Leadless solder of silverless Sn-Bi-Cu system and preparation method thereof

A lead-free solder, tin-bismuth technology, used in welding equipment, welding/cutting media/materials, welding media, etc., can solve the problems of brittleness that cannot be ignored, and the melting point of welding performance has no superiority, so as to improve mechanical and mechanical properties, The effect of cost reduction, convenient and precise dosing

Inactive Publication Date: 2009-10-28
广州冶炼厂有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Proposed a kind of Sn-Cu solder containing cobalt as Chinese patent CN101014726; Patent CN1721123 proposed a kind of Sn-Cu solder containing cerium, nickel element; Patent CN1806997 proposed the Sn-Cu solder containing nickel, indium, phosphorus; These The solder protected by the patent has no superiority in soldering performance, especially the melting point
The Chinese patent CN1927525 proposes that Sn-Cu solder containing a high proportion of bismuth can achieve a lower melting point, but the brittleness caused by high bismuth content cannot be ignored

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] No. 3 solder shown in Table 1 according to the composition ratio of the lead-free solder of the present invention. According to the total batching of 1000 grams, then weigh 70 grams of SnCu10 master alloy, 10 grams of pure bismuth, 8 grams of SnCe2.5 master alloy, 30 grams of SnNi1 master alloy, and 882 grams of surplus tin material. According to the principle of melting pure tin and bismuth first, and then adding the intermediate alloy, the target solder can be conveniently prepared. The melting point of the silver-free lead-free solder is about 221°C, the spreadability is equivalent to that of the widely used SnAg3Cu0.5 solder, the mechanical properties are better, and the tensile and shear strength of the solder joints are both better.

Embodiment 2

[0028] No. 4 solder shown in Table 1 according to the composition ratio of the lead-free solder of the present invention. According to the total batching of 1000 grams, then weigh 65 grams of SnCu10 master alloy, 30 grams of pure bismuth, 12 grams of SnCe2.5 master alloy, 60 grams of SnNi1 master alloy, and 833 grams of surplus tin material. According to the principle of melting pure tin and bismuth first, and then adding the intermediate alloy, the target solder can be conveniently prepared. The melting point of the silver-free lead-free solder is about 218°C, the spreadability is equivalent to that of the widely used silver-containing SnAg3Cu0.5 solder, the mechanical properties are better, and the tensile and shear strength of the solder joints are both better.

Embodiment 3

[0030] No. 5 solder shown in Table 1 according to the composition ratio of the lead-free solder of the present invention. According to 1000 grams of total batching, then weigh 55 grams of SnCu10 master alloy. 50 grams of pure bismuth. The SnCe2.5 master alloy is 24 grams, the SnNi1 master alloy is 120 grams, and the total amount of tin material is 751 grams. According to the principle of first melting pure tin and bismuth and then adding an intermediate alloy, the target solder can be conveniently prepared. The silver-free lead-free solder has a melting point of about 215°C. The spreadability is equivalent to the widely used silver-containing SnAg3Cu0.5 solder, the mechanical properties are better, and the tensile and shear strength of solder joints are better.

[0031] Table 1 lead-free solder composition distribution table of the present invention

[0032] Numbering

Cu

Bi

Ce

Ni

Ag

sn

Remark

1#

0.7

/

/

...

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Abstract

The invention relates to leadless solder of a silverless Sn-Bi-Cu system and a preparation method thereof, belonging to the technical field of leadless solder. The leadless solder of the silverless Sn-Bi-Cu system comprises the following elements by weight percentage: 1 to 6.5 percent of bismuth, 0.5 to 0.8 percent of copper, 0.01 to 0.1 percent of cerium as a rare-earth element, 0.01 to 0.2 percent of nickel as another rare-earth element and the balance of tin. The preparation method comprises the following steps: proportionally taking a fine tin ingot, pure bismuth and Sn-Cu, Sn-Ce and Sn-Ni medium alloy ingots; melting the tin ingot and then sequentially adding the pure bismuth and the Sn-Cu, Sn-Ce and Sn-Ni medium alloy ingots; and casting the mixture into a solder ingot or solder stocks in other shapes after the mixture is fully melted with the components being even. The leadless solder of the silverless Sn-Bi-Cu system not only has favorable welding performance and mechanical machinery performance, but also has the advantage of low cost.

Description

technical field [0001] The invention relates to the technical field of preparation of lead-free solder, in particular to a silver-free tin-bismuth-copper-based lead-free solder and a preparation method thereof. Background technique [0002] For a long time, near-eutectic Sn-Pb solder (eutectic composition is Sn-37Pb) has been widely used in modern soldering due to its good soldering performance, good wettability on Cu base, low melting point and reasonable price. Connection and assembly of electronic circuit boards. However, due to the high toxicity of Pb and its compounds, which are harmful to human health and the living environment, if human beings are exposed to them for a long time, they will bring greater harm to the living environment and safety. The question of alternatives to existing leaded solders is imminent. As a new type of lead-free electronic packaging solder, it should have the characteristics of good process performance, high process yield, good reliabilit...

Claims

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Application Information

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IPC IPC(8): B23K35/26C22C1/03
Inventor 高学功杨贺黄锦波薛涌波程晓农赵国平严学华李建新
Owner 广州冶炼厂有限公司
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