Method for mounting and soldering igbt modules

Abstract

The application provides an IGBT module mounting and welding method, which comprises the following steps: S01, connecting the back surface of a chip with double-sided sinterable or weldable surfaces to a cushion block to form a subunit semi-finished product; and S02, connecting the subunit semi-finished product with an upper lining plate, a lower lining plate and a frame respectively. The IGBT module mounting and welding method effectively shortens the patch packaging process flow. In the mounting and welding process, the entire surface of the chip is subjected to the pressure action of the cushion block. Compared with welding the cushion block on the front surface of the chip, only part of the area of the chip is subjected to the pressure action, and the action area is asymmetric. The uniformity of the welding layer is obviously improved, the contact area of the resin and the chip is reduced, the reliability of the module is improved, and thus the patch efficiency and the qualification rate of the module are improved.

Description

Technical Field

[0001] This invention relates to the field of IGBT module processing technology, and specifically to an IGBT module mounting and soldering method. Background Technology

[0002] Bilateral heat dissipation modules can effectively increase heat dissipation efficiency, reduce thermal resistance, and improve reliability, while also reducing module size and increasing power density. However, traditional bilateral heat dissipation modules generally use a stacked structure, with gates interconnected via bonding wires. The module mounting and soldering process involves: chip soldering to the lower substrate, gate wire bonding, pad soldering, and upper substrate soldering. This process is prone to problems such as cold solder joints, short circuits, uneven solder layers, and solder overflow, and the process route is also long. After module packaging, there is a large contact area between the chip and the resin, and the stress exerted by the resin on the bonding wires can easily lead to a long-term decrease in module reliability.

[0003] Therefore, the mounting and soldering method of the double-sided heat dissipation module needs to be optimized to improve the mounting efficiency of the double-sided heat dissipation module, reduce defects in the module packaging process, and improve the module packaging yield and reliability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an IGBT module mounting and soldering method, which can effectively solve various problems in the mounting process of double-sided heat dissipation modules, such as positioning, cold solder joints, short circuits, and solder layer uniformity. It reduces the contact area between the resin and the chip, effectively shortens the surface mount packaging process, and improves the module mounting efficiency and yield.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] An IGBT module mounting and soldering method includes the following steps: S01, connecting the back side of a double-sided sinterable or solderable chip to a pad to form a sub-unit semi-finished product; S02, connecting the sub-unit semi-finished product to the upper substrate, lower substrate and frame respectively.

[0007] According to the IGBT module mounting and soldering method of the present invention, the back sides of the double-sided solderable / sinterable IGBT chip and FRD chip are connected to the pad to form a sub-unit, and then the sub-unit is upside down and soldered onto the lower substrate, thereby eliminating the bonding wire process and effectively shortening the surface mount packaging process. During the mounting and soldering process, the entire surface of the chip is subjected to the pressure of the pad. Compared with soldering the pad to the front of the chip, only a part of the chip is subjected to pressure, and the area of ​​pressure is asymmetrical. This method significantly improves the uniformity of the solder layer. The chip and the pad are soldered into one piece. Based on the weight of the pad itself, it is similar to adding a counterweight to the chip, which can effectively solve problems such as chip positioning, cold solder joints and short sections during the mounting process. Since both the back and front sides of the chip are connected by solder filling, the contact area between the resin and the chip is reduced, improving the reliability of the module, thereby improving the module mounting efficiency and yield.

[0008] The above technical solution can be further improved as described below.

[0009] According to a preferred embodiment of the IGBT module mounting and soldering method of the present invention, step S02 includes the following sub-steps: S021, fixing solder pads on the auxiliary control electrode and the front area of ​​the chip on the lower substrate; S022, inverting and fixing the sub-unit semi-finished product on the lower substrate to form the lower substrate semi-finished product; S023, connecting the lower substrate semi-finished product to the upper substrate in sequence.

[0010] Specifically, a double-sided sinterable chip is used. The back of the chip is connected to the pad by silver sintering or soldering to form a sub-unit semi-finished product. Solder pads are then mounted and fixed on the auxiliary control electrode of the lower substrate and the front area of ​​the chip by spraying alcohol or applying glue. The sub-unit is then inverted onto the lower substrate to complete the welding of the lower substrate semi-finished product. During the mounting and welding process, the entire surface of the chip is subjected to the pressure of the pad. Compared with welding the pad to the front of the chip, where only a part of the chip is subjected to pressure and the area of ​​pressure is asymmetrical, the method of this invention significantly improves the uniformity of the solder layer. Finally, the upper substrate and frame are welded, which can effectively shorten the surface mount packaging process and improve the module mounting efficiency and yield.

[0011] Specifically, in another preferred embodiment, step S02 includes the following sub-steps: S021', connecting the sub-unit semi-finished product to the upper substrate to form the upper substrate semi-finished product; S022', fixing the solder pads on the auxiliary control electrode and the front area of ​​the chip on the lower substrate; S023', inverting the upper substrate semi-finished product onto the lower substrate and fixing it.

[0012] Specifically, a double-sided solderable chip is used. The back of the chip is connected to the pad by silver sintering or soldering to form a sub-unit semi-finished product. The sub-unit is then connected to the upper substrate by silver sintering or soldering to form an upper substrate semi-finished product. Solder pads are then mounted and fixed on the auxiliary control electrode and the front area of ​​the chip using alcohol spraying or glue application. Finally, the upper substrate semi-finished product is inverted onto the lower substrate to complete the module mounting and soldering. Similarly, the uniformity of the solder layer is significantly improved, which can effectively shorten the surface mount packaging process and improve the module mounting efficiency and yield.

[0013] Specifically, in another preferred embodiment, in step S01, a chip that can be sintered or soldered on both sides is connected to a pad and an upper liner to form an upper liner semi-finished product, and in step S02, the upper liner semi-finished product is inverted onto the lower liner and fixed.

[0014] Specifically, by employing silver sintering or solder welding, the interconnection of the chip, pads, and upper substrate is completed in one step, forming a semi-finished upper substrate. Solder pads are then mounted and fixed onto the auxiliary control electrode and the front area of ​​the chip using alcohol spraying or adhesive application. Finally, the semi-finished upper substrate is inverted onto the lower substrate to complete the module mounting and soldering. This method can further and effectively shorten the mounting and soldering process, significantly improve solder layer uniformity, and increase module mounting efficiency and yield.

[0015] Furthermore, in a preferred embodiment, the dimensions of the pad are larger than the dimensions of the chip.

[0016] Specifically, in order to facilitate the mounting of chips and pads and eliminate the influence of relative offset between chips and pads and the processing precision of pad raw materials, the pads are at least 0.2mm larger on one side than the chips.

[0017] Specifically, in a preferred embodiment, the thickness of the solder pad between the back of the chip and the pad is 0.05 to 0.3 mm.

[0018] The solder pads within the aforementioned thickness range can effectively ensure a strong solder joint between the back of the chip and the pad, while minimizing material waste due to excessive solder pad thickness, thus effectively saving costs.

[0019] Specifically, in a preferred embodiment, the thickness of the solder pad corresponding to the front side of the chip is 0.1 to 0.3 mm.

[0020] Similarly, the solder pads within the aforementioned thickness range can effectively ensure a secure solder joint between the chip front and the substrate, while minimizing material waste due to excessive solder pad thickness, thereby effectively saving costs.

[0021] Furthermore, in a preferred embodiment, a solder resist layer is added to the corresponding welding areas on the upper and lower liner plates.

[0022] Furthermore, adding a solder resist layer to the welding area corresponding to the liner can effectively prevent solder overflow.

[0023] Specifically, in a preferred embodiment, the size of the solder resist layer is smaller than the size of the chip gate pad soldering area on the chip, and the outer dimensions of the emitter pad on the front side of the chip and the chip emitter pad soldering area are smaller than the size of the solder resist layer.

[0024] Specifically, the solder mask size should be at least 0.2 mm smaller than the chip gate pad soldering area size, and the length and width of the emitter pads on the front side of the chip and the emitter pad soldering area should be at least 0.2 mm smaller than the solder mask size to achieve the best solder mask effect.

[0025] Specifically, in a preferred embodiment, a fixing pad is mounted on the auxiliary control electrode of the lower substrate and the front area of ​​the chip by spraying alcohol or applying adhesive.

[0026] The above-mentioned method for fixing the solder pads is simple to operate, low in cost, and can ensure that the solder pads are firmly fixed.

[0027] Compared with the prior art, the advantages of the present invention are: it can effectively solve various problems in the mounting process of double-sided heat dissipation modules, such as positioning, poor soldering, short circuits, and solder layer uniformity, reduce the contact area between resin and chip, effectively shorten the surface mount packaging process, and improve module mounting efficiency and yield. Attached Figure Description

[0028] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0029] Figure 1 The flowchart of Embodiment 1 of the present invention is illustrated schematically;

[0030] Figure 2 The illustration shows the IGBT module mounting process in Embodiment 1 of the present invention;

[0031] Figure 3 The flowchart of Embodiment 2 of the present invention is illustrated schematically;

[0032] Figure 4 The illustration shows the IGBT module mounting process in Embodiment 2 of the present invention;

[0033] Figure 5 The flowchart of Embodiment 3 of the present invention is illustrated schematically;

[0034] Figure 6 The schematic diagram illustrates the IGBT module mounting process in Embodiment 3 of the present invention;

[0035] Figure 7 The schematic diagram illustrates the planar structure of the chip in an embodiment of the invention.

[0036] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of protection of the present invention.

[0038] Figure 1 The flowchart of Embodiment 1 of the present invention is illustrated schematically. Figure 2 The illustration shows the IGBT module mounting process in Embodiment 1 of the present invention. Figure 3 The flowchart of Embodiment 2 of the present invention is illustrated schematically. Figure 4 The illustration shows the IGBT module mounting process in Embodiment 2 of the present invention. Figure 5 The flowchart of Embodiment 3 of the present invention is illustrated schematically. Figure 6 The illustration shows the IGBT module mounting process in Embodiment 3 of the present invention. Figure 7 The schematic diagram illustrates the planar structure of the chip in an embodiment of the invention.

[0039] Example 1

[0040] like Figure 1 and Figure 2 As shown, the IGBT module mounting and soldering method of this invention includes the following steps: S01, connecting the back side of a double-sided sinterable or solderable chip to a pad to form a sub-unit semi-finished product; S02, connecting the sub-unit semi-finished product to the upper substrate, lower substrate and frame respectively.

[0041] According to the IGBT module mounting and soldering method of the present invention, the back sides of the double-sided solderable / sinterable IGBT chip and FRD chip are connected to the pad to form a sub-unit, and then the sub-unit is upside down and soldered onto the lower substrate, thereby eliminating the bonding wire process and effectively shortening the surface mount packaging process. During the mounting and soldering process, the entire surface of the chip is subjected to the pressure of the pad. Compared with soldering the pad to the front of the chip, only a part of the chip is subjected to pressure, and the area of ​​pressure is asymmetrical. This method significantly improves the uniformity of the solder layer. The chip and the pad are soldered into one piece. Based on the weight of the pad itself, it is similar to adding a counterweight to the chip, which can effectively solve problems such as chip positioning, cold solder joints and short sections during the mounting process. Since both the back and front sides of the chip are connected by solder filling, the contact area between the resin and the chip is reduced, improving the reliability of the module, thereby improving the module mounting efficiency and yield.

[0042] Specifically, in this embodiment, step S02 includes the following sub-steps: S021, fixing solder pads on the auxiliary control electrode and the front area of ​​the chip on the lower substrate; S022, inverting and fixing the sub-unit semi-finished product on the lower substrate to form the lower substrate semi-finished product; S023, connecting the lower substrate semi-finished product to the upper substrate in sequence. Specifically, using a double-sided sinterable chip, the chip's back side is connected to a pad via silver sintering or soldering, or a solder paste printing and water cleaning process. This forms a sub-unit semi-finished product. Alcohol spraying or adhesive application is used to mount and fix the pads on the lower substrate's auxiliary control electrode and the chip's front side. The sub-unit is then inverted onto the lower substrate to complete the lower substrate semi-finished product welding. During the mounting and welding process, the entire chip surface is subjected to the pressure of the pads. Compared to welding the pads to the chip's front side, where only a portion of the chip is subjected to pressure and the pressure area is asymmetrical, the method of this invention significantly improves the uniformity of the solder layer. Finally, the upper substrate and frame are welded, effectively shortening the surface mount packaging process and improving module mounting efficiency and yield.

[0043] Furthermore, in this embodiment, the outer dimensions of the pad are larger than those of the chip. Specifically, to facilitate the mounting of the chip and the pad, and to eliminate the influence of relative misalignment during chip and pad mounting and the processing precision of the pad's raw materials, the pad is at least 0.2 mm larger on one side than the chip.

[0044] Specifically, in a preferred embodiment, the thickness of the solder pad between the back of the chip and the pad is 0.05–0.3 mm. This thickness range effectively ensures a secure solder joint between the back of the chip and the pad while minimizing material waste due to excessive solder pad thickness, thus effectively saving costs. Specifically, in a preferred embodiment, the thickness of the solder pad corresponding to the front of the chip is 0.1–0.3 mm. Similarly, this thickness range effectively ensures a secure solder joint between the front of the chip and the substrate while minimizing material waste due to excessive solder pad thickness, thus effectively saving costs.

[0045] like Figure 7 As shown, further, in this embodiment, a solder resist layer is added to the corresponding welding areas on the upper and lower substrates. Adding a solder resist layer to the welding areas corresponding to the substrates can effectively prevent solder overflow. Specifically, in this embodiment, the size of the solder resist layer is smaller than the size of the chip gate pad welding area, and the outer dimensions of the solder pads on the chip front side and emitter pad are smaller than the size of the solder resist layer. Specifically, the solder resist size is at least 0.2 mm smaller than the chip gate pad welding area size, and the length and width dimensions of the emitter solder pads on the chip front side and emitter pad welding areas are at least 0.2 mm smaller than the solder resist size, which optimizes the solder resist effect. Figure 7As shown, 1 is the chip gate pad welding area; 2 is the gate solder pad; 3 and 5 are solder resist layers; 4 is the chip emitter pad welding area; and 6 is the emitter solder pad.

[0046] Specifically, in this embodiment, solder pads are mounted and fixed on the auxiliary control electrode of the lower substrate and the front area of ​​the chip by spraying alcohol or applying adhesive. This method of fixing the solder pads is simple to operate, low in cost, and ensures that the pads are securely fixed.

[0047] Example 2

[0048] like Figure 3 and Figure 4 As shown, the difference between this embodiment and the above embodiment 1 is that step S02 includes the following sub-steps: S021', connecting the sub-unit semi-finished product with the upper substrate to form the upper substrate semi-finished product; S022', fixing the solder pads on the auxiliary control electrode and the front area of ​​the chip on the lower substrate; S023', inverting the upper substrate semi-finished product onto the lower substrate and fixing it.

[0049] Specifically, a double-sided solderable chip is used. The back of the chip is connected to the pad by silver sintering or soldering to form a sub-unit semi-finished product. The sub-unit is then connected to the upper substrate by silver sintering or soldering to form an upper substrate semi-finished product. Solder pads are then mounted and fixed on the auxiliary control electrode and the front area of ​​the chip using alcohol spraying or glue application. Finally, the upper substrate semi-finished product is inverted onto the lower substrate to complete the module mounting and soldering. Similarly, the uniformity of the solder layer is significantly improved, which can effectively shorten the surface mount packaging process and improve the module mounting efficiency and yield.

[0050] Example 3

[0051] like Figure 5 and Figure 6 As shown, the difference between this embodiment and the above embodiment 1 is that in step S01, the chip that can be sintered or soldered on both sides is connected to the pad and the upper substrate to form the upper substrate semi-finished product, and in step S02, the upper substrate semi-finished product is upside down on the lower substrate and fixed.

[0052] Specifically, by employing silver sintering or solder welding, the interconnection of the chip, pads, and upper substrate is completed in one step, forming a semi-finished upper substrate. Solder pads are then mounted and fixed onto the auxiliary control electrode and the front area of ​​the chip using alcohol spraying or adhesive application. Finally, the semi-finished upper substrate is inverted onto the lower substrate to complete the module mounting and soldering. This method can further and effectively shorten the mounting and soldering process, significantly improve solder layer uniformity, and increase module mounting efficiency and yield.

[0053] As can be seen from the above embodiments, the IGBT module mounting and soldering method of the present invention can effectively solve various problems in the mounting process of double-sided heat dissipation modules, such as positioning, cold solder joints, short circuits, and solder layer uniformity. It reduces the contact area between the resin and the chip, effectively shortens the surface mount packaging process, and improves the module mounting efficiency and yield.

[0054] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for mounting and soldering IGBT modules, characterized in that, Includes the following steps: S01. Connect the back side of a double-sided sinterable or solderable chip to a pad to form a sub-unit semi-finished product. S02. Connect the sub-unit semi-finished products to the upper liner, lower liner, and frame respectively; Step S02 includes the following sub-steps: S021. The auxiliary control electrode on the lower substrate and the solder pad on the front side of the chip are fixed. S022. Invert the sub-unit semi-finished product onto the lower liner plate and fix it to form the lower liner plate semi-finished product; S023. Connect the lower liner semi-finished product to the upper liner in sequence.

2. The IGBT module mounting and soldering method according to claim 1, characterized in that, Step S02 includes the following sub-steps: S021' Connect the sub-unit semi-finished product to the upper liner plate to form the upper liner plate semi-finished product; S022', Auxiliary control electrode on the lower substrate and solder pads fixed on the front area of ​​the chip; S023', Place the upper liner semi-finished product upside down on the lower liner and fix it.

3. The IGBT module mounting and soldering method according to claim 1, characterized in that, In step S01, a chip that can be sintered or soldered on both sides is connected to a pad and an upper substrate to form a semi-finished upper substrate. In step S02, the upper liner semi-finished product is inverted onto the lower liner and fixed.

4. The IGBT module mounting and soldering method according to any one of claims 1 to 3, characterized in that, The dimensions of the pad are larger than the dimensions of the chip.

5. The IGBT module mounting and soldering method according to any one of claims 1 to 3, characterized in that, The thickness of the solder pad between the back of the chip and the pad block is 0.05~0.3mm.

6. The IGBT module mounting and soldering method according to any one of claims 1 to 3, characterized in that, The thickness of the solder pad corresponding to the front side of the chip is 0.1~0.3mm.

7. The IGBT module mounting and soldering method according to any one of claims 1 to 3, characterized in that, A solder resist layer is added to the corresponding welding areas on the upper and lower liner plates.

8. The IGBT module mounting and soldering method according to claim 7, characterized in that, The size of the solder resist layer is smaller than the size of the chip gate pad soldering area on the chip, and the outer dimensions of the emitter pad on the front side of the chip and the emitter pad soldering area are smaller than the size of the solder resist layer.

9. The IGBT module mounting and soldering method according to any one of claims 1 to 3, characterized in that, Solder pads are mounted and fixed on the auxiliary control electrode of the lower substrate and the front area of ​​the chip by spraying alcohol or applying glue.

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