Test socket

Abstract

The present invention is a test socket, which is suitable for being fixed on a circuit board. The test seat includes a base, a conductive elastic sheet and a plurality of elastic metal parts. The base has a first surface and a second surface opposite to each other and a plurality of through holes. Each of the through holes comprises a large aperture section adjacent to the second surface and a small aperture section adjacent to the first surface, and a stepped structure is formed at the connection between the large aperture section and the small aperture section. The conductive elastic sheet is located on the second surface of the base. Each of the elastic metal parts is disposed in the plurality of through holes and has a shoulder and one end contacting the conductive elastic sheet, so that when the test socket is fixed to the circuit board, there is a distance between the shoulder and the stepped structure. According to the above, the present invention can reduce the warping problem caused by pre-load when the test socket is combined with the circuit board.

Description

[Technical Field]

[0001] This invention relates to semiconductor testing technology, and more particularly to a test socket. [Previous Technology]

[0002] In semiconductor packaging testing, test sockets with multiple probes are often used to place the test object, such as a semiconductor package or a chip, into the socket. After the probes are electrically connected to the semiconductor package or chip, the test signal is transmitted to the semiconductor package or chip through each probe to achieve the purpose of testing.

[0003] As testing conditions become increasingly stringent, the requirements for signal quality during testing are becoming higher and higher. Therefore, improving the contact between contact interfaces has become an industry development goal. In traditional testing processes, in order to ensure that the probe bottom of the test socket can maintain stable contact with the circuit board, a preload design is used when the test socket is fixed to the circuit board. However, as the number of probe pins increases, the reaction force caused by the preload also increases. This will cause the test socket itself to experience excessive reaction force when subjected to preload, resulting in test socket warping. The test socket body may warp too much, causing the probe bottom to lose stable contact with the circuit board pads.

[0004] In view of the above problems, how to provide a test socket, in particular, that can maintain stable contact between the probe and the circuit board, while avoiding the warping problem of the test socket caused by probe pre-pressure, has become the goal that those skilled in the art are eager to pursue. [Summary of the Invention]

[0005] To solve the problems of the prior art, the present invention discloses a test holder suitable for fixing on a circuit board. The test holder includes: a base having a first surface and a second surface opposite to each other and a plurality of through holes connecting the first surface and the second surface. Each through hole includes a large-diameter segment adjacent to the second surface and a small-diameter segment adjacent to the first surface, and a stepped structure is provided at the connection between the large-diameter segment and the small-diameter segment; a conductive elastic sheet located on the second surface of the base; and a plurality of elastic metal members respectively disposed in the plurality of through holes, each having a shoulder and one end contacting the conductive elastic sheet. When the test holder is fixed to the circuit board, the shoulder and the stepped structure are separated by a distance.

[0006] In one embodiment, each of the elastic metal parts includes a body, a bottom contact unit and a top contact unit, the top contact unit and the body forming the shoulder, and the length of the body plus the length of the bottom contact unit is less than or equal to the length of the large aperture section.

[0007] In one embodiment, the base includes a housing and a retainer, the housing including the small aperture segment and a portion of the large aperture segment, and the retainer including the remaining large aperture segment.

[0008] In the foregoing embodiments, the large-diameter section included in the retaining member is a through hole.

[0009] In the foregoing embodiments, the conductive elastic sheet further includes a frame for locking or attaching to the retainer to support the elastic metal parts.

[0010] In one embodiment, each of the elastic metal parts does not touch the stepped structure, so that each of the elastic metal parts does not generate pre-compression.

[0011] The present invention further discloses a test fixture suitable for fixing to a circuit board. The test fixture includes: a base having a first surface and a second surface opposite to each other and a plurality of through holes communicating with the first surface and the second surface; a conductive elastic sheet located on the second surface of the base; and a plurality of elastic metal members respectively disposed in the plurality of through holes, each having a shoulder and one end contacting the conductive elastic sheet, so that when the test fixture is fixed to the circuit board, each elastic metal member is substantially not compressed and has its natural length.

[0012] In one embodiment, each of the elastic metal parts includes a body, a bottom contact unit and a top contact unit, the top contact unit and the body are connected to form the shoulder, and each of the through holes includes a large aperture section adjacent to the second surface and a small aperture section adjacent to the first surface, and the length of the body plus the length of the bottom contact unit is less than or equal to the length of the large aperture section.

[0013] In one embodiment, the base includes a top cover and a retainer, the top cover including the small aperture segment and a portion of the large aperture segment, and the retainer including the remaining large aperture segment.

[0014] In the foregoing embodiments, the large-diameter section included in the retaining member is a through hole.

[0015] In one embodiment, the conductive elastic sheet further includes a frame for locking or attaching to the retainer to support the elastic metal parts.

[0016] As can be seen from the above, the test holder of the present invention, by increasing the height of the probe hole, creates a distance between the shoulder of the elastic metal part and the stepped structure of the through hole. When the test holder is fixed to the circuit board, the elastic metal part will not be under pre-pressure. In particular, since the elastic metal part is not under pre-pressure, a conductive elastic sheet can be set between the elastic metal part and the circuit board. In addition to serving as a buffer to avoid damage to the circuit board, the conductive elastic sheet can also improve the contact effect between the two. [Simplified Explanation of the Diagram]

[0040] Figure 1 is a schematic diagram of the overall structure of the test stand of the present invention.

[0041] Figure 2 is a cross-sectional view of the test stand of the present invention.

[0042] Figure 3 is a schematic diagram of how the elastic metal part of the present invention is placed into the test seat.

[0043] Figure 4 is a cross-sectional view of the elastic metal part of the present invention.

[0044] Figure 5 is a schematic diagram showing the proportional difference between the elastic metal part of the present invention as a single-acting needle and the prior art.

[0045] Figure 6 is a schematic diagram showing the proportional difference between the elastic metal part of the present invention with a double-acting needle and the prior art.

[0046] Figures 7A-7C are schematic diagrams of the present invention and other prior art pressure tests.

[0047] Figure 8 is a graph showing the relationship between the stroke and resistance of different bases of the present invention during pressure testing.

[0048] Figure 9 is a graph showing the relationship between the stroke and the applied force of different bases of the present invention during pressure testing.

Implementation Method

[0017] The technical content of the present invention will be described below through specific embodiments. Those skilled in the art can easily understand the advantages and effects of the present invention from the content disclosed in this specification. However, the present invention can also be implemented or applied through other different embodiments.

[0018] Figure 1 is a schematic diagram of the overall structure of the test base of the present invention, Figure 2 is a cross-sectional view of the test base of the present invention, Figure 3 is a schematic diagram of how the elastic metal part of the present invention is placed into the test base, and Figure 4 is a cross-sectional view of the elastic metal part of the present invention. Please refer to them together.

[0019] As shown in the figure, the test base 1 of the present invention includes a base 11, a conductive elastic sheet 12 located below the base 11, and a plurality of elastic metal parts 13 disposed in the base 11. In a specific embodiment, the test base 1 of the present invention may be a probe base or a probe card, and may be disposed on a circuit board (test circuit board) 2, so that each of the elastic metal parts 13 receives test signals from the circuit board 2, wherein the elastic metal part 13 may be a spring probe.

[0020] Further, the base 11 may include a top cover 114 and a retainer 115; in addition, the conductive elastic sheet 12 may include a frame 121, which is locked or glued to the retainer 115, so that the conductive elastic sheet 12 is located below the elastic metal parts 13, that is, it can support the elastic metal parts 13.

[0021] During the test, the base 11 is mounted on the circuit board 2 through the guidance of the mounting plate 117. That is, the conductive elastic sheet 12 is located between the base 11 and the circuit board 2. The test element 3 can be placed above the elastic metal part 13 through the guide plate 116 of the base 11. The elastic metal part 13 provides signal transmission between the test element 3 and the circuit board 2, thereby performing the test.

[0022] As shown in Figure 2, the base 11 has a first surface 111 and a second surface 112 opposite to each other and a plurality of through holes 113 connecting the first surface 111 and the second surface 112. The conductive elastic sheet 12 is located on the second surface 112 of the base 11. Each elastic metal member 13 is respectively disposed in each of the through holes 113. Each elastic metal member 13 has a shoulder 131 and the end of each elastic metal member 13 close to the conductive elastic sheet 12 contacts the conductive elastic sheet 12. The conductive elastic sheet 12 has a conductive elastic region R corresponding to each elastic metal member 13. There are conductive particles 120 in the conductive elastic region R. When the conductive elastic region R is squeezed from above and below, the conductive particles 120 inside it will gather to form a conductive path.

[0023] Further, each of the through holes 113 includes a large-diameter section 1131 adjacent to the second surface 112 and a small-diameter section 1132 adjacent to the first surface 111, and a stepped structure 1133 is formed at the connection between the large-diameter section 1131 and the small-diameter section 1132. When the test seat 1 of the present invention is fixed to the circuit board 2, there is a distance G between the shoulder 131 of each elastic metal member 13 and the stepped structure 1133. That is, each elastic metal member 13 will not contact the stepped structure 1133 and presents a state of near-zero preload or even zero preload.

[0024] As shown in Figure 4, the elastic metal part 13 includes a body 132, a top contact unit 133 and a bottom contact unit 134. The top contact unit 133 and the body 132 are connected to form a shoulder 131. When the elastic metal part 13 is placed in a through hole 113 with a large diameter section 1131 and a small diameter section 1132, the length of the body 132 plus the length of the bottom contact unit 134 is less than or equal to the length of the large diameter section 1131. This ensures that there is a gap G between the shoulder 131 and the stepped structure 1133 and that they do not contact each other.

[0025] In addition, the longitudinal cross-sectional width of the small-diameter section 1132 is smaller than the longitudinal cross-sectional width of the entire shoulder 131 of the elastic metal part 13 to avoid needle drop during installation. As shown in Figure 3, the process of inserting the elastic metal part 13 into the test seat 1 is different from that in Figure 2. The test seat 1 is inverted. First, the test seat 1 is inverted so that the top cover 114 is at the bottom. Then, the elastic metal part 13 is inserted. The shoulder 131 of the elastic metal part 13 will be held in place by the small-diameter section 1132 and will not come off. The base 11 is placed in the through hole 113. Then, the retainer 115 is placed on the top cover 114 so that the base 11 meets the required height. Then, the conductive elastic sheet 12 is placed on the other surface of the retainer 115 and fixed (e.g., locked). This completes the setting of the elastic metal part 13. When the test seat 1 is completely reversed, the elastic metal part 13 will move toward the conductive elastic sheet 12 and be supported by the conductive elastic sheet 12 and confined in the through hole 113. At this time, there is a distance between the shoulder 131 and the stepped structure 1133, namely the spacing G.

[0026] As shown in Figure 2, the section of the upper cover 114 corresponding to the through hole 113 includes a small diameter section 1132 and a part of the large diameter section 1131, while the section of the retaining member 115 corresponding to the through hole 113 includes the remaining large diameter section 1131. In other words, the section of the through hole 113 corresponding to the retaining member 115 is a straight through hole.

[0027] Compared with the prior art, in the prior art, when the base is fixed to the circuit board, the shoulder of the elastic metal part will contact the stepped structure at the large and small holes of the base, causing the elastic metal part to have a pre-compression phenomenon. The reaction force generated by the appropriate pre-compression can ensure the stable contact between the elastic metal part and the circuit board. However, if the reaction force is too large, it will cause the base to warp and further cause poor contact between the bottom of the probe and the circuit board. When the test base 1 is fixed to the circuit board 2, the elastic metal part 13 of the present invention is in the form of... The current state is almost zero preload, so there will be no reaction force that would cause the base 11 to warp and cause test failure. In addition, the conductive elastic sheet 12 supports the elastic metal part 13 and confines it within the through hole 113. Therefore, it is not necessary to design different apertures on the retainer 115 as in the prior art. The design of the retainer 115 as a straight through hole can maintain the impedance stability of high frequency and high speed transmission. Furthermore, the conductive elastic sheet 12 is located between the elastic metal part 13 and the circuit board 2, which can also provide better electrical contact, as will be explained later.

[0028] In another embodiment, since the elastic metal part 13 is almost zero pre-compression, or zero pre-compression, that is, the elastic metal part 13 is not actually compressed and is presented at its natural length.

[0029] It should be noted that the so-called near-zero pre-pressure or actual non-compression means that if, due to possible manufacturing tolerances, when the test base 1 is fixed on the circuit board 2, the shoulder 131 of the elastic metal part 13 will slightly contact the stepped structure 1133 and be slightly compressed (not the pre-pressure used in the prior art to make the probe and the circuit board make stable contact). The reaction force generated by this slight compression will not cause the base 11 to warp, so the purpose of the present invention can be achieved in practice.

[0030] The following uses different types of elastic metal parts to illustrate the differences between the present invention and the prior art elastic metal parts.

[0031] Figure 5 is a schematic diagram showing the difference between the elastic metal component of the present invention as a single-acting needle and the prior art. As shown in the figure, the elastic metal component of this embodiment is a single-acting needle. The left side shows the state after the probe is set in the prior art, and the right side shows the state after the elastic metal component of the present invention is set. In the left structure, the body length A plus the bottom length B minus the pre-pressure length C will be equal to the large aperture height (or large aperture depth), that is, A+BC must be equal to the large aperture height, which causes the elastic metal component (i.e., the probe) to have pre-pressure. In addition, in the right structure of the present invention, when the test seat is placed on the circuit board, the shoulder of the elastic metal component 13 will not be squeezed because there is no pre-pressure and the conductive elastic sheet 12 is used. When the body length A plus the bottom length B is less than or equal to the large aperture height, the present invention can be satisfied.

[0032] It should be noted that the single-acting needle refers to the retractable bottom contact unit of the elastic metal part. The body length A refers to the length from the shoulder to the bottom of the bottom contact unit, and the bottom length B refers to the amount of protrusion of the bottom contact unit.

[0033] Figure 6 is a schematic diagram showing the difference between the elastic metal part of the present invention being a double-acting needle and the prior art. The elastic metal part of this embodiment is a double-acting needle. The left side shows the state after the probe is set in the prior art, and the right side shows the state after the elastic metal part of the present invention is set. In the conventional structure on the left, the body length A plus the bottom length B minus the pre-pressure length C will equal the large aperture height, that is, A+BC must equal the large aperture height, which causes the elastic metal part (i.e., the probe) to have pre-pressure. On the other hand, in the structure of the present invention on the right, because there is no pre-pressure and the conductive elastic sheet 12 is used, the present invention can be satisfied when the body length A plus the bottom length B is less than or equal to the large aperture height.

[0034] It should be noted that the double-acting needle refers to the fact that both the top contact unit and the bottom contact unit of the elastic metal part can be extended and retracted. The body length A refers to the length from the shoulder to the bottom of the bottom contact unit, which is the total length of the body. The bottom length B refers to the amount of protrusion of the bottom contact unit.

[0035] Figures 7A-7C are schematic diagrams of pressure testing of the present invention and other prior art. This embodiment mainly discusses the design differences with and without pre-pressure. As shown in Figure 7A, in the case of a general fixture, both ends of the through hole have different diameters. When the elastic metal part is placed in the through hole, it protrudes only 0.6 mm from the surface of the base (i.e., the upper cover 114 and the retainer 115) due to the pre-pressure. As shown in Figure 7B, in the case of a through hole fixture, the through hole is a straight through hole design. In this state, the elastic metal part will not have pre-pressure, but the elastic metal part is in direct contact with the circuit board 2. Therefore, the elastic metal part protrudes 0.85 mm from the surface of the base, which is 0.25 mm less than the pre-pressure in Figure 7A. As shown in Figure 7C, in the design of the present invention, the through hole is also a straight through hole design. In addition to the absence of pre-pressure, a conductive elastic sheet is provided between the elastic metal part and the circuit board 2. The thickness of the conductive elastic sheet is about 0.2 mm.

[0036] Pressure tests were performed for the three different situations described above, namely, the elastic metal part is below the circuit board 2 and then contacts the test element 3 (as shown in Figure 1). Specifically, the test element 3 is pressed down so that the elastic metal part can transmit test signals to the test element 3 and the circuit board 2. The test results are shown in Figures 8 and 9. With a target contact resistance of 100 milliohms (mΩ), Figures 7A to 7C show the pressure test process. Of course, the shorter the stroke, the better, and the smaller the pressure under the stress at the aforementioned stroke, the better. Among them, Figure 8 is a graph showing the relationship between stroke and resistance for different bases of the present invention during pressure testing, and Figure 9 is a graph showing the relationship between stroke and force for different bases of the present invention during pressure testing.

[0037] As shown in Figure 8, since the contact resistance affects the pressure test effect, the contact resistance should not be too large. Here, it is desirable for the contact resistance to be less than 100 milliohms (mΩ). At this time, the travel of the elastic metal part of the general fixture (Figure 7A) is 0.3mm (including 0.25mm of preload and actual movement of 0.05mm), and the travel of the elastic metal part of the through-hole fixture (Figure 7B) is also 0.3mm, so that the contact resistance is less than 100 milliohms (mΩ). However, the present invention (Figure 7C) adopts the design of zero preload (or near-zero preload) and conductive elastic sheet, so that the travel of its elastic metal part is only 0.1mm, which can make the contact resistance less than 100 milliohms (mΩ).

[0038] Corresponding to the above stroke data in Figure 9, a general fixture (Figure 7A) will generate 8.5 gf under its corresponding stroke, and a through-hole fixture (Figure 7B) will generate 9.2 gf under its corresponding stroke. Conversely, the present invention (Figure 7C) will only generate 5.6 gf with a stroke of only 0.1 mm. In other words, under the condition of meeting the required resistance value, the present invention, through zero preload design and the cooperation of conductive elastic sheet, can achieve similar results (target contact resistance value) with less stroke and less force compared to other designs with preload or only through holes.

[0039] The above embodiments are merely illustrative and not intended to limit the present invention. Any person skilled in the art can modify and alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention is defined by the appended claims, and should be covered by this disclosure as long as it does not affect the effects and purpose of the present invention.

Claims

1. A test socket adapted to be fixed on a circuit board, the test socket system comprising: A base has a first surface and a second surface opposite to each other, and a plurality of through holes connecting the first surface and the second surface. Each through hole includes a large-diameter section adjacent to the second surface and a small-diameter section adjacent to the first surface, and has a stepped structure at the connection between the large-diameter section and the small-diameter section. A conductive elastic sheet is located on the second surface of the base. A plurality of elastic metal members are respectively disposed in the plurality of through holes, and each has a shoulder and one end contacts the conductive elastic sheet. When the test base is fixed to the circuit board, the shoulder and the stepped structure are separated by a distance.

2. The test fixture as described in request item 1, wherein, Each of the elastic metal parts includes a body, a bottom contact unit, and a top contact unit. The top contact unit is connected to the body to form a shoulder. The length of the body plus the length of the bottom contact unit is less than or equal to the length of the large-diameter section.

3. The test fixture as described in request item 1, wherein, The base includes a top cover and a retainer, the top cover including the small-diameter section and a portion of the large-diameter section, and the retainer including the remaining large-diameter section.

4. The test fixture as described in claim 3, wherein, The large-diameter section included in the retaining member is a through hole.

5. The test fixture as described in claim 3, wherein, The conductive elastic sheet further includes a frame for locking or attaching to the retainer to support the elastic metal parts.

6. The test fixture as described in claim 1, wherein, Each of the elastic metal parts did not touch the stepped structure, so that each of the elastic metal parts did not generate pre-compression.

7. A test socket adapted to be fixed to a circuit board, the test socket system comprising: The base has a first surface and a second surface opposite to each other and a plurality of through holes connecting the first surface and the second surface, and each of the through holes includes a stepped structure; a conductive elastic sheet is located on the second surface of the base; and a plurality of elastic metal members are respectively disposed in the plurality of through holes, each having a shoulder and one end contacting the conductive elastic sheet, so that when the test seat is fixed to the circuit board, each of the elastic metal members is not substantially squeezed by the stepped structure.

8. The test socket as described in claim 7, wherein, Each of the elastic metal parts includes a body, a bottom contact unit, and a top contact unit. The top contact unit is connected to the body to form a shoulder. Each of the through holes includes a large-diameter section adjacent to the second surface and a small-diameter section adjacent to the first surface. The length of the body plus the length of the bottom contact unit is less than or equal to the length of the large-diameter section.

9. The test socket as described in claim 8, wherein, The base includes a top cover and a retainer, the top cover including the small-diameter section and a portion of the large-diameter section, and the retainer including the remaining large-diameter section.

10. The test fixture as described in claim 9, wherein, The large-diameter section included in the retaining member is a through hole.

11. The test fixture as described in claim 9, wherein, The conductive elastic sheet further includes a frame for locking or attaching to the retainer to support the elastic metal parts.

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