| Due to the rapid development of electronic information,integrated circuit packaging is developing to high density and intelligent mode.The birth of Ball Grid Array(Abbreviated as SAC305)packaging technology makes electronic products have higher reliability,better heat dissipation and electrical performance.BGA becomes the most commonly used packaging technology.BGA packaging realizes the data transmission and mechanical connection by the solder ball arrayed at thebottom of the package substrate.Thus,the performance of solder ball directly affects the reliability of solder joints in BGA packaging.The quality of solder ball determines the packaging quality.Because of the advantages of Sn3.0Ag0.5Cu solder,high mechanical strength,good welding performance and high solder joint reliability,the BGA solder ball produced by it has become the main product in the electronic packaging industry.However,Sn3.0Ag0.5Cu solder has poor oxidation resistance.The solder balls produced by it are easy to be oxidized which affects the appearance quality and the yield of solder balls.Alloying is the main method to improve the oxidation resistance of solder.By adding suitable alloy elements,the oxidation resistance of solder can be improved.There are few researches studied on the oxidation resistance of Sn3.0Ag0.5u Cu solder.The large use of SAC305 solder ball in electronicpackaging industry makes the research necessary.In this paper,Sn3.0Ag0.5u Cu solder was taken as the research object.Ttrace P and Ga ware added to the solder.The alloy was melted by the medium frequency induction heating equipmentthe.The solder ball was produced by the principle of vibration injection and the diameter of solder ball was 0.4mm.By studying the effects of P and Ga on the roundness,color difference,wettability and the surface quality,the composition of solder alloy was optimized.We obtained solder balls with excellent comprehensive propert.The results showed:the addition of trace Ga or P element to Sn3.0Ag0.5u Cu solder made the melting temperature and the structure of oxide on the alloy surface change,thus affecting the roundness,color difference,wettability and surface quality.When the addition amount of P element is 0-0.1wt%,the roundness of solder balls decreased gradually,and the formability of solder balls became worse.Thus the addition of P element was bad for the formation of solder balls.When P element was 0.05wt%,the roundness of solder ball decreased from 98.9%to 98.6%;When P element was0.07wt%,the roundness of solder ball decreased to 98.5%;When P element is0.1wt%,the roundness of solder ball fell to 98.3%.As for the color difference,the color difference of solder balls decreased gradually with the increase of P element addition.When P element is 0.05wt%,the color value is 73.98NBS;When P element is0.07wt%,the color value of is 73.68NBS;When P element is 0.1wt%,the color value droped sharply and reached 71.54NBS.In terms of wettability,P element had a great influence on the spreading area of solder balls.When P element was not added,the spreading area was 61.3mm~2.When P element was added at 0.05wt%,the spreading area was reduced to 48.04mm~2.When P element is 0.07wt%,the spreading area was46mm~2.When P element was added to 0.1wt%,the spreading area decreased to 30.8mm~2.The spreading area was almost half of SAC305.The experimental results show that the addition of P element has a negative effect on the roundness,color value and spreading area SAC305 solder ball.When the addition amount of Ga element is 0-0.1wt%,The roundness of the solder ball showed a trend of increasing first and then decreasing with the increase of Ga element,and reached a maximum value of 99.1%when Ga element was 0.07wt%and meanwhile,the solder ball formability was the best;The color value showed a trend of increasing first and then decreasing with the increase of Ga element,and reached the maximum value of 75.02NBS when the Ga elementwas 0.05wt%;In terms of spreading area,the spreading area increased gradually with the increasing of Ga addition.The spreading area of SAC305 solder balls is 61.3mm~2;When Ga addition increased to0.1wt%,the spreading area reached a maximum value of 64.9mm~2,5.8%more than SAC305 solder balls.The results show that when the Ga element is 0.05wt%,the solder ball has excellent comprehensiveperformance and the surface quality is good.The solder balls of 0.1wt%P and 0.05%Ga were choosed to conduct shaking test.The results showed that the color value of the solder balls decreased with the placement and the mechanical vibration.When the shaking time was 6h,the color value of the solder ball decreased to 67.06 NBS and 69.92NBS. |
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