Preparation method of low-melting-point high-reliability lead-free solder

A lead-free solder, reliable technology, used in welding equipment, welding/cutting media/materials, welding media, etc., can solve the problems of limited improvement effect, difficult to greatly improve alloy processing performance, etc. The effect of improving plastic deformation performance and overcoming composition segregation

Inactive Publication Date: 2013-06-26
JIANGSU SHENGZHIXIANG ELECTRONICS TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In summary, in the field of lead-free solders, to improve the processing performance of Sn-Bi (tin-bismuth) alloys, the current research mainly relies on alloying and microalloying to improve the performance of Sn-Bi (tin-bismuth) based solders. performance, but the improvement effect is often limited, and it is difficult to greatly improve the processing performance of the alloy. There are also reports on the preparation of lead-free solder by powder metallurgy, but it is often used for high-temperature alloys, not necessarily suitable for low-temperature solder alloys

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Fully mix Bi powder and Sn powder with a particle size of 1-5um, wherein the mass percentage of Bi powder is 38%, and press it into a billet at 300Mpa, and slowly extrude the obtained billet through an extruder at a certain temperature. The temperature is controlled at 190°C, the pressure is controlled at 150Mpa, and the extrusion ratio is 20:1. The extruded blank was annealed at 100°C for 4 hours to obtain solder.

Embodiment 2

[0025] Fully mix Bi powder and Sn powder with a particle size of 1-5um, wherein the mass percentage of Bi powder is 48%, and press it into a billet at 350Mpa, and slowly extrude the obtained billet through an extruder at a certain temperature. The temperature is controlled at 180°C, the pressure is controlled at 175Mpa, and the extrusion ratio is 18:1. The extruded blank was annealed at 90° C. for 6 hours to obtain solder.

Embodiment 3

[0027] Fully mix Bi powder and Sn powder with a particle size of 1-5um, wherein the mass percentage of Bi powder is 58%, and press it into a billet at 400Mpa, and slowly extrude the obtained billet through an extruder at a certain temperature. The temperature is controlled at 170°C, the pressure is controlled at 200Mpa, and the extrusion ratio is 16:1. The extruded blank was annealed at 80°C for 8 hours to obtain solder.

[0028] The solder obtained in the above three embodiments can be drawn through a wire drawing machine for multiple passes to produce a welding wire with a diameter of 0.5 mm, and the welding wire maintains good plasticity.

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PUM

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Abstract

The invention relates to a preparation method of low-melting-point high-reliability lead-free solder. The preparation method of the low-melting-point high-reliability lead-free solder comprises the following steps: a, fully and evenly mixing bismuth powder and tin powder, wherein the mass percent of the bismuth powder is 38%-58%; b, pressing the evenly mixed bismuth powder and the tin powder to form blank under the pressure of 300Mpa-400Mpa; c, carrying out extrusion on the blank through an extruding machine at a certain extruding temperature; and d, carrying out annealing on the blank which is extruded, and obtaining the low-melting-point high-reliability lead-free solder. The preparation method of the low-melting-point high-reliability lead-free solder is applicable to production of lead-free solder with good performance.

Description

technical field [0001] The invention relates to the technical field of soldering and surface packaging materials, in particular to a method for preparing lead-free solder with low melting point and high reliability. Background technique [0002] Due to the great harm of lead to the human body and the environment, Sn-Pb (tin-lead) solder has been gradually replaced by lead-free solder. Among many lead-free solder systems, Sn-Bi (tin-bismuth) based solder is especially suitable for low-temperature soldering of electronic devices such as chips due to its low melting point (138°C) and good creep properties. However, the wettability, tensile strength, elongation and other properties of Sn-Bi (tin-bismuth) based solder have certain defects. [0003] Chinese patent CN201010301331.0 discloses a low-melting point Sn-Bi (tin-bismuth) solder and its preparation method to obtain Sn (tin), Bi (bismuth), Ag (silver) with low melting point, high solder joint strength and low cost. ) Tern...

Claims

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Application Information

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Patent Type & AuthorityApplications(China)
IPC IPC(8): B23K35/40B23K35/24
Inventor陈旭李冠洪周健薛烽
OwnerJIANGSU SHENGZHIXIANG ELECTRONICS TECH