CN1175956C

CN1175956C - Leadfree SnZn-base alloy solder containing rare-earth elements

Info

Publication number: CN1175956C
Application number: CNB021096236A
Authority: CN
Inventors: 杰赵; 赵杰; 黄明亮; 于大全; 王来
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2002-05-10
Filing date: 2002-05-10
Publication date: 2004-11-17
Anticipated expiration: 2022-05-10
Also published as: CN1390672A

Abstract

The present invention belongs to the technical field of metal material engineering and relates to the technical field of electronic packaging soldering material, particularly to a lead-free solder alloy with low cost. The present invention is characterized in that the alloy comprises the following components of 5 to 10 wt% of Zn, 0.05 to 0.5 wt% of rare earth elements which comprises one or more from La, Ce, Pr and Nd, optionally one or more from 0.1 to 6 wt % of Bi, 0.1 to 3 wt % of Cu, 0.5 to 3 wt % of In, 0.1 to 1 wt % of Al, 0.1 to 1 wt% of Ni, 0.001 to 1 wt% of P and Sn in balancing amount. The solder alloy has the advantages of good alloy wettability, fine organization, good mechanical property, no poison, no pollution, low price and good combination property, and can satisfy the requirements of electronic industry, particularly leadless solder application fields including household electric appliances, etc.

Description

The tin zinc-base contains the lead-free solder alloy of rare earth element

Technical field

The invention belongs to metal material field, relate to electronic packaging and brazing material technical field, specially refer to the lead-free solder alloy that is applicable to the soldering electronic component and does not cause thermal damage.

Technical background

Because traditional tin-lead solder contains the lead element that human body and environment is had very big harm, the development lead-free brazing has become present material scientific worker's a urgent task.The U.S., Japan and other countries were just actively made laws and are forbidden plumbous use, and European Union is according to the instruction of the waste of legislation case electrical and electronic product machinery, will completely forbid the uses of poisonous and harmful element electronic industry such as leaded, cadmium from January 1st, 2008.Thereby, in order to eliminate plumbous pollution, press for unleaded solder and replace the Sn-Pb solder and be applied in the Electronic Packaging welding technique.

In order to make the lead-free solder alloy composition satisfy relevant laws and regulations requirement, and make solder alloy have excellent mechanical property and brazed joint has higher reliability, solder alloy must have appropriate melting point, good wettability, component does not contain poisonous, hazardous property element, the feed rate abundance can satisfy the requirement of industrialization, alloy structure good stability, non-corrosiveness etc.In the binary and multicomponent alloy system of current research, extremely brazed joint research is more for Sn-Ag, Sn-Bi-Ag, Sn-Ag-Cu solder, has application promise in clinical practice.But the fusing point of these alloys is compared higher with 183 ℃ of Sn-37Pb solder between 216 ℃-227 ℃.High melt point will improve brazing temperature and raise, and higher brazing temperature can make electronic component and wiring board sustain damage.The more important thing is that these alloys are very expensive, is about 3 times of tinsel cost.

The Sn-9Zn alloy has 199 ℃ eutectic temperature, very near Sn-37Pb solder fusing point.And the Sn-9Zn alloy has good and economic and mechanical property.But the Zn element has the chemical property and the metallurgy of living and dialling, and makes the wettability of this alloy and erosion resistance very poor, has greatly influenced application.In recent years, in order to improve the performance of Sn-9Zn alloy, the investigator adds elements such as In, Bi, Al in the alloy to as alloy element, but effect is remarkable inadequately.And, contain thick β-Sn crystal grain in the Sn-9Zn alloy structure, because wettability difference brazed joint bonding strength is also lower.

Summary of the invention

The objective of the invention is, provide a kind of tin zinc-base to contain the lead-free brazing of rare earth element,, its wettability, erosion resistance and mechanical property are further improved, thereby can be widely used in the middle of the Electronic Packaging to solve the problem that present restriction red brass exists.

More specifically purpose of the present invention provides the lead-free solder alloy with following character:

1) 250 ℃ of following brazing temperatures are used, and avoid the thermal damage of electronic component in brazing process;

2) has good weldability;

3) brazed joint of Xing Chenging has sufficiently high bonding strength, and the brazed joint structure stability is good;

4) be processed to form wire rod easily, make it advance to deposit soldering with soldering bit.

Technical scheme of the present invention is, in the Sn-Zn alloy, added trace rare-earth element RE (by La, Ce, Pr, among the Nd one or more are elementary composition), one or more among the P of Ni, the 0.001-1 weight % of Al, the 0.01-1 weight % of In, the 0.1-1 weight % of Cu, the 0.1-3 weight % of optional simultaneously Bi, the 0.1-3 weight % that contains 0.1-6 weight %.

The solder alloy composition according to following reason is: micro-mixed rare-earth elements has suppressed thick β-Sn crystal grain and has generated, and makes the obvious refinement of alloy structure, and then has improved the mechanical property of alloy.Though in the past to studies show that 0.3% rare earth element adds unfavorable to wettability, when rare earth element is in the 0.05-0.2% scope, can significantly improve the wettability of alloy our studies show that.Selected In, Bi as alloy element improve alloy wettability, reduce fusing point, Cu, Al, Ni, P improve anti-oxidant, the corrosion resistance of alloy as alloy element.

Effect of the present invention and benefit be, because the adding of RE, Bi and other alloy elements makes solder alloy wettability, mechanical property better, fusing point is suitable, low price, can overcome the weakness of Sn-Zn alloy, can satisfy electronic industry, especially the unleaded demand of household electrical appliance.

Description of drawings

Fig. 1 is the Sn-9Zn alloy microscopic structure.

β-Sn white crystal grain thick among the figure can reach 100 μ m.

Fig. 2 is the Sn-9Zn-0.05%RE alloy microscopic structure.

β among the figure-Sn crystal grain has only several microns sizes.

Fig. 3 has reacted the wettability that trace rare-earth element has significantly improved the Sn-Zn alloy.

X-coordinate is represented temperature among the figure, and ordinate zou is represented wetting power.Data utilize MemiscoST50 to adopt the wettability equilibrium method to record.The brazing flux that uses is the active brazing flux of RA rosin, and the wetting power that records is a pairing experimental value in 10 seconds in the experiment.Article three, that broken line is represented from top to bottom is Sn-9Zn-0.05RE, Sn-9Zn-0.1RE, and the wetting power of Sn-9Zn alloy is with variation of temperature.At 245 ℃, 260 ℃, under 290 ℃ of three different temperature, it is better to contain trace rare-earth element Sn-9Zn alloy wettability.

Embodiment

The chemical ingredients (%) that tin zinc-base of the present invention contains the lead-free brazing of rare earth element is as follows: (5-10) Zn; (0.05-0.2) RE; (0.1-6) Bi, (0-3) Cu, (0-3) In, (0-1) Al, (0-1) Ni, (0-1) P; Surplus is that Sn and unavoidable impurities are formed.

Above-mentioned raw material of proportionately distributing is put into the vacuum for industrial use induction furnace smelt, under normal pressure, 500 ℃ of temperature are incubated 4-6 hour, and cast can obtain welding flux alloy.Produce solder powder by spraying, add brazing flux, just obtain soldering paste.

Below be described in detail optimum implementation of the present invention:

Choose following chemical components (%): (7-9) Zn; (0.05-0.15) RE; (0.5-3) Bi; (0.2-0.5) Al, surplus is Sn.Above-mentioned raw material of proportionately distributing is put into the vacuum for industrial use induction furnace smelt, under normal pressure, 500 ℃ of temperature are incubated 4-6 hour, and cast can obtain welding flux alloy, produces solder powder by spraying, adds brazing flux, just obtains soldering paste.Can be used for reflow welding.

Claims

1. a tin zinc-base contains the lead-free solder alloy of rare earth element, it is characterized in that composition is made up of following:

The Zn of 5-10 weight %, the rare earth element of 0.05-0.2 weight %, rare earth element comprises La at least, Ce, Pr, one or more among the Nd, 0.1-6 the Bi of weight %, the Cu of 0-3 weight %, the In of 0-3 weight %, the Al of 0-1 weight %, the Ni of 0-1 weight %, the P of 0-1 weight %, all the other are Sn, said solder alloy has greater than the tensile strength of 40MPa with greater than 20% unit elongation.

2. a kind of tin zinc-base according to claim 1 contains the lead-free solder alloy of rare earth element, it is characterized in that composition contains the Bi of 0.2-6 weight %, the In of 0.2-3 weight %.

3. a kind of tin zinc-base according to claim 1 contains the lead-free solder alloy of rare earth element, it is characterized in that containing among the P of Ni, 0.001-1 weight % of Al, 0.01-1 weight % of Cu, 0.1-1 weight % of 0.1-3 weight % one or more.

4. a kind of tin zinc-base according to claim 2 contains the lead-free solder alloy of rare earth element, and it contains among the P of Ni, 0.001-1 weight % of Al, 0.01-1 weight % of Cu, 0.1-1 weight % of 0.1-3 weight % one or more.

5. a kind of tin zinc-base according to claim 2 contains the lead-free solder alloy of rare earth element, and the temperature of fusion scope is between 185 ℃-196 ℃.