Saturday, March 6, 2010

The Loupe-Lamp

First thing, credit where credit is due: Dhananjay Gadre for the original idea.

I had to do my own - using EagleCAD of course. Here is the process - it's a pretty good rundown on the Toner-Transfer etch-resist method in my last entry.

Steps I'll insert later:

1) EagleCAD layout
2) Printing
3) Copper-clad board prep
4) Laminating the toner to the copper-clad

5) Soaking the paper off - love the way the HP Everyday Photo Paper releases when I print on the back-side of the paper:

6) Peeling the paper - it should lift right off...

After removing the paper, waiting for the etchant:

7) Etch (this picture is post-etching):

8) After removing the toner with Acetone:

Ready for population:

LED's and 56ohm resistors NOTE LED POLARITY!

10) Solder paste applied on pads and 11) components placed on paste. I could've used a wee bit more paste, but it was good enough:

After 12) Reflow:

Yay, it works!

Monday, March 1, 2010

Laserjet Toner PCB Etch Resist methods...

Ok, this is going to be a short post, only because so much is already googleable about the laser toner etch resist method... This post assumes you already know the basic procedure, ie:

* laser-print the mirror image of your circuit
* laminate or iron the toner onto the PCB
* soak the paper off the PCB, leaving the toner
* etch

Things that WORK WELL (and make this a useable process) for me:

1) Using the BACK SIDE of "HP Everyday Photo Paper" works great. The gloss of the front side is too sticky. The back side is "chalky" enough that the toner will release within minutes of soaking in water.

2) I got lucky and found a "heated roller" laminator at Goodwill of all places. It is the GBC Creative Laminator. I had to hack it a bit, adding a higher-temp fuse, and insulating the temperature-sensor a bit, so I could get a higher temperature. This is DANGEROUS. Hack at your own risk. In any case, the rollers now get up over 300 degrees F, which is perfect.

3) Having a color laser printer, I found that using full-color works much better than black-only. Also, I go into printer settings and manually crank up the density for each of the CMY and K colors all the way.

4) Lightly rough up the copper with 600 grit sandpaper before laminating. Clean with rubbing alcohol.

5) Two passes in the laminator seems to work well. Less, and it's doesn't want to fully adhere to the copper, more, and you risk smearing the toner.

At some point in time, I'll post a full procedure with pics and all. I just wanted to get some of my tips & tricks out there ASAP.