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Pinhole question

Pinhole question

2013-11-07 by <w6nim@...>

Just getting started with the toner transfer method. I found what I consider to be a great transfer paper:
http://www.ebay.com/itm/A4-10Pcs-Sheets-Heat-Toner-Transfer-Paper-For-DIY-PCB-Electronic-Prototype-Mak-/170900415631?pt=LH_DefaultDomain_0&hash=item27ca75648f
for $1.96/10 sheets, delivered. Prints nicely, perfect release, no soaking at all.

On to the problem: I'm using an HP printer with an aftermarket toner. It prints nicely onto the transfer paper, and transfers nicely to the PCB (using a GBC laminator, multiple passes). Appeared to etch nicely (ferric chloride, for now, since I had some on hand), but I didn't have acetone ready to clean the toner off the etched board. Three or four days later, acetone in hand, I cleaned the traces, and found numerous pinholes on all the traces. I'm speculating that the toner absorbed minute quantities of etchant, and continued to etch until wiped clean. Is this a reasonable assumption - that cleaning immediately after etching is required? Or is the aftermarket toner suspect??

Any thoughts would be appreciated.

Norm
W6NIM

Re: [Homebrew_PCBs] Pinhole question

2013-11-08 by Jan Kok




On Thu, Nov 7, 2013 at 11:18 AM, <w6nim@...> wrote:


Just getting started with the toner transfer method. I found what I consider to be a great transfer paper:
http://www.ebay.com/itm/A4-10Pcs-Sheets-Heat-Toner-Transfer-Paper-For-DIY-PCB-Electronic-Prototype-Mak-/170900415631?pt=LH_DefaultDomain_0&hash=item27ca75648f
for $1.96/10 sheets, delivered. Prints nicely, perfect release, no soaking at all.

I love the English(??) on that web page! :-)

Can you describe that paper, i.e. what kind of coating etc.?

On to the problem: I'm using an HP printer with an aftermarket toner. It prints nicely onto the transfer paper, and transfers nicely to the PCB (using a GBC laminator, multiple passes). Appeared to etch nicely (ferric chloride, for now, since I had some on hand), but I didn't have acetone ready to clean the toner off the etched board. Three or four days later, acetone in hand, I cleaned the traces, and found numerous pinholes on all the traces. I'm speculating that the toner absorbed minute quantities of etchant, and continued to etch until wiped clean. Is this a reasonable assumption - that cleaning immediately after etching is required? Or is the aftermarket toner suspect??

It's probably due to the toner being somewhat porous, and the pinholes were created when you etched the board, not later. I don't think it's due to the toner brand.

Any thoughts would be appreciated.

You can try sealing the toner with Toner Reactive Foil http://www.pcbfx.com/main_site/pages/products/toner_foils.html

You also want to deposit as much toner as possible. Turn the printer settings to Darkest, Best Quality, and tell the printer you're printing on Thick and Course paper.

Re: [Homebrew_PCBs] Pinhole question

2013-11-08 by Norm

On 11/7/2013 7:36 PM, Jan Kok wrote:



On Thu, Nov 7, 2013 at 11:18 AM, <w6nim@...> wrote:


Just getting started with the toner transfer method. I found what I consider to be a great transfer paper:


for $1.96/10 sheets, delivered. Prints nicely, perfect release, no soaking at all.


Can you describe that paper, i.e. what kind of coating etc.?


Paper is sort of vellum in texture, yellow in color - on the paper side. The working side is sort of glossy/waxy, orange in color. When the toner releases, it leaves an absence of the waxy appearance where the traces were - if that makes sense. It took the toner very well, and there were no apparent pinholes under 10x magnification.

For $1.95, it's worth experimenting with. Be aware that delivery takes a while.

Norm

Re: [Homebrew_PCBs] Pinhole question

2013-11-08 by H. Carl Ott


On Fri, Nov 8, 2013 at 12:57 AM, Norm <w6nim@...> wrote:
Paper is sort of vellum in texture, yellow in color - on the paper side. The working side is sort of glossy/waxy, orange in color. When the toner releases, it leaves an absence of the waxy appearance where the traces were - if that makes sense. It took the toner very well, and there were no apparent pinholes under 10x magnification.


Are your traces wide or narrow?

Do a test print on normal paper with largish filled areas. Hold it up and view it with a light source behind the paper.
Is it really a solid black? Or black on the edges of the printed area and grey(ish) in the middle.

Do the same test on the transfer paper.
The laminator faithfully transfers the toner to the copper. If it's not solid, you'll get pinholes.


carl
--------------------------------------------------------
Henry Carl Ott N2RVQ hcarlott@...

Re: Pinhole question

2013-11-08 by tda7000

I think it is a bit of both. I have had a few pinholes on large fill areas when doing toner transfer before, I would touch them up with a Dalo pen and it was fine.

One board I didn't clean the toner off for a week or so. There was some pitting to the surface in the larger areas. I also only rinsed it with water.

Now, straight after etching and rinsing I put my boards in a baking soda solution to neutralize any leftover acid. Then I clean everything soon after and coat with flux, conformal coating or tin them.

But I have mostly been doing the UV process now, and with negative resist it is easy to do large planes and fills - you just print nothing!


--- In Homebrew_PCBs@yahoogroups.com, <w6nim@...> wrote:
>
> Just getting started with the toner transfer method.....

....Three or four days later, acetone in hand, I cleaned the traces, and found numerous pinholes on all the traces.  I'm speculating that the toner absorbed minute quantities of etchant, and continued to etch until wiped clean.  Is this a reasonable assumption - that cleaning immediately after etching is required?  Or is the aftermarket toner suspect??
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> 
> Any thoughts would be appreciated.
> 
> Norm
> W6NIM
>

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