We are using ELECTROVERT 08 Hot Air Solder Levelling Machine for the
last 8 years. It has a solder bath of 500 kgs.

We have been regularly using KLEENOX for dross control and monitoring
the solder for trace impurities being built up during the use. As soon
as Cu contamination touches 0.3% mark we change the solder. This change
becomes due after an average throughput of 1500 sq mtrs .

On comparing notes with other PCB shops in India and Europe we realise
that very few people resort to changing of the whole bath. Most of them
keep removing 40-80 kgs from time to time and keep replacing it with
virgin chip solder. Another practice being resorted to by many is
raising of molten solder temperature to 300 Degrees Centigrade (572 F)
keeping it at that for a while then skimmimg out the top layer and
replenishing it to the desired level by virgin solder. This system the
practitioner's claim brings the Cu to the top and thereby controls
contamination more effectively.

I would be very glad to hear from the Tech netters on the best industry
practice in this regard.

Anil K Singh
Linaks Microelectronics Limited
Fax:+91-522-222061, 315978

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