donderdag 20 november 2014

PCB bitmap resize & print

I wrote this little tool because nothing seemed to do the job. I use freeware software to create my own PCBs (Printed Circuit Boards), and the freeware software comes with a major imperfection. It's actually written to create CAD files and send them online to a company that produces PCBs. I guess the author never bothered to create a normal 'Print' button because it's not of great use when working with PCB manufacturers.

However, I kinda like making my own stuff, usually there's no rocket science projects in my collection. Mostly small projects, but that doesn't mean the pcbs are always straightforward. The last one I wanted to create had an OLED display with a 30 pin SMT flex connector that needs to be soldered right on the pcb. That's a major issue if you don't have a 'Print' button.

I usually just made a printscreen and pasted it into Paint. Then, after a few tries, I could always resize it in Paint and then go and try to fit the most challenging component on the transparent sheet that comes out of my regular laserprinter. Two of these sheets aligned perfectly on top of each other create great results, but this time it's a no-go: the connector is just too small, its 30 pins are at 0.65 mm interval, leaving only a few hundreds of a millimeter error margin.

This tool gave me the answer. It's very straightforward to use: just open a bitmap image (created in any PCB design program) and mark two points in the image of which you know the exact distance. Any pcb has items which you can pinpoint at exact distances, say 100 mils, or any larger multiple. The larger the distance you can check, the better the result.

The tool lets you mark two points at the exact location (let's say two pins of an IC or a standard connector on the board), and then converts the image to the exact DPI needed for your type of printer. All you need to do is supply the DPI of the printer and hit 'Print'. As you can see on this macro image of a SMT Attiny 85 microcontroller, it's right on the spot. I still need to try that connector, though.

The tool can be downloaded here:

(unzip the file in any folder and run the executable, it's not a setup file)

This is a small instruction video:


OK, you have to admit, this is pretty amazing! I drew up the first draft of my pcb with the OLED display with 30 pins connector. I got it perfect the first time. I use FreePCB to create the pcb and then printscreened it. Then opened it in my resize tool and marked two points of the attiny chip. It fits amazingly well!

OK, It's not a pcb yet, but that shouldn't be any problem :)


The PCB: It also fits in real life :)


The PCB: soldered !

2 opmerkingen:

  1. Thank you for your post.
    I deal with similar things that is why it was very interesting for me to read your article!
    I'm wonder where did you get so tiny connectors. I can't find it somewhere. I looked over all web sites. Imagine even this - it is web site where I used to buy all hardware. But it can't suggest me something. Please help, share with me some information where do you buy it!

  2. Hi, your message was moved to spam, I just noticed today. I buy these small connectors on AliExpress in China (search result for JST 1.0mm) :