[chbot] PCBs

Russell & Heather Phillips heathruss at snap.net.nz
Wed Oct 21 00:20:06 BST 2020

Hi All,

What you need to do your own PCBs.

Print out design normal for top layer but inverted, bottom layer mirror 
and inverted.

Use special film to print your design on RS components P/N 286-6773 A4 
size on a laser printer. I use our HP Color Laserjet Pro MFP M281fdw, 
does excellent black, colour, both sides and is not expensive.

silk screen pcbs with negative photo resist PER-20 using a 100 mesh 
screen and squeege, all available from Uniscreen 31A Inversen Terrace. 
bake pcb at about 60 degrees C in an oven, boards will keep for years 
and not effected

under led lights.

After Using the silk screen clean with Acetone. From the 'Spray store', 
also from them I use 2 way thinner and MEK for gluing ABS air pipe to 
the fittings and pipe running from compressor to garage, workshops and 

weaving/ sewing room for her air operated computer controlled weaving 
Loom. To glue the fittings on etc. Make a glue by dissolving scraps of 
ABS in MEK. If buying from the 'Spray Store' minimum is 5 litres so if 
you want a small

amount I can give you some. (I will be putting up daisy's before I use 
it all.)

ABS pipe and fittings from PSL Total Air 30 Sonter Road

Apply the negative art work black side down on pcb under glass expose 
with UV light source long enough to harden the coating that is exposed 
through the clear parts and should not wash off if the exposure is long  

My light box is 4 Philips TL 20W/05, now you would use UV LEDs. In my 
case when I used 5 minutes exposure the board was wiped clean but 7 
minutes is good, with the new film the black is very dense so is not fussy.

Make up the DP10 developer from RS components P/N 489-9113  in 1 litre 
of water at 25 degrees C, immerse  board then after a while brush it 
down and wash under the warm tap, it is now ready to etch.

I use Ferric Chloride now available from Element14, Heat to 80 or so 
degrees, aeration and agitation is the key to getting the copper off 
quickly, for small boards a 2 liter preserving jar is excellent, half 
fill with Ferric Chloride,

heat up in hot water then take lid off, drop in pcb, screw lid on 
violently agitate and the copper will be stripped off in double quick 
time. Now I use 'Dipsy'.

She is made of Perspex, alkathene etc and the best part is the pump I 
bought from Aliexpress, Magnetic Drive Pump Model MP-6RZ about $40. This 
solved all the pump problems.

Perspex and Chloroform for gluing from FAB Plastics Limited.

Alkathene 16mm used to heat the etchant (garden irrigation pipe)


Russell Phillips.

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