Ultra-long and ultra-narrow gold-tin soldering strip and preparation method thereof

Abstract

The invention relates to the technical field of gold-tin soldering strips, and provides a method for preparing an ultra-long and ultra-narrow gold-tin soldering strip through pre-slitting. The method comprises the two main steps of cold stamping and presetting of the cutting opening and hot shearing and splitting. According to the continuous ultra-narrow slitting device for the gold-tin solder strip, continuous ultra-narrow slitting of the gold-tin ultra-long solder strip is achieved through the preset array pinhole-shaped pre-slitting notches in cooperation with hot shearing slitting, the probability that the whole strip is broken due to the fact that the edge of the solder strip is broken in the shearing slitting process is reduced, and the continuous slitting coiling capacity of the gold-tin solder strip is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of gold-tin soldering strips, and in particular relates to an ultra-long and ultra-narrow gold-tin soldering strip and a preparation method thereof. Background Art

[0002] Gold-tin eutectic solder (Au20Sn) is widely used in chip packaging, power device packaging, aerospace device airtight packaging, and high-reliability packaging of automotive electronic devices because of its melting point (280°C) similar to that of high-lead solder, narrow melting range, high strength, good creep resistance, excellent service reliability and wettability.

[0003] As a kind of solder, the preparation process of solder strip usually includes: melting - rolling - cutting (stripping). ’ -Au 5 Sn and δ-AuSn are two intermetallic compounds, which make the material brittle and difficult to cut and coil into ultra-long solder strips. Disc shearing and rolling shearing slitting use preheating shearing and continuous shearing after rolling to cut gold-tin solder strips respectively. Preheating shearing can indeed avoid the breakage of brittle solder strips during shearing, but during slitting, when the rear roller is rolled up, the temperature of the solder strip has dropped to room temperature, but the temperature of the uncut solder strip at the front end is still around 100°C. The uneven temperature distribution will cause the ultra-long solder strip to crack at the cutting edge during striping and winding, and cause the solder strip to break, which cannot meet the continuous production of ultra-long solder strips. Although multi-roller rolling shearing slitting can realize the calendering and slitting of ultra-thin solder strips, the continuous deformation caused by the multi-roller will still cause the ultra-long solder strip to break when it is cut, stripped and coiled. This kind of fracture is similar to the brittle fracture of crackers, and the fracture is broken and irregular at the cutting edge. Summary of the invention

[0004] In response to the above problems, this project proposed a method for pre-slitting and preparing ultra-long gold-tin solder strips based on cold stamping technology and hot shear stripping technology. Before the formal hot shearing, an array of pre-slits were punched out on the surface of the solder strip by stamping. In the subsequent slitting, the slitting was carried out along the edge of the pre-slit, realizing the continuous slitting production of 40-meter ultra-long solder strips.

[0005] The invention provides a method for obtaining an ultra-long and ultra-narrow gold-tin solder strip by cold stamping pre-slitting, which reduces the probability of the entire strip being broken due to shear edge breakage during the stripping process and improves the continuous rolling capability of the gold-tin solder strip.

[0006] A method for preparing an ultra-long and ultra-narrow gold-tin solder strip, wherein the gold-tin solder strip to be processed is thermally cut to obtain a finished gold-tin solder strip; the method is characterized in that the array holes of the pre-cut are prepared by cold stamping before the thermal cutting; the specific steps are as follows:

[0007] 1) Cold stamping pre-set slit

[0008] Using cold stamping equipment, stamping pre-cuts on the gold-tin solder strip to be processed;

[0009] 2) Hot shear stripping

[0010] The gold-tin solder strip obtained in step 1) is preheated in a hot shearing device, and then hot sheared along the pre-cut edge to obtain a rolled finished gold-tin solder strip;

[0011] The thickness of the gold-tin solder strip to be processed is 0.01-0.1 mm; the gold-tin solder strip to be processed can be obtained by processing, or can be directly purchased as a finished product;

[0012] The thickness of the finished gold-tin soldering tape is 0.015-0.2 mm, and the length of the finished gold-tin soldering tape is ≥20 m, preferably 25-45 m; more preferably 40-45 m;

[0013] The width of the finished gold-tin soldering strip is ≤2 mm, preferably ≤1 mm, and more preferably 0.01-0.5 mm.

[0014] In some preferred embodiments, the composition content of the gold-tin solder sheet is: Au: 78-82wt%; Sn: 18-22wt%; for example: Au: 80wt%, Sn: 20wt%, recorded as Au-20Sn, Au-21Sn, Au-22Sn, Au-18Sn, Au-19Sn;

[0015] In some preferred embodiments, in step 1), the pre-cut is circular;

[0016] The pre-cuts are arranged in an array; preferably, in a parallel array;

[0017] More preferably, the radius of the pre-cut is R; the length direction parallel to the welding strip is recorded as a row, and the length direction perpendicular to the welding strip is recorded as a column;

[0018] In some more preferred embodiments, the minimum position spacing L between two adjacent pre-cuts in each row is d The minimum vertical spacing between the pre-cuts of each adjacent column is T d ; (i.e., the width of the strip after stripping)

[0019] Preferably, R=0.05-0.30 mm;

[0020] Preferably, the T d =0.5~10mm; such as: L d ≥2R, L d=2R;, when the split cuts are arranged according to the above formula, the processing loss can be reduced while reducing the probability of processing fracture.

[0021] More preferably, R is based on T d choose,

[0022] When T d When <1mm, R is 0.05mm;

[0023] When 1≤T d When ≤5mm, T d =20R;

[0024] When T d When >5mm, R is 0.3mm.

[0025] In some preferred embodiments, in step 1), the cold stamping pressure is 15 to 30 tons, and the stamping speed is 0.4 s / time.

[0026] In some preferred embodiments, in the step 2), the slitting rate of the hot slitting is 1.5-2.5 m / min, and the slitting preheating temperature is 80-100°C.

[0027] In a second aspect, the present invention also provides an ultra-long and ultra-narrow gold-tin solder strip prepared by the preparation method, wherein the thickness of the gold-tin solder strip is 0.015-0.2 mm, and the length of the gold-tin solder strip is ≥20 m, preferably 25-45 m; more preferably 40-45 m.

[0028] The beneficial effects of the present invention are at least:

[0029] The present invention combines ultra-fast cold stamping and hot shearing stripping processes to propose a method for preparing ultra-long and ultra-narrow gold-tin solder strips (length greater than 30m, width less than 2mm) by first using stamping to preset an array of pinhole-type slits, and then using hot shearing to cut along the edges of the preset slits. Rapid cold stamping can quickly punch out the pre-slits and speed up processing efficiency (when punching is not performed, in order to ensure that the length of the solder strip meets the requirements, the shearing feed rate is less than 1m / min. After the pre-slits are preset, the feed rate can reach up to 2.5m / min, and the efficiency is increased by 200%); the pinhole-shaped continuous center pre-slit can reduce the processing loss of the gold-tin solder strip compared to other shapes. The smaller the size of the pre-slit, the lower the processing loss (the circular slit of the same width is 0.215mm lower than the square area). 2 , the processing loss is reduced by 0.215mm 2 / mm).

[0030] The array pre-slits can prevent the cracks initiated at the edge of the shear knife from extending into the solder strip when the brittle gold-tin solder strip is hot-sheared, reducing the probability of ultra-long and ultra-thin gold-tin solder strips breaking during ultra-narrow striping (about 70%), and improving the continuous processing capability of ultra-long and ultra-thin gold-tin solder strips during ultra-narrow striping. It can continuously process and prepare gold-tin solder strip rolls with a maximum length of 45m and a minimum length of 1mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the pre-cutting of the gold-tin solder tape;

[0032] Figure 2 Pre-cut sizes of other shapes in Comparative Example 2 (unit: mm). DETAILED DESCRIPTION

[0033] The technical solution of the present invention is: a method for preparing the ultra-long and ultra-narrow gold-tin solder strip, comprising the following two steps:

[0034] 1. Cold stamping pre-set slit

[0035] Take the ultra-thin gold-tin alloy coil after front-end vacuum melting, blanking, fine rolling and annealing, the strip thickness is 0.015-0.2mm. Use special stamping dies to cold stamp the above solder strips, punch out a series of circular pinhole arrays as preset cutting edges, and get the following Figure 1 The gold-tin solder strip with pre-cut is shown. The radius of the pre-cut circle is R = 0.05 ~ 0.3mm, and the stamping tolerance is ± 0.02mm. The lateral spacing of the cut is L d The longitudinal spacing T between the tangent lines of the two parallel slit circles is controlled at twice the circle radius (2R). d The width of the solder strip after cutting. Different pre-cutting sizes are selected according to the required strip width. d <1mm, R is 0.05mm; when 1≤T d When ≤5mm, T d =20R;

[0036] When T d When >5mm, R is 0.3mm.

[0037] 2. Hot shear stripping

[0038] Cut the above-mentioned gold-tin solder strip with pre-cutting on a slitting machine with thermal function into strips, and adjust the distance between the shear blades so that the cutting is along the Figure 1 The hot shear slitting line (pre-slit edge) is used for cutting.

[0039] Optionally, the stamping method in step 1 is cold stamping, the stamping pressure is 15 to 30 tons, and the stamping speed is set to 0.4s / time. While ensuring the integrity of the pre-cut edge under cold stamping, compared with hot stamping, the heating process is reduced and the stamping efficiency is improved.

[0040] Optionally, in step 1, the pre-cut radius R=0.05-0.30 mm, and the lateral spacing L of the cuts d =2R.

[0041] Optionally, the welding strip after fine rolling in step 1 has a length of 30 to 50 m and a thickness of 0.015 to 0.2 mm.

[0042] Optionally, the width of the welding strip after thermal shearing and stripping in step 2 is T d =0.5~10mm, shear feeding rate 1.5~2.5m / min, preheating temperature of the welding strip before shearing is 80~100℃.

[0043] Comparative Example 1

[0044] The preferred composition of the gold-tin alloy raw material is Au: 80wt%; Sn: 20wt%. After vacuum melting, vacuum melting, blanking, fine rolling and annealing, the gold-tin ultra-thin strip with a thickness of 0.05mm is obtained. The length of the solder strip is 40m. Using a micro-tension feeding-receiving system, it is first preheated at 80°C, and then a shearing knife is used to adjust the width of the solder strip after shearing to 5mm. The solder strip is sheared at a feeding rate of 1m / min. When the solder strip is divided into strips of 18m, it breaks brittlely, and almost more than half of the solder strip is lost in the processing.

[0045] Comparative Example 2

[0046] The preferred composition of the gold-tin alloy raw material is Au: 80wt%; Sn: 20wt%. After vacuum melting, vacuum melting, blanking, fine rolling and annealing, the gold-tin ultra-thin strip with a thickness of 0.05mm is obtained. The length of the solder strip is 40m. The micro-tension system is used for feeding and coiling. The slitting size is selected as follows Figure 2 As shown, the spacing is 9mm, and the stamping pressure is set to 15 tons according to the pre-cut radius, the stamping speed is 0.4s / time, and 2 rows*100 columns of array pre-cuts are punched out in one punch. The continuous punching is about 581s until the entire solder strip is punched out, and the front and rear tension systems are used to punch and reel at the same time. After stamping, the micro-tension feeding-receiving system is used again. First, it is preheated at 80°C, and then the shear knife spacing is adjusted to shear along the edge of the pre-cut at a feeding rate of 2.5m / min. The solder strip is sheared and broken in the middle of the shearing, and finally rolled to obtain a continuous length of 20m and a width of 5mm. Compared with the traditional shearing and stripping method, the length of the solder strip in Example 2 is increased by about 2m, and the probability of breakage is reduced by 10%. The processing loss of Example 1 is 1.299mm 2 / mm.

[0047] Embodiment 1:

[0048] The preferred composition of the gold-tin alloy raw material is Au: 80wt%; Sn: 20wt%. After vacuum melting, vacuum melting, blanking, fine rolling and annealing, the gold-tin ultra-thin strip with a thickness of 0.05mm is obtained. The length of the solder strip is 40m. The micro-tension system is used for feeding and coiling. The slitting radius R = 0.25mm and the pre-slitting spacing L are selected. d =0.50mm, slitting welding width T d =5mm, and according to the radius of the pre-cut, the punching pressure is set to 15 tons, the punching speed is 0.4s / time, and an array of 2 rows * 100 columns of pre-cuts are punched out in one punch. The punching is continuous for about 160s until the entire welding strip is punched out, and the front and rear tension systems are used to punch and reel at the same time. After punching, the micro-tension feeding-receiving system is used again. First, it is preheated at 80°C, and then the shear knife spacing is adjusted along the edge of the pre-cut. The feeding rate is 2.5m / min for shearing. After shearing, the second half of the welding strip is sheared and broken, and finally rolled to obtain a continuous length of 25m and a width of 5mm. Compared with Example 2, the length of the welding strip in Example 1 is increased by 7m, the processing efficiency is improved by 150%, the probability of welding strip processing fracture is reduced by 25%, and the processing loss of Example 1 is 0.196mm 2 / mm, which is reduced by 84.91% compared with Comparative Example 2.

[0049] Embodiment 2:

[0050] The preferred composition of the gold-tin alloy raw material is Au: 80wt%; Sn: 20wt%. After vacuum melting, vacuum melting, blanking, fine rolling and annealing, the gold-tin ultra-thin strip with a thickness of 0.05mm is obtained. The length of the welding strip is 40m. The micro-tension system is used for feeding, punching and winding. The slitting radius R = 0.15mm and the pre-slitting spacing L are selected. d =0.30mm, slitting welding width T d=3mm, and the punching pressure is set to 20 tons according to the radius of the pre-cut to ensure the precise forming of smaller punching holes. The punching speed is 0.4s / time, and an array of 2 rows * 100 columns of pre-cuts are punched out in one punch. The punching is continuous for 267s until the entire welding strip is punched out, and the front and rear tension systems are used to punch and reel at the same time. After punching, the micro-tension feeding-receiving system is used again. First, preheat at 80°C, and then adjust the shear knife spacing along the edge of the pre-cut. Shear at a feeding rate of 2m / min to adapt to the smaller pre-cut. The last 10 meters of welding strip are sheared and broken, and finally rolled to obtain a continuous length of 30m and a width of 3mm. Compared with Comparative Example 2, the length of the welding strip in Example 2 is increased by 5m, the processing efficiency is increased by 166%, and the probability of welding strip processing fracture is reduced by 50%. The actual processing loss of Example 2 is 0.117mm 2 / mm, which is 40.31% lower than that in Example 1.

[0051] Embodiment 3:

[0052] The preferred composition of the gold-tin alloy raw material is Au: 80wt%; Sn: 20wt%. After vacuum melting, vacuum melting, blanking, fine rolling and annealing, the gold-tin ultra-thin strip with a thickness of 0.05mm is obtained. The length of the welding strip is 40m. The micro-tension system is used for feeding, punching and winding. The slitting radius R = 0.05mm and the pre-slitting spacing L are selected. d =0.10mm, slitting welding width T d =1mm, and the punching pressure is set to 25 tons according to the radius of the pre-cut to ensure the precise forming of the small punching holes. The punching speed is 0.4s / time, and an array of 2 rows * 200 columns of pre-cuts are punched out in one punch. The punching is continuous for 400s until the entire welding strip is punched out, and the front and rear tension systems are used to punch and reel at the same time. After punching, the micro-tension feeding-receiving system is used again. First, it is preheated at 80°C, and then the shearing knife spacing is adjusted along the edge of the pre-cut. The feeding rate is 1.5m / min to adapt to the smallest pre-cut. After cutting, the welding strip does not break. Finally, the welding strip with a continuous length of 45m and a width of 1mm is rolled up. The edge of the welding strip is neat and free of burrs and flash. Compared with Example 2, the length of the welding strip in Example 3 is increased by 15m, the processing efficiency is increased by 200%, and the probability of welding strip processing fracture is reduced by 70%. The processing loss of Example 3 is 0.039mm 2 / mm, which is 66.67% lower than that of Example 2.

Claims

1. A method for preparing an ultra-long and ultra-narrow gold-tin solder strip, wherein the gold-tin solder strip to be processed is thermally cut to obtain a finished gold-tin solder strip; characterized in that: Before the hot slitting operation, cold stamping is used to prepare the pre-slit array holes; the specific steps are as follows: 1) Cold stamping pre-set slit Using cold stamping equipment, stamping pre-cuts on the gold-tin solder strip to be processed; 2) Hot shear stripping The gold-tin solder strip obtained in step 1) is preheated in a hot shearing device, and then hot sheared along the pre-cut edge to obtain a rolled finished gold-tin solder strip; The thickness of the gold-tin solder strip to be processed is 0.01 to 0.1 mm; The thickness of the finished gold-tin solder strip is 0.015 to 0.2 mm; The length of the finished gold-tin soldering tape is ≥20m, preferably 25-45m, more preferably 40-45m; The width of the finished gold-tin soldering strip is ≤2 mm, preferably ≤1 mm, and more preferably 0.01-0.5 mm.

2. The method for preparing an ultra-long and ultra-narrow gold-tin soldering tape according to claim 1, wherein: The gold-tin solder sheet has the following composition contents: Au: 78-82wt%; Sn: 18-22wt%; preferably Au: 80wt%; Sn: 20wt%; recorded as Au-20Sn.

3. The method for preparing an ultra-long and ultra-narrow gold-tin soldering ribbon according to claim 1, wherein: In the step 1), the pre-cut is circular; The pre-slits are arranged in an array; preferably, in a parallel array.

4. A method for preparing an ultra-long and ultra-narrow gold-tin soldering tape according to claim 1 or 3, wherein: In the step 1), the radius of the pre-cut is R; the length direction parallel to the welding strip is recorded as a row, and the length direction perpendicular to the welding strip is recorded as a column; The minimum position spacing L between two adjacent pre-cuts in each row d The minimum vertical spacing between the pre-cuts of each adjacent column is T d ; Preferably, R=0.05-0.30 mm; Preferably, the T d =0.5~10mm; such as: L d ≥2R, L d =2R.

5. A method for preparing an ultra-long and ultra-narrow gold-tin soldering tape according to claim 1 or 4, wherein: In step 1), the radius R of the pre-cut is based on T d choose, When T d When <1mm, R is 0.05mm; When 1≤T d When ≤5mm, T d =20R; When T d When >5mm, R is 0.3mm.

6. The method for preparing an ultra-long and ultra-narrow gold-tin solder ribbon according to claim 1, wherein: In the step 1), the cold stamping pressure is 15 to 30 tons, and the stamping speed is 0.4 s / time.

7. The method for preparing an ultra-long and ultra-narrow gold-tin solder ribbon according to claim 1, wherein: In the step 2), the slitting rate of the hot slitting is 1.5-2.5 m / min, and the slitting preheating temperature is 80-100°C.

8. An ultra-long and ultra-narrow gold-tin soldering tape prepared by the preparation method according to any one of claims 1 to 7, wherein the thickness of the gold-tin soldering tape is 0.015 to 0.2 mm, and the length of the finished gold-tin soldering tape is ≥ 20 m, preferably 25 to 45 m; more preferably 40 to 45 m.

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