Hi Tom,
I used to live in AZ and actually visited Circuit Specialists frequently. I
don't have a problem with presensitized boards per se except for the fact
that I tend to make complex boards with lots of mistakes-- I'll admit to
also having a habit of frequent tweaks as well. Presensitized boards just
don't make sense for me, especially when I purchased 20 _pounds_ of blank
PCB boards in many handy shapes, specifically for use with applied
photoresists. They were very cheap per board (A few cents each) in that
form, and when you use a hydrochloric-acid-based etchant and bulk materials
for photoresist/artwork/ink the cost is very low. I've also enjoyed the
challenge of rolling my own process from end-to-end without the need to buy
extra stuff per job. That, and I'm always assured of the freshness of my
resists since I'm the one applying them and I know the age of the materials.
My typical work flow will be to use gEDA to create a schematic/PCB layout,
then to print and image the artwork onto a sensitized board, followed by
developing. At that point I'll check the results for minimum trace
width/spacing, fit and location of components to make sure things aren't too
close together, or if I haven't goofed up a footprint. If everything looks
good I etch, otherwise I strip and recoat the board and by the time I'm
ready for another run it's dry/fixated and ready for anothering imaging
step. I may also find a mistake in the schematic and so the layout will
change accordingly. I may run through 5 strip-reimage steps before I
finally etch with that "perfect" result where all the features are clear,
it's not over/under-exposed, etc.
Regards,
Larry
Regards,
Larry
On Oct 11, 2011 9:54 AM, "Tom Biery" <judsquare@...> wrote:
>
> Larry, I have been getting my presensitized PCB material from the company
Circuit Specialists I believe they are located in Arizona, there material is
fresh and is delivered in about one week. Their website is ....
http://www.circuitspecialists.com/
> Usually I get the 4.6" x 6.6" size double sided boards
http://www.circuitspecialists.com/gd114.html and then trim them down to
3.3"'4.6" to match the size that eagle software allows. Are you offereing
boards like that?
> I use the UV exposure process and it seems to be working for me alright
here is a you tube video of... Making PCB for the FTDI Vinculum 2 Chip
> http://youtu.be/qK6DKbzm024
> If you interested in my youtube videos please subscribe. If you are going
to make up a bunch of double sided positive photoresist boards I would give
some a try. Let me know. Tom
>
>
> From: Larry Battraw <lbattraw@...>
>>To: homebrew_pcbs <Homebrew_PCBs@yahoogroups.com>
>>Sent: Tuesday, October 11, 2011 1:32 AM
>>Subject: [Homebrew_PCBs] The case for crowd-sourced PCB materials
>>
>>
>>
>>Hi All,
>>
>>I've been lurking on this list for some time and seen a lot of different
>>takes on making PCBs, whether it's toner-transfer, direct-print via
>>last/inkjet, or UV-exposed resist (And a few stranger ideas). One thing I
>>have noticed is that it is sometimes difficult or impossible to obtain the
>>raw materials for our projects. In some cases (Dry film resists) it either
>>takes forever (2 weeks to over a 3 months!) to get some from Hong Kong or
>>the Czech Republic (via eBay), or you have to buy a lot at one time
(Think'n
>>Tinker 100-foot rolls for example, at $150+ w/mandatory express shipping).
>>There are exceptions, but finding them and having any idea of how "fresh"
>>the film is (Which is important to get reasonable results) is problematic.
>>A couple years ago a company called Genesis MT sold a great product by the
>>name of AQ-3000 water-based photoresist. It worked very well, was very
>>reasonable for the amount you got for the price, and was available via
>>eBay. Recently I found they had been acquired by another "professional
>>services"-type company that requires large, company purchases of anything
>>(i.e. ask for a quote, and no way to buy electronically). It is now
>>impossible to get any of this great resist, the only water-based
photoresist
>>around. I don't consider the VOC-based resists as viable for use due to
>>health concerns.
>>
>>What I propose is that we as a group of hobbyists provide our own
materials,
>>where some of us will volunteer to be a source for a particular material,
in
>>this case photo-imaging materials. I know there has been a lot of
>>experimentation with direct/transfer tech but for repeatable, high-quality
>>boards you really can't beat photoresist-based boards. I'm sure some
people
>>will differ with me but I've read too much about problems with board
>>coatings, pre/post-heating, different inks (Sometimes very expensive), and
>>the challenges modifying inkjet printers to be very interested, especially
>>after I ruined a perfectly good printer trying it myself :-)
>>
>>Naturally I am volunteering for the dry film photoresist, since I have
>>already placed an order which should be here in a couple days. I'd like to
>>do the same for the Genesis AQ3000, although I have to find out the
minimum
>>order quantity (Apparently they make up a fresh batch for each order) and
>>available payment methods. I'd like to think that we can use enough of the
>>purchased products to have them avoid going bad (Shelf life for AQ3000 is
6
>>months, similar for dry-film). I would suggest charging actual cost plus a
>>small surcharge to cover gas and time spent (Maybe $3.00 per order?). I
>>want to make it possible for us to use high-quality products without a lot
>>of delay or uncertainty/experimentation in regards to product quality. The
>>cost would include cost of postage plus mailing materials (Padded envelope
>>or plastic bottle+box for AQ3000). If it's popular enough, I could offer
>>additional things like drill bits, PCB blanks, etc.
>>
>>I am certainly not adverse to having someone else take all the "business"
>>from me, as the whole point of this exercise is to provide the materials
at
>>near-cost, quickly. However, since nobody else has suggested this (That I
>>can remember) I figured I could at least start the process. I have to add
>>some disclaimers here: I reserve the right to ship within 2-3 business
days
>>of a prepaid order, and if there are unusual restrictions on shipping
items
>>there (i.e. countries that have export regulations for the USA) I also
will
>>not even try to ship an order. Likewise, if I find out after the order has
>>been placed it's going to be a lot of hassle to ship to I reserve the
right
>>to refuse/refund orders. Ditto for people who piss me off, sorry, I just
>>won't work with people who can't be polite. If there are unusual
>>circumstances like having a package refused and returned I also will
charge
>>a fee based on the time spent plus shipping/materials (Assuming the PCB
>>materials can be re-used and are not damaged). And finally, I reserve the
>>right to halt the service at any time, refunding any outstanding orders.
>>
>>This whole idea is an experiment in supply and demand and so I apologize
for
>>all the disclaimers. I don't want to be sued or even given a bad
reputation
>>because I had a package returned from Elbonia after being opened and
>>damaged, and the person is upset.
>>
>>I apologize for the length of this email, but I'd like to gauge the
interest
>>levels (And potential orders) from people in the group and elsewhere.
>>Please email me if you're interested, and what you would like to see
>>offered. I would probably accept PayPal (Yes, they aren't wonderful but
>>they're big and fairly reliable) for payment. Materials could either be
>>ordered direct from me or I could post auctions on eBay, but I'm more
>>interested in serving the community we have here rather than the entire
>>world. I have a day job and this is just a way to benefit a group of
>>like-minded people, so it can't be too much of a hassle or I will need to
>>either put a stop to it or raise prices. It may be necessary to go the
eBay
>>route just to avoid having materials expire but I'd like to avoid it. Let
>>me know!
>>
>>Kind regards-
>>Larry Battraw
>>
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