Method for covering preformed soldering lug on chip sealing cover plate

Abstract

The invention discloses a method for covering a preformed soldering lug on a chip sealing cover plate. The method comprises the following steps of firstly tinning the surface of an Au-Sn alloy preformed soldering lug; and downwards putting the tinned surface of the An-Sn alloy preformed soldering lug after the tinning on a sealing cover plate of which the surface is gilded, carrying out reflow soldering under the condition of 232-280 DEG C, and enabling the Au-Sn alloy preformed soldering lug to be fixedly connected with the sealing cover plate. The thickness of a tinned Sn layer is less than or equal to 1.5 times of that of a gilded Au layer of the sealing cover plate. Compared with the method used in the prior art, the chip sealing cover plate and the preformed soldering lug are firmly combined, and the reliability is high; and the method disclosed by the invention has the advantages that processing is convenient, the efficiency is high, an additional device is not needed, and the cost is saved.

Description

technical field [0001] The invention relates to the field of solder preforms and their use. Background technique [0002] Integrated circuit chips used in aerospace or military fields need to be sealed on the circuit board with a sealed box, which is composed of a lower shell and a sealed cover. The lower housing is first assembled on the circuit board, and the sealing cover is generally covered with gold-tin alloy solder preforms first, then the sealing cover is placed on the housing, and the gold-tin alloy solder preforms are melted by reflow soldering, so that It is assembled with the lower casing to realize the sealing of the integrated circuit chip. [0003] The method of covering the preform of gold-tin alloy on the cover plate, such as the invention patent with the publication number "CN1556544A" and the name "Preparation Method of Hermetic Packaging Cover Plate for Integrated Circuits", is to solder the preform of gold-tin alloy The sheet is welded to the sealing c...

AI Technical Summary

Problems solved by technology

[0003] The method of covering the preform of gold-tin alloy on the cover plate, such as the invention patent with the publication number "CN1556544A" and the name "Preparation Method of Hermetic Packaging Cover Plate for Integrated Circuits", is to solder the preform of gold-tin alloy The sheet is welded to the sealing cover by spot welding, but this spot welding method is not stable enough and easy to fall off, and a spot welding machine is required, which increases additional costs and low production efficiency

In the utility model patent with the publication number CN202172064U, a solder resist layer is set in the middle of the solder preform and the sealing cover plate, and then reflow soldering is performed to melt the solder preform and fix it on the surface of the sealing cover plate. Due to the high temperature of the reflow soldering At the melting point of Au80Sn20, the solder piece is melted, and its performance and shape have been completely changed, which will have a serious impact on the welding of the sealing cover plate and the lower shell

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