James,
I only have an incomplete know how of what's inside the baths cause I
bought the chemistry, but for those willing to also buy such chemistry,
this is a reliable, easy and quick way to homebrew thru hole plating.
The chemistry suppliers obviousely look at the exact formulas of their
baths as a trade secret and won't tell you the exact content. Apart from
those who want to mix their own chemistry me thinks that buying it is
definately a simple, feasable way. Remember that the chemistry
maufactures have spent years of reserch and developement on this. Adam,
also a member of this group showed in the past that you can suceed with
your own chemistry, but I doubth you get the same quality and
consistence as you do with the comercial products, and in order to do
this you would need a deep understanding of chemistry to an extent that
is definately beond me.
I meanwhile changed from buying the chemistry from small suppliers of it
to simply being in touch with a boardhouse which is kind enough to sell
me the rediculousely small amount of it that I need. I must say though
that I meanwhile have enough of it here so as it will last for the next
10 years or so. You will be surprized how many of the board houses are
acutally willing to help you out if you ask politely and make it obvious
to them that you are far away from being a competition. Most board
houses are not really well suited to produce one offs or prototypes, and
it should be easy to make them belive that you are after one offs and
prototypes only. As such you are no competition and also no customer -
unless you are sucessfull and then you need a series production which
the board house then would have good chances of doing for you. At least
that was the line of argumentation I used. Might be that you are not
sucessfull at the first attempt, but if your are presistent and ask
around, I'm 100% sure you would suceed. Anyways, the chemistry is also
available on the market. There are usually specialized firms who supply
it. At least a board house is willing to tell you the names of their
suppliers and you then could knock on their door. For those who live in
the EU and don't want to ask a board house, Bungard Elektronik is
selling a chemistry at reasonable prices and in quantities small enough.
I figure some members of this group which regularly do PCBs definately
fall into the cathegory of potential candidates of this aproach or else
they would not make their own boards in the first place.
The running times are no secret. The first bath is 7 minutes, second one
minute, third 7 minutes, fourth is 4 minutes, the plating bath starts at
20 miuntes up to the thickness you want. I usually run it ~30 minutes.
It also depends a little on the current. My bath allows me to run it at
~2.5amps per square decimeter. Between bath 1 and 2, and bath 3 and 4
and 4 and 5 you must rinse the board with running water for ~1minute. If
you do the math, this means that a board is tru plated in less than one
hour!
Regarding "keep the holes from being eched off ". That's the point why
you have to use dryfilm resist. The resist "tents" the holes (this is
called tenting) and therby protects them from being etched away. That
works very reliably. You just must take care to adjust the artwork
precisely with the previousely plated holes. Once you get the hang of
working with dryfilm resist you realize how flexible this method is and
you hardly will return to anything else. I meanwhile sometimes even
strip old base material that is coated with a photosensitive laquer and
laminate it therafter just because of the advantages of this method. One
advantage is i.e. that you can always start over if after exposing and
developping you discover that something is not shart enough etc. by just
stripping the resist away and relaminate the board.
Markus
James Newton schrieb:
>
> Wow...
>
> Are you willing to tell us the exact chemicals and times for those
> baths?
>
> How do you keep the holes from being eched off along with the
> unwanted copper on the boards? Do the holes get plugged somehow?
>
> --
> James.
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, Markus Zingg <homebrew-pcb@...>
> wrote:
> >
> > 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 ?
> > >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>