一种陶瓷封装AuSn熔封孔洞控制新工艺方法

A New Process Method for Controlling AuSn Sealing Voids in Ceramic Packaging

气密性封装工艺广泛应用于高可靠电子元器件封装领域。目前气密性封装主要采用Au80Sn20合金作为连接材料将盖板和管壳进行密封,但是由于陶瓷管壳基底上的钨金属层在固化时会收缩,使得焊环金属化区中间低两边高,呈凹字型。传统熔封盖板上焊料为平板型,若焊接时焊料流淌性不足,焊缝中的气孔无法排出,很容易在焊接区形成孔洞。本文首先将Au78Sn22合金焊片置于表面镀金的盖板上,在305℃真空环境下进行预熔,Au78Sn22合金焊片融化后呈凸起的弧形,冷却后牢固地结合于盖板表面。再将预熔好的盖板置于陶瓷管壳密封区上,使用回流炉进行合金熔封。由于焊料熔化后形成弧形,更加贴合管壳封接面,在进行合金熔封时有助于焊缝中气孔的排出,减少孔隙率,提升密封装强度及密封可靠性。通过本文所述方法所制备的器件,封接面几乎无孔隙,满足合金熔封质量要求。该方法有助于提高元器件封装质量,在行业内具有一定的指导意义。

Hermetic packaging technology is widely utilized in the realm of high-reliability electronic component packaging.The primary bonding material used is Au80Sn20 alloy to seal the cover plate and package body.However,the shrinkage of the tungsten metal layer on the ceramic package body during curing results in a concave shape of the metallization area of the solder ring,with the middle being lower and the sides being higher.Traditional sealing cover plates have flat solder,and insufficient solder flowability during welding can lead to air pockets in the weld that cannot be expelled,resulting in voids in the welding area.In this paper,an Au78Sn22 alloy solder sheet is first placed on a gold-plated cover plate and pre-melted at 305℃under vacuum conditions.The Au78Sn22 alloy solder sheet forms a convex arc shape after melting and firmly bonds to the surface of the cover plate upon cooling.The pre-melted cover plate is then placed on the sealing area of the ceramic package body,and the alloy sealing process is conducted using a reflow oven.The solder,after melting,forms an arc shape that better conforms to the sealing surface of the package body,facilitating the expulsion of air pockets in the weld during the alloy sealing process,thereby reducing porosity and enhancing the strength and reliability of the seal.Devices prepared using the method described in this paper exhibit almost no voids on the sealing surface,satisfying the quality requirements of alloy sealing.This method con-tributes to the improvement of component packaging quality and holds certain guiding significance within the industry.