声表面波器件小型化技术发展概述

芯片级尺寸封装的气密性被越来越广泛的关注，为了实现CSP器件的可伐管帽与陶瓷基板之间的气密性互连，采用分层电镀沉积的方法在高温共烧陶瓷(HTCC)基板表面制备了金/锡/金镀层，利用金与锡间的共晶反应以实现管帽和基板的气密性可靠封接. 文中分析了金/锡/金镀层质量、焊接工艺对Au80Sn20共晶焊料封接结果的影响. 结果表明，金/锡/金镀层厚度和层间的结合力决定了Au-Sn共晶焊料的封接质量. 在焊接升温过程中，锡镀层首先熔化形成“熔池”，溶解上下侧与之接触的金镀层，直至完成共晶反应；采用较短的焊接时间能够实现更好的金锡共晶封接；焊接温度为330 ℃、保温时间为30 s时，Au-Sn镀层共晶反应形成δ/(Au,Ni)Sn—ζ相—δ/(Au,Ni)Sn的分层共晶组织，实现了可伐管帽与HTCC基板的气密性封接.

Overview of the development of SAW miniaturization technology

Hermetical packaging in CSP component is increasingly investigated. In order to realize the hermetic interconnection between Kovar cap and ceramic substrate, the electroplating method was used and Au/Sn/Au sandwiched layers were fabricated on the HTCC substrate. Through the eutectic reaction between Au and Sn, a hermetic interconnection was realized. In this paper, the influence of Au/Sn/Au electroplated layer quality and soldering parameter on the packaging quality of Au-Sn eutectic solder was systematically investigated. It is found that the Au/Sn/Au electroplated layer thickness and interlayer bonding would directly determine the packaging results. During the soldering process, Sn electroplated layer firstly melted and a molten pool thus formed. The molten Sn then dissolved the surrounding Au electroplated layer and the Au-Sn eutectic reaction occurred. The shorter soldering time was better for the Au-Sn eutectic packaging. When the soldering temperature was 330 ℃ and holding time was set to 30 s, the (Au, Ni)Sn—ζ phase—(Au, Ni)Sn delaminated eutectic microstructures formed due to Au-Sn eutectic reaction and a reliable hermetical packaging between Kovar cap and HTCC substrate was eventually realized.