Electrical contact finger with surface modification
The problem of wear in the contact area is solved by introducing surface modifications such as grooves and elongated tines in the contact area, improving the service life and test reliability of the contact fingers.
Patent Information
- Application Number
- CN202410174908.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-07
- Publication Date
- 2025-08-08
AI Technical Summary
In existing integrated circuit testing equipment, the contact area of the contact fingers causes electroplating wear due to scratching and excavation with the external leads of the device under test, resulting in increased contact failure and elimination rate and short service life.
Introduce surface modifications, such as grooves, channels, bumps or ridges, in contact areas of the contact fingers, to increase pressure between the contact area and the external leads, ensure good contact, and to improve contact stability by forming adjacent elongated tines.
The service life of the contact fingers is increased by nearly three times, ensuring proper connection and conductivity on the device under test, and reducing phase-out rate.
Smart Images
Figure CN120446539A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to electronic devices, and more particularly to electrical contact fingers having surface modifications to improve contact with a device under test. Background Art
[0002] Integrated circuit (IC) test equipment utilizes contact fingers for IC testing. One such test equipment is a contact finger tester utilizing contact fingers. One end of the contact fingers is angled and positioned close together to contact external leads or terminals on the electronic device under test (e.g., an IC package). The opposing ends of the contact fingers are arranged in parallel and connected to a test board. The contact fingers are attached to a rigid holder that holds the contact fingers together, thereby forming a contact finger module. The contact fingers are arranged in a horizontal plane. There may be two contact finger modules positioned opposite each other, or four contact finger modules arranged in a square configuration when viewed from above. Summary of the Invention
[0003] In the described examples, a test assembly for electronic device testing equipment includes an electrically insulating holder and conductive contact fingers. The conductive fingers include first portions extending generally parallel to one another from a first side of the holder, and second portions extending at an angle from a second side of the holder, with distal ends of the second portions closely clustered. The second portions include contact regions at the distal ends that include surface modifications.
[0004] In yet another described example, a method includes providing a contact finger testing apparatus, wherein the contact finger testing apparatus includes a test board, a contact finger module attached to the test board via a fixture, and a holder. An electronic device is repeatedly placed on the holder, a test is performed on each of the electronic devices, and the electronic device is removed from the holder. The contact area of the contact fingers of the contact finger module is monitored to determine wear of the contact area. After the contact area has worn, the contact finger module is flipped 180°. Additional electronic devices are placed on the holder, a test is performed on each of the additional electronic devices, and the additional electronic devices are removed from the holder.
[0005] In another described example, a contact finger module for electronic device testing equipment includes an electrically insulating holder and electrically conductive contact fingers. The contact fingers include first portions extending generally parallel to one another from a first side of the holder, and second portions extending at an angle from a second side of the holder, with distal ends of the second portions closely clustered. The second portions include a contact region at the distal end, the contact region including grooves etched into the surface of the contact region to form elongated tines.
[0006] In yet another described example, an electronic device includes a leadframe including a die pad and leads, the leads including inner leads and outer leads; and a die attached to the die pad of the leadframe. An interconnect connects the die to the inner leads of the leadframe. A molding compound surrounds the die, the inner leads, and the interconnect. A residual mark is formed on a bottom surface of the outer lead, resulting from contact between the bottom surface of the outer lead and a surface modification of a contact area of a contact finger used during testing of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1 is a perspective view of an example contact finger testing apparatus.
[0008] Figure 2A is a top perspective view of an example contact finger module.
[0009] Figure 2B yes Figure 2A A close-up perspective view of an example contact area of a contact finger module.
[0010] Figure 2C is a close-up side view of the contact area.
[0011] Figure 3 is a close-up perspective view of another example of a contact area of another example contact finger.
[0012] Figure 4 is a side view illustration of a contact finger test for testing electronic devices.
[0013] Figure 5 is a block diagram flow chart illustrating the process of the contact testing process.
[0014] Figures 6A to 6D is a side view of an example contact area of an example contact finger, showing wear of the contact area due to repetition of testing.
[0015] Figure 7 is a cross-sectional view of an electronic device showing residual markings on the bottom surface of external leads. DETAILED DESCRIPTION
[0016] Integrated circuit (IC) test equipment utilizes conductive contact fingers for IC testing. One such test equipment is a contact finger tester utilizing conductive contact fingers. One end of the contact fingers is angled and arranged close together, and includes a contact area that contacts the external leads or terminals on the electronic device under test (e.g., an IC package). The opposing ends of the contact fingers are arranged in parallel and connected to a test board. The contact area is a flat surface that includes plating to provide an electrical connection between the contact fingers and the device under test. However, over time, due to constant scraping or digging between the contact area and the external leads on the device under test, the plating on the contact area begins to wear away and peel from the surface of the contact area. Scratching occurs whenever the external leads of the device under test come into contact with the contact area and apply pressure to ensure good contact. As the plating wears away, the contact between the contact area and the leads is compromised. This leads to an increased rejection rate for the devices under test because the current from the contact finger tester through the test fingers into the device under test is too low. As a result, the device under test fails the test and is rejected. Additionally, the contact fingers have a low service life (approximately 500k repetitions) due to flaking of the plating on the contact area.
[0017] Disclosed herein is a contact finger module (test assembly) having contact fingers with an improved contact area that overcomes the aforementioned shortcomings. The contact finger module includes contact fingers that are angled at one end and substantially parallel at the opposite end. The contact area (pad) of the angled portion of the contact finger includes surface modifications (e.g., grooves, channels, bumps, ridges, etc.) to increase contact between the contact area and the external leads or terminals on the electronic device. In embodiments where the surface modification includes grooves, the grooves have angled sidewalls that form adjacent elongated tines in the contact area. The tines increase pressure between the external leads and the contact area, thereby ensuring proper connection during testing of the device under test. Additionally, the tines increase the life of the contact fingers by approximately three times.
[0018] Figure 1 FIG1 is a partial perspective view of a test apparatus (e.g., a contact finger test apparatus) 100 for testing an electronic device (e.g., an IC package (e.g., SOP, SOT, DIP, QFN, etc.)) 102 incorporating an improved contact finger module. The test apparatus 100 includes a test board (e.g., a printed circuit board) 104 and a nest or holder 106 that holds the electronic device 102. The test apparatus 100 further includes a contact finger module 108 that includes contact fingers 110 and a holder 112. A clamp 114 and fasteners 116 secure the contact finger module 108 to the test board 104 such that one end of the contact fingers 110 is attached to the test board 104 and the opposite end of the contact fingers 110 is attached to the electronic device 102.
[0019] Figure 2A is used in the test apparatus 100 to test Figure 1 A perspective view of an example contact finger module (test assembly) 200 of an electronic device (eg, an integrated circuit (IC)) is shown. The contact finger module 200 may correspond to Figure 1 The contact finger module 108 is shown. Therefore, in the following description of the example of FIG. 2 , reference is made to FIG. Figure 1 Instance of .
[0020] The contact finger module 200 includes conductive contact fingers 202 and an electrically insulating holder 204. Figure 2A The contact finger module 200 shown in the example of FIG includes six contact fingers. However, the number of contact fingers 202 may vary based on the type of test equipment. Figure 2A The example contact finger module 200 shown in FIG. 2 is for illustrative purposes only and is therefore a non-limiting example.
[0021] The holder 204 may include one or more openings 206 to receive fasteners or pins to secure the contact finger module 200 to a test board. The contact fingers 202 extend through the holder 204 so that the holder 204 rigidly secures the contact fingers 202 in place, thereby forming a rigid structure. The first portion 208 of the contact fingers 202 includes a proximal end 210 attached to the holder 204. The first portion 208 of the contact fingers 202 extends from the proximal end 210 to a distal (contact) end 214 from a first side 212 of the holder 204. In the illustrated example, the first portions 208 of the contact fingers 202 are substantially parallel to each other and arranged in the same plane. Some or all of the first portions 208 of the contact fingers 202 may include a recess 216 at the distal end 214 to facilitate attachment of the contact fingers 202 to a test board as described above. The second portion 218 of the contact finger 202 includes a proximal end 220 that is attached to the holder 204. The contact finger 202 extends from the proximal end 220 to a distal (contact) end 224 from a second side 222 of the holder 204. The second portion 218 of the contact finger 202 extends from the second side 222 of the holder 204 at an angle relative to the holder 204 such that the distal ends 224 of the second portion 218 are proximally disposed.
[0022] Figure 2B is a close-up perspective view of the distal end 224 of the second portion 218 of the contact finger 202 and Figure 2C is a close-up side view. The distal end 224 includes a contact area 226. The contact area 226 is the area of the contact finger 202 that contacts an external lead or terminal on the electronic device under test. Figure 2BIn the example illustrated in FIG, the contact area 226 includes a surface modification 228. Figure 2B and 2C The surface modification 228 shown in FIG. 1 and illustrated herein includes a groove 230 having an angled sidewall 232 (see FIG. Figure 2C ). However, the surface modification 228 can be any type of surface modification (e.g., a groove with angled sidewalls, a channel with straight sidewalls (i.e., sidewalls that are substantially perpendicular to the surface of the contact area 226), a bump, a ridge, etc.). Therefore, it should be understood that the surface modifications shown and described herein are for illustrative purposes only and are therefore non-limiting examples.
[0023] See Figure 2C , the grooves 230 and angled sidewalls 232 formed in the contact area 226 create adjacent elongated tines 234. The tines 234 increase the pressure between the external leads of the electronic device under test and the contact area 226, thereby ensuring proper connection during testing of the electronic device under test. Specifically, using the formula that pressure (P) is equal to force (F) divided by surface area (A), where pressure is the pressure between the external leads and the contact area 226, as the surface area decreases, the pressure applied between the external leads and the contact area 226 increases. Therefore, the increase in pressure ensures proper contact between the external leads and the contact area 226, which results in better conductivity. In addition, the tines 234 increase the life of the contact finger 202 by approximately three times, as will be further described below. In some instances, two (or more) adjacent distal ends 224 of the second portion 218 of the contact finger 202 can be joined, such as Figure 2B However, in other examples, the distal end 224 may not be engaged. Figure 2B The examples shown in are for illustrative purposes only and are therefore non-limiting examples.
[0024] Figure 3 3 is a close-up perspective view of another example of a contact tip 300 of a contact finger used in a test device. In this example, the contact tip 300 includes a flat contact area 302. The flat contact area 302 is a flat plated surface and does not include any type of surface modification as described above. In fact, the flat contact area 302 is a flat surface that includes metal plating (e.g., gold). Figure 3 As shown in FIG, due to the repetition of the testing procedure, the metal plated portion 304 of the contact area 302 begins to wear away, thereby exposing the bare metal of the contact area 302.
[0025] Specifically, see Figure 4 , Figure 4FIG4 is a side view illustration of a contact finger test 400 testing an electronic device 402. For simplicity, only the electronic device 402 and the contact fingers 404 are shown. As illustrated, when the electronic device 402 is lowered toward the contact fingers 404, as indicated by arrow A1, the external leads 406 of the electronic device 402 engage the contact areas 408 of the contact fingers 404. When force is applied to the electronic device 402 to ensure an appropriate amount of pressure is applied between the external leads 406 and the contact areas 408 of the contact fingers 404, the external leads 406 move in an outward direction along the contact areas 408, as indicated by arrow A2. This outward movement causes the external leads 406 to scrape or dig into the contact areas 408 of the contact fingers 404. Consequently, the constant repetition of scraping and / or digging ultimately causes the plating on the contact areas 408 to weaken.
[0026] Return Reference Figure 3 , the worn plated portion 304 impairs the contact between the external lead and the contact area 302, which results in poor electrical conductivity. This causes electronic devices that may have been good to be rejected. Specifically, because the electrical conductivity of the contact area 302 of the contact finger is impaired, electronic devices that would normally pass the test may fail the test and thus be rejected. In addition, the flat contact area 304 has a greater Figure 2C The lifetime of the surface modified contact region 226 shown in FIG is approximately three times smaller. Specifically, the lifetime of the flat contact region 302 is approximately 500k repetitions, while the lifetime of the surface modified contact region 226 is approximately 1.5M repetitions, as will be further explained below.
[0027] Figure 5 is to illustrate the use of the above description and in Figures 2A to 2C 1 is a block diagram flow chart of a test process 500 for performing tests on a contact finger module having surface modifications of contact areas as shown in FIG. Although depicted sequentially for convenience, at least some of the actions shown may be performed in a different order and / or in parallel. Alternatively, some embodiments may perform only some of the actions shown. Furthermore, although Figure 5 The examples shown in are example methods, but other methods are possible.
[0028] The process begins at 502, where a test apparatus (e.g., 100) is provided for testing an electronic device (e.g., IC package 102). The test apparatus includes a test board (e.g., 104), a contact finger module (e.g., 108) attached to the test board via a fixture (e.g., 114), and a holder (e.g., 106). The test board is connected to a tester via a cable. The tester loads a test program based on the type of test to be performed (e.g., voltage test, current test, etc.). At 504, electronic devices are repeatedly placed on the holder, a test is performed on each of the electronic devices, and the electronic device is then removed from the holder. More specifically, a handler picks up the electronic device and places it on the holder. The handler then applies a downward force on the electronic device to ensure that the external leads on the electronic device make proper contact with the contact areas (e.g., 226) of the contact fingers (e.g., 202). Voltage or current is transmitted from the tester to the test board via the cable and then to the electronic device via the external leads through the contact fingers. The electronics then provide voltage or current feedback in reverse along the same path to the tester.
[0029] At 506, the contact area of the contact fingers is monitored to determine wear of the contact area. At 508, after it has been determined that the contact area has worn to the point where testing no longer provides accurate results, the contact finger module is flipped 180° so that the opposite side of the contact area is used for testing.
[0030] Specifically, see Figures 6A to 6D , Figures 6A to 6D Shows how the surface finish wears off on the contact area of the contact fingers due to repeated testing. Figure 6A In this example, the surface modification includes a groove 602 having an angled sidewall 604. The angled sidewall 604 forms an elongated tine 606 along a contact area 608 of a first portion 610 of a contact finger 612. Figure 6B As shown in , after several repetitions of the test, the tines 606 begin to wear due to the repeated contact and scraping of the external leads of the electronic device against the tines 606. Eventually, as Figure 6C As shown in , after a large number of repetitions, the grooves 602 and the tines 606 are substantially eradicated. Thus, the contact area 608 is a generally flat surface. At this point in the process, as shown in Figure 6D As shown in FIG, the contact finger module is flipped 180° and the opposite side 614 of the contact finger 612 is used as the contact area.
[0031] Return Reference Figure 5 At 510 , additional electronic devices are repeatedly placed on the holder, tests are performed for each of the additional electronic devices, and each of the additional electronic devices is removed from the holder.
[0032] See Figures 2A to 2C and Figure 7 , Figure 7 is used in the disclosure herein and in Figures 2A to 2C 7. A cross-sectional view of an example electronic device (e.g., an integrated circuit) 700 after the contact finger module 200 has undergone testing is shown in FIG. The electronic device 700 includes a lead frame that includes a die pad 702, inner leads 704, and outer leads 706. A die 708 is attached to the die pad 702 via a die attach material 710. Interconnects (e.g., wire bonds) 712 provide connections from the die 708 to the inner leads 704. A molding compound 714 is formed over and surrounds the die pad 702, the inner leads 704, the die 708, and the interconnects 712.
[0033] In implementation Figures 2A to 2C During testing of the electronic device 700 with the contact finger module 200 shown in FIG, the surface modification 228 leaves a residual mark 716 on the bottom surface 718 of the external lead 706. In the example described herein and shown in the figures, the residual mark 716 is an indentation resulting from contact between the elongated tines 234 formed by the grooves 230 on the contact areas 226 of the contact fingers 202 and the bottom surface 718 of the external lead 706. The presence of the residual mark 716 on the bottom surface 718 of the external lead 706 is an indication that good contact was achieved between the external lead 706 and the contact finger 202 during the testing process.
[0034] In the illustrated example, the residual marks 716 are formed on a bottom surface 718 of the outer lead 706 such that the residual marks 716 extend in a longitudinal direction (ie, front to back) that is generally orthogonal to the transverse direction or axis 720. Additionally, the residual marks 716 are generally parallel to each other.
[0035] As mentioned above, the elongated tines increase the lifespan of the contact fingers by approximately three times. Before incorporating surface modification into the contact area of the contact fingers, the contact finger module would have to be replaced approximately every 500,000 repetitions. Incorporating surface modification increases the number of repetitions by approximately three times. Specifically, the number of repetitions that can be performed until the surface modification is eradicated is approximately 1.0M. An additional 500,000 repetitions can be achieved by flipping the contact finger module 180° and using the opposite side of the contact finger as the contact area.
[0036] The examples of the present disclosure are described above. Of course, it is not possible to describe every conceivable combination of components or methods for the purpose of describing the present disclosure, but those skilled in the art will recognize that many other combinations and arrangements of the present disclosure are possible. Therefore, the present disclosure is intended to cover all such changes, modifications and variations that fall within the spirit and scope of the appended claims. In addition, where the present disclosure or claims state "one", "a", "first" or "another" element or its equivalent, it should be interpreted as comprising one or more than one such element, neither requiring nor excluding two or more such elements. In addition, insofar as the term "comprising" is used in a specific embodiment or in the claims, such terms are intended to be inclusive in a manner similar to the term "including", as explained when "including" is used as a transition word in the claims. Finally, the term "based on" is interpreted to mean at least partially based on.
Claims
1. A test assembly for an electronic device testing apparatus, comprising: Electrically insulating holders; as well as Conductive contact fingers comprising: first portions of the contact fingers extending generally parallel to each other from a first side of the holder; as well as The second portion of the contact finger extends angularly from a second side of the holder with distal ends of the second portion closely clustered, the second portion including a contact area at the distal end including a surface modification.
2. The test assembly of claim 1, wherein the surface modification comprises grooves, channels, bumps, or ridges.
3. The test assembly of claim 1 , wherein the surface modification comprises a groove having angled sidewalls.
4. The test assembly of claim 3, wherein the angled sidewalls form elongated tines along the contact area.
5. The test assembly of claim 1, wherein the first portion and the second portion are on the same plane.
6. The test assembly of claim 1, wherein the distal ends of the second portions of two adjacent contact fingers are engageable.
7. The test assembly of claim 1, wherein distal ends of some of the first portions of the contact fingers include recesses to facilitate attachment of the test assembly to a test board.
8. The test assembly of claim 1, wherein the holder includes at least one opening to secure the test assembly to a test board.
9. A method comprising: providing a contact finger testing apparatus comprising a test board, a contact finger module attached to the test board via a fixture, and a holder; repeatedly placing electronic devices on the holder, performing a test on each of the electronic devices, and removing the electronic devices from the holder; monitoring contact areas of contact fingers of the contact finger module to determine wear of the contact areas; flipping the contact finger module 180° after the contact area has worn; and Additional electronic devices are repeatedly placed on the holder, the test is performed for each of the additional electronic devices, and the additional electronic devices are removed from the holder.
10. The method of claim 9, wherein the contact area of the contact finger includes a surface modification, wherein monitoring the contact area of the contact finger of the contact finger module to determine wear of the contact area includes determining whether the surface modification on the contact area has diminished.
11. The method of claim 10, wherein the surface modification comprises grooves, channels, bumps, or ridges.
12. The method of claim 9, wherein the contact area of the contact finger comprises a groove having angled sidewalls, the groove etched into a surface of the contact area to form elongated tines on the contact area.
13. The method of claim 12, wherein monitoring the contact area of the contact fingers of the contact finger module to determine wear of the contact area comprises determining whether the elongated tines have worn to a substantially flat surface.
14. The method of claim 9, wherein repeatedly placing an electronic device on the holder includes engaging external leads from the electronic device with the contact areas of the contact fingers.
15. A contact finger module for an electronic device testing apparatus, comprising: Electrically insulating holders; as well as Conductive contact fingers comprising: first portions of the contact fingers extending generally parallel to each other from a first side of the holder; as well as A second portion of the contact finger extends angularly from a second side of the holder with a distal end of the second portion closely clustered, the second portion including a contact area at the distal end, the contact area including grooves etched into a surface of the contact area to form elongated tines. The contact finger module of claim 15 , wherein the groove comprises angled sidewalls.
17. The contact finger module of claim 15, wherein the first portion and the second portion are on the same plane.
18. The contact finger module of claim 15, wherein the distal ends of the second portions of two adjacent contact fingers are engageable.
19. The contact finger module of claim 15, wherein distal ends of some of the first portions of the contact fingers include recesses to facilitate attachment of the contact finger module to a test board.
20. The contact finger module of claim 15, wherein the holder includes at least one opening to secure the contact finger module to a test board.
21. An electronic device comprising: a lead frame comprising a die pad and leads, the leads comprising inner leads and outer leads; a die attached to a die pad of the lead frame; interconnects connecting the die to the inner leads of the leadframe; a molding compound surrounding the die, the inner leads, and the interconnects; as well as Residual marks, which are formed on the bottom surface of the external lead, are generated by contact between the bottom surface of the external lead and surface modification of contact areas of contact fingers used during testing of the electronic device.
22. The electronic device of claim 21, wherein the surface modification comprises a groove having angled sidewalls to form elongated tines, and wherein the residual mark is an indentation formed by the elongated tines.
23. The electronic device of claim 22, wherein the indentation extends in a longitudinal direction that is generally orthogonal to a transverse axis of the electronic device. The electronic device of claim 23 , wherein the indentations are substantially parallel to each other.