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Low-temperature lead-free solder alloy

A lead-free solder alloy, solder alloy technology, applied in welding/cutting media/materials, welding media, welding equipment, etc., can solve the adverse effects of increasing temperature performance and assembly quality, increasing electronic assembly energy consumption, comprehensive energy It can improve the mechanical shock resistance and drop performance, improve the coarse grain size of Bi phase, and reduce welding defects.

Active Publication Date: 2015-12-30
EUNOW ELECTRONICS TECH CO LTD SUZHOU
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  • Summary
  • Abstract
  • Description
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Problems solved by technology

Although the above lead-free alloys avoid the use of Pb in traditional Sn / Pb solder alloys, which effectively protect the environment and human health, they have the following problems: ①The melting point of this type of lead-free alloy is in the range of 217-227°C, which is higher than that of traditional solder alloys. The melting point of Sn63Pb37 is 35-45°C. Therefore, in electronic assembly, the wave furnace or reflow furnace needs to be set at a higher temperature, which increases the energy consumption of electronic assembly.
According to statistics, after the electronic assembly is converted from the traditional Sn / Pb to the lead-free process, the comprehensive energy consumption has increased by 25-30%.
②The increase of electronic assembly temperature increases the adverse effect of temperature on the performance of electronic components due to overheating and assembly quality
Its melting point ranges from 85 to 100°C, but it contains about 50% In, and the cost is extremely high, and the alloy contains Zn that is easily corroded and oxidized, which is also greatly limited in the application of solder paste

Method used

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Examples

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Embodiment Construction

[0080] The formulations of the solders of the specific examples and comparative examples of the present invention are shown in Table 1, wherein the contents of the main components Sn and Bi of comparative examples 1 and 2 are basically the same as those of the examples so that performance comparisons can be carried out.

[0081] Table 1: Examples and Comparative Examples

[0082]

[0083] The steps of the manufacturing method of each of the above-mentioned embodiments are as follows:

[0084] (1) The Si is heated to 1450-1500° C. for 2-3 hours in a vacuum induction heating furnace according to the proportion (percentage by weight) of Sn-0.25% in powder form, and cast into a Sn-Si master alloy ingot after cooling ;

[0085] (2) Prepare the above-mentioned Sn-Si master alloy ingot by mechanical crushing method or metal atomization method to make alloy powder with particle size less than 100 microns;

[0086] (3) melting one or more of the above-mentioned microalloying eleme...

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Abstract

The invention discloses a low-temperature lead-free solder alloy, containing larger than or equal to 30% of and smaller than or equal to 60% of Bi, larger than 0.001% of Si and smaller than or equal to 0.02% of Si, as well as microalloy elements (alterant), rare earth elements, antioxidant elements and the balance of Sn and inevitable impurities. The large crystal grains of a Bi phase in a traditional Sn-Bi alloy system and the problem of reliability of brittle rupture of a welding joint is caused by that Bi is segregated at a Cu / Cu3Sn interface to form a brittle Bi layer in a long-term service process of the traditional Sn-Bi alloy system are effectively improved, and the mechanical impact and falling resistance of the traditional Sn-Bi system alloy can be greatly improved.

Description

Technical field: [0001] The invention relates to the technical field of electronic soldering, in particular to soldering using lead-free tin alloys, in particular to a low-melting-point Sn-Bi-Si lead-free solder alloy. Background technique: [0002] Since electronic assembly became lead-free, Sn / Cu-based and Sn / Ag / Cu-based lead-free solder alloys are commonly used for wave soldering and reflow soldering processes. For example, in the wave soldering process, SnCu0.7, SnCu0.7-Ni, SnCu0.7-Si, SnAg0.3Cu0.7 (SAC0307) are commonly used, while in the reflow soldering process, SnAg3.0Cu0.5 (SAC305 ), SnAg3.8Cu0.7 (SAC387), SnAg1.0Cu0.5 (SAC105), SnAg0.3Cu0.7 (SAC0307), etc. Although the above lead-free alloys avoid the use of Pb in traditional Sn / Pb solder alloys, which effectively protect the environment and human health, they have the following problems: ①The melting point of this type of lead-free alloy is in the range of 217-227°C, which is higher than that of traditional solde...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/26B23K35/40C22C12/00
CPCB23K35/0222B23K35/264B23K35/40C22C12/00
Inventor 罗登俊桑俊峰
Owner EUNOW ELECTRONICS TECH CO LTD SUZHOU
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