On 12/10/08, Vasile Surducan wrote: > Looking to the attached picture I see there is a very large insulation > between routes. > Component footprint is ugly. That's partially because of the etching > process. Choose such dillution for the solution to keep the etching > process slow. > A 0.5 oz PCB is better for high pitch density than 1 oz. More, if you send to a serious PCB house a design with 3mil traces in very high density ( 3 mil trace, 4 mil isolation) they will ask to start from a 0.25 oz copper and add copper to 0.5oz using electrochemical deposition. > However the picture still shows a low quality homebrew process. If you > really want to use 0.5mm pitch or lower and large number of pin > package, my recommandation is to forget this methode and use CNC, > which is much better for low quantity of PCB even if the CNC machine > is homebrewed (of course using proffesional drill&mill bits) > > Vasile > > On 12/10/08, A K <00@case.edu> wrote: > > > > > > Vitaliy wrote: > > > Andrew, if you don't mind I'd like to clarify a few things because this is > > something I can definitely make use of (the instant gratification aspect is > > very appealing). > > > > > > - Which mailing labels are you talking about? Avery, FedEx? > > > - I'm assuming you're printing on the side that the paper used to be on, > > after you peel the paper off? > > > - How much do you have to rub the waxy surface in order for the toner to > > stick? > > > - Do you have a favorite source of copper clad boards? > > > - For double sided boards, how do you ensure the two sides line up? > > > - Are there any tricks for the ironing part? > > > > > > Do you tin your boards after etching? > > > > > > In the past, I have used the photo method (2001), the plotter method > > (2002-2003, actually made hundreds of boards using this one), and relatively > > recently (2006) the direct toner transfer method. I wasn't very happy with > > the last one, as the toner would often rub off with the paper (plus it took > > a long time). > > > > > > By the way, what's considered the proper way to dispose of used etchant? > > > > > > Best regards, > > > > > > Vitaliy > > > > > > > I'd be glad to expound.. > > > > This was the first time I had used the mailing label backing material so I > > just used what happened to be around. This was HP Q2593A address labels. > > The first time I didn't scuff it and the toner didn't stick well, so I > > scraped the toner off with a credit card, buffed it with a dry paper towel, > > and ran it through again (after a blank sheet of paper to remove excess > > toner particles from the fuser) and it worked perfectly. Even though this > > was the first time using this material, it worked better than any other I > > had tried. > > > > > - I'm assuming you're printing on the side that the paper used to be > > > on, after you peel the paper off? > > > > Yes. > > > > > - How much do you have to rub the waxy surface in order for the toner > > > to stick? > > > > In this case, just enough to remove the first failed run, or 'a few swipes > > with a credit card and a few rubs with a paper towel' > > > > > - Do you have a favorite source of copper clad boards? > > > > Not really, they all seem to work although the copper might lift off of the > > cheap stuff more easily if you do soldering rework. > > > > > - For double sided boards, how do you ensure the two sides line up? > > > > Registration marks, pre-drilled alignment holes in the corners, and a lot of > > patience. > > > > > - Are there any tricks for the ironing part? > > > > I use a hot laminating press at 125C for 3-4 seconds. I have heard ironing > > works too... > > > > > Do you tin your boards after etching? > > > > No, but have the stuff so should try it some time. > > One thing to remember, like most processes involving adhesion, is that you > > never want to touch the surfaces of the paper or board with your bare oily > > grubby little hands, no matter how clean you think they are. Touch the paper > > only at the edges or wear gloves. Also, as you can see in the photo > > attached, I scrub the copper board while wearing gloves with a brillo pad > > twice in orthogonal directions. This textures the copper, making the toner > > stick better. You can see a deeper scratch in the bottom left, it is not as > > deep as the lighting makes it look. After this, the board is rinsed with > > Ethanol and allowed to dry. > > > > Etched with preheated FeCl solution.. Once it is past its useful life I have > > heard you can neutralise the rest of the solution then it is safe to dispose > > of in a 'normal' way. > > > > -Andrew > > > > > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist