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Lead-free solder

A lead-free solder, mass percentage technology, applied in the direction of welding/cutting media/materials, welding media, metal processing equipment, etc., can solve the problem that the IMC inhibition effect of the solder joint interface is not obvious, ignore the reliability of solder solder joints, Unfavorable maintenance of solder joint reliability and other issues, to achieve the effect of ensuring long-term service reliability, improving the stability of solder joint structure, and inhibiting excessive growth

Inactive Publication Date: 2014-04-30
THE 41ST INST OF CHINA ELECTRONICS TECH GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The general disadvantage of the prior art is that it only pays attention to the research on the wettability of solder and the mechanical properties of solder joints, while ignoring the reliability of solder solder joints in the actual service process. The excessive growth of the IMC layer at the solder joint interface has a great impact on The maintenance of solder joint reliability is extremely unfavorable, and the existing technology has no obvious inhibitory effect on the growth of IMC at the solder joint interface
At the same time, although the addition of rare earth elements can inhibit the excessive growth of IMC at the solder joint interface to a certain extent, as a surface active element, it is easy to oxidize, thus affecting its active role.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] A lead-free solder, the composition of which is: 0.1% Cu, 1.0% Ni, 1.5% Sb, 0.01% P, 0.01% RE, and the balance is Sn.

[0022] The Sn-Cu-Ni lead-free solder containing Sb, P and mixed rare earth RE (Pr, Nd) obtained by the above composition ratio has a solidus temperature of 229.6°C and a liquidus temperature of 236.8°C; it has excellent performance on copper plates. Wetting performance, the maximum wetting force is 3.5mN, the minimum wetting time is 0.52s; the tensile force of the QFP pin is 29N, and the shear force of the chip resistor is 65N.

[0023] It can be seen from Table 1 that after aging at 125°C for 1000 h, the Sn-Cu-Ni lead-free solder with Sb, P and mixed rare earth RE (Pr, Nd) was more than that without Sb, P and mixed rare earth RE (Pr, Nd). Nd) The average thickness of the IMC layer at the interface of the lead-free solder joint is reduced by about 21%.

[0024] Table 1 Changes of IMC layer thickness d at the interface of two kinds of solder joints und...

Embodiment 2

[0027] A lead-free solder, the composition of which is: 2.0% Cu, 0.01% Ni, 0.1% Sb, 1.0% P, 1.0% RE, and the balance is Sn.

[0028] The Sn-Cu-Ni lead-free solder containing Sb, P and mixed rare earth RE (Pr, Nd) obtained by the above composition ratio has a solidus temperature of 229.8°C and a liquidus temperature of 236.3°C; it has excellent performance on copper plates. Wetting performance, the maximum wetting force is 2.9mN, the minimum wetting time is 0.68s; the tensile force of the QFP pin is 30N, and the shear force of the chip resistor is 62N.

[0029] It can be seen from Table 2 that after aging at 125 °C for 1000 h, the Sn-Cu-Ni lead-free solder with Sb, P and mixed rare earth RE (Pr, Nd) was more than that without Sb, P and mixed rare earth RE (Pr, Nd). Nd) The average thickness of the IMC layer at the interface of the lead-free solder joint is reduced by about 20%.

[0030] Table 2 Changes of IMC layer thickness d at the interface of two kinds of solder joints und...

Embodiment 3

[0033] A lead-free solder, its composition is: 0.7% Cu, 0.05% Ni, 0.7% Sb, 0.5% P, 0.5% RE, and the balance is Sn.

[0034] The Sn-Cu-Ni lead-free solder containing Sb, P and mixed rare earth RE (Pr, Nd) obtained by the above composition ratio has a solidus temperature of 230.1°C and a liquidus temperature of 237.1°C; it has excellent performance on copper plates. Wetting performance, the maximum wetting force is 3.6mN, the minimum wetting time is 0.55s; the tensile force of the QFP pin is 35N, and the shear force of the chip resistor is 68N.

[0035] It can be seen from Table 3 that after aging at 125°C for 1000 h, the Sn-Cu-Ni lead-free solder with Sb, P and mixed rare earth RE (Pr, Nd) was more than that without Sb, P and mixed rare earth RE (Pr, Nd). Nd) The average thickness of the IMC layer at the interface of the lead-free solder joint is reduced by about 24%.

[0036] Table 3 Changes of IMC layer thickness d at the interface of two kinds of solder joints under differe...

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Abstract

The invention provides a lead-free solder. The lead-free solder consists of the following components in percentage by mass: 0.1-0.2 percent of Cu, 0.01-1.0 percent of Ni, 0.1-1.5 percent of Sb, 0.01-1.0 percent of P, 0.01-1.0 percent of RE and the balance of Sn. In the scheme, the Sb, P and mixed rare earth elements RE (Rr and Nd) are added into the Sn-Cu-Ni lead-free solder in a compounding way and cooperate with each other in an organic combination way, thereby suppressing excessive growth of a welding spot interface IMC in a service process, enhancing the structure stability of welding spots, and effectively ensuring the long-term service reliability of welding spots.

Description

technical field [0001] The invention belongs to the field of soldering technology, and in particular relates to a lead-free solder, which is suitable for electronic manufacturing industries such as microelectronic package and assembly and SMT surface mounting. Background technique [0002] With the entry into force of the RoHS (The Restriction of the Use of Certain Hazardous Substance in Electrical and Electronic Equipment) directive, the replacement of traditional Sn-Pb solder has always been a hot research topic for technicians in the electronics industry. [0003] At present, the representative lead-free solders mainly include binary or ternary alloy systems such as Sn-Ag, Sn-Cu, Sn-Zn, Sn-Ag-Cu, and Sn-Cu-Ni. Compared with Sn-Pb solder, there is still a certain gap in solder cost, solder melting point and comprehensive brazing performance. For example, the melting point of Sn-Zn solder is the closest to that of Sn-Pb solder, but due to the extremely easy oxidation of Zn...

Claims

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Application Information

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IPC IPC(8): B23K35/24
CPCB23K35/262
Inventor 罗家栋路波李春灵张超曹乾涛
Owner THE 41ST INST OF CHINA ELECTRONICS TECH GRP