ＲＩＴＥ−ＳＨＩＭＯＤＡＴＥ ＮＯ．２ LＡＢＯＲＡＴＯＲＹ in Hitachi Chemical Co., Ltd.

[Purpose of Development]

Mounted printed circuit boards which are made of petroleum materials such as phenol resin and epoxy resin, and mineral resources including toxic heavy metals such as copper, lead, and tin, are the key constituents of electronic equipment which is essential for the rapidly spreading information society.

When used electronic equipment is discarded when the equipment is upgraded to a new product or due to equipment service life, most of the discarded electronic products are dumped into landfills even though they are partly disposed of by incineration, causing contamination of land and water resources due to the above mentioned toxic heavy metals and materials decomposed from resins.

In addition to the contamination, it creates environmental pollution due to gases generated during incineration such as hydrogen bromide and formalin.

As a countermeasure for these problems, a valuable material reclamation technology using a separation method with the use of the specific gravity after crushing of the mounted printed circuit boards, is under research and development today. However, the valuable material reclamation technology is not successful yet in finding the application of reclaimed products with high added value due to the high cost of crushing and low purity of reclaimed products.

This study has been promoted as a three year plan since 1995 to develop technology which decomposes and refines the constituents of mounted printed circuit boards to recycle them into new materials that are as pure as possible.

1. We have designed and manufactured a system which consists of the five processes that are separation of electronic components from the mounted printed circuit board, removal of soldering iron and calcination, separation of flux residue and separation of generated gas.

2. To separate the electronic components from mounted printed circuit boards, the method of press-cut by a knife first t hen removing soldering iron by hot air knife is used to prevent printed circuit boards from deterioration.

3. The calcination furnace calcinates printed circuit boards still in the original shape and fixes the combusted carbon by supplying steam into the furnace using exhaust heat.

4. Active carbon of about 450 m²/gram of a relative surface area is obtained from a paper-phenol printed circuit board. We found that active carbon can be used in the application as a deodorizing agent.