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High reliability low-silver lead-free solder and preparation method thereof

A lead-free solder, lead-free solder alloy technology, applied in welding equipment, welding/cutting medium/material, welding medium, etc., can solve the problems affecting the reliability of electronic products, high material cost, large surface tension, etc. Low cost, low cost, formation and growth inhibition effect

Inactive Publication Date: 2010-02-10
太仓市首创锡业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] 1. High melting point, high surface tension; poor wettability;
[0004] 2. The material cost is high, especially the Sn-Ag-Cu lead-free solder, whose Ag content is as high as 3-3.8%;
[0005] 3. Cu is easy to form between the solder and the substrate interface 6 sn 5 The metal compound layer of the brittle phase, which ultimately affects the reliability of electronic products

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] The low-silver lead-free solder according to this embodiment contains Ag 0.3 wt%, Cu 0.5 wt%, Ni 0.03%, Co 0.03%, and Sn 99.14%.

[0025] The preparation process of the above-mentioned low-silver lead-free solder is as follows:

[0026] (1) Prepare and weigh raw materials according to the formula;

[0027] (2), at a temperature of 500°C-550°C and under the protection of an inert gas, the master alloys Sn-(10)Ag, Sn-(10)Cu, Sn-(2)Ni, Sn-(2)Co were prepared by melting respectively, Among them, Sn-(10)Ag represents the tin-silver master alloy with a mass percentage content of Ag of 10%, Sn-(10)Cu represents a tin-silver master alloy with a Cu mass percentage content of 10%, and Sn-(2)Ni represents Ni A tin-nickel master alloy with a mass percentage content of 2%, Sn-(2)Co means a tin-cobalt master alloy with a Co mass percentage content of 2%;

[0028] (3), each intermediate alloy prepared in step (2) is mixed with the remaining tin at a temperature of 420°C on a resista...

Embodiment 2

[0032] The low-silver lead-free solder according to this embodiment contains Ag 0.4 wt%, Cu 0.6 wt%, Ni 0.02%, Co 0.02% and Sn 98.96%, and its preparation is the same as that of Embodiment 1.

[0033] After testing, the melting point of the solder in this embodiment is between 217°C and 226.8°C, the expansion rate is greater than 80% (Cu calibration, 260°C), and the surface tension is 420 dyne / cm (droplet method, 255°C) .

Embodiment 3

[0035] The low-silver lead-free solder according to this embodiment contains 0.5wt% Ag, 0.7wt% Cu, 0.025% Ni, 0.025% Co and 98.75% Sn, and its preparation is the same as in Example 1.

[0036] After testing, the melting point of the solder in this embodiment is between 217°C and 226°C, the expansion rate is greater than 80% (Cu correction, 260°C), and the surface tension is 420 dynes / cm (droplet method, 255°C) .

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Abstract

The invention relates to a high reliability low-silver lead-free solder based on Sn-Ag-Cu lead-free solder alloy and a preparation method thereof. Based on the total weight of the low-silver lead-freesolder, the lead-free solder comprises: 0.2-0.6% of silver, 0.01-0.06% of nickel, 0.5-0.8% of copper, 0.01-0.06% of cobalt and the rest of tin. The preparation method of the lead-free solder comprises the steps: first, in a state of melting protection, respectively smelting and preparing tin-silver preliminary alloy, tin-copper preliminary alloy, tin-nickel preliminary alloy and tin-cobalt preliminary alloy; then, mixing the obtained preliminary alloys and the rest tin at the temperature of 400-550 DEG C, and preparing the low-silver lead-free solder. The lead-free solder is low in cost and good in welding spot reliability, and can meet the demand of the clients. Furthermore, the preparation method can be carried out at lower temperature, has simple and convenient operation and lower cost.

Description

technical field [0001] The invention belongs to the technical field of low-silver lead-free solder preparation. Background technique [0002] At present, the main lead-free solder varieties at home and abroad include tin-silver-copper (Sn-Ag-Cu) lead-free solder and tin-copper (Sn-Cu) lead-free solder, all of which have the following deficiencies: [0003] 1. High melting point, high surface tension; poor wettability; [0004] 2. The material cost is high, especially the Sn-Ag-Cu lead-free solder, whose Ag content is as high as 3-3.8%; [0005] 3. Cu is easy to form between the solder and the substrate interface 6 sn 5 The metal compound layer of the brittle phase will eventually affect the reliability of electronic products. [0006] In view of the above shortcomings, it is of great significance to study the reduction of Ag content and the improvement of reliability of tin-silver-copper lead-free solders such as the European recommended product Sn-3.8Ag-0.7Cu. Content...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/26B23K35/40
Inventor 王文明徐菊英王国银
Owner 太仓市首创锡业有限公司
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