Test probe and test device
The test probe design with a radially protruding spring stopper and support surface addresses the challenge of achieving high contact force in fine-pitch semiconductor testing, ensuring stable and repeatable performance.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- LEENO IND INC
- Filing Date
- 2025-12-23
- Publication Date
- 2026-07-02
AI Technical Summary
Conventional pogo pins for fine-pitch semiconductor devices face limitations in achieving high contact force due to spatial constraints that restrict the design of the spring, leading to reduced maximum contact force and stability.
A test probe design featuring a spring stopper that protrudes radially beyond the spring, allowing for a larger spring diameter and greater freedom in selecting wire diameter and number of turns, coupled with a spring support surface for improved axial alignment and torsional resistance, enhancing mechanical strength and durability.
The design achieves stable and repeatable contact force even at fine pitches, minimizing spring buckling and improving contact resistance and reproducibility, while maintaining precise contact with small terminals.
Smart Images
Figure KR2025022566_02072026_PF_FP_ABST
Abstract
Description
TEST PROBE AND TEST DEVICE
[0001] The disclosure relates to a test probe and a test device for testing the electrical characteristics of a device under test, such as a semiconductor device.
[0002] A compressible pogo pin that connects a ball terminal of a semiconductor device and a signal terminal of a test circuit board. The pogo pin includes a cylindrical body, a terminal partially inserted into one end of the body, a plunger slidably inserted into the other end of the body, and a spring interposed between the terminal and the plunger inside the body.
[0003] To test fine-pitch semiconductor devices, a test device employs a pogo pin having a diameter (φ) of, for example, 0.10 mm or less. In test performance, the contact force of the pogo pin is a critical factor; the higher the contact force, the lower the resistance becomes and the more advantageous the testing is. In conventional pogo pins for fine-pitch applications, a spring is accommodated within a body, which imposes a spatial constraint of requiring the outer diameter of the spring to be smaller than the inner diameter of the body, thereby lowering the maximum value for designing the contact force of the spring. Accordingly, there is a need for improving the structure to allow for higher contact force while maintaining the preset diameter (φ) of the pogo pin.
[0004] An aspect of the disclosure is to provide a test probe and a test device for fine pitch applications, which are configured to increase the contact force of a spring.
[0005] According to an embodiment of the disclosure, there is provided a test probe. The test probe includes: a barrel shaped like a cylinder and inserted and accommodated in a probe accommodating portion formed through the socket block along an axis; a plunger comprising an insert portion having a diameter corresponding to an inner diameter of the barrel, the insert portion being inserted into a second end of the barrel and configured to slide in an axial direction within the barrel, and a stem extending from the insert portion; a spring stopper provided at an end portion of the stem and protruding in a radial direction with respect to the axis; and a spring shaped like a coil, provided on an outer circumference of the stem, with both ends being respectively supported in the axial direction by the second end of the barrel and the spring supporter, and operating to be compressed and restored upon sliding of the plunger.
[0006] The spring may have an inner diameter corresponding to an outer diameter of the stem, and an outer diameter larger than an outer diameter of the spring stopper and corresponding to an outer diameter of the barrel, and the spring stopper may have a protrusion height greater than the inner diameter of the spring. Therefore, the spring can be designed with a large diameter, thereby having a greater degree of freedom in selecting the wire diameter and the effective number of turns, and stably achieving the target contact force even at the same pitch. In addition, because the spring stopper protrudes radially beyond the inner diameter of the spring, the end of the spring does not pass over and disengage from the spring stopper, thereby preventing the buckling and loss of the spring and improving the repeatability of the preload setting.
[0007] The spring stopper may be shaped like a cylinder, have an inner circumference of which at least a region is fixed to an outer circumference of the stem, and have a spring support surface provided along a circumferential direction at a first end for supporting the spring. As a result, axial alignment and torsional resistance between the spring stopper and the stem are improved, thereby reducing backlash during repeated strokes. In addition, the circumferentially continuous spring-support surface uniformly distributes the load applied to the end of the spring, thereby suppressing passing-over and eccentricity of the end and improving the reproducibility of the linear load-displacement characteristics.
[0008] The spring stopper may include a test end portion made of a metal material and provided at an end opposite to the spring support surface. As a result, such a single-piece metal structure improves mechanical strength and durability against repeated impact and vibration loads, and an electrical conduction path provided by the stopper reduces contact resistance and heat generation.
[0009] The plunger may include a test end portion exposed from the spring stopper. As a result, a contact shape on the pad terminal side of the test circuit board is diversified, thereby ensuring the stability of initial and repetitive contact resistance while minimizing terminal damage. Furthermore, precise contact with small pad terminal becomes possible.
[0010] According to an embodiment of the disclosure, there is provided a test device. The test device includes the test probe having the foregoing features; and the socket block including the probe accommodating portion. The probe accommodating portion includes a barrel accommodating hole that accommodates the barrel and the spring, and a stopper accommodating hole that accommodates the spring stopper and has an inner diameter smaller than an inner diameter of the barrel accommodating hole, and includes a probe retaining portion formed by a difference in inner diameter between the barrel accommodating hole and the stopper accommodating hole. As a result, the spring is caught by the stopper accommodating hole and thus prevents the test probe from coming out of the socket block, thereby facilitating the transport and installation of the test device.
[0011] The test probe according to an embodiment of the disclosure may employ a spring having a relatively high spring contact force even with very fine the dimensions or the sizes, for example, a diameter (φ) of 0.10 mm or less.
[0012] FIG. 1 is a side view of a test probe according to an embodiment of the disclosure.
[0013] FIG. 2 is an exploded perspective view of the test probe of FIG. 1.
[0014] FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1.
[0015] FIG. 4(a) and 4(b) are views illustrating the test probe of FIG. 1 before and after operation.
[0016] FIG. 5 is an enlarged view illustrating the structure of a spring stopper.
[0017] FIG. 6 is a view illustrating the structure of an end portion in the spring stopper of FIG. 5.
[0018] FIG. 7 is a view illustrating the structure of a spring stopper according to another embodiment of the disclosure.
[0019] FIG. 8 is a cross-sectional view illustrating a portion of a test device according to an embodiment of the disclosure.
[0020] FIG. 9 is an enlarged view illustrating a portion of FIG. 8.
[0021] FIG. 10 is a view partially illustrating an application of the spring stopper of FIG. 7 to a socket block.
[0022] Below, a test probe 1 according to an embodiment of the disclosure will be described in detail with reference to the accompanying drawings.
[0023] FIG. 1 is a side view of a test probe according to an embodiment of the disclosure; FIG. 2 is an exploded perspective view of the test probe of FIG. 1; FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1; FIG. 4(a) and 4(b) are views illustrating the test probe of FIG. 1 before and after operation; FIG. 5 is an enlarged view illustrating the structure of a spring stopper; and FIG. 6 is a view illustrating the structure of an end portion in the spring stopper of FIG. 5.
[0024] Referring to FIGS. 1 to 3, the test probe 1 includes a barrel 11 shaped like a cylinder and inserted and accommodated in a probe accommodating portion (see '23' in FIG. 8) formed through a socket block (see '2' in FIG. 8) along an axis; a terminal 12 fixedly inserted into a first end of the barrel 11; a plunger 13 that includes an insert portion 131 inserted into a second end of the barrel 11 and slidable within the barrel 11 in an axial direction, and a stem 132 extending from the insert portion 131; a spring stopper 14 provided in an end portion of the stem 132 and protruding in a radial direction with respect to the axis; and a coil-shaped spring 15 provided on the outer circumference of the stem 132 so that both ends thereof can be respectively supported by the second end of the barrel 11 and the spring stopper 14 in the axial direction, and operating to be compressed and restored as the plunger 13 slides.
[0025] The barrel 11 is shaped like a cylinder, which may be formed of a conductive metal tube or a precision-machined component taking into account machinability and dimensional stability. The barrel 11 may include a terminal holding portion 111 for holding the terminal 12 inserted therein, and an insert portion stopper 112 for preventing the insert portion 131 of the plunger 13 from disengaging from the barrel 11 during the sliding of the plunger 13.
[0026] The terminal holding portion 111 is formed to protrude inward from the barrel 11 by roll pressing at a position corresponding to a rolling groove 123 of the terminal 12.
[0027] The insert portion stopper 112 is formed to protrude inward from the barrel 11 along the circumferential direction at a predetermined position of the second end of the barrel 11 by the roll pressing. The second end of the barrel 11 may be formed with a spring support surface 113 on which a first end of the spring 15 is contact-supported.
[0028] The terminal 12 is shaped like a rod, which may be made of a copper alloy or stainless steel plated with gold or palladium. The terminal 12 includes a contact tip 121 sharply formed to come into contact with a ball terminal 31 of a device under test 3, and a barrel insert portion 122 provided on the opposite side of the contact tip 121 and inserted and fixed into the first end of the barrel 11.
[0029] The contact tip 121 may be implemented in a flat, round, crown or tapered shape to come into contact with the ball terminal 31 of the device under test 3.
[0030] The barrel insert portion 122 includes the rolling groove 123 recessed along the circumferential direction at a position corresponding to the terminal holding portion 111, thereby ensuring mechanical engagement with the terminal holding portion 111 of the barrel 11. The rolling groove 123 may be implemented as a plurality of dimple grooves recessed in a semicircular shape.
[0031] The plunger 13 is shaped like a rod, which a rod, which may be made of a copper alloy or stainless steel plated with gold or palladium. The plunger 13 includes the insert portion 131 inserted into the barrel 11, and the stem 132 extending outward.
[0032] The insert portion 131 has a diameter so that a minimum clearance can be formed between the insert portion 131 and the inner surface of the barrel 11, thereby allowing the insert portion 131 to be slidably fitted within the barrel 11.
[0033] The stem 132 extends with a diameter smaller than the diameter of the insert portion 131 to form a retaining shoulder resulting from the difference in diameter between the stem 132 and the insert portion 131. In this case, the retaining shoulder engages with the insert portion stopper 112 protruding inward from the barrel 11 to prevent the insert portion 131 from falling out of the barrel 11. The stem 132 includes a rolling groove 133 that engages with a stem holding portion 141 of the spring stopper 14 to stabilize the coupling with the spring stopper 14. The stem 132 includes a test end portion 134 to come into contact with a pad terminal 41 of a test circuit board 4. In this case, the test end portion 134 projects out of the spring stopper 14 in the axial direction as shown in (b) of FIG. 6. The test end portion 134 may be implemented in a flat, round, crown or tapered shape to come into contact with the ball terminal 31 of the device under test 3. As necessary, the test end portion 134 may be replaced with a test end portion 142 of the spring stopper 14 (to be described later).
[0034] The spring stopper 14 is shaped like a cylinder, which may be implemented as a single-piece metal processed type or a press-formed and subsequently heat-treated type, considering durability and manufacturability.
[0035] The spring stopper 14 is provided at the end of the stem 13 and protrudes higher than the inner diameter of the spring 15 in the radial direction with respect to the axis. As a result, the end of the spring 15 may be supported by the spring stopper 14. As shown in FIG. 5, the spring stopper 14 includes a stem holding portion 141 formed at a position corresponding to the rolling groove 133 of the stem 132 and protruding inward by roll pressing, and the test end portion 142. The spring stopper 14 includes a spring support surface 143 provided at an end portion opposite to the test end portion 142 and extending along the circumferential direction to support a second end of the spring 15.
[0036] The stem holding portion 141 engages with the rolling groove 133 of the stem 132 by roll pressing.
[0037] The test end portion 142 selectively comes into contact with the pad terminal 41. As shown in (a) of FIG. 6, the test end portion 142 may be curved inwardly.
[0038] The spring 15 is shaped like a coil, which may be made of a stainless steel-based or precipitation hardening alloy.
[0039] The spring 15 has an inner diameter corresponding to the outer diameter of the stem 132, and an outer diameter larger than the outer diameter of the spring stopper 14 and corresponding to the outer diameter of the barrel 11. A minimum clearance is formed between the inner diameter of the spring 15 and the outer surface of the stem 132 so that the spring 15 can be slidably fitted on the outer circumference of the stem 132. The outer diameter of the spring 15 may be at least equal to the outer diameter of the barrel 11. When the outer diameter of the spring 15 is smaller than the outer diameter of the barrel 11, the wire diameter of the spring 15 becomes smaller, thereby decreasing the contact force. When the outer diameter of the spring 15 is larger than the outer diameter of the barrel 11, it is unsuitable because the dimensions or the sizes of other components of the test probe 1 need to decrease in consideration of the arrangement of the test probes 1 based on the pitch between the ball terminals 31. The spring 15 is interposed and constrained between the spring support surface 113 of the barrel 11 and the spring support surface 143 of the spring stopper 14. Therefore, the spring 15 has a greater degree of freedom in selecting the wire diameter and the effective number of turns, and stably achieves the target contact force even at the same pitch. In addition, because the spring stopper 14 protrudes radially beyond the inner diameter of the spring 15, the end of the spring 15 does not pass over and disengage from the spring stopper 14, thereby preventing the buckling and loss of the spring 15 and improving the repeatability of the preload setting.
[0040] The operation of the test probe 1 according to an embodiment of the disclosure will be described below with reference to FIGS. 4(a) and 4(b).
[0041] In FIG. 4(a), the contact tip 121 of the terminal 12 is brought into contact with the ball terminal 31 of the device under test 3, and the lower end of the spring stopper 14 is brought into contact with the pad terminal 41 of the test circuit board 4. Then, when the test probe is pressed in the longitudinal direction by the device under test 3, as shown in FIG. 4(b) the spring 15 interposed between the spring support surface 113 of the barrel 11 and the spring support surface 143 of the spring stopper 14 is compressed, thereby transmitting a test signal between the ball terminal 31 of the device under test 3 and the pad terminal 41 of the test circuit board 4.
[0042] FIG. 7 is a view illustrating the structure of a spring stopper 14 according to another embodiment of the disclosure. Hereinafter, descriptions of parts identical to those of the spring stopper 14 shown in FIG. 5 will be omitted to avoid redundancy.
[0043] Referring to FIG. 7, the spring stopper 14 includes a stopper flange 144 at the end facing the spring 15. The stopper flange 144 protrudes from the spring stopper 14 along the circumference in the radial direction with respect to the axis. The stopper flange 144 corresponds to the outer diameter of the spring 15.
[0044] FIG. 8 is a cross-sectional view of a test device 10 according to an embodiment of the disclosure, and FIG. 9 is an enlarged view illustrating a portion of FIG. 8.
[0045] Referring to FIG. 8, the test device 10 includes a socket block 2 supporting a plurality of test probes 1.
[0046] The socket block 2 may be made of an insulating material. When the socket block 2 is made of a conductive material, the test probes 1 for signal and power need to be supported without being in contact with the conductive socket block 2.
[0047] The socket block 2 includes an upper block 21 for accommodating and supporting a portion of the test probe 1, and a lower block 22 for accommodating and supporting the remaining portion of the test probe 1. The socket block 2 is provided with a probe accommodating portion 23 that penetrates along the axis to accommodate and support the test probes 1.
[0048] The probe accommodating portion 23 includes a barrel accommodating hole 231 in which the barrel 11 and the spring 15 of the test probe 1 shown in FIG. 1 are slidably accommodated, a terminal accommodating hole 232 in which the terminal 12 is slidably accommodated, and a stopper accommodating hole 233 in which the spring stopper 14 is slidably accommodated.
[0049] The outer diameters of the barrel 11 and the spring 15, the terminal 12, and the spring stopper 14 are formed to have minimum clearances with the inner surfaces of the barrel accommodating hole 231, the terminal accommodating hole 232, and the stopper accommodating hole 233, respectively, thereby allowing the barrel 11 and the spring 15, the terminal 12, and the spring stopper 14 to slide within their respective accommodating holes.
[0050] The diameter of the terminal accommodating hole 232 is smaller than the diameter of the barrel accommodating hole 231. The diameter of the barrel accommodating hole 231 is larger than the diameter of the adjacent stopper accommodating hole 233. The socket block 2 includes a probe retaining portion 234 formed between the barrel accommodating hole 231 and the stopper accommodating hole 233 based on the difference in inner diameter between the barrel accommodating hole 231 and the stopper accommodating hole 233. Therefore, the socket block 2 is transported with the test end portion 142 of the spring stopper 14 protruding downward as shown in (a) of FIG. 9. In this case, the test probe 1 is prevented from being pulled out of the socket block 2 downward because the spring 15 is caught by the probe retaining portion 234. Likewise, the test probe 1 is prevented from being pulled out of the socket block 2 upward because the upper end of the barrel 11 cannot pass through the terminal accommodating hole 232. The transported socket block 2 is then placed to bring the test end portion 142 of the spring stopper 14 into contact with the pad terminal 41 of the test circuit board 4, and undergoes a test as shown in FIGS. 4(a) and 4(b).
[0051] Referring to FIG. 9(a), the test probe 1 is inserted into the probe accommodating portion 23, with the test end portion 142 of the spring stopper 14 protruding downward from the lower block 22. In this case, the spring 15 of the test probe 1 is caught by the probe retaining portion 234. Referring to FIG. 9(b), the test probe 1 is inserted into the probe accommodating portion 23, with the test end portion 142 of the spring stopper 14 being in contact with the pad terminal 41 of the test circuit board 4 provided on the lower side of the lower block 22. In this case, the spring 15 of the test probe 1 is pushed upward by the spring stopper 14 and is in an initially compressed state.
[0052] FIG. 10 is a view partially illustrating an application of the spring stopper 14 of FIG. 7 to the socket block 2.
[0053] Referring to FIG. 10, the end of the spring 15 is in contact with the stopper flange 144. Because the stopper flange 144 has a diameter corresponding to the outer diameter of the spring 15, the stopper flange 144 is securely caught by the probe retaining portion 234 and does not disengage from the stopper accommodating hole 233.
[0054] As described above, because the spring 15 is arranged around the stem 132 outside the barrel 11, the outer diameter of the spring 15 can be designed without being constrained by the inner diameter of the barrel thereby stably ensuring the required contact force-displacement characteristics even under fine pitch conditions (e.g., a pitch of 0.10 mm or less). As an example of dimensions and tolerances for fine-pitch implementation, the inner diameter of the spring 15 is set to have a minimum clearance with the outer diameter of the stem 132 while allowing for slidable fitting, and the outer diameter of the spring 15 is set to have a predetermined clearance with the inner diameter of the barrel accommodating hole 231 while considering the length, the free height, and the effective number of turns to prevent buckling. The relationship between the outer diameter of the barrel 11 and the outer diameter of the spring 15 is established by taking into account the machining tolerances and the thermal expansion and contamination allowances of the barrel accommodating hole of the socket block while ensuring the minimal interference between the outer surface of the barrel and the outer surface of the spring.
[0055] As a modified embodiment, the spring support surface 143 of the spring stopper 14 may be formed in a flat or micro-groove shape in accordance with the end coil shape of the spring 15 to suppress passing-over, eccentricity, and local stress concentration at the end of the spring 15, thereby enhancing reliable repeatability.
[0056] The test probe according to an embodiment of the disclosure may employ a spring having a relatively high spring contact force even with very fine the dimensions or the sizes, for example, a diameter (φ) of 0.10 mm or less.
[0057] Although a few embodiments of the disclosure have been illustrated and described above, the disclosure is not limited to the foregoing specific embodiments. Various modifications may be made in the embodiments by those skilled in the art without departing from the scope of the disclosure as claimed in Claims, and these modified embodiments should not be understood separately from the technical spirits or prospects of the disclosure.
Claims
1.A test probe supported by a socket block to test electrical characteristics of a device under test, the test probe comprising:a barrel shaped like a cylinder and inserted and accommodated in a probe accommodating portion formed through the socket block along an axis;a plunger comprising an insert portion having a diameter corresponding to an inner diameter of the barrel, the insert portion being inserted into a second end of the barrel and configured to slide in an axial direction within the barrel, and a stem extending from the insert portion;a spring stopper provided at an end portion of the stem and protruding in a radial direction with respect to the axis; anda spring shaped like a coil, provided on an outer circumference of the stem, with both ends being respectively supported in the axial direction by the second end of the barrel and the spring supporter, and operating to be compressed and restored upon sliding of the plunger.2.The test probe of claim 1, whereinthe spring has an inner diameter corresponding to an outer diameter of the stem, and an outer diameter larger than an outer diameter of the spring stopper and corresponding to an outer diameter of the barrel, andthe spring stopper has a protrusion height greater than the inner diameter of the spring.3.The test probe of claim 2, wherein the spring stopper is shaped like a cylinder, has an inner circumference of which at least a region is fixed to an outer circumference of the stem, and has a spring support surface provided along a circumferential direction at a first end for supporting the spring.4.The test probe of claim 3, wherein the spring stopper comprises a test end portion made of a metal material and provided at an end opposite to the spring support surface.5.The test probe of claim 3, wherein the plunger comprises a test end portion exposed from the spring stopper.6.A test device comprising:the test probe of any one of claims 1 to 5; andthe socket block comprising the probe accommodating portion, whereinthe probe accommodating portion comprises a barrel accommodating hole that accommodates the barrel and the spring, and a stopper accommodating hole that accommodates the spring stopper and has an inner diameter smaller than an inner diameter of the barrel accommodating hole, and comprises a probe retaining portion formed by a difference in inner diameter between the barrel accommodating hole and the stopper accommodating hole.