CN103028863B

CN103028863B - A kind of High-anti-oxidation lead-free solder

Info

Publication number: CN103028863B
Application number: CN201110295191.5A
Authority: CN
Inventors: 胡洁
Original assignee: CHENZHOU GOLD ARROW SOLDER Co Ltd
Current assignee: CHENZHOU GOLD ARROW SOLDER Co Ltd
Priority date: 2011-09-29
Filing date: 2011-09-29
Publication date: 2016-01-20
Anticipated expiration: 2031-09-29
Also published as: CN103028863A

Abstract

The invention discloses a kind of SnAgCu base High-anti-oxidation lead-free solder, wherein, the component of solder and mass percent are the tin of the silver of 0.3 ~ 3.0, the copper of 0.1 ~ 1.5 and surplus, on this basis, and cerium, the neodymium of the gallium of interpolation 0 ~ 1.0, the germanium of 0 ~ 1.0, the antimony of 0 ~ 0.7, the nickel of 0-0.2 and trace.By the mode of intermediate alloy, SnAgCu parent metal is added to the metallic element of different ratio, the non-oxidizability of solder is greatly improved, there is good wetability, creep properties and tensile strength, satisfactory mechanical property simultaneously, Electronic Packaging solder can be widely used in and connect.

Description

A kind of High-anti-oxidation lead-free solder

Technical field

The present invention relates to a kind of lead-free solder alloy being applied to electronics industry solder, furthermore, be the high anti-oxidation under a kind of working environment that can be used for higher temperature and the SnAgCu series lead-free solder alloy of good mechanical performance.

Background technology

Tin-lead solder has that cost is low, fusing point is low, the feature of good mechanical performance, but due to the toxic of lead, bring in the process that solder is produced and the mankind use and inevitably pollute and injury, since the enforcement that European Union RoHS decree in 2006 specifies six kinds of harmful substance maximum limit values, increasing lead-free brazing instead of tin-lead solder and is applied to technical field of electronic encapsulation, and SnAgCu system solder becomes the first-selection of the universally recognized tin-lead solder substitute of welding field with its good mechanical property.

But SnAgCu series lead-free solder cost is high, the power of its non-oxidizability will the mechanical strength of butt welding point, and the generation of electric conductivity and scruff impacts, for a change this phenomenon, usually adopts the method adding antioxidant to carry out modification to lead-free solder.

China's publication number is the patent of invention of CN102039496A, disclose a kind of oxidation resistant low-silver lead-free solder and production method thereof, the non-oxidizability of solder is improved by adding a certain amount of Ga, P, but because P not easily disperses in the alloy, and the collection skin layers of one deck densification can be formed on the surface of metal separation, difficulty is brought to processing further, simultaneously high to the requirement of solder flux, affect follow-up welding effect.

China's publication number is the patent of invention of CN101992362A, disclose a kind of leadless welding alloy with oxidation resistance of suitable powder process, add the further oxidation that Ge can suppress solder, crystal grain thinning simultaneously, but its non-oxidizability can not obtain very high guarantee, by adding Sb, wetability is had some improvement simultaneously.

Summary of the invention

The present invention adopts the method for intermediate alloy to prepare SnAgCu base lead-free solder, by adding the metallic element of different ratio, the performance such as non-oxidizability, wetability, creep properties, mechanical strength of solder is improved, final acquisition combination property is good, can be used for the High-anti-oxidation lead-free solder alloy under the working environment of higher temperature.

Object of the present invention is achieved through the following technical solutions:

A kind of SnAgCu base High-anti-oxidation lead-free solder, by weight percentage, comprises following composition: Ag0.3 ~ 3.0wt%, Cu0.1 ~ 1.5wt%, Ga0 ~ 1.0wt%, Ge0 ~ 0.5wt%, Sb0 ~ 0.7wt%, Ni0-0.2wt%, Ce0-0.1wt%, Nd0-0.1wt%, Sn is surplus.

Wherein, consider the cost of lead-free solder, the content of preferred Ag at 0.3 ~ 1.0wt%, the leadless welding alloy of gained be the wetability of the alloy of 3.0wt% close to Ag content.

Described Cu element, along with the increase of its content, improves the tensile strength of solder, increases the wetability of alloy, when Cu too high levels, easily forms intermetallic compound (IMC) Cu ₆sn ₅, reduce the reliability of solder joint, therefore preferably Cu content is 0.2-1.2wt%.

The clean-up effect that described Ga is stronger because alloy has and kelvin effect, have good antioxidant effect, can be evenly distributed on the surface of metal dust, and preferred Ga is 0.01 ~ 0.5wt%.

The same alloy of described Ge has clean-up effect and kelvin effect, improves the non-oxidizability of alloy, simultaneously can crystal grain thinning, and make the heterogeneous microstructure homogenising of crystal grain, preferred Ge content is 0.01 ~ 0.2wt%.

Described Sb element can improve the wetability of alloy, puies forward heavy alloyed hardness and tensile strength, and extend fatigue life, preferably its content is 0.1 ~ 0.5wt%.

Described Ni element, fusing point is high by (1445 ^oc), can suppress the growth of IMC, refinement solder microstructure and raising mechanical property, as shock resistance, preferably its content is 0.01 ~ 0.08wt%.

Described rare earth element ce, Nd, for surface active element, the surface tension of solder too can be reduced, improve sprawling and wetability of solder alloy, thinning microstructure, suppress the growth of IMC, but when its content is greater than 0.1wt%, because Rare-Earth Element Chemistry character is active, oxidizable, oxidizing slag can be produced at brazing process, certain negative effect can be caused to its wetability and spreadability, therefore be preferably 0.005 ~ 0.08wt%.

The present invention is by the mode of intermediate alloy, and prepare SnAgCu base High-anti-oxidation lead-free solder, method is as follows:

1. batching element Ni, Ce, Nd of needing in the present invention to add are smelted into alloy by the ratio of 5:95,4:96,4:96 and Sn respectively;

2. add the silver of 0.3 ~ 1.0wt% in a furnace, the copper of 0.2 ~ 1.2wt%, the gallium of 0.01 ~ 0.5wt%, the germanium of 0.01 ~ 0.2wt%, the antimony of 0.1 ~ 0.5wt%, 0.2 ~ 1.6wt% tin-nickel alloy, the tin-cerium alloy of 1.25 ~ 2wt%, the tin neodymium alloy of 1.25 ~ 2wt% and remaining refined tin, to fusing, stir, constant temperature insulation half an hour, casting process is cooled to solder alloy fast.

Accompanying drawing explanation

Fig. 1 is the comparison of wetability in specific embodiment, under the condition using identical rosin flux, obtains comparing of the angle of wetting of reference examples and embodiment.

Detailed description of the invention

Below in conjunction with specific embodiment, further describe the present invention, but protection scope of the present invention is not limited to following embodiment.

Table 1: reference examples and embodiment component list.

Above embodiment all can be produced as follows:

(1) smelting furnace will be put into by load weighted refined tin in proportion, be heated to 320 ^oc, adds silver, copper successively under the condition stirred, persistently overheating to 380 ^oc, constant temperature keeps 20 minutes;

(2) tin-nickel alloy, tin-cerium alloy, tin neodymium alloy stir 30 minutes is added successively;

(3) continue heat up and stir, 400 ^oCcondition under add gallium, germanium, constant temperature 420 ^oC, stir 10 minutes;

(4) constant temperature stirs 30 minutes, and casting process cools fast, makes tin slab, can make tin bar, solder and glass putty etc. further.

Table 2: scruff and solder joint compare.

Embodiment	Heating-up temperature	Retention time	Scruff rate %	Solder joint gloss
					Comparative example	380	24	1.853	Brighter
1	380	24	1.117	Light
					2	380	24	0.878	Metallic luster
3	380	24	0.723	Metallic luster
					4	380	24	1.022	Light
5	380	24	0.954	Metallic luster

Known through above-mentioned test, the interpolation of gallium, germanium substantially increases the non-oxidizability of solder alloy, and scruff productive rate reduces, and solder joint is glossy, meanwhile, controls the adding proportion of silver, antimony, cerium and neodymium, obtains welding process angle of wetting 0 ~ 30 ^obetween, wetability is excellent, SnAgCu solder alloy (wetability is good) of comparing is enhanced, and this illustrates that the SnAgCu based solder alloy according to formula of the present invention and preparation method's gained can meet the requirement of high anti-oxidation and excellent wetability, and ensure that its corresponding mechanical property.

Claims

1. a preparation method for High-anti-oxidation lead-free solder, is characterized in that, comprising:

A) will put into smelting furnace by load weighted refined tin in proportion, and be heated to 320 DEG C, under the condition stirred, add Ag, Cu successively, persistently overheating to 380 DEG C, constant temperature keeps 20min;

B) add Sn-Ni alloy, Sn-Ce alloy, Sn-Nd alloy successively, and stir 30min;

C) continue heat up and stir, under the condition of 400 DEG C, add Ga and Ge, be warming up to 420 DEG C and keep constant temperature, stir 10min;

D) constant temperature stirs 30min, and casting process cools fast, obtained tin slab;

The described High-anti-oxidation lead-free solder prepared is made up of the component of following mass percent:

Ag:0.7%, Cu:1.2%, Ga:0.08%, Ge:0.08%, Sb:0.28%, Ni:0.01%, Ce:0.008%, Nd:0.006%, surplus is Sn.