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16th November 2013
This is a follow up of the previous post for home made pcbs. Most of you who are
shopping for the first time for raw materials for making pcb must be in a
confusion as where to go....so i decided to compile some useful information for
them..
CHEMICALS : Galaxy Scientific, opposite CMC Hospital, (near the bus stand),
Vellore
CHEMICALS :
1. Laboratory supplies (Behind Pothees super market) Old Sreekandeswaram
Road ( cheap and reliable)
2. A shop in SS Kovil road (near the SBI bank)
3. A shop near martyr's column, palayam along the shops near the mosque
(haven't gone there)
Posted 16th November 2013 by Aby Raj
Labels: chemicals, pcb, shop
Shopping guide for chemicals
Careful.....The following info is for electronics
hobbyists in Vellore and Trivandrum city only
VELLORE
BLANK PCB :Ganesh Radio House, Sarathy Mansion, New bus stand, Vellore
TRIVANDRUM
BLANK PCB :
1. AB Electronics, Thakaraparambu street, East Fort
2. Power electronics, Thakaraparambu street, East Fort
3. Telematics, Thakaraparambu street, East Fort
4. Vrindha electronics, Thakaraparambu street, East Fort
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16th November 2013
Home made PCB tutorial
Aby Raj P.M. Advanced Embedded Systems,
Keltron IT Education Center
I hate storytelling and lengthy explanations but people have been
asking me for a write up on making PCBs using toner transfer
process.So I decided to make this tutorial. Here, I describe my
method of making prototype PCBs using ferric chloride. I made my
first custom PCB around 2007or 2008 and since then I have learnt a
lot regarding the various advantages and disadvantages of this
process. Way back then, I was able make only thick tracked PCBs
with few crowding of lines and took a time of 30-45 minutes. Now I
am able to make SMD PCBs and PCBs with fine traces within a
time of 5-15 min. What I mean is that making mistakes is not a
problem if you never give up. They make you learn all the important
process variables in the process.
Other processes are also there with diff chemicals but I’ll stick to
Ferric chloride based process for this tutorial since it is affordable
and safe enough. There are a lot of tutorials on the web and
relatively this tutorial is a big one but I want the reader to be fully
aware of the process and the process variables to achieve 100 %
success.
One word of caution: The following activity involves exposure to
organic/ inorganic chemical fumes, heat and PCB dust. Use
appropriate safety precautions like gloves / face mask / chemical
resistant apron during working. Although the chemicals used are not
dangerous, still it’s advisable to follow the safety guidelines properly
during working, handling and disposal.
Raw materials required
Homemade PCBs
[http://3.bp.blogspot.com/-2GPw_jklUNo/Uoc2-
j9XCaI/AAAAAAAAAFc/0CJ8OS7FVnY/s1600/raw+materials.jpg]
Single side-copper clad PCB blankUse good quality PCB blank board for your work. Good quality
boards have a nice bending strength whereas poor quality boards
bends very easily.
Glossy paper or special toner transfer paperRefer the printer manual for the correct gsm for your printer. I use
120-130 gsm paper. Improper paper usage can harm the printer or
its fuser. Please take care in this regard.
Ferric chloride (FeCl3) etchant powder
I use a low cost FeCl3 from nice chemicals. It costs around 200 Rs
max. The plastic jar shouldn’t be kept open unnecessarily since the
chemical is hygroscopic and tends to form lumps in presence of
excess moisture.
Paint thinnerCommon paint thinner can be used. Costs around 71 Rs/500 mL
Water for cleaningWater is very important because if you clean the utensils
immediately after the process, the ferric chloride stains can be
removed easily.
Equipments required
[http://3.bp.blogspot.com/-mqgTPhCKYmU/Uoc-
sD9MSLI/AAAAAAAAAH8/p6cZySHOwzs/s1600/Equipments+required.jpg]
Laser printerNormal B/W laser printer
Electric iron (1000 W works best)I use a Philips 1200 W iron for this purpose. When I used a low
wattage iron, I got varying performance. That’s why I suggest a min
of 1000 watts. The toner transfer phase needs a decent amount of
heat.
Paper cutterFor cutting the glossy paper.
A metallic utensil for heating chemicalUsually people don’t use this but I suggest a metal vessel for heating
chemical and water mixture since heat can accelerate the reaction.
It’s very useful in case the reaction slows down during the reaction
phase.
Heat resistant plastic container for etchingIts advantage is three fold. We may need to handle the container
during etching. So it’s better to use a plastic container for this
purpose. Also plastic won’t react with the chemicals or transfer
away the useful heat needed for the reaction.
Medium grade Tooth brush for cleaning
Required for PCB cleaning. Medium grade works best
Pcb drill-electric/handheldThere are situations when you have everything else except the drill
for making holes. Use a manual spring-action drill or an electric drill.
Electric bench drills are expensive enough for a student but you may
find one in your college PCB lab. Portable hand drill for PCB are
very rare and usually people like me tinker with small hand drills for
working with PCBs.
Another word of caution: When you make PCB designs in cad
software, make sure that drill holes are not under-dimensioned.
Sometimes people unknowingly make designs for .4 mm drill holes
while they have only .8 mm drill bits. This can be a head ache if one
fail to notice this prematurely during the design phase. When you
have limited equipment you need to make some adjustments !!
Scotch BriteBelieve me….this humble piece of equipment actually plays a very
important role.
Cleaning clothI strongly suggest to keep a waste cloth/ rag nearby to clean away
accident spillovers and also for handling uses.
A BRIEF OVERVIEW OF THE PROCESS
[http://2.bp.blogspot.com/-
q3lmsqk1Zow/Uoc3CTrSjOI/AAAAAAAAAFk/iYTjyAt1DIY/s1600/PROCESS.jpg]
PREPARE THE ARTWORK
The artwork can be made using cad softwares like Express PCB,
Cadsoft Eagle, Orcad, Altium etc… I won’t be teaching you about
making the cad layout now. Lets just assume that you have made the
layout. Evenmore, the layout can be taken from a magazine also as
popular magazines like EFY, EPE, publish PCB layouts along with
the articles.
After you prepare the artwork, print it on a glossy paper with a
good amount of resolution. I use 600 dpi but if the artwork is not
good enough then you can use a higher resolution.
PREPARE THE BOARD
For boards with lot of imperfections, use the a file, square and hacksaw to
prepare the board. If you don't have much equipment with you, use a sand paper
or scratch the edges on a rough surface to polish the board in a much
inexpensive way. Newly purchased boards are often perfect to be toner
transferred without polishing or preparation
[http://1.bp.blogspot.com/-
uD34uDTv418/Uoc_t_KpMUI/AAAAAAAAAIE/_rPDpz0BD_g/s1600/board+prepare.jpg]
Make the artwork ready for printing alongwith the glossy paper
for printing it. Use max dpi like 1200 if you are doing for the first
time. I normally settle down for 600 dpi but if you are doing this
for the first time, I recommend 1200 dpi or highest
available. Some printers have options for printing settings like
heavy paper. Use according to the manual given.
It’s always better to take a min of two copies for a given artwork
since you can always use the second one if the first one goes
wrong. Take one cut portion, place the artwork portion on shiny
copper side and fold the remaining paper as shown in the
pictures below.
TONER TRANSFER, CLEANING AND
TOUCH UP
THIS IS A SERIES OF CRITICAL STEPS THAT
DETERMINES THE INTEGRITY OF THE
RESULTING PCB
Printing and Preparation
[http://4.bp.blogspot.com/-
auknMa_2MXI/UodE45PSCxI/AAAAAAAAAIc/NxlmMazx4Nk/s1600/print.jpg]
TONER TRANSFER
[http://1.bp.blogspot.com/-FKUFbUnU8AQ/UodHF-
AN6XI/AAAAAAAAAIo/5fMCFhtgADY/s1600/print_1.jpg]
Now, heat the copper side with the artwork placed on it as shown
before. The heat of iron will melt the toner and it will stick to the
copper side facing it. Notice that the while ironing the un-laminated
side is placed down and the iron touches the copper side covered
with paper. I obtained the best results by using irons of around one
kilowatts or higher. Set the iron’s thermostat on the cotton/wool
mark. When I was a novice, after reading several web pages, I used
the highest setting. Although it turns out to be good for PCB tracks
with large inter-track spacing, it doesn’t work for small spacings. A
medium setting of wool is good for most applications. Time is also
a critical factor. Too much time like 1 min will result in separation of
copper laminate from PCB causing blisters on the laminate making it
unusable. An average time is somewhere between 5-11 seconds.
Place the iron uniformly over the copper side rather than constantly
over one area. Also try to heat all tracks by moving the uniformly or
some tracks may not get properly heated up. Tracks along
boundaries should be taken care of in this way , if they are
present…
[http://1.bp.blogspot.com/-yVWnL9PeQDc/UodI_UV59-
I/AAAAAAAAAJM/OGmrZ6vngyw/s1600/print_2.jpg]
Put the PCB immediately in water and let it soak for some 30
seconds. After that start peeling off the paper from the PCB
carefully along the tracks.
[http://3.bp.blogspot.com/-
RVWcMBy8Swc/UodIdWKJWQI/AAAAAAAAAJI/lKvCTeflRYY/s1600/print_3.jpg]
If the paper remaining seems stubborn first try to put it in running
water and simultaneously remove by gently rubbing the paper. Dry
removal will cause broken tracks.
[http://1.bp.blogspot.com/-3_WRedMpJm4/UodIdmvyyYI/AAAAAAAAAJE/86x7BJhP394
/s1600/print_4.jpg]
Still paper needs to be removed from forming interconnections and
bridges or they may cause shorts after etching. Use a tooth brush to
remove the removing traces of paper.
TOUCH UPIf some tracks are broken or a minor problem comes, do
touchup operation by using a permanent marker ink which is
good enough. Some inks will not withstand the etching
process so select a good pen or do multiple touches on the
same area.
WHAT IF THE TRACKS ARE TOO BAD….
If you get into a major problem like only 50% tracks getting
transferred, you need to start over again by removing the
toner using scrotchbrite or thinner. You can use the same
board but clean it well. This is why I recommend using
multiple copies of artwork output.
STEP 4: ETCHING, DRILLING, AND
SOLDERING THE PCB
Preparation of the chemical solution
[http://4.bp.blogspot.com/-
AU1eVuDnPv8/UodKNDR_47I/AAAAAAAAAJs/Ip4v9klZ9m8/s1600/solution.jpg]
Etching, stripping toner, drilling and
soldering
[http://2.bp.blogspot.com/-0nMz--
h_tGw/UodKNOEhQyI/AAAAAAAAAJo/0fziuhd1doY/s1600/etching.jpg]
After cleaning the etched PCB, rub vigorously with thinner soaked
cotton or cloth to strip the toner from the PCB. Drilling will finish
the whole process.
I’ve detailed the whole steps for you in a lengthy story
kind of way but once you master it, the whole thing can
be done in 5-15 minutes.
[http://4.bp.blogspot.com/-T4_ic0g3dYE/UodKMTpAR-
I/AAAAAAAAAJc/6ZRuJrdKv8w/s1600/finished.jpg]
Posted 16th November 2013 by Aby Raj
Location: Thiruvananthapuram, Kerala, India
Labels: etching, ferric chloride, pcb
2 View comments
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