Two things now have come up.

One the heat required to do these transfers while okay for the hobby field are not so great for any other venue. Mainly the heat stress put into the copper to laminate layer. This glue is only stable to about 350°F before you rip out vias with the drills or worse yet you lose a single pad when you solder. This is why the industry makes it with a photo resist which I am trying soon.

The other is a solder mask. The toner being what it is is susceptible to alcohol. That means cleaning the board post assembly the toner will fail under a tough scrub needed to remove flux. I know that some say do not remove the flux, I simply disagree. So again the solder mask or any silkscreen needs to be done with a silkscreen process and not an iron on. You also get better registration because you can see thought the screen to properly place the board before you spread the paint. Again all cold processes and you have not stressed out the board.

I think this process has come along way. I see people here have done a great job refining down their process. I will post next week my findings on a photoprocess. My goals are to find the cheapest "home brew" one off method while being able to see great looking traces down to 3 mils and maybe even smaller.

 

Most PCB stock does not have a problem with the toner transfer method. I have one batch that likes to shed traces but that may or may not be related to the heat.

Solder masks are nice but you can do without them. Many a QFP has been soldered to a DIY PCB without a mask. Liquid solder beads up and heads for the metal.

If you want to do a toner solder mask use a flux that can be cleaned with soap and water and a tooth brush.

3v0

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Not to be negative, but like somebody mentioned before, this subject has been experimented on for years. If you think you have something new to add, go through the Homebrew mailing list, and check out the archives to see what other people have tried.

Homebrew_PCBs : Homebrew Printed Circuit Boards

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Mark Higgins

 

My first attempt did not have the exposure times right but since it was exposed I developed it anyway and etched it. It includes 1 to 6 mil traces. The one mil will not work, the 2 mil is flaky, the 3 mil is fine, and the 6 mil no problem.

I will post a compete report later as I perfect the timing. Twice the cost, about the same time to etch, better control of the registration and line widths, and no heat into the board.

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Mark,

You showed me three examples of 20 mil traces. There is no components with 10 or 8 mil pads and all these traces look to be the same size as the pads so again .020" is the minimum reasonable size for thermal transfer, which is the width of the smallest pads. I have included a photo of what I am talking about. This is a snapshot of ExpressPCB with three of the smallest components and the smallest pads. The pads line up nicely with 20 mil traces. Do you disagree? can you prove to me where your 10 mil traces are again. And no those also are not 8 mil traces. Again the smallest pad is 24 mil. so your traces should be much smaller than the smallest pad.

The good news is the photo transfer method just using the sun and the same laser output with Pulsars foil can achieve 6 mils without a problem which again is an industry standard as the minimum for PC boards.

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Your mistake is thinking that I'm using 0.05" lead spacing IC's. Your image shows spacing relative to a 0.05" lead pitch IC. The IC's on my boards are 0.5mm. If I used 20mil traces then there would be no space between the traces at all. 0.5mm is about 19mil length. The 8mil trace image is using an IC with 0.4mm lead spacing, that's less than 16mils from centre lead to centre lead.

I've been doing this for quite a while now. Try to assume I know the basics like the difference between 10 and 20 mil.

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Mark Higgins

 

e.g. For the Pulsar paper experiment the board I made was for the LM3S811 Luminary Micro. You can see the package information at the end of the datasheet. Annoyingly you need to register to download it, though.

Luminary Micro - LM3S811 Microcontroller

The first RF Node board I show uses a QFN chip (it's an MSP430F2012). As far as I know, QFN only comes in 0.5mm spacing.
DIY Toner Transfer Paper (cheap and easy))



0.5mm lead spaced parts are very common; If ExpressPCB doesn't have them, you should at least try using something more advanced like Eagle CAD.

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Mark Higgins

 

I do not doubt you are very experienced at making PC boards, that is not the issue here. What I can see is that you are quite good at making PC boards. Can you please take a zoomed in picture of the top of the board where we can read the printing on the top of the MSP430F2012 chip. Do you have a link showing photos how you did this with pictures of all the steps. Can you replicate your board, and have it come out the same? Have others replicated your board using your same steps?

This is important because I do not believe any manufacturer using the thermal transfer method can put down anything less than a .020" trace repeatable and reliably. This is an issue here and it should be resolved one way or another. Especially in relation to Pulsar's product line.

If you can show your steps and a zoomed in pic of the top of the TI chip, I will believe you, and if that bears out truth, you are leader amongst us who can do what most cannot. Believe me that is a big deal especially mounting these components.

I also have shown the ability to put down reliable traces with a photo resist traces down to 3 mils, 0.080 mm. Currently the smallest width lead in resist etching system is 3 mil limited, no matter what system you use. That is the width of a human hair. I plan to put in a solder mask and use a low temp solder paste. The goal I have is to see if an industry standard can be done at home with minimal expense and done with maximum safety.

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There is NOTHING to resolve ! What you believe is irrelevant in the face of reality.

DirtyLude, myself, and several others have used the system and it works. Many people who know how to do toner transfer can do below .020" even without the Pulsar paper.

The Australian distributor for Pulsar has made a tutorial that is about the best I have seen to date. There is no point in duplicating it.

The quality of result from any of these methods depends to some extent on the operators skills.

Nuff said.

3v0

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So, let me get this straight. Out of the two alternatives; you not doing the Toner Transfer process properly, or me and others in this thread lying, you chose to believe that we are probably lying without doing any research on your own to verify either story. You must have a lot of friends.

1. Because you gave it one try and cannot do less than 20mil does not mean others can't. For once, do something that I suggest and go to the Homebrew ML that I linked earlier. Pulsar advertises all over their site less than 10mil and shows plenty of images. IF YOU CAN'T GET LESS THAN 20mil YOU ARE DOING IT WRONG. Talk to the Pulsar support guy, who is very helpful, about fixing your process. It's obvious that you don't have a lot of experience here, why can you not take advice? If you want more examples of people being able to do Toner Transfer with finer pitch, they have a search site called google. "toner transfer pcb" will give you loads of examples.

2. There is a post right here in this thread that I've already linked to that shows my process. It's using Pulsar paper, but it's the same process I use for Photo paper. I'm not going to take video if that's what you want.
DIY Toner Transfer Paper (cheap and easy))

3. In the 8mil example close up picture you can clearly see the Wiznet W5100 markings on the chip. Here is the datasheet with package description. 0.4mm pin pitch
Image:
http://www.electro-tech-online.com/a...02-pcb-003.jpg
Datasheet with Package description.
http://www.wiznet.co.kr/rg4_board/do...ey=0&mode=down

It's nice to get really small traces but ultimately not useful to me or I would say most hobbyists. There's a reason I haven't done less than 8mil on a real board that I've made and populated, that's because I just don't need any smaller. I don't get any benefit out of it and without small easy vias, I don't see general hobbyists having any use for it either. ARM7 chips have all sorts of core power supply pins and PLL pins all mixed in with regular I/O pins, which makes making single sided boards with ARM7 chips a complete mess and even double sided board are a mess without being able to make vias under the chip. Those pcb's I have to get made in a boardhouse. If all you want is accuracy, check the direct print inkjet work done by some people. Check the pics in the Homebrew PCB group under 'C88 Test PCB'. Perfect solid 1mil trace test. Really nice. Unfortunately too much work for me for something I don't need.

I'll take a close up picture of a couple of my MSP430 QFN chips mounted on boards for you after work. Here's the Eagle board and schema files for that RF Node test board, for now, though. They can be viewed in the free version of Eagle Lite.

http://www.higginstribe.com/msp430/r...accel_temp.brd
http://www.higginstribe.com/msp430/r...accel_temp.sch

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Mark Higgins

 

Guys,

As you know there's lots of threads here that show it works and lots of methods (all about the same really). Maybe AngelGoove should go search/read the forums here before preaching to the MANY that are doing it, some for a long time.

AngelGroove, you are doing something wrong based on what I saw with your pictures. Needing to load the image in a graphic editor? Maybe that's your printer or toner.

 

Okay gang,

I tried the thermal transfer again and you can see the high resolution picture below. In it notice the traces and the ground-plane. The ground plane has little to no etch per sq mm. Compare that to any trace and you see pitting on all of them. That again tells me the larger the pads the larger the traces the larger the pins on the components gets one to a better board. The board measures 1-1/4" square or 30 mm square.

Another thing too, without a wave machine, how on earth does anyone reasonably solder this chip up. Even with a fine needle solder tip, you need a microscope and a robot to solder these up by hand. By all means, please tell how you assemble this chip.

I will do this same circuit in a photo resist method next week and post its results. Hopefully no pitting.

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I for one with any internet form, with out the references, the dates, the paper than cannot be found or anything like that is merely an opinion and not fact filled.

What I am doing here is reasonably trying to replicate what other have done and simply report it. That is the scientific process. Take it with a dose of salt if you like it is merely my opinion and if there is a fact it then is true. I show everything based on facts like the outside board dimensions so that anyone can verify the leads. I also do not dispute the process merely am saying what are the problems. I am not about to spend money on new equipment that may or may not fix any problem. I have spent too many years of chasing down problems and it usually ends up as a giant rat hole with no end in sight. If I cannot do it with my high end equipment, I am not about to trade it in for specialized equipment simply to prove a point. I am quite happy with 20 mil traces. If I need smaller, it will then be a photo resist method.

I think what has happened is you have spent a lot of time and money getting all of this just right. I am not interested in doing that and merely want to do simple boards that I can reasonably put one together. That is it in a nutshell. If that means 20 mil traces then so be it.

What I also hear is hurt ego. Well simply do the scientific process to your proofs. If you do not, it is merely an opinion, and expect to be questioned. If that is all this website is about, Puslar better take the front row here and show their work and how they did it. Because after all it looks to me Pulsar is making a lot of money here, and its is no wonder why some do not trust the process.

 

For QFN I use a hot air rework station. I really like working with QFN now as it's pretty easy. I put down a bit of paste, tiny bit on the thermal and a bit around the pads, drop it on and hit it with some hot air and it sits right down in place. Parts will align themselves to a degree, with tension when in reflow.

You can see in the close up, the little beads that are left behind from my cheap solder paste. Since doing this one I've been mixing a little extra flux in my paste before using it.



I tried to take a close up of my breakoutboard chip, but close up, the text was way too faint and unreadable.



...and here is the assembled board with the vias. Unfortunately this will not be the final prototype for my generic RF Node. I just found too many improvements I can make to it.

Attached Thumbnails

     

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Mark Higgins

 

You did absolutely no research and declared less than 20mil impossible using toner transfer. That's not scientific, that's being lazy and jumping to conclusions based on almost no evidence. A simple google search or even referencing the Pulsar site where you bought your product, or using the references provided you earlier would have helped you, but instead you told me I was wrong.

There's being thorough and there's being disrespectful. What you are doing is being disrespectful.

Pulsar has documented the method a lot. Check their website. I'm not certain what more I can say about that. You've been told again and again to do so and you simply don't for some reason. Talk to the support guy at Pulsar. He'll chat you up for a week about this.

You think this is what has happened because of all of the evidence to suggest this? For someone that likes proof and facts you jump to conclusions so easily it's frightening.

I don't actually use Pulsar paper. I've used it a few times to test with, but I still don't get results with it using a clothes iron that I get with regular Staples Photo Paper. I use a regular clothes Iron and I have no expensive equipment for making these. I do have a hot air rework station, but it's a cheap chinese one for $160.00, and it has nothing to do with making boards. You would know this if you had read this thread and the many others on here about PCB's.

I found a picture a while ago of the first pcb I ever made using this process and posted it in another thread. This was sometime in 2005. Probably lucky, but right from the start I was able to do a decent board using nothing but my HP laser, my iron, and some ferric chloride. I attribute the success to following instructions. My methods and tools haven't changed since then.



He was told that a while ago and like all advice in here he ignored it.

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Mark Higgins