Spring probe structure of a variable-pitch spring

Abstract

The application discloses a spring probe structure of variable-pitch spring, which comprises a needle head, a spring, a needle tube and a needle tail, the spring is arranged in the needle tube, the needle head comprises a needle head tail part arranged in the needle tube and in contact with one end of the spring and a needle tip part arranged outside the needle tube, the needle tail comprises a needle tail head part arranged in the needle tube and in contact with the other end of the spring and a needle tail tail part arranged outside the needle tube, the two ends of the needle tube limit the needle head tail part and the needle tail head part in the needle tube through dotting, the spring is provided with a first pitch spring part and a second pitch spring part, and the pitch size of each circle in the axial direction of the first pitch spring part is set to be greater than the pitch size of each circle in the axial direction of the second pitch spring part. The application makes the spring provide stable lateral force, improves the stability of the probe resistance value, and further guarantees the reliability of the test result.

Description

Technical Field

[0001] This invention relates to the technical field of spring probes, and more specifically to a spring probe structure for a variable pitch spring. Background Technology

[0002] A test probe is a spring probe composed of basic components such as a needle tip, spring, needle tube, and needle tail. The lateral force of the spring is one of the main factors affecting the probe resistance.

[0003] The springs in existing spring probes are all set as equal-pitch springs, such as Figures 1-2 As shown, the needle tail, spring, and needle tip are sequentially placed in the syringe. The junction of the syringe and needle tip is secured with rivets, thus completing the probe assembly. The needle tip contacts the object being tested, the needle tail contacts the spring inside the syringe, the spring contacts the needle tail, and the needle tail contacts and connects with the PCB, thus achieving conductivity. The contact between the needle tip and the object being tested, and the contact between the needle tail and the PCB, are both related to the elasticity and material, requiring relatively stable and reliable contact.

[0004] The contact between the needle tip and the syringe tube, and the contact between the needle tail and the syringe tube, are both related to the lateral force provided by the spring. When a spring with equal pitch is subjected to force, each pitch segment changes uniformly, and exhibits S-shaped creep when compressed. However, because the pitch is equal, the number and position of the torsion points each time it is pressed will change randomly, that is, the creep is uncontrollable. Therefore, the lateral force of the spring is inconsistent or unstable, which will directly cause the spring resistance to jump, affecting the test results of the probe. Summary of the Invention

[0005] To overcome the aforementioned problems, the present invention aims to provide a spring probe structure for a variable pitch spring, which enables the spring to provide a stable lateral force, improves the stability of the probe resistance, and thus ensures the reliability of the test results.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a spring probe structure for a variable pitch spring, comprising a needle head, a spring, a needle tube, and a needle tail. The spring is disposed inside the needle tube. The needle head includes a needle tail portion disposed inside the needle tube and in contact with one end of the spring, and a needle tip portion disposed outside the needle tube. The needle tail includes a needle tail head portion disposed inside the needle tube and in contact with the other end of the spring, and a needle tail tail portion disposed outside the needle tube. The two ends of the needle tube are respectively positioned within the needle tube by dotting. The spring is provided with a first pitch spring portion and a second pitch spring portion. The pitch dimension per circumference in the axial direction of the first pitch spring portion is set to be greater than the pitch dimension per circumference in the axial direction of the second pitch spring portion.

[0007] Preferably, the first pitch spring portion is disposed near the tail end of the needle tip, and the second pitch spring portion is disposed near the head end of the needle tip.

[0008] Preferably, the first pitch spring portion is in contact with the tail portion of the needle tip.

[0009] Preferably, the second pitch spring portion contacts the needle tail head.

[0010] Preferably, the spring is further provided with a third pitch spring portion, the second pitch spring portion is located between the first pitch spring portion and the third pitch spring portion, and the pitch dimension per circumference in the axial direction of the third pitch spring portion is set to be greater than the pitch dimension per circumference in the axial direction of the second pitch spring portion.

[0011] Preferably, the third pitch spring portion is disposed near the head end of the needle tip, and the first pitch spring portion is disposed at the tail end of the needle tip.

[0012] Preferably, the third pitch spring portion is in contact with the head of the needle tail, and the first pitch spring portion is in contact with the tail of the needle tip.

[0013] Preferably, the pitch dimension per circumference in the axial direction of the third pitch spring portion is set to be equal to the pitch dimension per circumference in the axial direction of the first pitch spring portion.

[0014] The beneficial effects of this invention are: replacing the constant pitch spring with a variable pitch spring will fix the twisted shape and position of the spring near the tail and head of the needle, providing a stable lateral force with each press, improving the stability of the probe resistance, and ensuring the reliability of the test results. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a test probe in the background art;

[0016] Figure 2 This is a schematic diagram of the structure of an equal-pitch spring in the background art;

[0017] Figure 3 This is a schematic diagram of the overall structure of this embodiment. Figure 1 ;

[0018] Figure 4 This is a schematic diagram of the spring structure in this embodiment;

[0019] Figure 5 This is a schematic diagram of the overall structure of this embodiment. Figure 2 ;

[0020] Figure 6 This is a schematic diagram of the variable pitch spring in this embodiment;

[0021] Figure 7 The resistance and stability diagrams for a conventional spring probe are shown.

[0022] Figure 8 The diagram shows the resistance and stability of the spring probe in this embodiment.

[0023] In the diagram: 1. Needle tip; 2. Spring; 3. Needle tube; 4. Needle tail; 5. Needle tip tail; 6. Needle tip; 7. Needle tail head; 8. Needle tail tail; 9. First pitch spring section; 10. Second pitch spring section; 11. Third pitch spring section. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0025] See Figures 3-6 As shown, this embodiment discloses a spring probe structure for a variable pitch spring, including a needle head 1, a spring 2, a needle tube 3, and a needle tail 4. The spring 2 is disposed inside the needle tube 3. The needle head 1 includes a needle tail 5 disposed inside the needle tube 3 and in contact with one end of the spring 2, and a needle tip 6 disposed outside the needle tube 3. The needle tail 4 includes a needle head 7 disposed inside the needle tube 3 and in contact with the other end of the spring 2, and a needle tail 8 disposed outside the needle tube 3. The two ends of the needle tube 3 are connected by a dotting method to the needle tail 5 and the needle head 7 respectively. Part 7 is confined within the needle tube 3. The spring 2 is provided with a first pitch spring part 9 and a second pitch spring part 10. The pitch dimension of the first pitch spring part 9 in the axial direction per circumference is set to be greater than the pitch dimension of the second pitch spring part 10 in the axial direction per circumference. The first pitch spring part 9 is located near the end of the needle tail 5 and is in contact with the end of the needle tail 5. The second pitch spring part 10 is located near the end of the needle head 7 and is in contact with the end of the needle head 7.

[0026] In one embodiment, the spring 2 is further provided with a third pitch spring portion 11, the second pitch spring portion 10 is located between the first pitch spring portion 9 and the third pitch spring portion 11, and the pitch dimension of the third pitch spring portion 11 in the axial direction per circumference is set to be greater than the pitch dimension of the second pitch spring portion 10 in the axial direction per circumference. The third pitch spring portion 11 is located near the needle head 7 end, the first pitch spring portion 9 is located at the needle tail 5 end, the third pitch spring portion 11 is in contact with the needle head 7, and the first pitch spring portion 9 is in contact with the needle tail 5.

[0027] Furthermore, the pitch dimension per circumference of the third pitch spring portion 11 in the axial direction is set to be equal to the pitch dimension per circumference of the first pitch spring portion 9 in the axial direction.

[0028] For springs with the same wire diameter and outer diameter, fewer coils (larger pitch) result in greater spring force for the same compression stroke. Similarly, when the required spring force is the same, a spring with fewer coils (larger pitch) requires a shorter compression stroke. When the probe is compressed, the internal spring twists to provide a lateral force to the needle tip. This lateral force is mainly related to the twisting state of a small section of the spring on the contact side with the needle tip and tail. Too many twisting points can also offset the spring's own lateral force. This structure connects a large-pitch spring and a small-pitch spring in series to form a variable-pitch spring. The large-pitch spring section is close to the needle tip and tail, where it experiences less deformation under stress. The main twisting is concentrated in the middle small-pitch spring section, which exhibits multiple S-shaped twists. The large-pitch spring sections at both ends exhibit C-shaped twists. The position and number of twists are relatively fixed, and the C-shaped twist provides a greater lateral force than the S-shaped twist of an equidistant spring, ensuring reliable internal contact and stable resistance of the probe.

[0029] This structure improves the contact reliability inside the probe without changing the cost, assembly method, or assembly difficulty, and enables the probe resistance to be stable, meeting the contact reliability requirements of high-requirement testing.

[0030] See Figure 7 and Figure 8 , Figure 7 Probes for installing equal-pitch springs. Figure 8 The figure shows the probes for installing the variable pitch spring. The horizontal axis represents the number of compression cycles (1k, 2k, 3k, etc.), and the vertical axis represents the measured resistance value. Points with the same horizontal axis but different vertical axes represent the resistance readings of multiple probes corresponding to the same number of compression cycles. Comparing the two figures, it is clear that the resistance and stability of this structure are improved compared to those of the conventional structure.

[0031] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A spring probe structure for a variable pitch spring, comprising a needle head, a spring, a needle tube, and a needle tail, wherein the spring is disposed within the needle tube, the needle head includes a needle tail portion disposed within the needle tube and in contact with one end of the spring, and a needle tip portion disposed outside the needle tube, the needle tail includes a needle head portion disposed within the needle tube and in contact with the other end of the spring, and a needle tail portion disposed outside the needle tube, wherein the two ends of the needle tube are respectively positioned within the needle tube by a dotting method, characterized in that... The spring is provided with a first pitch spring part and a second pitch spring part. The pitch dimension per circumference in the axial direction of the first pitch spring part is set to be greater than the pitch dimension per circumference in the axial direction of the second pitch spring part.

2. The spring probe structure of the variable pitch spring according to claim 1, characterized in that, The first pitch spring portion is located near the tail end of the needle, and the second pitch spring portion is located near the head end of the needle.

3. The spring probe structure of the variable pitch spring according to claim 2, characterized in that, The first pitch spring portion contacts the tail portion of the needle tip.

4. The spring probe structure of the variable pitch spring according to claim 2 or 3, characterized in that, The second pitch spring portion contacts the head of the needle tail.

5. The spring probe structure of the variable pitch spring according to claim 1, characterized in that, The spring is further provided with a third pitch spring portion, the second pitch spring portion is located between the first pitch spring portion and the third pitch spring portion, and the pitch dimension per circumference in the axial direction of the third pitch spring portion is set to be greater than the pitch dimension per circumference in the axial direction of the second pitch spring portion.

6. The spring probe structure of the variable pitch spring according to claim 5, characterized in that, The third pitch spring portion is located near the head end of the needle, and the first pitch spring portion is located at the tail end of the needle.

7. The spring probe structure of the variable pitch spring according to claim 6, characterized in that, The third pitch spring portion contacts the head of the needle, and the first pitch spring portion contacts the tail of the needle.

8. The spring probe structure of the variable pitch spring according to claim 5, characterized in that, The pitch dimension per circumference in the axial direction of the third pitch spring portion is set to be equal to the pitch dimension per circumference in the axial direction of the first pitch spring portion.

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