Using transparencys for pcbs?

[Mike]

I have heard that laser transparencies are good for making custom pcbs. two questions, though. First, will it do small traces (for surface mount) with no problems, and second, wouldn't the plastic melt under the iron 4 5 minutes?<p>thx,
Mike

[amuron]

I use great white transparencies for making the negatives. I can get reliable results at 12/12. Less than that, I create a 2X print, and then have a print shop reduce it and put the image on film.<p>Not sure what you are refering to heat wise. The UV exposure bulbs do not get more than a few degree temp rise. I have 8 FTBL bulbs roughly 1" from the negative.<p>If you are referring to toner transfer, I doubt it would work with a transparency. In fact, I've never had much success with it even with DynaArt paper and a hot roll laminator. The photo method is simpler, faster, almost as cheap, and 95-100% reliable. The only downside is having to get presensitized laminate.<p>Ron

[L. Daniel Rosa]

I use paper for gross and P'n'P blue for fine detail. The imperfections are inarguable there, I have to touch up before etching. Though P'n'P claims to be capable of better, I don't go any finer than 15mil.

[wd5gnr]

I've used transparencies. The key is to use ones meant for a laser printer since they will hold up under the heat. Also use a piece of paper between the iron and plastic just in case (hard to clean that plastic off the iron -- um, not that I'd know from first hand experience -- NOT!).<p>The good part about transparencies is they are stable so if you peel it partially up and see that you need more iron time, you can usually just put it right back down. The downside is that it takes a lot more heat/pressure I don't feel like fine lines come out as well. The non glossy photo paper seems to work best for me.<p>N&V now carries my book on PC board making. It talks about using the regular photo method, the iron method, and sending boards off. It also covers Eagle (and has a copy of the free version of Eagle on the CDROM). <p>Find it here.

[Mike]

i use glossy paper from kinkos that is designed for laser. <p>what is the better type? just regular copy paper?<p>and I want to make a surface mount board which needs small traces. the glossy is not that good for it. i thought transparencies were the best.<p>
Mike

[Mike]

Well, If transparancies aren't the best thing to use, what is? I don't really like the paper I use now, since it doesn't all stick. I need to do some surface mount boards, and if it peels off large traces, i don't thing any small ones would stick.<p>I don't want to try wallpaper or anything else not designed for lasers.<p>Thanks
Mike

[dyarker]

I don't think direct transfer is going to work for SMD. I second amuron, do a photo resist.

[Mike]

O I really want to use a laser transfer method, since radioshack doesn't sell the stuff for it and i don't want to pay a ton for shipping though. I do have some boards for negative photo resist, but i don't have that developer stuff.<p>Are there any good laser toner transfers for smds?<p>The project i am working on are some headphone amps using the lm4881M chip, and smaller is better.<p>-Mike

[amuron]

The developer is usually sodium carbonate. Its pretty inert stuff, and as long as you aren't buying a ton of it, I don't think you get hit with the hazmat fees. It might be worth trying washing soda from your grocery store, as it is a hydrated form of sodium carbonate.<p>Once you do photo, it is unlikely you will ever go back to toner transfer. 99% of my boards have traces below 18mil, which makes toner transfer a little risky.<p>Heres a heads up on the LM4881. Be sure to star ground, and use fairly large leads on the bypass and supply bypass caps. The pcb layout will determine how well the LM4881 performs. A good layout, and they work perfect. A layout done just by connecting the leads has a very high probability of stability and oscillation problems.<p>Good luck
Ron

[Mike]

the lm4881 is a 400mW headphone amplifier (and thats into 8ohm, more like 150mW into 32ohm)...
so i don't think that is neccesary. Thanks for the tip though. Just wondering, whenever i build high power amps (3886 or somthing like that) I always use about 6000-8000uf on each ps rail. but what does the star ground do?<p>I will try that washing solution.<p>My boards are negative. is there a difference between negative and positive?<p>Finally, would you mind guiding me through this? I can get it all printed and positioned on the board, but how long do i expose it? How much developer and how long do i keep it in the developer? In what order? once it is developed, can it go right into the ferric clroride etchant?<p>Thanks!
-Mike