PCB Etching: Difference between revisions

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==Professional Options==
==Professional Options==
batchpcb for fairly quackish and cheap turnaround - 1 month
 
seedstudio for opening your product up and/or cheap as low as 30 bucks for 5 boards
=== Local ===
* [[Local Resources#Electronics|Avanti Circuits]] - located in North Phoenix. You have to buy a full board apx 18in x 24in for a few hundred dollars, but it's completely panelizable and customizable, they work for your business and will do rapid turnaround or weird requests. Go in on it with some friends.
 
=== Internet ===
* [http://batchpcb.com/ BatchPCB] for fairly quackish and cheap turnaround - 1 month
* [http://www.seeedstudio.com/depot/fusion-pcb-service-p-835.html?cPath=185 Seedstudio Fusion PCB] for qty10, relatively cheap for small sizes. 2-5 week turnaround typical.
* [http://dirtypcbs.com/ Dirty PCBs] done dirt cheap (dubious quality)


otherwise find a deal with the big boys
otherwise find a deal with the big boys
advanced pcb  (4pcb.com) has 2 layer 33 each at 33each.com (min 4+1free comes to like 150 shipped) a and they have a decent system for checking your design at freedfm.com
* [http://4pcb.com Advanced PCB] has 2 layer 33 each at 33each.com (min 4+1free comes to like 150 shipped) a and they have a decent system for checking your design at freedfm.com


One problem you should already have noticed is these places have 100 domains so its hard to know if you're dealing with the same shop.
One problem you should already have noticed is these places have 100 domains so its hard to know if you're dealing with the same shop.
Cheap Chinese PCB fab houses - they make surprisingly good PCBs for the price and have SMT assembly services, but shipping takes a while. Though they have really fast turnaround time (24hrs) compared to American PCB fab houses.
* https://jlcpcb.com $2 for 5 pieces of 100mmx100mm maximum size, shipping not included
* https://www.pcbway.com/ $5 for 5 pieces, shipping not included (you get a lot more customization options compared to JLCPCB)


haven't tried them but
haven't tried them but
http://www.goldphoenixpcb.biz
* http://www.goldphoenixpcb.biz
http://www.expresspcb.com/ExpressPCBHtm/HowWorks.htm
* http://www.expresspcb.com/ExpressPCBHtm/HowWorks.htm
http://www.sunstone.com/QuoteQT.aspx (pcbexpress, pcb123)
* http://www.sunstone.com/QuoteQT.aspx (pcbexpress, pcb123)
www.batesquote.com
* http://www.batesquote.com
 
* https://www.7pcb.com


some good but perhaps outdated info from ladyada
some good but perhaps outdated info from ladyada
http://www.ladyada.net/library/pcb/manufacturers.html
* http://www.ladyada.net/library/pcb/manufacturers.html
 
 
 
==HOMEMADE==
 
 
Several options, but they all boil down to covering up the copper you DONT want to take off, and bathing the rest in acid
 
photo resist-using light to affix your pattern
heat transfer-using heat
straight sharpie on copper-yep sharpie will resist etching, too
 
 
 
youll need some copper clad, available at fry, radio shack, elsewhere
(several places are also selling flexible pcb material called Kapton!)
 
yowl also need some chemicals
 
etching chemicals
ferric chloride-radio shack --don't get powder and deal with mixing it--realize you cant just toss this stuff down the drain when you're done with it (after a bunch of etches mind you)-- hence:
cupric chloride
http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html
more…
 
 
Im a fan of the heatsync transfer.  method.
 
Youll need a laserjet printer, not the common home inkjet kind, but the kind you have at work and kinks
 
You typically buy a transfer paper from someone, I like pulsar prefix but I've seen reference to pressnpeel as well
 
press-n-peel
http://www.techniks.com/
 
pulsarprofx-LOTS of info on the process on their site
http://www.pulsarprofx.com/
 


Because toner doesn't apply densely enough, you probably want to seal as well, pulsar sells a green foil for this too.
==Homebrew==
There are several options for home etching, but they all boil down to covering up the copper you DON'T want to take off, and bathing the rest in acid.


*[[PCBLaserEtch]] - using paint and a laser engraver
*photo resist - using light to affix your pattern
*heat transfer - using heat
*permanent marker - yep sharpie will resist etching, too


Youll need some non metal container to etch in, and some gloves as ferric chloride at least stains your hands. I do small work so I can agitate in a dixie cup
===Design===
*spacing: 10-12mil
*route: 5-10mil
*Adjust routing and/or footprints as necessary.


bubble tank
===Laser Process===
http://www.instructables.com/id/Build-your-own-PCB-bubble-tank!/
See also: [[Stencil Etching]] -- for solder stencils.


* Single-sided only unless you're very handy with a jig. This means single-sided copper board, too, unless you feel like wasting a bunch of FeCl/time trying to get rid of a whole side of copper to avoid shorting out the whole board.
* Spray paint the copper with an even, not-goopy coat of matte spray paint. Let dry for awhile and then put on a second layer for best results. Glossy paint is somewhat elastic and will "curl" under the laser producing imprecise results.
* Make sure your image is mirrored so you end up etching your circuit "on the back" -- in other words, if you put all your traces and pads on the top layer without mirroring and then etch the board, you're going to have a hard time soldering your components on the top side, fitting your soldering iron in between the component and its tiny little lead. So just mirror it and solder on the back like a normal person. Also, test the whole process with cardboard first so you don't laser, etch, and drill, and realize you've wasted 4 hours.
* Our laser only accepts B&W images so you'll need to convert it to the right format. In Photoshop, you can convert an image to 2-bit (actually probably 1-bit) mode by going to Image>Mode>Grayscale and Image>Mode>Bitmap. Choose Diffusion Dither. Save as a .bmp and import into the laser. Double check that the dimensions are accurate. If it whines about being 2-bit bitmap, you likely didn't do the bitmap mode correctly and it's 1 or 2 bits of color stored in a 32-bit format or something.
* Make sure that the colors are right: I think our laser engraves away all black pixels, which means those pixels will be exposed to acid, which means black = "empty space" and white = "copper traces". Double-check by running a preview beforehand and making sure that the red "cut" areas are the areas you want to end up as "empty space".
* To get accurate sizing when importing into LaserCut, you'll also probably want to save your file at 254dpi / 100 dots per centimeter / 10 dots per millimeter. In other words, LaserCut seems to interpret a 254-pixel image as being 1 inch because (as far as I can tell) it doesn't respect DPI settings in files.
* Follow the normal laser cutter directions and precautions.
* Engrave ("raster") the image using power/speed settings recommended by the laser cutter job log. It's a good idea to test a small unused corner first; you want to ablate all the black paint leaving behind only the settled dust which can easily be wiped off. Avoid using too much power / too low speed because heating up the copper may "glue" the paint dust back on the board and the copper reflection may damage the laser.
* Clean up the paint dust using rubbing alcohol or water (not acetone)
* Follow the [[#Etch|Etch]] instructions below.


You generally then apply the transferred image over to your board. The cheap way is with an iron, I prefer the pulsarprofx laminator method. I found their laminator on ebay for 20-30 shipped
===Preparation===
You will need:
*copper clad board
**Available at Fry's Electronics, Radio Shack, and other electronics supply shops.
**Several places are also selling flexible PCB material called Kapton.
*transfer material
**Some use magazines or transparencies.
**Special-purpose toner transfer paper is available.
***Pulsar Pro FX - http://pulsarprofx.com
***Press'n'Peel - http://www.techniks.com/
*sealing foil (optional) - http://pulsarprofx.com
*source of either UV light or heat
**Desktop paper laminator works great.
**Clothes/craft iron also works.
*laser printer
**Ink jet will NOT work.
*scouring pad (NOT steel wool)
*chemicals
**dish soap
**ferric chloride (FeCl)
***Use this OR CuCl.
***Get liquid so you don't have to mix the powder.
***You can't just dump this down the drain when you're done with it (after several of etches).
**cupric chloride (CuCl)
***Use this OR FeCl
***Easier to work with
***http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/
***http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html
**vinegar, peroxide (H2O2, table salt (NaCl)
***Inexpensive
***Much less toxic
***Easier cleanup
***http://www.stephenhobley.com/blog/2011/03/02/still-messing-with-forces-i-dont-understand-the-formula/
*non-metal container(s) and/or bubble tank larger than your board
**http://www.instructables.com/id/Build-your-own-PCB-bubble-tank!/
*protective gloves
**latex or nitrile
*paper cutter to trim board (optional)
**only use for thinner boards (0.032-)
**abuses blade
*we also have a sheet metal brake/shear which can be used for boards




with pulsarprofx .032 boards a Simple paper cutter from staples works well for cutting, though I think the blade is degrading quickly
30 minutes prior to transfer, turn on laminator. Use thickest setting for highest heat.


Now you etch! 
===Print===
When printing your design, there are two critical things to keep in mind.
*Print a mirror image, scale to 1.
*Set printer to maximum density. Use Transparency setting, if available.


These instructions assume you're using toner transfer paper.


Theres been a lot of hullabo about etching with just a  sponge--MEH
#Mark top sheet in paper tray for side and orientation.
My results have been very messy and annoying and slow like this. I find the main lesson to learn here is to break the surface tension with your gloved finger occasionally while you're regularly agitating in order to speed up the process.
#Print circuit.
http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/
#*top OR bottom layer, pads, vias
#*no docu/caption
#*Verify components fit on their footprints.
#*Verify all traces are clear and distinct.
#Cut transfer paper slightly larger than image.
#Tape transfer paper over image, shiny side exposed.
#*Be sure not to cover important parts with tape!
#*Cover entire leading edge with tape to avoid jams.
#Place paper back in tray, noting orientation.
#Print image again with darkest setting.
#Remove transfer paper.


==The Homemade Process==
===Transfer===
Design:
[[image:pcb_transfer.jpg|right]]
*Create your eagle design, use 10-12 mil spacing in your DRU, route to 5mil, you may also find you need to alter your footprints to get the spacing between, say, smd pins to somewhere the process can handle it
#Cut board to appropriate size
#*Leave enough board to push through laminator; At least two inches.
#Scour copper surface
#*Use scouring pad and a dab of soap
#*Use very light pressure. You're trying to roughen the copper, not remove it.
#*Surface should be slightly dull, with no gouges.
#Rinse/dry board.
#Partially fill one container with clean, cool tap water.
#Align image on transfer paper with board.
#Carefully trim excess paper with a razor or sharp scissors.
#Maintaining alignment, apply heat with either laminator or iron.
#*Laminator - Depending on the power of your machine, run your board through 2-6 times changing direction at least once.
#*Iron - I have no experience with this method. The more heat and pressure, the better.
#Place board in water. Paper will release after a few seconds.
#Remove board from water, ensuring all paper has been removed.
#*Be careful not to remove toner.
#Inspect traces for excess/light toner.
#*If small amounts of toner are missing, use fine-point permanent marker to carefully draw them in.
#*If large amounts of toner are missing, wipe the toner off and restart.
#*Remove excess toner with a razor blade.


Setup:
If not using sealing foil, proceed to Etch section.
*30 minutes prior to wanting to create your board, turn on lamintor making sure 5mil switch is turned on for hotter operation
*set your printer to ink density 5, mark the page which will print so you know how to position


If using sealing foil:
#Allow board to dry. (Do NOT wipe dry!)
#Cut piece of foil slightly narrower, and 1"-2" longer than board.
#Place foil, dull side down, such that all the toner is covered, and a large flap is folded under the board. This will prevent slipping when applying heat.
#Being careful to avoid folds and wrinkles, run foil-wrapped board through laminator twice.


Print:
Traces should now be covered in green. If there are still black portions, this should be fine. Toner is sufficient to mask; the sealant is merely added protection.
*print gtl layer (top or bottom, pads and vias), make sure you mirror and make the scale 1 with no caption
*check that all your individual components fit on their footprints properly and that all your traces and components are sufficiently distinct
*cut out blue transfer paper larger than printed design and scotch tape over top of printed design
*place back in printer properly so blue gets printed on(shiny side printed on)
*when it comes out, remove tape


Transfer:
===Etch===
*cut a peice of board with the paper cutter to the size of your design, but make sure board is long enough to be fed through laminator.  (a couple inches long--you could attempt multiple designs at a time to fill the space or just trim this off later before etching)
[[image:pcb_etched.jpg|right]]
*buff board a little bit with green scotch pad and a little detergent and clean and dry any residue
Some prefer using a sponge to apply the etchant. This is messy and slow, so we will use the submersion method. If you're interested in the sponge method, more information is at [http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/ Instructibles]
*ready some water deep enough to later submerse your completed copper with fused transfer paper
*put printed blue face down on copper and insert into laminator and when it comes out the other side, insert again same face up but from the other direction
*when it comes out immediately submerse in water and agitate until the blue paper falls off
*remove from water and carefully dry
*again check that your traces are distinct, you may want to carefully clean them up with a razor blade or add to them with a sharpie


Seal:
#Trim excess copper board to avoid wasting etchant.
*cut a peice of green foil not quite as wide as your copper but several inches longer than your design
#If only using one container, dump water out.
*place it dull side over the design overlapping the forward edge an inch or 2, and feed this edge to the laminator
#Fill container with enough etchant to cover board.
*when it comes out again, feed the exact same way again
#Place board in etchant bath.
*when it comes out second time slowly remove green foil, wrinkles are what we were attempting to avoid, if you get wrinkles you may just try your etch anyway, but in future I find best way to remove wrinkles is to overlap more foil over the front so you can feed it tightly, and making sure foil does NOT overlap on the sides
#*Be careful to avoid splashing. This stuff stains, and is a skin/eye irritant. Reading the MSDS for unfamiliar chemicals is always a great idea.
*the green foil I find tends to blur traces together a bit more even, so I tend to use a razor blade to very carefully make all traces and pads distinct again if need be
#Agitate bath 5-10 minutes. (unless using bubble tank)
#*Shake container
#*Gently rub board with (gloved!) finger. Avoid touching things afterwards, this stuff stains everything.
#*Check board frequently.
#*Most of the visible etching happens very quickly toward the end of the process.
#Submerge board in water or rinse in sink to remove all etchant.
#Pour used etchant back into bottle for reuse.
#*You can get several boards from a single batch of etchant.
#*Do not dispose of used etchant down drain.
#Dry board.


Etch:
Congratulations! Your board is now ready for drilling, if necessary, and population.
*you should now cut the copper down to the smallest size to speed up etching and avoid wasting etchant
*put not used up acid in a tub or cup deep enough to submerge design
*put gloves on as etchant stains permanently
*you may want to use electrical tape on the edge of your copper to give yourself something to hold on to when you submerge design
*you should then agitate the design in the etchant for several minutes
*the design will etch from the outside in so you can help the process along by lifting it out of the acid and gently rubbing your finger over the design, breaking hte surface tension and mixing up the etchant
*eventually all visible copper will be eaten away and all your traces and pads are distinct
*drop finished design back into water bath to nuetralize acid


Cleanup:
===Cleanup===
*return printer to ink density 3
*Return used etchant to container for future reuse.
*if etch went fine and acid still seems fresh, replace etchant back into a container for reuse, we need to find disposal method for non fresh acid, please dont dump down drain as it contains copper heavy metals and is toxic
**DO NOT dump down train. Etchant is toxic and contains heavy metals. Check MSDS or city hazardous waste department for disposal instructions.
*dump water and clean any spilled acid thoroughly
*Thoroughly clean up any spilled etchant.
*Return printer to typical settings.

Latest revision as of 20:29, 30 March 2024

Professional Options

Local

  • Avanti Circuits - located in North Phoenix. You have to buy a full board apx 18in x 24in for a few hundred dollars, but it's completely panelizable and customizable, they work for your business and will do rapid turnaround or weird requests. Go in on it with some friends.

Internet

  • BatchPCB for fairly quackish and cheap turnaround - 1 month
  • Seedstudio Fusion PCB for qty10, relatively cheap for small sizes. 2-5 week turnaround typical.
  • Dirty PCBs done dirt cheap (dubious quality)

otherwise find a deal with the big boys

  • Advanced PCB has 2 layer 33 each at 33each.com (min 4+1free comes to like 150 shipped) a and they have a decent system for checking your design at freedfm.com

One problem you should already have noticed is these places have 100 domains so its hard to know if you're dealing with the same shop.

Cheap Chinese PCB fab houses - they make surprisingly good PCBs for the price and have SMT assembly services, but shipping takes a while. Though they have really fast turnaround time (24hrs) compared to American PCB fab houses.

  • https://jlcpcb.com $2 for 5 pieces of 100mmx100mm maximum size, shipping not included
  • https://www.pcbway.com/ $5 for 5 pieces, shipping not included (you get a lot more customization options compared to JLCPCB)

haven't tried them but

some good but perhaps outdated info from ladyada

Homebrew

There are several options for home etching, but they all boil down to covering up the copper you DON'T want to take off, and bathing the rest in acid.

  • PCBLaserEtch - using paint and a laser engraver
  • photo resist - using light to affix your pattern
  • heat transfer - using heat
  • permanent marker - yep sharpie will resist etching, too

Design

  • spacing: 10-12mil
  • route: 5-10mil
  • Adjust routing and/or footprints as necessary.

Laser Process

See also: Stencil Etching -- for solder stencils.

  • Single-sided only unless you're very handy with a jig. This means single-sided copper board, too, unless you feel like wasting a bunch of FeCl/time trying to get rid of a whole side of copper to avoid shorting out the whole board.
  • Spray paint the copper with an even, not-goopy coat of matte spray paint. Let dry for awhile and then put on a second layer for best results. Glossy paint is somewhat elastic and will "curl" under the laser producing imprecise results.
  • Make sure your image is mirrored so you end up etching your circuit "on the back" -- in other words, if you put all your traces and pads on the top layer without mirroring and then etch the board, you're going to have a hard time soldering your components on the top side, fitting your soldering iron in between the component and its tiny little lead. So just mirror it and solder on the back like a normal person. Also, test the whole process with cardboard first so you don't laser, etch, and drill, and realize you've wasted 4 hours.
  • Our laser only accepts B&W images so you'll need to convert it to the right format. In Photoshop, you can convert an image to 2-bit (actually probably 1-bit) mode by going to Image>Mode>Grayscale and Image>Mode>Bitmap. Choose Diffusion Dither. Save as a .bmp and import into the laser. Double check that the dimensions are accurate. If it whines about being 2-bit bitmap, you likely didn't do the bitmap mode correctly and it's 1 or 2 bits of color stored in a 32-bit format or something.
  • Make sure that the colors are right: I think our laser engraves away all black pixels, which means those pixels will be exposed to acid, which means black = "empty space" and white = "copper traces". Double-check by running a preview beforehand and making sure that the red "cut" areas are the areas you want to end up as "empty space".
  • To get accurate sizing when importing into LaserCut, you'll also probably want to save your file at 254dpi / 100 dots per centimeter / 10 dots per millimeter. In other words, LaserCut seems to interpret a 254-pixel image as being 1 inch because (as far as I can tell) it doesn't respect DPI settings in files.
  • Follow the normal laser cutter directions and precautions.
  • Engrave ("raster") the image using power/speed settings recommended by the laser cutter job log. It's a good idea to test a small unused corner first; you want to ablate all the black paint leaving behind only the settled dust which can easily be wiped off. Avoid using too much power / too low speed because heating up the copper may "glue" the paint dust back on the board and the copper reflection may damage the laser.
  • Clean up the paint dust using rubbing alcohol or water (not acetone)
  • Follow the Etch instructions below.

Preparation

You will need:


30 minutes prior to transfer, turn on laminator. Use thickest setting for highest heat.

Print

When printing your design, there are two critical things to keep in mind.

  • Print a mirror image, scale to 1.
  • Set printer to maximum density. Use Transparency setting, if available.

These instructions assume you're using toner transfer paper.

  1. Mark top sheet in paper tray for side and orientation.
  2. Print circuit.
    • top OR bottom layer, pads, vias
    • no docu/caption
    • Verify components fit on their footprints.
    • Verify all traces are clear and distinct.
  3. Cut transfer paper slightly larger than image.
  4. Tape transfer paper over image, shiny side exposed.
    • Be sure not to cover important parts with tape!
    • Cover entire leading edge with tape to avoid jams.
  5. Place paper back in tray, noting orientation.
  6. Print image again with darkest setting.
  7. Remove transfer paper.

Transfer

File:Pcb transfer.jpg
  1. Cut board to appropriate size
    • Leave enough board to push through laminator; At least two inches.
  2. Scour copper surface
    • Use scouring pad and a dab of soap
    • Use very light pressure. You're trying to roughen the copper, not remove it.
    • Surface should be slightly dull, with no gouges.
  3. Rinse/dry board.
  4. Partially fill one container with clean, cool tap water.
  5. Align image on transfer paper with board.
  6. Carefully trim excess paper with a razor or sharp scissors.
  7. Maintaining alignment, apply heat with either laminator or iron.
    • Laminator - Depending on the power of your machine, run your board through 2-6 times changing direction at least once.
    • Iron - I have no experience with this method. The more heat and pressure, the better.
  8. Place board in water. Paper will release after a few seconds.
  9. Remove board from water, ensuring all paper has been removed.
    • Be careful not to remove toner.
  10. Inspect traces for excess/light toner.
    • If small amounts of toner are missing, use fine-point permanent marker to carefully draw them in.
    • If large amounts of toner are missing, wipe the toner off and restart.
    • Remove excess toner with a razor blade.

If not using sealing foil, proceed to Etch section.

If using sealing foil:

  1. Allow board to dry. (Do NOT wipe dry!)
  2. Cut piece of foil slightly narrower, and 1"-2" longer than board.
  3. Place foil, dull side down, such that all the toner is covered, and a large flap is folded under the board. This will prevent slipping when applying heat.
  4. Being careful to avoid folds and wrinkles, run foil-wrapped board through laminator twice.

Traces should now be covered in green. If there are still black portions, this should be fine. Toner is sufficient to mask; the sealant is merely added protection.

Etch

File:Pcb etched.jpg

Some prefer using a sponge to apply the etchant. This is messy and slow, so we will use the submersion method. If you're interested in the sponge method, more information is at Instructibles

  1. Trim excess copper board to avoid wasting etchant.
  2. If only using one container, dump water out.
  3. Fill container with enough etchant to cover board.
  4. Place board in etchant bath.
    • Be careful to avoid splashing. This stuff stains, and is a skin/eye irritant. Reading the MSDS for unfamiliar chemicals is always a great idea.
  5. Agitate bath 5-10 minutes. (unless using bubble tank)
    • Shake container
    • Gently rub board with (gloved!) finger. Avoid touching things afterwards, this stuff stains everything.
    • Check board frequently.
    • Most of the visible etching happens very quickly toward the end of the process.
  6. Submerge board in water or rinse in sink to remove all etchant.
  7. Pour used etchant back into bottle for reuse.
    • You can get several boards from a single batch of etchant.
    • Do not dispose of used etchant down drain.
  8. Dry board.

Congratulations! Your board is now ready for drilling, if necessary, and population.

Cleanup

  • Return used etchant to container for future reuse.
    • DO NOT dump down train. Etchant is toxic and contains heavy metals. Check MSDS or city hazardous waste department for disposal instructions.
  • Thoroughly clean up any spilled etchant.
  • Return printer to typical settings.
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