On 19/03/2011 21:56, Vitaliy wrote:
> Oli Glaser wrote:
>> This does seem to be a recurring subject. My experiences are much the
>> same as above. We use the photo method (tried other ways but found this
>> the best/most repeatable) to make the odd prototype board when needed
>> quickly. Have used it for most SMD footprints (apart from BGA) with
>> pitch down to 0.4mm and traces down to 10mil with no problems. We use
>> through hole rivets (available down to 0.4mm dia) from Mega for double
>> sided stuff.
> Can anyone recommend a US source for the through hole rivets?
>
>

I remember having a hard time finding them in the first place - just=20
looked quickly now for a US source but no luck.
We get them from Mega:
https://www.megauk.com/through_hole_rivets.php
The brand is Favorit, they are meant to be used with a special punch but=20
we didn't get one, as they work well anyway for our purposes.
I got some ideas from this page (very good in general for PCB making)
Look under the Through-Plating header - some of the links may still work=20
(I remember a couple being out of production though)
http://www.electricstuff.co.uk/pcbs.html

>> Works well to quickly try ideas out (but does not save money)
> Do you use UV or regular light? For hobby use (=3Dtime is cheap) the phot=
o
> method is about half the price of any board house.
>
>

We use a UV light box (4 x 15W tubes, timer etc, bought on eBay, very=20
good quality and cheaper than RS/Mega offerings. If anyone wants to know=20
exactly which one let me know and I'll check)
I imagine for hobby purposes the price will be more of a factor and some=20
savings could be made, probably as you say about half the price of a=20
board house for materials.
However there is a free 2-layer service available here (UK, Spirit=20
Circuits) although I think it is directed more at companies (they ask=20
for company details, though it does not specifically mention that they=20
will not deal with hobbyists)


>> Hot
>> etching fluid (40 - 45 deg C) and proper agitation make a big difference
>> to results/etching time (~5 min for hot/agitated compared with up to 1
>> hour for cold)
> Absolutely, I wouldn't even try it cold. Do you use Ammonium Sulfate for =
the
> etchant?
>
> We recently improved the process by buying a more powerful fishtank pump =
and
> replaced the dremel with a Proxxon drill press:
>
> http://hackaday.com/2009/02/27/tools-proxxon-drill-press-tbm115tbm220/
>
> No more broken drill bits.

I use Ferric Chloride - have you had better results with Ammonium Sulphate?
I do use Sodium Metasilicate rather than Sodium Hydroxide for developing=20
as it's far easier to use (not as sensitive to timing, temperature etc)
I made a small etch tank using nichrome wire for the heater driven by=20
PWM/MOSFET with a PIC16F, and a DS18B20 with PID to control temperature.=20
Used a fishtank pump for the agitation also.
We could do with a proper drill press though (did have one but it was=20
old and broken, so we gave it away), that's probably the most time=20
consuming part currently, plus as you mention broken drill bits. I'm=20
thinking it's worth spending the money to get another half decent one,=20
as it will have plenty of other uses too. The Proxxon one looks nice and=20
a decent price - are you happy with it?

> Vitaliy
>


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