I'm right now through plating a board, and quickly took a picture for
you. The board is now in the last step, the copper plating bath.
The station you see on the picture was built by myself. It's the second
generation, and I intend to put a website online about several processes
around making even multilayer boards at home with home built equipement.
I just did not had the time yet to upload and document everything. The
old page I once had online is gone due to me changing providers.
You basically need a laminator and laminate (since you must tent the
through plated holes cause you have to make them bevore you etch the
artwork). You also need a through plating station. I use one with five
baths. It's acutally not all that complicated, and does also not have to
be expensive, but you must be prepared for initial costs of ~$1000 if
you have nothing. I mean you need copper anodes (coper is expensive
these days), a relatively simple electronic cirquit, some motors, some
heaters, a lot of plastic sheets, a big plastic box and a lot of time
and ideas :-). I intend to sell stations once said page is up but also
publish plans for those who want to build one on their own. The selling
part is more thought as a help for those who don't want to spend the
time on building one themselves or those who want to take profit from
the experience made here.
The plating process can be done differently. I use an aproach as it's
also used in the industry. The advanteage of this is that you get very
consistant beautiful absolutely repeteable results. The disadvantage is
that you have to buy the chemistry. It's however relatively easy to buy
and if you buy it at the right place not at all that expensive.
Anyways, I use five baths. The process I use in the order applied follows:
- The first bath micro etches the FR4 material (and of course also a
little the copper but thats a side effect). The purpose of this is to
assure that the palladium emulsion which is applied in the fourth bath
(see below) can stick to the FR4 makeing it conductive to the degree
needed for the effective plating process. You have to rinse the PCB with
water after this step.
- The second bath is a so called predip. It's a sodium cloride solution
with aditives and the same as the third bath, but there is no palladium
emusion in it. The purpose of this bath is to aclimate the PCB to the
following bath and thereby avoiding contamination of the third, bath
which is a bit critical and contains the most expensive chemistry (the
palladium emusion). There is therfore NO rinsing after this step.
- The third bath is the one makeing the holes conductive for the
subsequent plating process. It's the same as above, but contains the
palladium emulsion. The emusion is somewhat expensive, but to give you
an idea, half a litter costs ~80$, and said half litter will last you
for the next ten years with a station of the size of the one I build, so
costs are relative. You must rinse the PCB after this step.
- The fourth bath is hardening the palladium. This is having the effect
that it sticks better to the FR4, but splitters of from the copper. Also
rinse after this step.
- The fifth bath is the effective copper plating. The attached picture
(don't know if this works with this group, if I see that the picture is
not attached, I will upload it to the files secion and post in a second
mail where it is) showes the board in this bath. You apply ~2.5 amps per
square decimeter of copper material to this bath and run the PCB in
there acording to the thikness of copper you want to end up with. After
this the plating is done. What's left is to trughly rinse the PCB, and
then of course continue with laminating dryfilm resist, expose and etch
the outher layers (or only layers in case of a double sided board).
On the picture you see that you need several tanks and a mechanical
construction to swing the PCB back and forth.
HTH
Markus
pic of throughplating station
peripherin schrieb:
>
> Now I am going to ask a question that I have tryed at before and
> failed.
> Does anybody know how to thru hole plate useing home equipment ? Also
> any good websites would be welcome ?
>
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