TO-254AA metal package insulation resistance testing device and method

Abstract

The present application belongs to the field of insulation resistance test, and relates to a TO-254AA metal package insulation resistance test device and method. The device lead hole on the jig base is used for the insertion connection of the device lead-out end, and the device lead hole provides necessary electrical connection points for the test. The three-terminal lead-out end is used for external circuit resistance test. During the test, the needle implanting plate moving end is pushed to compress the elastic component, the device shell is placed on the jig base, the device lead-out end is arranged in the device lead hole, the needle implanting plate moving end is released, the elastic component pushes the needle implanting plate moving end, the spring needle is in close contact with the surface of the device shell, and the insulation resistance test of the device shell is realized. The setting of the elastic component avoids the problem of excessive extrusion or insufficient contact of the spring needle and the device shell, ensures the stability of the contact between the spring needle and the device shell, and avoids scratching the device shell during detection.

Description

Technical Field

[0001] This invention belongs to the field of insulation resistance testing, and relates to a TO-254AA metal-encapsulated insulation resistance testing device and method. Background Technology

[0002] The insulation resistance of electronic components can sensitively reflect the insulation status of the components and effectively detect widespread moisture absorption, localized severe moisture absorption, and through-hole defects. The TO-254AA metal package is one of the most commonly used housings for power devices. In actual use, users typically connect the package to the chassis or other structural components (lowest potential) for heat dissipation. When the device's three-terminal leads are not fully insulated from the package, the lowest potential of the package will affect the normal operation of the device. Therefore, implementing insulation testing between the TO-254AA metal package leads and the package is of significant practical importance.

[0003] In existing insulation testing methods, manual measurement is commonly used. This involves using a megohmmeter by contacting the leads with the casing to test the insulation, as detailed below: 1. Since the device casing has no lead-out ports, the current method mainly uses the test probes to directly contact the lead-out to test the insulation between the lead-out and the casing. Since indirect testing cannot be performed through a test fixture, the test probes are very likely to damage the appearance of the device. 2. Testing a single device with a megohmmeter requires contacting the leads and casing three times with the probes. Furthermore, after completing the insulation resistance test, a DC parameter test is required to ensure device performance and test reliability, resulting in very low testing efficiency. 3. Existing test equipment's test fixtures and test adapters can only bring out the device pins as leads, and cannot bring out the device's metal casing, thus making it impossible to directly perform insulation resistance testing.

[0004] This manual measurement method suffers from low testing efficiency, poor device appearance protection, and the inability to directly perform insulation resistance testing. It is also prone to missing device measurements, which seriously affects the reliability of the device. Summary of the Invention

[0005] The purpose of this invention is to provide a TO-254AA metal package insulation resistance testing device and method to solve the technical problems of low efficiency of manual measurement and testing, poor protection effect of device appearance, and inability to directly achieve insulation resistance testing.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a TO-254AA metal-packaged insulation resistance testing device, comprising: The fixture base has three device lead sockets, which are used for the insertion and connection of device leads. Each device lead socket is electrically connected to two three-terminal leads. The needle plate moving end is slidably arranged on the fixture base. The needle plate moving end is also connected to the fixture base through an elastic component. The needle plate moving end is provided with two spring needles. The end of the spring needle near the device lead insertion hole protrudes from the surface of the needle plate moving end. The spring needle is electrically connected to the outer shell lead end.

[0007] Furthermore, the lead sockets of the three devices are arranged in the same plane and at equal intervals.

[0008] Furthermore, the fixture base is also provided with a pin plate fixing end, which is fixedly connected to the fixture base, and the pin plate fixing end is connected to the pin plate moving end through an elastic component.

[0009] Furthermore, the fixture base is provided with a first contact surface for the device housing, the opening of the device lead insertion hole is located on the first contact surface for the device housing, the moving end of the pin plate is provided with a second contact surface for the device housing, the protruding end of the spring pin is located on one side of the second contact surface for the device housing, both the first contact surface and the second contact surface for the device housing are flat surfaces, and the first contact surface and the second contact surface for the device housing are perpendicular to each other.

[0010] Furthermore, the spring pins are arranged in parallel and are perpendicular to the second contact surface of the device housing.

[0011] Furthermore, the end face of the spring pin near the device lead socket is a hemispherical contact surface.

[0012] Furthermore, the elastic component consists of several parallel springs, which connect the fixed end of the implantation plate to the moving end of the implantation plate.

[0013] Furthermore, both the three-terminal lead-out terminal and the housing lead-out terminal are connected to a relay.

[0014] This invention also discloses a method for testing the insulation resistance of TO-254AA metal-packaged metal structures, based on a TO-254AA metal-packaged insulation resistance testing device, comprising the following steps: Push the moving end of the pin plate, compress the elastic component through the moving end of the pin plate, place the device housing on the fixture base, so that the device lead end passes through the device lead socket, release the moving end of the pin plate, so that the spring pin is in close contact with the surface of the device housing. Three-terminal contact test: Detects the contact impedance between the three device leads and the three device lead sockets; TO-254AA Device Functional Test: Apply rated voltage to the TO-254AA device and detect operating current deviation; Contact test between the three leads and the outer casing: After shorting the three device leads, perform a contact test with the outer casing to ensure that the physical connection is normal before the insulation resistance test; Insulation resistance test: The insulation resistance is tested by applying pressure and measuring current. DC parameter testing: DC parameter testing is performed using the three-terminal leads to ensure the safety of the TO-254AA device after high-voltage testing.

[0015] Furthermore, the rated voltage applied to the TO-254AA device is 500V.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The device lead socket on the fixture base of this invention is used for the insertion and connection of device leads, providing necessary electrical connection points for testing. The three-terminal leads are used for external circuit resistance testing. During testing, the moving end of the pin plate is pushed, compressing the elastic component and placing the device housing on the fixture base, facilitating the insertion of the device leads into the lead socket. Releasing the moving end of the pin plate causes the elastic component to push the pin plate, ensuring close contact between the spring pin and the surface of the device housing, thus achieving insulation resistance testing of the device housing. The elastic component avoids excessive compression or insufficient contact between the spring pin and the device housing, ensuring stable contact and preventing scratches on the device housing during testing. This invention achieves insulation resistance testing of the device housing, significantly improving testing efficiency and preventing damage to the device appearance caused by the test leads during testing.

[0017] 2. The three-terminal lead-out terminal and the housing lead-out terminal of this invention are all connected to relays, which facilitates the automated testing of TO-254AA devices and improves testing efficiency.

[0018] 3. The end face of the spring pin near the device lead insertion hole of the present invention is a hemispherical contact surface, which ensures that the spring pin is in close contact with the surface of the device housing while avoiding scratching the surface of the device housing.

[0019] 4. In this invention, after placing the device casing on the fixture base, the following tests are performed sequentially: three-terminal contact test, TO-254AA device functional test, contact test between the three terminals of the pins and the casing leads, insulation resistance test, and DC parameter test. The three-terminal contact test ensures good contact between the device pins; the TO-254AA device functional test ensures normal device function; the contact test between the three terminals of the pins and the casing leads ensures a normal physical connection before the insulation resistance test; the insulation resistance test ensures complete disconnection between the casing and the three terminals of the pins; and the DC parameter test ensures the safety of the TO-254AA device after high-voltage testing. This invention avoids electrostatic failure caused by directly applying voltage when the device pins and metal casing are not in contact with the test equipment, thus improving test safety. Attached Figure Description

[0020] Figure 1 This is a side view of the test fixture of the present invention; Figure 2 This is a top view of the test fixture of the present invention; Figure 3 This is a cross-sectional view of the movable needle plate of the present invention; Figure 4 This is a schematic diagram of the electrical connection control of the housing lead-out end of the present invention; Figure 5 This is a schematic diagram of the electrical connection control of the three-terminal leads of the present invention; Figure 6 This is a schematic diagram of the testing process of the present invention.

[0021] The components are: 1. Fixture base; 2. Device lead-out end; 3. Movable pin plate; 4. Spring pin; 5. Device lead-in hole; 6. TO-254AA device; 7. Device lead-out end; 8. Elastic component; 9. Moving end of pin plate; 10. Fixed end of pin plate; 11. Housing lead-out end; 12. Three-terminal lead-out end; 13. First contact surface of device housing; 14. Second contact surface of device housing; 15. Device housing; 16. Relay. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of 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 skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 The present invention discloses a TO-254AA metal package insulation resistance testing device, comprising: a fixture base 1 and a needle plate moving end 9; The fixture base 1 is provided with three device lead sockets 5, which are used for inserting and connecting the device lead-out terminals 2, providing necessary electrical connection points for testing. Each device lead socket 5 is electrically connected to two three-terminal leads 12, which are used for connecting external circuits for resistance testing. The fixture base 1 is the basic part of the testing device.

[0025] The movable end 9 of the implantation plate is slidably arranged on the fixture base 1. The movable end 9 of the implantation plate is also connected to the fixture base 1 through an elastic member 8. The movable end 9 of the implantation plate is provided with two spring pins 4. The end of the spring pin 4 near the device lead socket 5 protrudes from the surface of the movable end 9 of the implantation plate. The spring pin 4 is electrically connected to the housing lead 11, which is used for external circuit resistance testing. During testing, the movable end 9 of the implantation plate is pushed, which compresses the elastic member 8, placing the device housing 15 on the fixture base 1, so that the device lead 2 can pass through the device lead socket 5. The movable end 9 of the implantation plate is released, and the elastic member 8 pushes the movable end 9 of the implantation plate, so that the spring pin 4 is in close contact with the surface of the device housing 15, realizing the insulation resistance test of the device housing 15. The elastic component 8 avoids excessive pressure or insufficient contact between the spring pin 4 and the device housing 15, ensuring the stability of the contact between the spring pin 4 and the device housing 15. Simultaneously, it prevents the spring pin 4 from scratching the device housing 15 during testing. This invention enables insulation resistance testing of the device housing 15, significantly improving testing efficiency and preventing the test leads from easily damaging the device's appearance during testing.

[0026] Example 1: See Figure 1 and Figure 2 The present invention discloses a TO-254AA metal package insulation resistance testing device, comprising: a fixture base 1 and a needle plate moving end 9; See Figure 2 The fixture base 1 is provided with three device lead insertion holes 5. The three device lead insertion holes 5 are coplanar and equally spaced. The device lead insertion holes 5 are used for the insertion and connection of device lead-out terminals 2. Each device lead insertion hole 5 is electrically connected to two three-terminal lead-out terminals 12. (See figure) Figure 5 ; See Figure 2 and Figure 3 The fixture base 1 is also provided with a needle plate fixing end 10, which is fixedly connected to the fixture base 1. The needle plate fixing end 10 is connected to the needle plate moving end 9 through an elastic component 8.

[0027] Preferably, the sliding component consists of a slide rail and a slider to ensure the stability of the moving end 9 of the implantation plate sliding on the fixture base 1.

[0028] See Figure 1 and Figure 2 The fixture base 1 is provided with a first contact surface 13 for the device housing, the opening of the device lead insertion hole 5 is located on the first contact surface 13 for the device housing, the moving end 9 of the needle plate is provided with a second contact surface 14 for the device housing, the protruding end of the spring needle 4 is located on one side of the second contact surface 14 for the device housing, both the first contact surface 13 and the second contact surface 14 for the device housing are flat surfaces, and the first contact surface 13 and the second contact surface 14 for the device housing are perpendicular to each other.

[0029] The spring pins 4 are arranged in parallel and are perpendicular to the second contact surface 14 of the device housing.

[0030] The end face of the spring pin 4 near the device lead socket 5 is a hemispherical contact surface, which ensures that the spring pin 4 is in close contact with the surface of the device housing 15 while avoiding scratching the surface of the device housing 15.

[0031] See Figure 1 and Figure 2 The needle plate moving end 9 is slidably arranged on the fixture base 1. The needle plate moving end 9 is also connected to the fixture base 1 through an elastic component 8. Two spring needles 4 are provided on the needle plate moving end 9. The end of the spring needle 4 near the device lead hole 5 protrudes from the surface of the needle plate moving end 9. The spring needle 4 is electrically connected to the outer shell lead end 11.

[0032] See Figure 3 The elastic component 8 consists of several parallel springs, which connect the fixed end 10 of the implantation plate to the moving end 9 of the implantation plate.

[0033] See Figure 4 and Figure 5 Both the three-terminal lead-out terminal 12 and the housing lead-out terminal 11 are connected to the relay 16, which facilitates automated testing of the TO-254AA device and improves testing efficiency.

[0034] Based on the above structure, this invention also discloses a method for testing the insulation resistance of a TO-254AA metal package, see [link to relevant documentation]. Figure 6 This includes the following steps: Step 1: Push the needle plate moving end 9 to compress the elastic component 8 through the needle plate moving end 9, place the device housing 15 on the fixture base 1, so that the device lead end 2 passes through the device lead insertion hole 5, release the needle plate moving end 9, so that the spring needle 4 is in close contact with the surface of the device housing 15. Step 2, Three-terminal contact test: Check the contact impedance between the three device leads 2 and the three device lead sockets 5 to ensure good contact of the device pins; Step 3, TO-254AA device functional test: Apply the rated voltage to the TO-254AA device to detect the operating current deviation and ensure that the device functions normally; Step 4, Contact test between the three leads and the outer casing: Short-circuit the three device leads 2 and then test the contact with the outer casing leads 11 to ensure that the physical connection is normal before the insulation resistance test; Step 5, Insulation Resistance Test: The insulation resistance is tested by applying pressure and measuring current. Step 6, DC parameter test: Use the three-terminal lead 12 to perform DC parameter test to ensure the safety of the TO-254AA device after high voltage test. This can prevent the device from failing due to electrostatic discharge if the device pins, metal casing and test equipment are not in contact.

[0035] Example 2: This embodiment utilizes automated equipment resources to design a dedicated insulation resistance testing fixture that safely leads out the casing. An automated testing process is designed to achieve insulation resistance and DC parameter testing in a single operation, improving testing efficiency while ensuring device safety under high voltage conditions. The invention employs the following technical solution: Insulation resistance testing fixtures such as Figure 1 , Figure 2 and Figure 3 As shown.

[0036] This invention employs two circular spring pins 4 to bring out the device housing 15. The circular spring pins 4, when in contact with the device housing 15, reduce damage to the metal plating, ensuring that the appearance meets standard requirements. Simultaneously, the design of the two spring pins 4 enables Kelvin connection, guaranteeing test accuracy. Furthermore, a contact resistance test is performed before the insulation test to ensure complete contact between the device housing 15 and the spring pins 4, guaranteeing the reliability of the insulation resistance test. The design incorporates a movable pin plate 3. When the movable pin plate 3 is pushed back, the device lead-out end 2 is inserted into the device lead socket 5, preventing scratches caused by friction between the device housing 15 and the spring pin 4. After the device lead-out end 2 is inserted, the reaction force of the spring ensures that the device housing 15 and the spring pin 4 are in close contact. This design ensures testing reliability while preventing scratches on the device's appearance.

[0037] This invention discloses a dedicated circuit for insulation resistance testing, which utilizes automatic testing equipment resources to realize an automatic insulation resistance testing process.

[0038] The connection between the test fixture housing leads and three-terminal leads and the automatic test equipment resources is achieved using relays, see [link to documentation]. Figure 4 and Figure 5 As shown.

[0039] Based on the resource design of automated testing equipment, an automated insulation resistance testing process is implemented. (See...) Figure 6 As shown. During testing, first, a three-terminal contact test and a functional test are performed on the device pins to ensure good pin contact and normal device function. Then, the three terminals of the device are short-circuited using a relay to perform a contact test on the device's metal casing and an insulation resistance test. This testing method avoids electrostatic discharge failure caused by directly applying voltage when the device pins, metal casing, and test equipment are not in contact.

[0040] This process can simultaneously test insulation resistance and device electrical parameters in one test program, improving testing efficiency. In addition, it can also realize real-time monitoring of device performance after insulation resistance testing, ensuring test safety.

[0041] Compared with existing technologies, this invention facilitates the accurate measurement of insulation resistance of TO-254AA metal package, improves test safety and production efficiency during mass production testing, and saves test costs.

[0042] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for testing the insulation resistance of TO-254AA metal-encapsulated packages, based on a TO-254AA metal-encapsulated insulation resistance testing device, the device comprising: The fixture base (1) is provided with three device lead sockets (5). The device lead sockets (5) are used for the insertion and connection of the device lead-out end (2). Each device lead socket (5) is electrically connected to two three-terminal lead-out ends (12). The needle plate moving end (9) is slidably arranged on the fixture base (1). The needle plate moving end (9) is also connected to the fixture base (1) through an elastic component (8). The needle plate moving end (9) is provided with two spring needles (4). The end of the spring needle (4) near the device lead hole (5) protrudes from the surface of the needle plate moving end (9). The spring needle (4) is electrically connected to the outer shell lead end (11). The method is characterized by comprising the following steps: Push the needle plate moving end (9), compress the elastic component (8) through the needle plate moving end (9), place the device shell (15) on the fixture base (1), so that the device lead end (2) passes through the device lead socket (5), release the needle plate moving end (9), so that the spring needle (4) is in close contact with the surface of the device shell (15); Three-terminal contact test: Detect the contact impedance between the three device leads (2) and the three device lead sockets (5); TO-254AA Device Functional Test: Apply rated voltage to the TO-254AA device and detect operating current deviation; Contact test between the three pin terminals and the lead-out terminals of the casing: After shorting the three device leads (2), conduct a contact test with the lead-out terminals (11) of the casing to ensure that the physical connection is normal before the insulation resistance test; Insulation resistance test: The insulation resistance is tested by applying pressure and measuring current. DC parameter test: DC parameter test is performed using the three-terminal lead (12) to ensure the safety of the TO-254AA device after high voltage test.

2. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, The three device lead sockets (5) are arranged in the same plane and at equal intervals.

3. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, The fixture base (1) is also provided with a needle plate fixing end (10), which is fixedly connected to the fixture base (1) and the needle plate fixing end (10) is connected to the needle plate moving end (9) through an elastic component (8).

4. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, The fixture base (1) is provided with a first contact surface (13) of the device housing. The opening of the device lead insertion hole (5) is located on the first contact surface (13) of the device housing. The moving end (9) of the needle plate is provided with a second contact surface (14) of the device housing. The protruding end of the spring needle (4) is located on one side of the second contact surface (14) of the device housing. Both the first contact surface (13) and the second contact surface (14) of the device housing are flat surfaces. The first contact surface (13) and the second contact surface (14) of the device housing are perpendicular to each other.

5. The method for testing the insulation resistance of TO-254AA metal package according to claim 4, characterized in that, The spring pins (4) are arranged in parallel and are perpendicular to the second contact surface (14) of the device housing.

6. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, The end face of the spring pin (4) near the device lead socket (5) is a hemispherical contact surface.

7. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, The elastic component (8) consists of several parallel springs, which connect the fixed end (10) of the implantation plate to the moving end (9) of the implantation plate.

8. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, Both the three-terminal lead-out terminal (12) and the housing lead-out terminal (11) are connected to a relay (16).

9. The method for testing the insulation resistance of TO-254AA metal package according to claim 1, characterized in that, The rated voltage applied to the TO-254AA device is 500V.

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