As an FYI... .047" (actually 3/64") Copper Clad Laminate is an industry standard thickness and when you include plating (typically <.0005") and solder mask, the board thickness will increase .002" - .003". A typical 1/16" board (our typical thickness) measures .0645" or .065" depending on where you take your measurement. I am not sure why people have had a difficult time finding this (3/64") stuff, but it is quite common. If the only standard stock was 1/16", imagine how thick a 16 layer board would be! We have 4 layer boards which are 1/32" total.
Regarding the photo-resist. I "think" our local board house purchases their laminate pre-coated... We used to purchase it that way when we made one-off prototypes. You could certainly (using a silk screen) apply (liquid) resist over your track & pad areas, but this method is not common these days (the screens stretch and there are definite registration issues). Designing a SIMM should be fairly simple, but tooling costs would kill you unless you had a fair number of buyers. I believe it runs us something like $500.00 for an initial production run of 5 flats (roughly 64 sq. in. each)... This includes all gerber and tooling costs. Granted you would get a fair number of SIMMs in a flat, but how many do we need? I know of the low cost board houses (4pcb.com among others), but they do not provide the full range of services you get from a traditional pcb mfg. (one I tried insisted we supply the files in a specific gerber version which our CAD software does not support). Is there really enough demand for this stuff to justify the cost? Derek > About 2 years ago Gamba and I collaborated on making a ROM SIMM to > fit the SE/30, which had the IIci ROM code on board. When we were > nearly done we discovered that the ROM SIMM in the SE/30 is around > .050" thick, whereas all the modern PCBs and commonly available > laminate stock is .062" thick. > > As it happens, the circuit boards for 30 pin SIMMs are also .050" thick. > > Anyway, I found that this seller on Ebay, > <http://search.ebay.com/_W0QQsassZstarstreasuresQQhtZ-1> has several > lots of .047" thick copper clad laminate stock. No connection, > relationship, etc. > > I don't know if anyone else is making boards, but if you are, this > could be useful. I've been thinking about trying to make some IIfx > SIMMs... > > On the topic of PCB making, if one starts with copper clad stock, how > does one put a photosensitive surface on it, so that one can do > photolithographic circuit board masking for etching? Is there some > kind of stick-on material? The only clue I came up with seemed to > indicate that one needed an expensive laminating machine. > > Jeff Walther > > P.S. Gamba, I hope you're still out there. Your mailbox is full, > but at least it's still active (as opposed to "Unknown User"). -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[email protected]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com ---------------------------------------------------------------
