Fixing device of power switch transistor

By using a combination of thermally conductive insulating pads and insulating bushings between the power switching transistor and the structural frame, the problems of thermal conductivity and insulation reliability are solved, achieving stable installation and good insulation effect of the power switching transistor.

CN224165117UActive Publication Date: 2026-04-24BEIJING RES INST OF TELEMETRY
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
BEIJING RES INST OF TELEMETRY
Filing Date
2025-03-19
Publication Date
2026-04-24

AI Technical Summary

Technical Problem

Power switching transistors have poor thermal conductivity and insulation reliability during installation, and their reliability is easily reduced due to damage to the thermal insulation pad.

Method used

The structure employs a combination of thermally conductive insulating pads and insulating bushings. The thermally conductive insulating pads provide insulation and heat conduction between the power switching transistors and the structural frame, while the insulating bushings provide thermal insulation between the structural frame and the mounting screws, thus preventing damage to the thermally conductive insulating pads during screw tightening.

Benefits of technology

This improves the installation reliability of power switching transistors, ensures thermal insulation performance, prevents damage to the thermal insulation pad during fastening, and achieves good insulation and thermal conductivity.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model provides a fixing device for a power switch transistor. The fixing device comprises the power switch transistor, a structural frame, an insulating bush, a heat-conducting insulating pad, a soldering lug, a mounting screw and a nut. Insulation and heat conduction between the flange of the power switch transistor and the structural frame are realized through the heat conduction insulation pad, and heat conduction and insulation are realized through the bushing with the large end and the small end. The diameter of a pin via hole in the structural frame is larger than that of a pin via hole in the heat-conducting insulating pad, so that the pins are prevented from being in contact with the frame in a screw fastening process; the diameter of the mounting hole of the heat-conducting insulating pad is greater than that of the small end of the insulating bush, so that friction between the heat-conducting insulating pad and the insulating liner in a screw fastening process and damage of the heat-conducting insulating pad caused by shearing of the edge of the bush to the heat-conducting insulating pad can be avoided, and good insulation is ensured; the thickness of the small end of the lining is larger than the thickness of the structural frame and smaller than the sum of the thicknesses of the structural frame and the heat-conducting insulating pad, and a compression reserved space is generated when the nut is screwed.
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Description

Technical Field

[0001] This utility model relates to the field of electrical component technology, specifically to a mounting device for a power switching transistor. Background Technology

[0002] The full name of the power switching transistor is NPN power switching transistor. It has an F-0 metal hermetically sealed structure with two pins, which are the base and emitter, and the case is the collector. When the device is mounted on the metal frame of the equipment, the impedance insulation characteristics between the case and the mounting frame must be ensured. At the same time, the heat dissipation of this device is relatively large, so a thermally conductive and insulating fixing device is required.

[0003] Because thermally conductive insulating pads are generally thin, they are easily damaged when installed with insulating bushings and power switching transistors, leading to reduced reliability.

[0004] Therefore, a highly reliable thermally conductive and insulating fixing device is needed. Summary of the Invention

[0005] This invention addresses the issues of thermal conductivity and insulation reliability during the installation of power switching transistors. It provides a fixing device for power switching transistors, which uses a thermally conductive insulating pad placed between the structural frame and the power switching transistor to insulate and conduct heat between the transistor's flange and the frame. A bushing with large and small ends, placed between the structural frame and the mounting screws, provides both thermal conductivity and insulation. The diameter of the pin through-hole on the structural frame is larger than the diameter of the pin through-hole on the thermally conductive insulating pad, preventing contact between the pins and the frame during screw tightening and ensuring reliable insulation. The diameter of the mounting hole on the thermally conductive insulating pad is larger than the diameter of the small end of the insulating bushing, preventing friction between the thermally conductive insulating pad and the insulating bushing during screw tightening, and preventing shearing damage to the thermally conductive insulating pad by the bushing edge, thus ensuring good insulation. The thickness of the small end of the bushing is greater than the thickness of the structural frame but less than the sum of the thicknesses of the structural frame and the thermally conductive insulating pad, providing space for compression when the nut is tightened. This prevents direct contact between the small end and the thermally conductive insulating pad after tightening, thus preventing damage to the pad and improving reliability.

[0006] This utility model provides a fixing device for a power switching transistor, including a power switching transistor, a structural frame, an insulating bushing, a thermally conductive insulating pad, a solder pad, mounting screws, and nuts;

[0007] The power switching transistor includes a flange, pins connected to the lower end of the flange, mounting holes connected to both sides of the flange, and a power switching transistor body connected to the top of the flange and communicating with the pins.

[0008] The structural frame includes a power switch transistor mounting slot and a first mounting hole and a first pin via connected in the power switch transistor mounting slot;

[0009] The insulating bushing is a T-shaped cylinder, including a large end, a small end, and a central through hole connected to the center of the large end and the small end;

[0010] The thermally conductive insulating pad includes a thermally conductive insulating pad body and a second mounting hole and a second pin via connected to the thermally conductive insulating pad body;

[0011] A thermally conductive insulating pad is placed between the power switch transistor mounting slot and the flange. The pins pass through the second pin through hole and the first pin through hole in sequence. The small end passes through the first mounting hole, and the large end is located on the lower surface of the power switch transistor mounting slot. The mounting screw passes through the middle through hole, the second mounting hole, the solder pad, and the nut threaded connection in sequence.

[0012] The outer diameter of the small end is smaller than the diameter of the first mounting hole, and its thickness is greater than the thickness of the first mounting hole but less than the sum of the thickness of the first mounting hole and the thermally conductive insulating pad.

[0013] In a preferred embodiment of the power switching transistor fixing device of the present invention, the number of mounting holes, the first mounting hole and the second mounting hole are the same and their positions correspond, and the number of insulating bushings, solder pads, mounting screws and nuts is the same as the number of mounting holes.

[0014] The hardness of the thermally conductive insulating pad is less than that of the insulating bushing.

[0015] In a preferred embodiment of the fixing device for a power switching transistor described in this utility model, the diameters of the pins are successively smaller than the diameters of the second pin via and the first pin via.

[0016] In a preferred embodiment of the power switching transistor fixing device described in this utility model, the diameters of the first mounting hole and the second mounting hole are the same.

[0017] In a preferred embodiment of the power switch transistor fixing device described in this utility model, the outer edge dimension of the thermally conductive insulating pad body is larger than the outer edge dimension of the flange but smaller than the mounting groove dimension of the power switch transistor.

[0018] In a preferred embodiment of the fixing device for a power switching transistor described in this utility model, the diameter of the pin is 0.5mm, the diameter of the first pin via is 3mm, and the diameter of the second pin via is 2mm.

[0019] There are two pins, two first pin vias, and two second pin vias.

[0020] In a preferred embodiment of the fixing device for the power switching transistor described in this utility model, the diameter of the mounting hole is 3mm, the diameter of the first mounting hole is 4.6mm, the outer diameter of the small end is 4.4mm, and the outer diameter of the large end is 6mm.

[0021] In a preferred embodiment of the fixing device for the power switching transistor described in this utility model, the thickness of the power switching transistor mounting groove is 2mm, the thickness of the small end is 2.3mm, and the thickness of the thermally conductive insulating pad body is 0.5mm.

[0022] In a preferred embodiment of the fixing device for the power switching transistor described in this utility model, the diameter of the central through hole is 2.6 mm, and the mounting screw is M2.5X10 mm.

[0023] In a preferred embodiment of the fixing device for a power switching transistor described in this utility model, the frame is made of aluminum alloy, the insulating bushing is made of polyimide, and the thermally conductive insulating pad is made of thermally conductive insulating rubber.

[0024] Power switching transistors are metal-packaged, with their flanges serving as collectors and not directly contacting the frame. Furthermore, the transistors themselves have significant heat dissipation, and rising temperatures can affect their normal operation. Therefore, the installation of power switching transistors requires addressing both thermal conductivity and insulation issues.

[0025] This utility model discloses a power switching transistor fixing device, including a power switching transistor, a structural frame for mounting the power switching transistor, an insulating bushing, a thermally conductive insulating pad, a solder pad, mounting screws, and nuts. The frame has a mounting groove similar in shape to but slightly larger than the power switching transistor flange. The bottom of the groove has mounting holes and pin through holes for the power switching transistor. The opening size and position of the thermally conductive insulating pad are consistent with the power switching transistor, and its shape is similar to but slightly larger than the power switching transistor flange, and smaller than the bottom surface of the mounting groove. The insulating bushing is a T-shaped cylinder with a through hole in the middle. During installation, the thermally conductive insulating pad is first placed at the bottom of the mounting groove with its opening aligned with the groove opening. The pin-side of the power switching transistor flange is placed on the thermally conductive insulating pad, with the pins passing through the thermally conductive insulating pad and the pin holes at the bottom of the mounting groove. The small end of the insulating bushing is installed from the reverse side of the power switching transistor mounting groove in the frame, inserted into the power switching transistor mounting hole, and passes through the bottom surface of the groove and part of the insulating pad. The mounting screw passes through the insulating bushing, frame, thermally conductive insulating pad, power switching transistor flange, and solder pad, and is then tightened with the nuts. This device enables thermally insulated mounting of power switching transistors. It is suitable for thermally insulated mounting of power switching transistors or similar devices. It features a compact design and reliable installation.

[0026] This utility model has the following advantages:

[0027] (1) This utility model achieves insulation and heat conduction between the flange of the power switching transistor and the structural frame by setting a thermally conductive insulating pad between the structural frame and the power switching transistor, and achieves heat conduction and insulation by setting a bushing with large and small ends between the structural frame and the mounting screw.

[0028] (2) In this utility model, the diameter of the through hole of the tube on the structural frame is larger than the diameter of the through hole of the thermally conductive insulating pad, so as to avoid the tube and the frame from contacting each other during the screw tightening process and ensure reliable insulation.

[0029] (3) In this utility model, the diameter of the mounting hole of the thermally conductive insulating pad is larger than the diameter of the small end of the insulating bushing, which can avoid friction between the thermally conductive insulating pad and the insulating bushing during the screw tightening process, as well as the shearing of the thermally conductive insulating pad by the edge of the bushing, thereby ensuring good insulation.

[0030] (4) In this utility model, the thickness of the small end of the bushing is greater than the thickness of the structural frame and less than the sum of the thickness of the structural frame and the thermally conductive insulating pad. This provides a space for compression when the nut is tightened, so that the small end of the nut does not directly contact the thermally conductive insulating pad after tightening, thus preventing damage to the thermally conductive insulating pad and improving reliability.

[0031] (5) This utility model solves the problems of heat dissipation and insulation of power switching transistors. It is simple in design, easy to process, and reliable in assembly.

[0032] (6) This utility model is applicable to the installation and fixing of similar components with similar shapes and functions. The frame slot size, mounting hole size and position, thermally conductive insulating pad and bushing size are adjusted according to the flange size and pin position of the electronic components. It can be used for the installation of similar devices, with strong versatility and wide applicability. Attached Figure Description

[0033] Figure 1a A schematic diagram of a mounting device for a power switching transistor;

[0034] Figure 1b A schematic cross-sectional view along the FF direction of a mounting device for a power switching transistor;

[0035] Figure 2 A schematic diagram of a fixed device for a power switching transistor;

[0036] Figure 3 A schematic diagram of the lead-out terminals of a power switching transistor in a fixed device.

[0037] Figure 4a A frame diagram of a mounting device for a power switching transistor;

[0038] Figure 4b A cross-sectional view along the CC direction of a mounting frame for a power switching transistor;

[0039] Figure 5 A schematic diagram of an insulating bushing for fixing a power switching transistor;

[0040] Figure 6This is a schematic diagram of a thermally conductive insulating pad used to mount a power switching transistor.

[0041] Figure label:

[0042] 1. Power switching transistor; 11. Flange; 12. Pin; 121. Base; 122. Emitter; 13. Mounting hole; 14. Power switching transistor body; 2. Structural frame for mounting the power switching transistor; 21. Power switching transistor mounting slot; 22. First mounting hole; 23. First pin via; 3. Insulating bushing; 31. Large end; 32. Small end; 33. Central through hole; 4. Thermally conductive insulating pad; 41. Thermally conductive insulating pad body; 42. Second mounting hole; 43. Second pin via; 5. Solder tab; 6. Mounting screw; 7. Nut. Detailed Implementation

[0043] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Example 1

[0044] like Figures 1a-1b As shown, a thermally conductive and insulating fixing device for a power switching transistor includes a power switching transistor 1, a structural frame 2 for mounting the power switching transistor, an insulating bushing 3, a thermally conductive insulating pad 4, a solder pad 5, mounting screws 6, and nuts 7.

[0045] like Figure 2 As shown, the power switching transistor 1 includes a flange 11, two pins 12 with a diameter of Ф0.5mm, and two mounting holes 13 with a diameter of Ф3mm.

[0046] like Figure 3 The diagram shows the polarity arrangement (leads facing upwards), where 121 is the base, 122 is the emitter, and the casing is the collector.

[0047] like Figures 4a-4b As shown, the frame 2 includes a power switch transistor mounting slot 21 with a wall thickness of 2mm at the bottom, two power switch transistor mounting holes (first mounting holes) 22 with a diameter of Ф4.6mm, and two pin vias (first pin vias) 23 with a diameter of Ф3mm.

[0048] like Figure 5 As shown, the insulating bushing 3 is a T-shaped cylinder, including a large end 31 with a diameter of Ф6mm and a thickness of 1mm, a small end 32 with a diameter of Ф4.4mm and a thickness of 2.3mm, and a central through hole 33 with a diameter of Ф2.6mm.

[0049] like Figure 6As shown, the thermally conductive insulating pad 4 includes a thermally conductive insulating pad body 41, two mounting holes (second mounting holes) 42 with a diameter of Ф4.6mm, two pin through holes (second pin through holes) 43 with a diameter of Ф2mm, and a thickness of 0.5mm.

[0050] The frame 2 is made of aluminum alloy, the insulating bushing 3 is made of polyimide, and the thermally conductive insulating pad 4 is made of thermally conductive insulating rubber.

[0051] During installation, the thermally conductive insulating pad 4 is first placed in the power switch transistor mounting slot of the frame 2, and then the power switch transistor 1 is placed on the thermally conductive insulating pad 4, with the flange pin face of the power switch transistor 1 in contact with the thermally conductive insulating pad 4. The thermally conductive insulating pad 4 is used to achieve electrical insulation between the power switch transistor 4 and the frame 2, and to form a thermally conductive path between the power switch transistor 1 and the frame 2. The small end 32 of the insulating bushing 3 is inserted into the transistor mounting hole 22 from the reverse side of the transistor mounting slot of the frame 2, and the large end 31 protrudes out of the transistor mounting hole 22. The mounting screw 6 is M2.5X10, which passes through the mounting hole 13 of the power switch transistor 1 and the solder pad 5 through the middle through hole 32 of the insulating bushing 3, and is tightened with the M2.5 nut 7. The insulating bushing 3 ensures electrical insulation between the flange 11, solder pad 5, mounting screw 6, nut 7 of the power switch transistor 1 and the frame 2. The two mounting holes 41 of the thermally conductive insulating pad 4 have a diameter of Ф4.6mm, which is larger than the diameter of the small end 32 of the insulating bushing 3 (Ф4.4mm). The thickness of the small end 32 of the insulating bushing 3 (Ф2.3mm) is larger than the thickness of the bottom of the mounting groove of the frame 2 (Ф2mm). This design allows the thermally conductive insulating pad 4 to be positioned by the insulating bushing 3. During the tightening of the mounting screws 6 and nuts 7, friction between the small end 32 of the bushing and the thermally conductive insulating pad 4 is avoided, which could damage the thermally conductive insulating pad 4 and cause insulation failure. The two pin through holes 42 of the thermally conductive insulating pad 4 have a diameter of Ф2mm, which is smaller than the diameter of the pin through holes 23 of the frame 2 (Ф3mm). This design avoids contact between the pins and the frame, ensuring reliable insulation.

[0052] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A fixture for power switching transistors, characterized by: It includes a power switching transistor (1), a structural frame (2), an insulating bushing (3), a thermally conductive insulating pad (4), a solder pad (5), mounting screws (6) and nuts (7); The power switching transistor (1) includes a flange (11), a pin (12) connected to the lower end of the flange (11), mounting holes (13) connected to both sides of the flange (11), and a power switching transistor body (14) connected to the top of the flange (11) and communicating with the pin (12). The structural frame (2) includes a power switch transistor mounting slot (21) and a first mounting hole (22) and a first pin via (23) connected in the power switch transistor mounting slot (21); The insulating bushing (3) is a T-shaped cylinder, including a large end (31), a small end (32) connected together, and a central through hole (33) connected to the center of the large end (31) and the small end (32); The thermally conductive insulating pad (4) includes a thermally conductive insulating pad body (41) and a second mounting hole (42) and a second pin through hole (43) connected to the thermally conductive insulating pad body (41); The thermally conductive insulating pad (4) is placed between the power switch transistor mounting slot (21) and the flange (11). The pin (12) passes through the second pin through hole (43) and the first pin through hole (23) in sequence. The small end (32) passes through the first mounting hole (22). The large end (31) is located on the lower surface of the power switch transistor mounting slot (21). The mounting screw (6) passes through the intermediate through hole (33), the second mounting hole (42), the solder pad (5), and is threaded to the nut (7) in sequence. The outer diameter of the small end (32) is smaller than the diameter of the first mounting hole (22), and its thickness is greater than the thickness of the first mounting hole (22) and less than the sum of the thickness of the first mounting hole (22) and the thermally conductive insulating pad (4).

2. A power switch transistor fixing device according to claim 1, characterized in that: The number of mounting holes (13), the first mounting hole (22) and the second mounting hole (42) are the same and their positions are corresponding. The number of insulating bushings (3), welding pieces (5), mounting screws (6) and nuts (7) are the same as the number of mounting holes (13). The hardness of the thermally conductive insulating pad (4) is less than that of the insulating bushing (3).

3. The power switching transistor fixture of claim 1, wherein: The diameter of the pin (12) is successively smaller than the diameter of the second pin via (43) and the diameter of the first pin via (23).

4. The power switching transistor fixture of claim 1, wherein: The diameter of the first mounting hole (22) is the same as the diameter of the second mounting hole (42).

5. The power switching transistor fixture of claim 1, wherein: The outer edge dimension of the thermally conductive insulating pad body (41) is larger than the outer edge dimension of the flange (11) and smaller than the dimension of the power switch transistor mounting groove (21).

6. The power switching transistor holder of claim 1, wherein: The diameter of the pin (12) is 0.5 mm, the diameter of the first pin via (23) is 3 mm, and the diameter of the second pin via (43) is 2 mm. The number of pins (12), the first pin via (23), and the second pin via (43) are all two.

7. The power switching transistor fixture of claim 1, wherein: The diameter of the mounting hole (13) is 3 mm, the diameter of the first mounting hole (22) is 4.6 mm, the outer diameter of the small end (32) is 4.4 mm, and the outer diameter of the large end (31) is 6 mm.

8. The power switching transistor fixture of claim 1, wherein: The thickness of the power switch transistor mounting groove (21) is 2mm, the thickness of the small end (32) is 2.3mm, and the thickness of the thermally conductive insulating pad body (41) is 0.5mm.

9. The power switching transistor fixture of claim 1, wherein: The diameter of the intermediate through hole (33) is 2.6 mm, and the mounting screw (6) is M2.5X10 mm.

10. The power switching transistor fixture of claim 1, wherein: The frame (2) is made of aluminum alloy, the insulating bushing (3) is made of polyimide, and the thermally conductive insulating pad (4) is made of thermally conductive insulating rubber.