NTC welding correction assembly and bottom plate welding tool

Abstract

This invention provides an NTC welding straightening assembly and a base plate welding fixture. The NTC welding straightening assembly includes: a horizontal mounting arm; one end for connection to the base of the base plate welding fixture; a guide portion connected to the other end of the horizontal mounting arm, which can only move in a direction perpendicular to the horizontal mounting arm; a straightening pressure block located at the bottom of the guide portion, with a cavity at the bottom open, the cavity being a frustum shape; and an elastic element located on the guide portion, between the bottom surface of the horizontal mounting arm and the top surface of the straightening pressure block, configured to apply a downward force to the straightening pressure block. When using this base plate welding fixture for reflow soldering, after the NTC solder melts, the straightening pressure head continuously presses down under the action of the elastic element. The vertical downward pressure is converted into a horizontal correction force through the guide slope of the sidewall of the straightening pressure block cavity, pushing the NTC to the correct position, allowing the solder to fully wet the NTC, solving problems such as NTC end lifting, horizontal position deviation, and angular skew, and enabling defect repair of NTC welding.

Description

Technical Field

[0001] This invention belongs to the technical field of power device packaging methods, specifically relating to an NTC welding correction component and a base plate welding fixture. Background Technology

[0002] The NTC thermistor is the core temperature sensing element inside the IGBT module, directly soldered to the surface of the DBC substrate for real-time monitoring of the module's junction temperature. The current mainstream packaging process completes the core soldering in two steps: 1. DBC chip soldering: The power chip and NTC are simultaneously mounted and reflow soldered on the DBC substrate. In this step, the same high-temperature solder is typically used for both the chip and NTC to ensure reliable soldering. 2. Baseplate soldering: The DBC assembly with the soldered chip and NTC is then soldered to the heat sink baseplate using a solder with a lower melting point. The peak temperature only melts the baseplate solder, preventing remelting and misalignment of the chip solder joints.

[0003] Due to the small size of NTC components and pads, and the fact that DBC chip soldering processes generally do not utilize dedicated NTC positioning fixtures, placement deviations and uneven solder wetting tension during reflow can lead to NTCs exhibiting phenomena such as one end lifting, horizontal position shifting, and angular skew. Excessive deviations can result in NTC cold solder joint defects. To address these NTC soldering defects, the industry currently employs two main measures: 1. Fixture pre-positioning prevention: NTC displacement is limited before the initial soldering process using positioning grooves, limiting frames, and pre-fixing with adhesive. For example, Chinese patent CN119772296A discloses an adhesive-positioning soldering process for NTC soldering, involving adhesive dispensing at the connection points between the module substrate soldering plate and the NTC thermistor. This process eliminates the need for NTC positioning fixtures during the packaging process. Another example is Chinese patent CN222873535U, which discloses a soldering positioning device for NTC temperature sensor processing. Pre-positioning of tooling is a front-end yield improvement solution that can effectively reduce defects. However, it requires an additional tooling placement step, increasing production line complexity, and cannot repair existing defects. 2. Manual rework: Defective NTCs are manually cut off, residual solder is cleaned, and the NTCs are remounted, followed by a separate reflow soldering. Manual rework is redundant, extremely inefficient, has a large fluctuation in rework yield, and a high proportion of secondary cold solder joints. Furthermore, separate reflow soldering causes the already soldered chip and DBC to undergo an additional thermal cycle, exacerbating the thermal stress mismatch between the ceramic layer and the copper layer, and reducing reliability. Summary of the Invention

[0004] The technical problem solved by this invention is to provide an NTC welding straightening assembly and a base plate welding fixture. During reflow soldering, after the NTC solder melts, the straightening head is continuously pressed down under the elastic force of the elastic element. The vertical downward pressure is converted into a horizontal correction force through the guide slope of the cavity sidewall of the straightening block, which pushes the NTC to the correct position, so that the solder can be fully wetted. This solves problems such as NTC end lifting, horizontal position deviation, and angle skew, thereby enabling defect repair of NTC welding.

[0005] To address the above problems, a first aspect of the present invention provides an NTC welding straightening assembly, comprising: A horizontal mounting arm; one end of the horizontal mounting arm is used to connect to the base of the welding fixture for the base plate; Guide portion; the guide portion is connected to the other end of the horizontal mounting arm, and the guide portion can only move relative to the horizontal mounting arm in a direction perpendicular to the horizontal mounting arm; Correcting pressure block; the correcting pressure block is located at the bottom of the guide part; the bottom of the correcting pressure block has a cavity with an opening at the bottom end, and the cavity is a truncated quadrangular shape; An elastic element; the elastic element is disposed on the guide portion and located between the bottom surface of the horizontal mounting arm and the top surface of the straightening pressure block, the elastic element being configured to apply a downward force to the straightening pressure block.

[0006] Preferably, one end of the horizontal mounting arm is provided with a guide hole; the guide part is a guide post; the guide post passes through the guide hole and is in a small clearance sliding fit with the guide hole; the guide hole is provided with an anti-rotation protrusion, and the guide post is provided with an anti-rotation notch correspondingly, the anti-rotation notch and the anti-rotation protrusion cooperate to prevent the horizontal rotation of the guide post; the top end of the guide post is provided with a limiting pin to restrict the top end of the guide post from coming out of the guide hole.

[0007] Preferably, the elastic element is a compression spring; the compression spring is sleeved on the outside of the guide post and is coaxially arranged with the guide post; the upper end of the compression spring abuts against the bottom surface of the horizontal mounting arm, and the lower end of the compression spring abuts against the top surface of the straightening block.

[0008] Preferably, the angle between the sidewall of the cavity of the corrective pressure block and the vertical direction satisfies the following condition: , in, The angle between the sidewall of the cavity of the corrective block and the vertical direction; H represents the maximum offset of one side of the NTC; V represents the effective vertical downward stroke of the correction block; The coefficient of friction between the NTC's packaging surface and the straightening block; The coefficient of friction between the NTC electrode and the DBC substrate under molten solder lubrication.

[0009] Preferably, the spring stiffness of the compression spring satisfies the following condition: k≤F / ; Where k is the spring stiffness of the compression spring; F represents the destructive load of the NTC; This refers to the working compression of the spring.

[0010] Preferably, the side of the corrective block is provided with a plurality of vent holes penetrating the side wall of the corrective block, and the vent holes are in communication with the cavity.

[0011] Preferably, the horizontal mounting arm is made of stainless steel or titanium alloy; The corrective pressure block is made of alumina ceramic or aluminum nitride ceramic.

[0012] Preferably, the vent is located at the top or upper side wall of the cavity of the correcting block.

[0013] A second aspect of the present invention provides a base plate welding fixture, comprising: Base; used to fix the heat sink base plate and DBC; At least one of the aforementioned NTC welding straightening components, wherein one end of the horizontal mounting arm of the NTC welding straightening component is connected to the side wall of the base, and the other end extends above the DBC, such that the straightening pressure block is located above the NTC.

[0014] Preferably, the top of the side wall of the base is provided with a rectangular groove; one end of the horizontal mounting arm is embedded in the rectangular groove and is detachably connected to the rectangular groove by a positioning pin.

[0015] Compared with the prior art, the present invention has the following advantages: The NTC welding straightening assembly of this invention can be installed on the side wall of the base plate welding fixture. During reflow soldering, after the NTC solder melts, the straightening head continuously presses down under the elastic force of the elastic element. The guide slope of the cavity side wall of the straightening block converts the vertical downward pressure into a horizontal correction force, pushing the NTC to the correct position, allowing the solder to fully wet the NTC. This solves problems such as NTC end lifting, horizontal position deviation, and angular skew, thereby enabling defect repair of NTC welding. Furthermore, only a detachable straightening unit is added to the side wall of the fixture, without altering the original positioning reference and cavity structure, making it fully compatible with existing welding processes.

[0016] The base plate welding fixture of the present invention is based on the modification of the original base plate welding fixture. It retains all the original positioning references and only needs to add an installation interface on the side wall. The modular correction unit can be quickly disassembled and assembled without interfering with the original loading and unloading operations, and the implementation cost is extremely low.

[0017] The base plate welding fixture of this invention can be combined with solder system optimization to deeply couple NTC defect repair with the base plate welding process: during operation, the melting point of the NTC solder is adjusted so that it melts synchronously with the base plate solder; a detachable NTC welding correction component is set on the original base plate welding fixture, and the base plate welding and NTC defect repair are completed in one reflow, eliminating redundant steps of manual rework and improving rework efficiency several times; no separate reflow is required, avoiding the DBC and chip undergoing an extra thermal cycle, reducing thermal stress mismatch between the ceramic layer and the copper layer, reducing the risk of DBC delamination, and improving the long-term reliability of the module; the use of mechanized correction by the fixture eliminates individual differences in manual operation, and the correction position accuracy and welding consistency are far higher than those of manual rework, significantly reducing yield fluctuations. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the base plate welding fixture described in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the NTC welding straightening assembly described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the base of the welding fixture for the base plate described in an embodiment of the present invention; Figure 4 This is a force analysis diagram of the straightening pressure block and NTC in an embodiment of the present invention; Figure 5 This is a diagram showing the travel distance of the correction block and the NTC correction circuit in an embodiment of the present invention; Figure 6 This is a schematic diagram of the guide portion in the NTC welding straightening assembly described in an embodiment of the present invention.

[0019] Wherein: 1-Horizontal mounting arm; 2-Guide part; 3-Correcting pressure block; 4-Elastic element; 5-Base; 6-Cavity; 7-Guide hole; 8-Anti-rotation notch; 9-Anti-rotation protrusion; 10-Limit pin; 11-Exhaust hole; 12-Positioning pin; 13-Rectangular groove; 14-NTC; 15-DBC; 16-Boss structure; 17-Heat dissipation base plate. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1 , Figure 2 , Figure 3 As shown, the NTC welding straightening assembly of this embodiment includes: Horizontal mounting arm 1; one end of the horizontal mounting arm 1 is used to connect to the base 5 of the welding fixture for the base plate; Guide section 2; guide section 2 is connected to the other end of horizontal mounting arm 1, and guide section 2 can only move relative to horizontal mounting arm 1 in a direction perpendicular to horizontal mounting arm 1; Correcting pressure block 3; Correcting pressure block 3 is located at the bottom of guide part 2; The bottom of the correcting pressure block 3 is provided with a cavity 6 with an open bottom end, and the cavity 6 is a quadrangular frustum shape; Elastic element 4; the elastic element 4 is provided on the guide part 2 and is located between the bottom surface of the horizontal mounting arm 1 and the top surface of the straightening pressure block 3. The elastic element 4 is configured to apply a downward force to the straightening pressure block 3.

[0022] The NTC welding straightening assembly of this invention can be installed on the side wall of the base plate welding fixture. During reflow soldering, after the NTC solder melts, the straightening head continuously presses down under the elastic force of the elastic element. The guide slope of the cavity side wall of the straightening block converts the vertical downward pressure into a horizontal correction force, pushing the NTC to the correct position, allowing the solder to fully wet the NTC, and solving problems such as NTC end lifting, horizontal position deviation, and angular skew, thereby enabling defect repair of NTC welding. When the straightening block presses down, the upward reaction force generated on the horizontal mounting arm forms a torque at the connection between the horizontal mounting arm and the base, preventing the entire straightening assembly from moving upward. Furthermore, only a detachable straightening unit is added to the side wall of the fixture, without changing the original positioning reference and cavity structure, and is fully compatible with the original welding process.

[0023] Preferably, one end of the horizontal mounting arm 1 is provided with a guide hole 7; the guide part 2 is a guide post; the guide post passes through the guide hole 7 and has a small clearance sliding fit with the guide hole 7; the guide hole 7 is provided with an anti-rotation protrusion 9, such as... Figure 6As shown, the guide post is provided with a corresponding anti-rotation notch 8, which cooperates with the anti-rotation protrusion 9 to prevent the horizontal rotation of the guide post; the top of the guide post is provided with a limiting pin 10, which can prevent the top of the guide post from coming out of the guide hole 7, and prevent the pressure block from falling off when installing the straightening component on the base. The limiting pin can be removed before welding. The guide post can provide precise vertical movement guidance for the straightening pressure block and limit horizontal movement; the cooperation of the anti-rotation notch and the anti-rotation protrusion can prevent the horizontal angular rotation of the straightening pressure block.

[0024] Preferably, the elastic element 4 is a compression spring; the compression spring is sleeved on the outside of the guide post and coaxially arranged with the guide post; the upper end of the compression spring abuts against the bottom surface of the horizontal mounting arm, and the lower end of the compression spring abuts against the top surface of the straightening block. Further, the compression spring is a high-temperature resistant cylindrical helical compression spring. In its free state, the compression spring pushes the straightening block to its lower limit of stroke; after installation, it is compressed, providing a stable preload to the NTC. Optionally, the elastic element can also be a miniature high-temperature cylinder or a piezoelectric ceramic actuator to achieve active control of the pressing timing and pressure.

[0025] The cavity of the corrective pressure block is a frustum shape, which is a three-dimensional shape formed by cutting off the top of a four-sided pyramid with a plane parallel to the base of the pyramid. The lower opening edge is a guide slope that tapers inward, forming a funnel-shaped entrance that is wider at the outside and narrower at the inside. This can convert the vertical downward pressure into a horizontal corrective force. During the downward pressing process, the slope first contacts the offset and tilted NTC, and pushes it to the center as it moves downward, simultaneously completing the offset correction, angle alignment, and warping flattening.

[0026] Among them, the guide slope angle of the cavity of the correcting block 3 (i.e., the angle between the side wall of the cavity of the correcting block that applies force to the NTC and the vertical direction). Both the mechanically permissible condition and the travel coverage condition must be satisfied simultaneously. Specifically: a. The force on the straightening block and NTC is as follows Figure 4 As shown, the force equilibrium equations are listed respectively:

[0027]

[0028] ,

[0029]

[0030] when At that time, NTC can be driven, and simplification yields... Maximum value: .

[0031] in, To correct the angle between the guide slope of the pressure block and the vertical direction (correct the angle between the side wall of the cavity of the pressure block that applies force to the NTC and the vertical direction). The tangential pressure between the NTC and the straightening block; The friction between the NTC package surface and the straightening block; To correct the downward pressure of the pressure block; To correct the downward vertical force on the NTC caused by the pressure block; The coefficient of friction between the NTC electrode and the DBC substrate under molten solder lubrication; The coefficient of friction between the NTC package surface and the straightening block; The frictional force between the NTC electrode and the DBC substrate under molten solder lubrication; To correct the force that drives the NTC to move horizontally; Guide slope angle The larger the value, the smaller the horizontal correction force. To ensure that the NTC can be horizontally pushed in the molten state, therefore... Cannot exceed the upper limit ; b. such as Figure 5 The relationship between the downward displacement of the correction block and the correctable offset is as follows:

[0032] in, This represents the horizontal displacement of the NTC. To correct the vertical displacement of the pressure block; Guide slope angle The smaller the value, the smaller the maximum correction amount; to ensure coverage of the maximum NTC offset, therefore It cannot be less than the lower limit ;

[0033] in, H This represents the maximum offset on one side of the NTC. V To correct the effective vertical downward stroke of the pressure block.

[0034] Therefore, the final design perspective Values ​​in and between.

[0035] Preferably, the angle between the sidewall of the cavity of the straightening block and the vertical direction satisfies the following condition: , in, To correct the angle between the sidewall of the cavity of the pressure block and the vertical direction; H represents the maximum offset of one side of the NTC; V represents the effective vertical downward stroke of the correction block; The coefficient of friction between the NTC's packaging surface and the straightening block; The coefficient of friction between the NTC and DBC substrates under molten solder lubrication.

[0036] The spring compression force must be sufficient to prevent the NTC from being crushed; it must follow Hooke's Law: F=k Δx; where F is the compressive force of the straightening block, k is the spring stiffness, and Δx is the working compression of the spring.

[0037] Preferably, the spring stiffness of the compression spring satisfies the following condition: k≤F / ; Where k is the spring stiffness of the compression spring; F represents the destructive load of the NTC; This refers to the working compression of the spring.

[0038] This invention further derives a quantitative design formula for the slope angle and spring force, which can flexibly adjust parameters according to different NTC sizes and different production line defect levels, covering multiple series of modular products.

[0039] Preferably, the straightening block 3 has multiple vent holes 11 penetrating the side wall of the straightening block, and the vent holes 11 communicate with the cavity 6. The vent holes 11 penetrate the wall thickness of the straightening block, connecting the lower cavity of the straightening block to the outside. During reflow soldering, the flux vapors released by the melting solder are smoothly discharged through the vent holes, avoiding gas accumulation between the straightening block and the NTC and DBC, thereby preventing solder void defects and secondary NTC displacement caused by gas pressure.

[0040] Preferably, the vent 11 is located at the top or high on the side wall of the cavity 6 of the straightening block to ensure that the air passage is not blocked during the solder filling process.

[0041] Preferably, the horizontal mounting arm 1 is made of stainless steel or titanium alloy. This minimizes deformation at high temperatures, ensuring accurate pressing positions.

[0042] Preferably, the straightening block 3 is made of alumina ceramic or aluminum nitride ceramic. It is heat-resistant, non-stick to solder, and has good insulation properties. More preferably, the straightening block 3 is integrally formed.

[0043] Example 2 The base plate welding fixture in this embodiment includes: Base 5; used to fix the heat sink base plate to DBC 15; At least one of the above-described embodiments of the NTC welding straightening assembly has a horizontal mounting arm with one end connected to the side wall of the base and the other end extending above the DBC, so that the straightening pressure block is located above the NTC14.

[0044] In this embodiment, the base plate welding fixture retains all the original base plate positioning pins, DBC limiting blocks, and other structures intact, with the positioning reference completely consistent with the original fixture. Only the NTC welding correction component is installed on the base sidewall corresponding to the NTC position, without altering the base cavity or support surface, and without affecting the original welding process. The fixture base has a DBC limiting block with a small clearance fit between the limiting block and the edge of the DBC substrate, preventing observable planar slippage of the DBC component. The heat dissipation base plate 17 itself has a boss structure 16; the distance between the top surface of the boss and the lower surface of the DBC is the design thickness of the base plate solder layer; the solder layer thickness is precisely controlled by the boss height. The NTC welding correction component is a cantilevered modular independent structure. After the workpiece is in place, it can be detachably installed on the base sidewall. Each unit corresponds to one NTC, and its position can be independently adjusted and replaced without affecting other workstations or the functions of the original fixture.

[0045] The base plate welding fixture in this embodiment is based on the original base plate welding fixture. It retains all the original positioning references and only requires the addition of installation interfaces on the side wall. The modular correction unit can be quickly disassembled and assembled without interfering with the original loading and unloading operations, resulting in extremely low implementation costs.

[0046] Preferably, the top of the side wall of the base 5 is provided with a rectangular groove 13; one end of the horizontal mounting arm 1 is embedded in the rectangular groove 13 and is detachably connected to the rectangular groove 13 by a positioning pin 12. The NTC welding straightening assembly can be quickly assembled and disassembled without affecting other workstations or the functions of existing tooling. When the straightening block is pressed down, the upward reaction force generated on the horizontal mounting arm forms a torque on the positioning pin 12, preventing the entire straightening assembly from moving upward.

[0047] The base plate welding fixture of this embodiment is used as follows: S1. Using solder with a melting point of T1, the chip is soldered onto the DBC substrate, and using solder with a melting point of T2, the NTC is soldered onto the DBC substrate to obtain the DBC soldering assembly; T1 T2≥20℃; S2. Fix the heat dissipation base plate to the base of the base plate welding fixture, place the solder with a melting point of T2 and the DBC welding assembly on the heat dissipation base plate in sequence, and fix the heat dissipation base plate and the DBC welding assembly through the base; S3. Install the NTC welding straightening assembly to the corresponding position on the side wall of the base, so that the inner wall of the cavity of the straightening block contacts the NTC; S4. The assembled base plate welding fixture is heated according to the standard temperature curve for heat dissipation base plate welding and then reflow soldered.

[0048] The base plate welding fixture in this embodiment can be optimized in conjunction with the solder system. High-melting-point solder is used to weld the power chip to the DBC substrate, while the same medium-melting-point solder used in subsequent base plate welding is used for NTC mounting and welding. After the heat sink base plate and DBC substrate are positioned and installed, during reflow soldering, the temperature is increased according to the standard temperature curve for base plate welding. When the temperature reaches above T2 and below T1, the NTC solder and base plate solder melt synchronously. The straightening head continuously presses down under elastic force, converting the vertical downward pressure into a horizontal correction force through the guide slope, pushing the NTC to the correct position. The solder fully wets the NTC, completing defect repair. Throughout this process, the chip solder remains solid, and its position is unaffected. In step S2, when the heat sink base plate and DBC welding assembly are precisely positioned using the fixture base, the straightening unit is not installed, there is no structural interference, and the workpiece loading and unloading operations are completely consistent with the original process.

[0049] The base plate welding fixture of this invention can be optimized and matched with the solder system to deeply couple the NTC defect repair with the base plate welding process: on the one hand, the melting point of the NTC solder is adjusted so that it melts synchronously with the base plate solder; on the other hand, a detachable NTC welding correction component is added to the original base plate welding fixture, so that the base plate welding and NTC defect repair are completed in one reflow, eliminating redundant steps of manual rework and improving rework efficiency by several times; no separate reflow is required, avoiding the DBC and chip undergoing an extra thermal cycle, reducing thermal stress mismatch between the ceramic layer and the copper layer, reducing the risk of DBC delamination, and improving the long-term reliability of the module; the use of mechanized correction by the fixture eliminates individual differences in manual operation, and the correction position accuracy and welding consistency are much higher than those of manual rework, significantly reducing yield fluctuations.

[0050] Example 3 This embodiment is applied to the vacuum reflow soldering process of the base plate of an IGBT module. The NTC body is a cylindrical structure with a diameter of 2mm and a length of 3.2mm. The destructive load... The original production line has a maximum single-sided offset of 1.5mm for NTC; the base plate welding fixture as described in Example 2 is used, and the structural parameters of the NTC welding correction component are as follows.

[0051] 1. Solder system configuration The chip DBC solder uses SnSb5 high-temperature solder with a melting point of [missing information]. The NTC-DBC solder and DBC-baseplate solder use SAC305 solder, with a melting point of [missing information]. The melting point difference is 23℃, which meets the design criterion of ≥20℃; the peak welding temperature of the base plate is set to 230℃, which is between the two melting points.

[0052] 2. NTC Welding Straightening Component Parameter Design (1) Angle of the guide slope The straightening clamp is made of 95% alumina ceramic, and its friction coefficient with the NTC borosilicate glass encapsulation surface is [missing information]. 4; The coefficient of friction between NTC electrode and DBC under molten SnSb5 solder lubrication ; Calculated ; The effective vertical downward stroke of the pressure block is , needs to be covered The offset is calculated. ; Therefore, select .

[0053] (2) Spring compression force design The safety factor is taken as 5.88, and the working pressure is... .

[0054] Spring working compression The spring stiffness is calculated as follows: .

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An NTC welding straightening assembly, characterized in that, include: Horizontal mounting arm; One end of the horizontal mounting arm is used to connect to the base of the welding fixture for the base plate; Guiding department; The guide portion is connected to the other end of the horizontal mounting arm, and the guide portion can only move relative to the horizontal mounting arm in a direction perpendicular to the horizontal mounting arm; Correcting pressure block; the correcting pressure block is located at the bottom of the guide part; the bottom of the correcting pressure block has a cavity with an opening at the bottom end, and the cavity is a truncated quadrangular shape; An elastic element; the elastic element is disposed on the guide portion and located between the bottom surface of the horizontal mounting arm and the top surface of the straightening pressure block, the elastic element being configured to apply a downward force to the straightening pressure block.

2. The NTC welding straightening assembly according to claim 1, characterized in that: One end of the horizontal mounting arm is provided with a guide hole; the guide part is a guide post; the guide post passes through the guide hole and is in a small clearance sliding fit with the guide hole; the guide hole is provided with an anti-rotation protrusion, and the guide post is provided with an anti-rotation notch correspondingly, the anti-rotation notch and the anti-rotation protrusion cooperate to prevent the horizontal rotation of the guide post; the top end of the guide post is provided with a limiting pin to restrict the top end of the guide post from coming out of the guide hole.

3. The NTC welding straightening assembly according to claim 2, characterized in that: The elastic element is a compression spring; the compression spring is sleeved on the outside of the guide post and is coaxially arranged with the guide post; the upper end of the compression spring abuts against the bottom surface of the horizontal mounting arm, and the lower end of the compression spring abuts against the top surface of the straightening block.

4. The NTC welding straightening assembly according to claim 1, characterized in that: The angle between the sidewall of the cavity of the corrective pressure block and the vertical direction satisfies the following condition: , in, The angle between the sidewall of the cavity of the corrective block and the vertical direction; H represents the maximum offset of one side of the NTC; V represents the effective vertical downward stroke of the correction block; The coefficient of friction between the NTC package surface and the straightening block; The coefficient of friction between the NTC electrode and the DBC substrate under molten solder lubrication.

5. The NTC welding straightening assembly according to claim 3, characterized in that: The spring stiffness of the compression spring satisfies the following condition: k≤F / ; Where k is the spring stiffness of the compression spring; F represents the destructive load of the NTC; This refers to the working compression of the spring.

6. The NTC welding straightening assembly according to claim 1, characterized in that: The side of the corrective block is provided with a plurality of vent holes that penetrate the side wall of the corrective block, and the vent holes are connected to the cavity.

7. The NTC welding straightening assembly according to claim 1, characterized in that: The horizontal mounting arm is made of stainless steel or titanium alloy. The corrective pressure block is made of alumina ceramic or aluminum nitride ceramic.

8. The NTC welding straightening assembly according to claim 6, characterized in that: The vent is located at the top or upper side wall of the cavity of the corrective block.

9. A base plate welding fixture, characterized in that, include: Base; Used to fix the heat sink base plate and DBC; At least one NTC welding straightening assembly as described in any one of claims 1-8, wherein one end of the horizontal mounting arm of the NTC welding straightening assembly is connected to the side wall of the base, and the other end extends above the DBC, such that the straightening pressure block is located above the NTC.

10. The base plate welding fixture according to claim 9, characterized in that: The top of the side wall of the base is provided with a rectangular groove; one end of the horizontal mounting arm is embedded in the rectangular groove and is detachably connected to the rectangular groove by a positioning pin.

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