AVR Freaks

I'm not sure I understand you on this one. Cause I'm sure you know, but I'm only dealing with the top plane, and I just want to allow the light that is perpendicular to the plane to be able to pass through.

Seems like you do know your stuff though!

But I still think it should help quite a bit, at least with my specific setup.

I'm not 100% sure, but it seems like the bleed is caused from having to double up the masks, as well as from the thickness of the transparency film.

If I don't double up the mask, I get light bleed everywhere, not just on the edges.

I do always make sure that the toner is on the board's side, but its still not enough to stop it, and so I need the second layer.

But because there is 2 layers, one of the masks is farther from the board, so when the light is coming in from an angle, it manages to pass right beside the top mask, and will hit the bottom one's edge. This is why (I believe) I get some edge bleed.

Here is an illustration of what I think is going on.

I'll admit that the bleed isn't really that bad at all, I'm still able to make 0.2mm traces, with 0.2mm spacing.

But when I'm not consistent with how I hold and move the light, it can cause some traces to have sections that don't etch.

Building something like a curing box would solve my problem, but I think this would be a good quick fix, and probably help the box as well.

Cause I like to be able to have a prototype by the end of the day.

And most of the time, something is really wrong on my first board, so it really helps me make sure I'm sending a working design to a fab house.

It would really suck to spend $50, wait a week or 2 and find out I made a huge mistake.

I actually just made a board 3 days ago, unfortunately one of the parts I made had its mounting holes in the wrong spot(Its hard to measure conductive rubber pads with a caliper), so I fixed the mistake and remade it last night.

Also, I'm getting really good at making boards. The only thing I really need to improve on is solder mask.

I'm going to design a little CNC machine that squeegees it on, then I should be able to make boards as good as a fab house.

Thanks for all the replies guys. I will definitely try everything that was advised.

Please excuse any shotty writing, it was a lot to reply to!

The problem is 1 mask will partly cure the traces as well.

I use a 2400dpi printer, and yeah the real problem is that its not as black as I need it to be.

Not really sure how to describe my light, but its this exact one.

I have plans to make a curing box, already have all the LEDs, but I just haven't found the time to get around to it.

I'm using photo-resist, but the masks I make to cure the photo-resist are just transparent sheets with toner.

Its not really about resolution, its about the consistency. A lot of the time my whole board will be almost perfect, but there will be one or two traces that get over cured. Then I have to use either an exact-o knife, or a CNC router to fix it.

The toner methods never worked well for me, it would always leave residue from either the paper, or possible the stuff that's mixed with the toner while printing, on the board. Everywhere that residue was, would not etch, which was literally everywhere.

I was using tiny rivets for my vias, but I just recently got everything I need to electroplate them.

Literally all I need to do (after I get the consistency down) is make something that will spread solder mask evenly, and then I should be able to make near fab house quality boards.

Sounds expensive haha. But anyway, I did briefly look it up, but couldn't really find anything that I could use. What I really need is a film.

I'm still pretty sure a polarizer would help, if they are using them in DLP printers there must be a reason(other than the fact LCD's use them).

It may take a bit longer since it would be blocking some of the light, but in the end this would be just an experiment.

A curing box may also be the answer too, my light source is basically a point, so no doubt that someone more evenly distributed would help. 

I was planning on making one as I said to sparrow. Already have the LED's, and now I'm just waiting for some free time to open up.

Unfortunately I don't have an inkjet printer, but I'll definitely try that out. My dad has an ink jet, but I just hope it has a decent enough DPI.

Ahh! That stoufer gauge looks pretty awesome. I've narrowed it down to about 5 minutes, but the whole time, I'm having to hold the light at a certain height and move it around constantly.

What exactly does a spray etcher do, constantly spray etching solution on the board?

I just looked at an Instructable, as well as a YouTube video, but they haven't really said what it does exactly.

As for plated through holes, I used to use 0.9mm rivets, but just recently I bought everything I need to do electroplating.

I've been waiting to do it, but just haven't needed to do any double sided boards since I got it all.

The container is all ready to go, and all I really need to do is mix the ink and prepare the bath.

Ahh very cool, I'm from Canada, but I wonder why they would send it off to Australia to be done.

I see that you see the value in making a quick board before sending it off.

There are always people who say "Why don't you just send it to a fab house, its so cheap and you cant beat the quality."

In fact there was 2 in this topic (Nothing against you guys :) )

Yep, that's pretty much exactly what I do, with some minor differences.

Others were saying to use an inkjet printer instead of laser printer, correct me if I'm wrong, but you use their laser printer for the DPI? Do inkjets just not have the resolution needed for small traces?

That baking paper is exactly what I'm looking for! But what are your thoughts on using a polarizing film for that purpose?

I'm guessing that chemical dip is "Liquid Tin" correct?

I've also been using that, but I find that its sometimes a little uneven. But I'd put money on it being caused by forgetting to clean the board after etching.

That helps for sure, next board I will try using parchment paper.

Though I'd still like to hear what you think about replacing the parchment paper with a polarizing film.

Thanks

I'm not actually using pre-sensitized boards, I purchase rolls and laminate them. I had no idea there were positive and negative films, but it turns out that I've been using negative the whole time.

I had said to someone above, but I'll definitely try using an inkjet. The only thing I'm worried about is the DPI on my dads printer. My laser is 2400 dpi so its pretty hard to beat the resolution, but it definitely doesn't have the best blacks on transparency film. I actually print a blank page onto the sheet a few times before I print the actual mask. I do this to get as much binder on the page as possible, it does seem to help.

My pockets are definitely shallow. But you can actually get about 100 5054(SMD size) LEDs, that are 365-370nm/395-400nm, and 1 watt for only about $13 CAD.

Even though diffusion is the opposite of polarization, the whole point is basically to remove the pinpoint effect, which I still think a polarizing film would achieve.

Next board I'll try the baking paper, but I think its still worth a shot to try the polarizing film. My DLP printer uses one, and its not one of the regular films the LCD would already use.

Why not UV stable plastic? What is the difference?

I am using glass, but what is a photo tool?

I actually have been doing 8mil traces, and the last board I made has 2 traces going between my DIP pads. ;)

But exactly like you said, the problem is with reliability.

As you can see in the image, in the red areas there is some messy shit.

There was a tiny bit of bleed in the red circles, causing the traces to not etch, and so I had to use my cnc router like a band saw, and hand fed the board to fix the traces.

A curing box would probably fix this issue, cause I'm having to move my pinpoint light around constantly, and it causes some areas to bleed if they are exposed too long.

The board is for a NES (Nintendo Entertainment System) controller, just need to drill and mill and its done. Just a little side project for a tutorial that I'm currently making.

Ok, I kind of thought that's what it was.

Yeah I will do that. I just thought there must be a reason that my DLP printer uses one (its not one that the LCD always uses).

I know it won't straighten the light, but I thought that if the light was coming in from an angle, it wouldn't be able to pass through.

I'm probably not understanding something though.

I always make sure that one of my masks has its toner flat against the PCB, but when I didn't add the second mask it didn't work at all. There wasn't enough time to cure it, before the masked parts started to cure.

Next time I make another board, if its before I create a curing box, I'll try increasing the distance like you said.

Oh yeah, I've seen that video before, hasn't he also made a board with a DLP printers LCD screen as well? It may have been another similar YouTuber, but I'm pretty sure that was him too. 

I completely forgot about that video, I actually have the same laser too. Its interchangeable with my desktop router's spindle. Only have used it once because I haven't had a use for it, but maybe now I will.

Ahh, did not know he made videos like that, I've only seen his tear down videos.

My results are definitely not horrible with toner, its just not as reliable as I'd like it to be. 

If you look at it under a microscope they actually look very nice too. Nice smooth traces, unlike toner transfer.

Its about 90% reliable, but every once in a while I'll get an issue like image in the board above.

I'm not sure I understand what you mean.

Will it allow light to pass through?

So that's basically Kiwojet?

Do you know if that's PET film?

Yes that is true. Turns out my dads printer is 600dpi for black and white, and then 2400dpi for color.

I'll try making the curing box before I invest in a new printer, because the laser is doing pretty good, apart from needing 2 masks.

Very cool, maybe some day I'll follow your tutorial. At the moment I'm able to do letter sized board so there isn't any rush.

Photo tool, gotchya.

Oh that's interesting, I'm guessing that old plastics go yellow because the lack of UV stabilizing agents?

I will for sure, was going to make a timer or something along those lines.

Ok I'll skip the film, I was looking at a 30x20cm piece that would only cost $20 CAD with shipping, but I guess for even that its not worth it.

I noticed that ink jet transparency film is pretty darn expensive. I managed to find a huge roll of unbranded PET film (advertised for inkjets) that was only like $30, I was hoping it would be the same. Still may give it a try if I get an inkjet.

What do you think of this?

It would have to be cut to size, but man, if it works it would be a great value.

Ah, thats right, I totally knew that, but just was not able to put two and two together.

I actually have stood outside a friends house before and turned his TV off with a remote as a prank.

Won't be able to tell you how it worked though, I have also seen similar IR videos of viewing a human through a panel of glass and it was like they weren't even there.

Not stupid at all, yes I have tried it. I could never get it to align properly. That was on my old printer though, and this new one is a ton better. I just might give it another go.

I have actually been printing a blank page a few times (on the same sheet) before I actually print the mask. It seems to help, I guess it just gets a bit of extra toner that was left on the rollers. Really not sure why it helps though.

I saw you mention the WD40 thing, I haven't yet. I just don't really know what you mean by that. I asked in one of the last huge replies, I don't blame you for missing it.

Is that a toner transfer method? I tried to do that with alcohol and acetone with no avail.