paravia@csd4.csd.uwm.edu (Mark David Kakatsch) (08/25/89)
Does anyone have any techniques or ideas on how to through plate a PC board at home, sans expensive equiptment? All I know about it is that it involves some sort of electroplating...Thanks. Mark -- | Albert Einstein got his name after he got| Mark D. Kakatsch | | smashed from drinking only only one stein| paravia@csd4.csd.uwm.edu | | of beer. Hence; Albert EinStein. | ...uwmcsd1!uwmcsd4!paravia |
henry@utzoo.uucp (Henry Spencer) (08/26/89)
In article <4003@csd4.csd.uwm.edu> paravia@csd4.csd.uwm.edu (Mark David Kakatsch) writes: >Does anyone have any techniques or ideas on how to through plate a PC board >at home, sans expensive equiptment? ... As I understand it, if you want reliable results (i.e. you want to use the boards, not just play with the technique), there ain't no way. Taking copper *off* boards is a fairly crude process where home equipment can do the job easily. Putting copper onto boards, and getting good solid copper that adheres strongly to the board, is a very tricky business that tends to require fussy control of things like solution chemistry and temperature. It's not practical for hobbyists. (Alas.) -- V7 /bin/mail source: 554 lines.| Henry Spencer at U of Toronto Zoology 1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
barry@hprmokg.HP.COM (Barry Fowler) (08/28/89)
The electronics industry doesn't plate traces on pc boards. They etch the copper off already plated boards. Take it off, take it off....
dtubbs@esunix.UUCP (Dave tubbs) (08/29/89)
What follows is a quick introduction into the way most double-sided
printed circuit boards are manufactured. There are other techniques,
and they get much more involved especially when manufacturing multi-layer
boards. After this intro, I have included steps as to how this might be
done at home.
A) An image of the board is transferred to the raw copper board using
photographic techniques.
B) The holes are drilled in the board, using the photo as a reference.
C) The board is dipped in a chemical solution called "Electroless
Copper". This solution deposits a thin layer of copper everywhere
on the board (including the sides and inside the holes). The layer
is generally between .001 - .002 thick, which is just enough to
support electo-plating.
D) The board is electro-plated with another .002 - .004 inches of
copper, using the Electroless Copper layer as a plating conductor.
E) A reverse image of the board is applied using photo techniques.
That is, all copper areas that you want to remain are left exposed,
while all copper that will eventually be removed are covered.
F) Solder is electro-plated to the exposed areas of the board, using
the copper previously applied as a plating conductor. About .002
inches of solder is applied.
G) The image is "stripped" from the board.
H) The board is etched. The solder that was previously plated to the
board acts as the resist.
I) Once the board has been etched, it is "fused". This process melts
the solder on the board so that it flows and covers all exposed
copper. This step is necessary to prevent the copper from oxidizing.
The board is now completed. The plating process has plated though the
holes, so traces on one side of the board are electrically connected to
traces on the other. Here is how to do this at home:
A) Apply the image to the raw pc board.
B) Using small hand tools, drill the board using the image as a guide.
C) Dip the board into the Electroless Copper solution. This can be
obtained locally from most chemical supply houses, and instructions
as to usage and amount of time in the solution will be included.
D) Apply a reverse image to the raw pc board.
E) Dip the board in rosin and then into molten solder. How you get the
solder molten is up to you.
F) Now etch the board in your favorite etchant. If you don't want to
wait for the Ferric Chloride you purchased at Radio Shack to etch
the board, check for something stronger when you buy your Electroless
solution at the chemical supply house.
Your board is done. You may find some of the holes are plugged with
solder. To unplug them, simply melt the solder in the hole and remove it.
That pretty well does it, except for a few notes:
A) In some (most) states, the chemicals used in this procedure require
special disposal techniques. DO NOT FLUSH THEM DOWN YOUR TOILET!
Toxic waste fines can be very expensive, so check with the chemical
supply house on disposal tips. They may even offer a service for a
nominal fee.
B) Wear appropriate clothing, as well as hand and eye protection.
These chemicals can be nasty. Remember those little chemistry sets
you got for Christmas? Chicken feed compared to these chemicals.
C) Do this in a well-ventilated area. And I don't mean turning on the
bathroom fan. Try it in the garage with a fan going, or outside.
I know of people who have landed in the hospital because of too much
exposure.
D) There are several books on the subject. I don't have the titles and
author names handy, but if any of you are interested, e-mail me and
I'll post them.
E) The example above was greatly simplified. It was meant as an overview,
not as instructions. I'm sure that there are pcboard gurus out there.
If I botched something, please post the corrections. No flames!
*** Disclaimer ***
The opinions expressed above are my own. Neither myself or my employer
shall be liable for any damages, either incidental or consequential,
with regard to the use of this information.
---------------------------------------------------------------------------
Dave Tubbs UUCP:{ihnp4,decvax}!decwrl!esunix!dtubbs
Evans & Sutherland Computer Corp. INET: esunix!dtubbs@cs.utah.edu
580 Arapeen Drive PHONE: (801) 582-5847 Ext. 3277
Salt Lake City, Utah 84108 FAX: (801) 582-8208
---------------------------------------------------------------------------jac@paul.rutgers.edu (Jonathan A. Chandross) (08/29/89)
paravia@csd4.csd.uwm.edu (Mark David Kakatsch) writes: > Does anyone have any techniques or ideas on how to through plate a PC board > at home, sans expensive equiptment? ... henry@utzoo.uucp (Henry Spencer) > As I understand it, if you want reliable results (i.e. you want to use the > boards, not just play with the technique), there ain't no way. Henry is right. Plated through holes are best done by professionals. I got a tour of a PCB factory through a friend once. Very interesting. The bare copper board is drilled with the desired hole pattern. Then the photoresist is applied, and the board exposed to a UV source. The board surface is then developed and the resist is washed away. Now the copper is etched away. At this point there are traces on both sides of the board and holes where the vias should be. (A via joins 1 layer to another.) Now comes the interesting part. The board is then dunked in polonium. Polonium is very very sticky, and coats the copper traces as well as joining the layers together through the vias. Now the board is places in a copper ion bath and electroplated. The copper will displace the polonium, and plate through the hole. All that remains is to add a tin coating to make soldering easier. The copper plating baths are very dangerous, both because of the currents involved as well as because of the copper ions and catalysts used to make plating easier (cyanide is one.) Kids, don't try this at home. Jonathan A. Chandross Internet: jac@paul.rutgers.edu UUCP: rutgers!paul.rutgers.edu!jac
johne@hpvcfs1.HP.COM (John Eaton) (08/30/89)
<<<<< > Does anyone have any techniques or ideas on how to through plate a PC board > at home, sans expensive equiptment? ... ---------- Insert a piece of wire into the unplated hole and solder both ends. John Eaton !hpvcfs1!johne
sparks@corpane.UUCP (John Sparks) (09/01/89)
<6684@stiatl.UUCP>
Sender:
Reply-To: sparks@corpane.UUCP (John Sparks)
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We have a circuit board repair kit here at work (brand name is PACE)
and it has feed-thru repair pieces.
Basically you drill out the feed thru and replace it with this two part feed
thru made of tin. It's basically like a rivet. I will attempt to draw a side
view:
___________
*************|| ||***********
************* | | ***********
---------
The **** is the board. The two pieces fit together thru the hole and you use
a special tool to press fit them together.
I assume that instead of using this method to repair boards you could use it
to make feed thrus that look pretty professional on boards that you make.
--
John Sparks | {rutgers|uunet}!ukma!corpane!sparks | D.I.S.K. 24hrs 1200bps
||||||||||||||| sparks@corpane.UUCP | 502/968-5401 thru -5406
Lead me not into temptation. I can find it myself.