A study on solder stripping of discarded IC board

• Main Author: 蕭寧允
• Other Authors: 蔡敏行
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/04400776290109314117

碩士 === 國立成功大學 === 資源工程研究所 === 89 === The IC board consists of electronic components and mainboard that join with solder. The mainboard mainly cotains epoxy and copper, the solder contains tin and lead which is hazardous and the electronic component contains many kinds of valuable and recoverable metal such as gold、silver、iron、nickle、aluminium、zinc and so on. The composition of IC board is very complicated which results in the complex of the recycle process and reducing of the recycle efficiency of discarded IC board. If the solder is removed from discarded IC board before the discarded IC board is sent to recycle. In one side, the most hazarsous lead metal can be separated from the recycling process and in the other side, the electronic components and mainboard can be separated completely. In doing so, the recycling process will become simple and all the metals can be recycled more efficiently. The purpose of this study is searching for a leaching solution which can remove solder from IC board efficiently, but will not etch other metals in the IC board. By changing the type and concentration of the acid and inhibitor that is added in the leaching solution, leaching time and atmosphere of the leaching solution to observe the mass lost of the copper foil and solder in the leaching solution in case to obtain a leaching solution which can remove solder from IC board properly. The researching results show： The mass lost of copper foil is mainly much more than the mass lost of solder in nitric acid solution. Even by adding inhibitor in the nitric acid solution that the efficiency of inhibiting mass lost is limited. So the nitric acid solution is not suitable for being used as the leaching solution of removing solder. The mass lost of copper foil is mainly much fewer than the mass lost of solder in hydrochloride acid solution. So the hydrochloride acid is more suitable for being used as the leaching solution of removing solder. The hydrochloride acid solution with higher concentration is more suitable for being used as leaching solution of removing solder because it can leach out solder completely in the shorter time which results in the fewer mass lost of copper foil. With adding many kinds of inhibitors to inhibit the mass lost of metal in leaching solution, the results show that when the leaching solution contains 12N hydrochloride acid, 10-2M BTAH and being exposed to the nitrogen, the mass lost of copper foil will be the fewest while the solder is completely removing. The result is outstanding when use the leaching solution mentioned above to remove solder from the discarded IC board. When the solder is completely removed from the discarded IC board, the leaching rate of copper in the discarded IC board is only 1.42%. The electronic components and mainboard of the discarded IC board in which the solder is removed can be separated completely and that can be taked advantage of the recycling process of the discarded IC board afterwards.