Re: [Homebrew_PCBs] Ferric Chloride - dry film
2003-01-22 by Adam Seychell
Ron Amundson wrote: > Its a dry film negative acting materal. Please see > http://www.kepro.com/cprecut.htm for details. > thanks, yep the "DF" sounds similar to what I and most PCB manufactures use. > How do you apply your own dryfilm, do you have a laminator, and if so how > big.. I can only buy it in huge rolls, and I'm worried about its shelf life > expiring. Or are you indicating that the shelf life starts once its applied? > No, the shelf life I was talking about was only after being applied to the board. I don't know the shelf life of the dryfilm at room temp. It releases a smell so my guess something is evaporating and will eventually cause problems. I store the roll in the fridge and haven't notices any degradation of the 1 year I've had it. I bought some from a guy who manufactured PCBs and he sold be the last 20 metres off two old rolls. Try contacting any PCB fabricators near your area. Applying the film is a problem in itself. I spent lots of time experimenting before I gould even get usable result. I build a device that has two rubber rollers (old ink printing rollers) and I roll the film on the cleaned PCB while wet with distilled water. I then heat the board in the oven at 80C\ufffd for 5 min and that fixes the film. There are other techniques that have been posted on the group before. Do a search in yahoo groups web site for past posts.
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> I like the idea of your concept of appying the film one day and processing > the boards the same day. It would alleviate lots of problems. > > Thanks > Ron > ----- Original Message ----- > From: "Adam Seychell" <adam_seychell@...> > To: <Homebrew_PCBs@yahoogroups.com> > Sent: Tuesday, January 21, 2003 7:29 PM > Subject: Re: [Homebrew_PCBs] Ferric Chloride > > > >>I once tried to built a bubble agitated developer but found the >>bubbles could not reliably remove the dry-film from the board. In the >>end I found best results using something similar to what Tom described >> with the brush. >>I also agree with Tom that you could be suffering dry-film residue, >>which is an invisible scum left behind after developing and is >>impermeable to the etchant. I am only familiar with negative dryfilm, >>are you sure the boards are this film or is it positive pre coated PCB >>material often sold at hobby shops ? >>The way to check if you have a residue problem is after about 1 minute >>in the etchant you should see the copper turn matte pink. If it still >>shows shinny scrubbing marks then its dry-film scum. This happens when >>the dry film has been on the board longer than a few weeks. I have >>some stuff that's over a year old and is a problem to develop. The way >>to develop these boards is to extend the developing time (brushing >>over the board for upto 3 minutes). I put it in the etcher and if the >>copper doesn't become matte pink over the entire board then I take it >>back to the developer and brush over it for another minute. The second >>pass usually gets it all. I apply my own dry-film these days and >>develop the board the same day so I never have residue problems. >> >>Ron Amundson wrote: >> >>>I'll give the brush solution a try tomorrow. As I purchase my boards pre >>>laminated with dry film, I'm sure cleanliness is not the issue, but >>>underdeveloped dry film resist probably is. >>> >>>I do my developing in a tray with agitation too, looks like I'll need to >> > set > >>>up a simple to do spraying. >>> >>>Thanks >>>Ron >>>----- Original Message ----- >>>From: <twb8899@...> >>>To: <Homebrew_PCBs@yahoogroups.com> >>>Sent: Tuesday, January 21, 2003 10:09 AM >>>Subject: [Homebrew_PCBs] Ferric Chloride >>> >>> >>> >>> >>>>Ron mentioned in a previous post that he was getting uneven etching >>>>with ferric chloride. When this happens it's usually due to under >>>>development of the photoresist. I am assuming that dry film resist is >>>>being used. The best way to develop dry film is with a spray tank set >>>>up with a 1% sodium carbonate (soda ash)solution. Find out how long >>>>it takes to "break through" to bare copper and then go about that >>>>same time again for final developing. For example if the bare copper >>>>shows up in 1 minute then continue the process for an additional 1 >>>>minute and then you can etch. >>>> >>>>Another good idea is to make up a tray of weak etchant from a couple >>>>of ounces of ferric chloride in one gallon of water. If a developed >>>>board is put into this solution for a minute or so the areas that are >>>>fully developed will turn a dark color and the under developed spots >>>>will show bright copper. This will amaze you the first time you see >>>>it because the panel still has some dry film "scum" on the surface >>>>when the board looked like it was fully developed. If the board has >>>>scum, just put back in the developer for a bit longer and try again. >>>>When a uniform dark color appears across the entire surface you will >>>>be ready for final etching and obtain excellent results. >>>> >>>>If developemnt is being done in a tray, try using a very soft >>>>bristled brush to gently work the solution across the board surface. >>>>This will help to break through any scum on the board. The bottom >>>>line is that this scum must be removed or you will never obtain >>>>uniform etching. Hope this idea helps out. >>>> >>>>Tom >>>> >>>> >>>> >>>> >>>>Be sure to visit the group home and check for new Bookmarks and files: >>>>http://groups.yahoo.com/group/Homebrew_PCBs >>>> >>>>To unsubscribe from this group, send an email to: >>>>Homebrew_PCBs-unsubscribe@yahoogroups.com >>>> >>>> >>>> >>>>Your use of Yahoo! Groups is subject to >>> > http://docs.yahoo.com/info/terms/ > >>> >>>Be sure to visit the group home and check for new Bookmarks and files: >>>http://groups.yahoo.com/group/Homebrew_PCBs >>> >>>To unsubscribe from this group, send an email to: >>>Homebrew_PCBs-unsubscribe@yahoogroups.com >>> >>> >>> >>>Your use of Yahoo! Groups is subject to >> > http://docs.yahoo.com/info/terms/ > >>> >> >> >>Be sure to visit the group home and check for new Bookmarks and files: >>http://groups.yahoo.com/group/Homebrew_PCBs >> >>To unsubscribe from this group, send an email to: >>Homebrew_PCBs-unsubscribe@yahoogroups.com >> >> >> >>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ >> > > > Be sure to visit the group home and check for new Bookmarks and files: > http://groups.yahoo.com/group/Homebrew_PCBs > > To unsubscribe from this group, send an email to: > Homebrew_PCBs-unsubscribe@yahoogroups.com > > > > Your use of Yahoo! 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