DIY Low Cost Flexible Sticky PCB Fabrication

Zohar Messeca Fara | idiot.io 2020

Materials: Chemicals: Tools: Software:
Copper Tape 50mm
Kapton Tape 50mm
Masking Tape 20mm
Sellotape (clear)
A4 Printer Paper
A4 pvc for laser printer
Steel Wool 		PhotoSensitive Dry Film
Sodium Carbonate
Ferric Chloride
Citric Acid
Acetone 		Ruler (30cm)
Precision Knife
Scissors
Laser Printer
Laminator (A4)
UV Box
Etching Tank
Timer
Scale
Disposable Gloves
Kitchen Towel
Cotton Ball 		Inkscapeimg_20200827_121558.jpg

Process:

1 . Preparing Flexible Copper Tape Clad

a) Remove copper tape gently from
the application paper. 		b) Attach application paper glossy side
To the kapton tape sticky side. 		c) Cut kapton tape.
d) Apply copper tape on
kapton tape upper side. 		e) Clean copper side
gently with steel wool. 		f) Flexible clad is ready!

2 . Applying PhotoSensitive Dry Film on Flexible Copper Tape Clad
a) The PhotoSensitive dry Film is sensitive to UV
light do this part in a dark room. 		b) Cut a piece of PhotoSensitive Dry Film at the size
of the copper clad. 		c) Remove protective cover from one side of
The PhotoSensitive Dry Film.
d) Add few drops of water on the copper clad
and apply The uncovered side of PhotoSensitive
Dry Film onto the copper clad.
try to avoid air bubbles wipe the clad gently with
a kitchen towel from center to edges. 		e) Place the copper clad inside two A4 papers
folded to half. 		f) Feed the folded papers with clad through
a hot laminator . do this process twice!
g) Done!!

3 . Circuit PhotoMask Design and PhotoLithography Transfer

Circuit design is made with Inkscape a free open source vector graphics editor
Photolithography Technique uses UV light to transfer a geometric pattern from a photomask (also called an optical mask)
to a photosensitive (light-sensitive) chemical film on the substrate.

a) Design your circuit graphicly with inkscape. b) Duplicate Circuit design and print on
A4 transparent PVC with a laser printer. 		c) Cut PhotoMask use a precision knife and ruler.
d) Tape two PhotoMask layers with a clear
sellotape. check for alignment and direction!.
two layers are used for a darker black
color and better light proof.
 e) Cut Copper clad at the size of the circuit
cut it a bit smaller from the photomask. 		f) Position photo mask onto the copper clad
and tape it from the bottom side with 20mm
masking tape.
check for alignment and direction!
h) Place copper clad taped with photomask
onto UV light Box face down.
lock the UV box lid. 		i) Expose to UV light for 1:15 min. j) Remove photomask from the copper clad
keep the clad in a dark place!
remove photosensitive dry film top protection layer
from the copper clad before developing stage.

4 . Developing Process

a) Prepare Developing solution in a plastic container
2g sodium carbonate : 200 ml water 		b) Place the exposed clad in the developer
and wait for 3-3.5 minutes.
when clad is completely developed, take out
from developing solution and rinse
the clad gently in water. 		c) Place developed clad on
a kitchen towel and let it dry.

5 . Etching

a) We use ferric chloride as our etchant
based on the Edinburgh Etch for Copper mix
1 liter saturated ferric chloride solution(40%)
200ml tap water, 66.6g citric acid
working temperature 50C.
work with disposable gloves on etching part! 		b) Etching time takes around 7 - 20 min.
depends on clad size and copper surface to etch. 		c) Once Circuit is fully etched
rinse it gently with water.
Place Etched Circuit on a kitchen towel
and let it dry.

6 . Removing PhotoSensitive Dry Film From Copper Traces

a) Place etched circuit in a plastic container.
pour acetone on the circuit and wait few seconds
till the photosensitive dry film dissolves. 		b) Wipe gently the dissolved photosensitive dry
film. use a cotton ball. 		c) Once all the photosensitive dry film is removed
from copper traces. rinse the circuit with water.
Place Etched Circuit on a kitchen towel
and let it dry. Done!