re why circuit boards are green in sci electronics swanee megadata mega oz au geoff swan writes rubbish the reason for the colour of the boards depends on the solder the may cover of qst has a picture of three different boards without any solder mask you can tell from the copper colored traces the box labeled transverter has the brown teflon glass board while the one in the center has the grayish board exposed on the left is some fiberglass board that looks green to me i see no reason for putting solder mask on circuit board used for box covers i wonder if any manufacturer actually puts a solder mask on their low noise microwave preamps often microwave circuits have odd bits of wire foil metal attached to wherever whatever is necessary to make the unit work properly this is a commercial product a solder mask would certainly make doing this tougher never mind the finding something that minimally degrades the circuits q dope for coils does not improve the q it just holds things together with minimal loss zack lau kh cp internet zlau arrl org working on ghz ssb cw gear operating interests ghz cw ssb fm us mail c o arrl lab cw main street station capability qrp mhz to ghz newington ct modes cw ssb fm packet amtor baudot phone if you really have to zack lau kh cp internet zlau arrl org working on ghz ssb cw gear operating interests ghz cw ssb fm us mail c o arrl lab cw main street station capability qrp mhz to ghz newington ct modes cw ssb fm packet amtor baudot phone if you really have to mask that is used older boards bakelite and phenolic rarely used a solder mask these boards are not suited well to automatic stuffing and soldering techniques and hence are the colour of the compound used to make them these days boards are made of fibreglass for most general purpose uses and have a solder mask applied to them to prevent close traces shorting to one another during soldering and also to prevent the decomposition of traces under harsh environments the light and dark green boards ofter seen have a dry film mask applied to them usually applied as a complete film photographically produced the blue and red or orange boards are a two part epoxy or a liquid imageable resist formulation and are applied in a different manner there s a lot of info about the pro s and con s of each but that s another story sla n go fo ill risky b geoff swan research development swanee mega com au megadata pty ltd waterloo rd north ryde nsw australia v fax
