I must try that. My old PCB exposure box might work best if I use it upside= down. I've not used the miller in a while as most of my boards lately have= been SMD. Thanks for the tip.... Joe ________________________________________ From: piclist-bounces@mit.edu [piclist-bounces@mit.edu] On Behalf Of Jason = White [whitewaterssoftwareinfo@gmail.com] Sent: 19 November 2014 21:59 To: Microcontroller discussion list - Public. Subject: Re: [EE] CNC machine for PCB prototyping. Solder mask is very easy to do, especially if you have ever done PCBs via the photo resist method. Step 1: Print transparency ("mask") with black areas where you do not want solder resist to harden Step 2: Apply liquid solder resist (a 10cc syringe of it can be had for about $3 USD on Ebay) and flatten into a thin consistent layer without air bubbles using a thin sheet of disposable plastic transparency. Leave disposable transparency stuck down. Step 3: Lay your printed transparency (the "mask") on top of the stuck down disposable transparency and expose to UV light until solder resist hardens (roughly 30 minutes with a 13W "Party bulb" 6-8 inches above PCB) Step 4: Remove mask transparency and peel off the disposable transparency stuck to the solder resist layer Step 5: The unexposed areas of solder resist will still be liquid, wash PCB in acetone/paint thinner/etc. to remove uncured solder resist Done! Now you have a decently functional PCB with solder mask. (I have had no issues doing the resist pattens QFP ICs) Only try to cure solder resist when it is liquid and with UV light. I have tried drying the resist first in an oven so that the liquid resist does not stick to the transparency. Sadly heat seems to prematurely cure the solder resist. On Wed, Nov 19, 2014 at 4:28 PM, Joe McCauley wrote: > Using a 'proper' PCB milling machine, I've been easily able to do 13mil t= racks. I've never tried to go lower as I never really needed to. I was usin= g a cone shaped miller so the tracks would end up less than 13 mil although= I would design them to be 13mil. Using a 'straight' cutter, I'd say you co= uld easily get narrower traces. > > The beauty of one of these machines is that you can have a prototype in y= our hands really quickly. The down side is that you can't really do PTH (Fo= rget about those PTH bails, they will break your heart). Doing SMD on one o= f these is a bit of hardship as well due to lack of solder resist I find. > > They are certainly good for hole mounted components (you can solder legs = to top & bottom layers in many cases) if you actively try to minimise vias = in the layout. > > Joe > ________________________________________ > From: piclist-bounces@mit.edu [piclist-bounces@mit.edu] On Behalf Of John= Chung [kravnus@yahoo.com] > Sent: 19 November 2014 18:22 > To: Microcontroller discussion list - Public. > Subject: Re: [EE] CNC machine for PCB prototyping. > > Hi Neil, > What use do you use your CNC for? It does look convoluted with the PCB pr= ocess when I first thought of it. From what I gatherhere most of the guys d= o actually farm out to PCB companies. > John > > From: Neil > To: Microcontroller discussion list - Public. > Sent: Thursday, November 20, 2014 12:27 AM > Subject: Re: [EE] CNC machine for PCB prototyping. > > I have a couple CNC machines and have considered this a few times, but > the process seems so convoluted and messy for a single PCB that still > won't be ideally what I want, as I usually need 6mil trace/space and a > lot of 0.015" plated-through holes. If it's just for some quick testing > before I make a formal proto or production unit, I use perf board, and > if it's complex enough I just order a proto for ~$160 shipped, and toss > a bunch of other projects on there also. > > Cheers, > -Neil. > > > > > > On 11/19/2014 5:18 AM, John Chung wrote: >> Just wondering if it is worth the hassle to get a CNC china made machine= and fiddle with it to produce a PCB board at the end.Would like to hear yo= ur thoughts on it. I am looking at the CNC 3020 or 6040 model for this work= .. >> >> I do find the CNC beneficial on wood carvings more :) >> John > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- Jason White -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .