Lead-free Soldering Of Quartz Crystal Resonators

Quartz-crystal resonators is one of common electronic components which is a core and non-substitutable frequency component in electronic equipment because of its high precision and high stability. With the RoHS directive of EU, the soldering temperature of quartz-crystal resonators increases from210℃with lead to260℃lead-free which brings new requirements for the designs and manufacture processes of quartz-crystal resonators.This article researches the reasons of lead-free soldering failure which is basically affected by the poor high temperature properties of TB3302B conductive adhesive. It is found that TB3301F adhesive is more stable at the temperature of lead-free soldering by studying the high temperature properties so it will be good solution for soldering failure with TB3301F substituted by TB3302B. It has been found that the quake-proof can be promoted when the size of quartz blank decreased from8mm to6.5mm through studying of quartz blank design theory. Meanwhile it has been concluded that the adhesion of silver electrode can be strengthened by increasing Cr transition layer with magnetron sputtering through study of the Silver electrode film preparing process and the influencing factor for adhesion of thin film. The effects of Cr transition layer to equivalent resistance of quartz-crystal resonators has also been studied.Based on above research, the samples have been made successful which has reached the requirements of lead-free soldering proved by tests. All these achievements obtain good economic beneficial result by applying in ECEC Ltd.