Elastic sheet microneedle manufacturing method for crimping test

Abstract

The invention relates to a method for manufacturing an elastic sheet microneedle for a crimping test, which is characterized by comprising the following steps: S1, designing a processing pattern according to an outline pattern and a micro bridge contact of the elastic sheet microneedle, the outline pattern comprises a connecting part, a bending elastic part and a test needle body part, the bending elastic part comprises a straight line part and an arc line part, and the test needle body part comprises a connecting part, a bending elastic part and a test needle body part; micro-bridge contacts are formed at two ends of the bent elastic part, and the end parts of the micro-bridge contacts extend into the outline pattern of the elastic sheet micro-needle; s2, a cutting track path of laser cutting equipment is formed according to the machining pattern; s3, the metal sheet with the thickness ranging from 10 micrometers to 500 micrometers is cut through picosecond or femtosecond ultrashort pulse laser according to the cutting track path; s4, redundant metal scraps on the product obtained after laser cutting are removed, and an elastic piece microneedle and a frame are formed; s5, plating a nickel layer and a gold layer on the upper surface of the elastic sheet microneedle in a chemical plating manner; and S6, separating the micro-bridge contacts to obtain a single elastic sheet micro-needle. According to the elastic sheet micro-needle, the micro-bridge connection points extending inwards are arranged at the two ends of the bending elastic part, sheet cutting is carried out in combination with picosecond or femtosecond ultrashort pulses, the produced elastic sheet micro-needle has good consistency, and it is detected that the elastic sheet micro-needle can still keep good consistency after being tested for 300,000 times, and the test requirement is still met.

Description

Technical Field

[0001] The invention relates to the technical field of electronic testing, in particular to a method for manufacturing a spring microneedle for crimping testing. Background Art

[0002] In the manufacturing process of electronic component modules such as liquid crystal panels and integrated circuits, electrical functional testing is often required to test various electrical parameters of the product to ensure that the product can operate normally.

[0003] Traditional two-point contact tests on the same terminal under test, such as Kelvin tests, mostly use a parallel and parallel distribution of double ejector pins or double gold fingers. As the size of semiconductor products continues to shrink, the size of the terminals under test and the spacing between different terminals under test are also shrinking. In order to adapt to this trend, the bottleneck of the traditional parallel and parallel distribution of double ejector pins or double gold fingers in the problem of dense spacing is becoming increasingly prominent, and the accuracy requirements are getting higher and higher. Some are even impossible to achieve. In order to achieve two-point contact testing in a limited space on the terminal under test, the ejector pins or gold fingers are becoming thinner and thinner, and their mechanical structure strength is becoming weaker and weaker. The test contact heads of traditional ejector pins or gold fingers are more susceptible to wear, especially when higher accuracy requirements are put forward and the mechanical strength is relatively low. The degree of wear is greater, thereby reducing the service life of the test fixture. In order to meet the development needs of semiconductors that are thin and short, shrapnel needles came into being.

[0004] At present, the shrapnel microneedle is processed by photosensitization, development, and chemical etching. The processing accuracy of the chemical etching method is affected by many factors and is difficult to control, resulting in the geometric size of the metal pattern deviating from the design requirements, which is not suitable for manufacturing extremely fine structures. For example, due to the low accuracy of pattern transfer and side corrosion effects, it has long been a difficult problem in the processing of shrapnel microneedles. The defects of the shrapnel microneedle produced by the etching method affect the mechanical elasticity and contact electrical properties of the shrapnel microneedle.

[0005] Due to the precision of the shrapnel microneedles, they are usually used in pairs or groups. Therefore, the difference between a pair or a group of shrapnel microneedles is an important indicator. If the difference between a pair or a group of shrapnel microneedles is large, it may cause a series of problems such as inaccurate testing and affect the life of the shrapnel microneedles. Due to the problems existing in etching, the individual differences of the shrapnel microneedles produced by etching include not only the individual differences of the shrapnel microneedles when leaving the factory, but more importantly, the differences in the mechanical elasticity and contact electrical properties of each shrapnel microneedle after a period of testing. Summary of the invention

[0006] The present invention provides a method for manufacturing a spring-type microneedle for crimping test, which cuts metal sheets by picosecond or femtosecond lasers to obtain more uniform individuals, which not only have more stable internal resistance, but also have more consistent elastic force and better service life.

[0007] To cut a material with laser, it is necessary to apply a laser with a power density greater than the threshold value of destroying the material. In order to obtain a higher power density, Q-switching and other technical means are used to accumulate the laser energy generated by the laser material, and when it reaches a higher energy value, it is quickly released, and this cycle repeats, forming a series of laser energy released at a certain time interval within a certain length of time. This is a pulsed laser, which is characterized by a much higher power density than uninterrupted continuous release.

[0008] Picosecond and femtosecond lasers refer to laser technologies that release accumulated energy within picoseconds and femtoseconds. This type of laser releases pulses in a very short time and at a very fast speed, so it is also called ultrashort pulse or ultrafast laser. Ultrashort pulse lasers have good coupling rates with various materials, and the heat generated during the processing is very small. By controlling the number and method of applied pulses, picoseconds and femtoseconds in the infrared, green, or ultraviolet bands can complete the cutting task in the method of the present invention.

[0009] A method for making a spring-type microneedle for crimping test comprises the following steps:

[0010] S1. Design and process the pattern according to the outline pattern and micro-bridge point of the shrapnel microneedle, wherein the outline pattern includes a connecting portion, a curved elastic portion, and a test needle body portion, wherein the curved elastic portion includes a straight portion and an arc portion, and micro-bridge points are formed at both ends of the curved elastic portion, and the ends of the micro-bridge points extend into the outline pattern of the shrapnel microneedle;

[0011] S2. Forming a cutting trajectory path of a laser cutting device according to the processing graphics;

[0012] S3. Cutting a metal sheet having a thickness of 10-500um by using a picosecond or femtosecond ultrashort pulse laser according to the cutting trajectory path;

[0013] S4. removing the excess metal waste on the laser-cut product to form a shrapnel microneedle and a frame, wherein the shrapnel microneedle is connected to the frame through a micro-bridge point;

[0014] S5. A nickel layer and a gold layer are plated on the upper surface of the shrapnel microneedle by chemical plating;

[0015] S6. Separate the micro-bridge points to obtain a single spring microneedle.

[0016] Furthermore, the metal sheet is one of nickel, titanium, stainless steel, beryllium copper or an alloy thereof.

[0017] Furthermore, the elastic microneedle has multiple outline patterns, and the number of micro-bridge points matches that of the elastic microneedle.

[0018] Furthermore, the micro-bridge points extend 20-100 um into the contour pattern of the spring microneedle, and the width of the smallest connection of the micro-bridge points is 20-100 um.

[0019] Furthermore, the curved elastic portion is in an S shape.

[0020] Furthermore, the laser cuts the metal sheet using the PSO pulse position synchronization output function.

[0021] The present invention has the following beneficial effects:

[0022] 1. The processing pattern of the present invention includes micro-bridge points located at both ends of the curved elastic part, thereby effectively fixing the spring microneedle on the frame, preventing individual differences in the curved elastic part caused by thermal deformation during picosecond and femtosecond laser processing, and effectively preventing deformation of the curved elastic part caused by subsequent processes such as waste removal and gold plating.

[0023] 2. Use picosecond or femtosecond ultrashort pulse laser to cut 10-500um metal sheets, which can ensure effective cutting of sheets to form spring microneedles, and avoid recasting of cutting edge materials to reduce elastic mechanical properties and repeated life. It truly realizes cold processing, and the processed metal sheets have no melting and residue on the edges, and can obtain a maximum accuracy of +-1um, and a cutting size of less than 20um.

[0024] 3. By configuring the PSO pulse position synchronous output function, the laser is triggered to emit at a constant spatial (rather than temporal) interval in all stages of the motion trajectory, including acceleration, deceleration and uniform speed sections, so that the pulse energy acts evenly on the processed object, thereby ensuring that the produced shrapnel microneedles have consistency in internal resistance and elasticity.

[0025] 4. The present application adopts an inwardly arranged micro-bridge point, which forms a small inwardly recessed notch after being disconnected, which will not cause interference during the test process, thereby effectively avoiding deformation of the bent elastic part caused during long-term testing.

[0026] 5. The inwardly extending micro-bridge points are set at both ends of the curved elastic part, and the sheet cutting is carried out in combination with picosecond or femtosecond ultrashort pulses, so that the produced shrapnel microneedles have good consistency. After testing, the shrapnel microneedles produced in this application can still maintain good consistency after 300,000 tests and still meet the test requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of Example 1.

[0028] Figure 2 Schematic diagram of the processing effects of two rounded rectangles with and without the PSO function.

[0029] Figure 3 This is a picture of the metal sheet after laser processing in Example 1.

[0030] Figure 4 for Figure 3 Schematic diagram of the structure after removing metal waste.

[0031] FIG. 5( a ) is a schematic diagram of a microbridge contact structure in the prior art.

[0032] FIG. 5( b ) is an enlarged schematic cross-sectional view of a micro-bridge connection in the prior art after disconnection.

[0033] FIG. 6( a ) is a schematic diagram of the micro-bridge structure of the first embodiment.

[0034] FIG6( b ) is an enlarged schematic cross-sectional view of the micro-bridge connection of the first embodiment after being disconnected.

[0035] Beryllium copper 1, connecting part 2, bending elastic part 3, test needle body 4, straight part 41, arc part 42, micro-bridge point 5, end 51, A\B spring microneedle 7, frame 6. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Embodiment 1:

[0038] A method for making a shrapnel microneedle for crimping test, wherein the shrapnel microneedle is an integrally formed shrapnel structure formed by processing a sheet of metal shrapnel, and the middle of the curved elastic part 3 is set as a hollow structure, and the hollow structure can ensure that the curved elastic part can smoothly undergo a large range of elastic probe deformation. The shrapnel microneedle body is made of metal or metal alloy, and the metal or metal alloy is selected from: copper or its alloy, such as copper-beryllium, copper-silver, copper-niobium, or rhodium or its alloy; or nickel or its alloy, such as nickel-manganese, nickel-cobalt, nickel-iron, nickel-beryllium alloy, or tungsten or its alloy, such as tungsten-copper, tungsten-rhenium, such as iron or iron-manganese or its alloy, or titanium or its alloy, such as rhodium-ruthenium, or iridium or its alloy. In particular, the metal material is selected to have a resistivity value less than 50μΩ / cm. The metal thickness is generally selected in the range of 10-500um. In this embodiment, beryllium copper 1 with a thickness of 150um is selected.

[0039] The following steps are involved:

[0040] S1, the shrapnel microneedle 7 includes a connecting portion 2, a curved elastic portion 3, and a test needle body 4, wherein the curved elastic portion 4 includes a straight portion 41 and an arc portion 42, and micro-bridge points 5 are formed at both ends of the curved elastic portion, and the end 51 of the micro-bridge point 5 extends into the contour of the shrapnel microneedle. The CAD data of the shrapnel microneedle contour is formed by design. It can be understood that this is not limited to CAD data, and any graphic data that can be accurately converted into a laser trajectory can be used.

[0041] S2. According to the CAD data of the shrapnel microneedle contour, a set of 8 pcs of slabs are assembled using the dedicated CAM software of the laser equipment. The micro-bridge point extends into the body of the shrapnel microneedle contour line by a length of A, in this embodiment A = 100um, and the minimum connection width of the micro-bridge point is B, in this embodiment B = 100um. Generally speaking, the length of the micro-bridge point extending into the body of the shrapnel microneedle contour line and the minimum connection width are 20-100um. The number of shrapnel microneedles per plate can be adjusted according to actual conditions, and the number of micro-bridge points matches the shrapnel microneedles.

[0042] Considering that the microneedles, especially the S-shaped parts that generate elastic force, will shift during the laser processing, it is necessary to consider setting limits on both sides of the S-bend elastic part that generates elastic force. We use 20-100um wide micro-connection points to fix them on the frame; this facilitates the material and its subsequent electroplating process, facilitates operation, and improves electroplating efficiency. The present invention has made an innovative design for the micro-connection bridge point, extending the outline of the bridge into the body by 20-100um, and the minimum connection part width is designed to be 20-100um. According to the material thickness and the small size of the shrapnel microneedle, such a micro-connection point design is not easy to drop the product. In addition, we designed a 20-100um wide micro-connection design, which is also convenient for separating a single microneedle from the entire plate after electroplating.

[0043] S3, using a 30-watt femtosecond ultraviolet pulse laser device to cut the 150-um thick beryllium copper; it is understandable that in the actual production process, the laser power, light source and metal sheet can be adjusted according to actual conditions.

[0044] Selection of laser processing light source: Conventional microsecond and nanosecond lasers, the heat effect during processing will cause melting and slag on the edge of the metal laser cutting, affecting the dimensional accuracy of the shrapnel microneedle and making it difficult to process particularly fine sizes below 100um. The heat effect also causes the material at the cutting edge to be recast, reducing the elastic mechanical properties and repeated life. Picosecond or femtosecond ultrashort pulse lasers have ultrashort pulse duration and ultra-high peak power. They use the electrons inside the material to instantly excite ionization, causing the positively charged particles in the material to erupt outward in the form of plasma due to the strong Coulomb repulsion, thereby achieving material removal. It is a true cold processing. The S1 metal sheet has no melting and residue on the edge, and can obtain a maximum accuracy of +-1um and a cutting size of less than 20um. We selected picoseconds and femtoseconds in the infrared, green and ultraviolet bands. The trajectory paths made according to S2 have completed the cutting tasks in the method of the present invention. See Table 1 for details:

[0045]

[0046] Table 1

[0047] Laser processing applications for shrapnel microneedles all include motion trajectories such as rounded corners and curves. For such trajectories, the straight part is usually cut faster, and the rounded part moves slowly. If the laser pulses are emitted at a fixed frequency, the process will be highly variable due to different speeds on the trajectory, and unnecessary "aging" will occur in the lower motion speed segment due to higher pulse overlap. To ensure the processing quality of such rapidly changing speed trajectories, industrial ultrafast laser systems need to coordinate the movement of the processing platform with the output of the trigger laser or data acquisition device to achieve high-speed, high-quality motion control.

[0048] In order to obtain balanced pulses in curved and straight parts, we configured the PSO (position synchronized output) pulse position synchronous output function, that is, by collecting real-time encoder feedback for position comparison, and synchronizing the phase with the laser synchronous output signal, the laser is triggered at a constant spatial (not temporal) interval in all stages of the motion trajectory, including acceleration, deceleration and uniform speed sections, so that the pulse energy can act evenly on the processed object. Figure 2The schematic diagrams of the processing effects of two rounded rectangles with and without the PSO function are listed and compared. It can be clearly observed that with the PSO function, the light spot emitted by the laser is evenly distributed throughout the entire motion trajectory, and the aging phenomenon caused by over-processing is avoided even at the corner curve, thereby ensuring the consistency of the overall shrapnel microneedle processing quality.

[0049] The dimensional accuracy of the S part of the shrapnel directly affects the elastic force of the shrapnel, and further affects the mechanical and electrical properties of the shrapnel microneedle; the dimensional accuracy of the shrapnel needle ensures accurate elastic force and consistency of the elastic force of each needle; the accuracy of the laser cutting trajectory and the melting of the cutting edge affect the dimensional accuracy of the shrapnel microneedle. Step 2 obtains a smooth cutting edge without residue or melting. In order to obtain a stable high-precision laser cutting trajectory, one of the following methods is used to fix the optical path or the product: 1) Use a high-end scanning galvanometer. 2) The light beam is fixed and a high-precision mobile platform is used. The product is fixed to the mobile platform by vacuum adsorption or a fixture. In order to prevent laser smoke from adhering to the processing surface again, we set a laser smoke collection device on the upper part of the laser cutting to absorb the smoke from the laser processing in time.

[0050] S4, removing the excess metal waste on the product after laser cutting to form the spring microneedle 7 and the frame 6, wherein the spring microneedle is connected to the frame 6 via the micro-bridge point 5.

[0051] S5, a nickel layer 81 is plated on the surface of the substrate of the shrapnel microneedle by chemical plating or sputtering. This can not only enhance the binding force of copper, nickel and gold, but also enhance the wear resistance of the contact part of the microneedle, and improve the service life of the microneedle. The thickness of the nickel plating layer is 1um. A gold layer 82 is plated on the surface of the shrapnel microneedle by chemical plating or sputtering. This can not only enhance the conductivity of the shrapnel microneedle, but also increase its heat dissipation efficiency. The thickness of the gold plating layer is 2um.

[0052] S6, disconnect the micro-bridge point 5 to obtain a single spring-type microneedle 7.

[0053] The shrapnel microneedles produced by the method of the present invention were tested and compared with the shrapnel microneedles on the market, and the test data are shown below, where Tables 2(a) and 2(b) are the test data of the shrapnel microneedles of this embodiment, and Tables 3(a) and 3(b) are the test data of the existing shrapnel microneedles. According to the life test data, the shrapnel microneedles produced by the present invention can still meet the requirements of internal resistance and elastic force at 300,000 times, and maintain the consistency of the sheet needle, while the existing shrapnel has basically reached the life limit after being used for 150,000 tests. Therefore, the shrapnel microneedles produced by this application have better service life and individual consistency, and can reduce the attenuation of the resistance and elastic force of the shrapnel microneedles.

[0054]

[0055] Table 2(a)

[0056]

[0057] Table 2(b)

[0058]

[0059] Table 3(a)

[0060]

[0061] Table 3(b)

[0062] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for making a spring microneedle for crimping test, characterized in that: The following steps are involved: S1. Design and process the pattern according to the outline pattern and micro-bridge point of the shrapnel microneedle, wherein the outline pattern includes a connecting portion, a curved elastic portion, and a test needle body portion, wherein the curved elastic portion includes a straight portion and an arc portion, and micro-bridge points are formed at both ends of the curved elastic portion, and the ends of the micro-bridge points extend into the outline pattern of the shrapnel microneedle; S2. Forming a cutting trajectory path of a laser cutting device according to the processing graphics; S3. Cutting a metal sheet having a thickness of 10-500um by using a picosecond or femtosecond ultrashort pulse laser according to the cutting trajectory path; S4. removing the excess metal waste on the laser-cut product to form a shrapnel microneedle and a frame, wherein the shrapnel microneedle is connected to the frame through a micro-bridge point; S5. A nickel layer and a gold layer are plated on the upper surface of the shrapnel microneedle by chemical plating; S6. Separate the micro-bridge points to obtain a single spring microneedle.

2. The method for making a spring-type microneedle for crimping test according to claim 1, characterized in that: The metal sheet is one of nickel, titanium, stainless steel, beryllium copper or their alloys.

3. The method for making a spring-type microneedle for crimping test according to claim 1, characterized in that: The elastic microneedle has a plurality of contour patterns, and the number of micro-bridge points matches that of the elastic microneedle.

4. The method for making a spring-type microneedle for crimping test according to claim 1, characterized in that: The micro-bridge points extend 20-100um into the contour pattern of the spring microneedle, and the width of the smallest connection of the micro-bridge points is 20-100um.

5. The method for making a spring-type microneedle for crimping test according to claim 1, characterized in that: The curved elastic portion is in an S shape.

6. The method for making a spring-type microneedle for crimping test according to claim 1, characterized in that: When laser cuts metal sheets, the PSO pulse position synchronization output function is used for cutting.

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