basis of the wire package assembly. The wire package assembly formed by winding the cable is arranged in the winding groove. The ceramic pad is bonded and fixed to the bottom of the main magnet. The main basic structure of the miniaturized surface-mount return transformer can be assembled. On this basis, the wiring assembly installed on the ceramic pad is used to connect the lead-out of the wire package assembly. The wires can be reliably connected to complete the overall assembly and corresponding installation and operation of the miniaturized surface-mount return transformer. There is no need to install and arrange components such as the frame and frame lead-out pins, which greatly optimizes the internal component structure and layout space of the miniaturized surface-mount return transformer, provides sufficient structural space for the cable layout of the wire package assembly, improves the utilization rate of the wire package layout space, and makes the overall structure of the miniaturized surface-mount return transformer more regular and sophisticated, occupies less assembly space, and has a higher space utilization rate, thus realizing the overall miniaturized design of the miniaturized surface-mount return transformer, and the structural layout on related hybrid integrated circuit power products and other equipment can also be optimized accordingly.

[0112] The miniaturized surface-mount return transformer provided by the present invention and the method for manufacturing the miniaturized surface-mount return transformer used for the miniaturized surface-mount return transformer are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A miniaturized surface mount return transformer, characterized in that: It comprises a main magnet formed by aligning and bonding an upper magnet and a lower magnet, wherein the main magnet has a winding groove inside, and a wire package component formed by winding a cable is embedded in the winding groove; A ceramic pad is bonded and fixed to the bottom of the main magnet, and a wiring assembly connected to the lead-out wire of the wire package assembly is arranged on the ceramic pad.

2. The miniaturized surface mount return transformer according to claim 1, characterized in that: The wiring assembly includes a metal pad and a wiring pin. The metal pad is welded at high temperature on the bottom of the ceramic pad. The assembly end of the wiring pin is connected to the metal pad. The free end of the wiring pin extends out of the side of the main magnet and is connected to the lead wire of the wire package assembly.

3. The miniaturized surface mount return transformer according to claim 2, characterized in that: The lead wire of the wire package assembly is an enameled wire, and the free end of the wiring pin is protrudingly provided with a wiring terminal for winding the enameled wire.

4. The miniaturized surface mount return transformer according to claim 3, characterized in that: There are two wiring terminals, and the two wiring terminals are symmetrically arranged on the end surface of the free end of the wiring pin, and the gap between the two wiring terminals is matched to form a U-shaped groove that is welded and fixed to the lead wire of the wire package assembly.

5. The miniaturized surface mount return transformer according to claim 2, characterized in that: The lead wire of the wire package assembly is an enameled copper strip with a positioning hole at the end, and the free end of the wiring pin is protrudingly provided with a wiring boss that is inserted and adapted to the positioning hole and fixed by welding.

6. The miniaturized surface mount return transformer according to claim 2, characterized in that: The exterior of the terminal assembly is coated with a nickel plating layer.

7. The miniaturized surface mount return transformer according to claim 6, characterized in that: The exterior of the nickel plated layer is coated with a gold plated layer.

8. The miniaturized surface mount return transformer according to claim 2, characterized in that: The metal pad and the connection pin are fixed by welding with high melting point solder.

9. A method for manufacturing a miniaturized surface-mount return transformer, used to manufacture the miniaturized surface-mount return transformer as claimed in any one of claims 1 to 8, characterized in that: Includes steps: Prepare the substrate, process the ceramic pad into shape using a high-temperature sintering process or a high-temperature welding process, and arrange the wiring components in place; Substrate assembly: Use tooling to position the ceramic pad and wiring assembly reliably; Main body assembly, using tooling to wind the cable into a wire package assembly, then assemble the wire package assembly on the lower magnet, and then align and bond the upper magnet and the lower magnet to form the main magnet, and ensure that the wire package assembly is located in the winding groove of the main magnet, and remove the paint and tin the lead wire of the wire package assembly; The overall assembly is to reliably bond and fix the ceramic pad to the bottom of the main magnet, and reliably connect the lead wires of the wire package assembly to the wiring assembly to complete the overall assembly of the miniaturized surface mount return transformer.

10. The method for manufacturing a miniaturized surface mount return transformer according to claim 9, characterized in that: The step of assembling the substrate further includes the following subdivision steps which are implemented in sequence: Initial forming, using a forming process, to obtain a blank plate frame with a plurality of tube pin blanks arranged inside, each tube pin blank being connected to the inner side of the blank plate frame through a connecting rib; Initial assembly: fix the metal pad to the bottom of the ceramic pad by high-temperature sintering, then align the blank sheet frame to the metal pad, and use high-melting-point solder to weld each pin blank to the metal pad. Plating protection: electroplating nickel on the surface of metal pads, high melting point solder layers and pin blanks. After the nickel plating is formed by electroplating, gold is electroplated on the surface of the nickel layer. Pin forming, separating the pin blank from the connecting rib, and then using a tool to bend the pin blank into a connection pin with a desired shape; In the main body assembly of the step, the lead wires on the wire package assembly that have been depainted and tinned are welded to the free ends of the connection pins.

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