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 Post subject: Stains on PCB
PostPosted: 11 Apr 2014, 05:23 

Joined: 11 Apr 2014, 04:51
Posts: 1
:? :?
good morning

I have made a hobby purpose , many printed circuit boards.
They are the first experience in creating simple double-sided printed circuit boards .

I would like to ask anyone who has happened this strange defect that is seen in the photos. In one case, a facade was clean ( TOP) while the other had appeared shapeless stain of copper.
After the first failure due to a spot of copper that also occupied a part of the slopes, I decided to try to burn a new base , being careful not to take too light to the exposed from the film. But even in the second circuit of the spots have appeared inform copper after the bath of ferric chloride .

Using this procedure.

Using an inkjet printer , filling the black tank every time I get ready to print.

After an initial test on paper, I continue with the printing of the master on acetate sheets in triplicate , and look at least 2 hours for the ink to dry completely .
Creo overlapping with the 3 films lined up perfectly a single master , not to make light filter where there are tracks .

I place the master on the glass of the contact printer , and I can impress to 3 minutes, this time I found it attempts to use DipTrace when I started about four years ago .

IF the circuit is double-sided, take off the last film a few seconds before repeating the cycle in the contact printer .

Then bathe in the developing mixture of about 30-50 seconds to appear when I see the tracks work the circuit and then put into immersion in ferric chloride .

Usually in an hour or so can make excellent printed circuit boards, but this time I can not understand if it is a problem of the master , base , or some error that I do.

I hope someone who can tell me a solution.
thank you in advance




 Post subject: Re: Stains on PCB
PostPosted: 14 Apr 2014, 15:35 

Joined: 12 Sep 2013, 23:28
Posts: 17
It looks as if that portion is simply underetched. Most likely from a contamination such as fingerprint oils. I say this because the rest of the board looks like it etched away fine.

Ensure that the PCB is completely clean before using your mask. I like to use steel wool or 3M green scotch brite pads to clean the surface until shiny. Once you scrub the entire board, clean it with a solvent. I like to use acetone, but naptha or isopropyl alcohol will work fine too.

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