3d Printed Negative PCB with solder paste traces - Page 1
Forum section: electronics / projects

author: sourcecharge
author_rank: Regular Contributor
timestamp: October 23, 2018, 04:25:01 am
content: So, I recently did an experiment on a throw away piece of 3d printed PLA that had a 1mm deep by 4mm wide channel in it. The throw away piece was about 3 mm in depth total. I put a beed of solder paste directly out of the solder paste tube without a nozzle on to make about a 1/8 inch thick 2.5 inch line along this channel that was about 3 inchs long. I then used my solder hot air unit at 300C on the bead using normal hot air soldering movement and clearence.I found that it melted the solder but not the PLA that much....I measured the resistance and found it to be lower than the meter's ability.So that got me thinking....PLA melts at about 170C, but ABS and PETG melts at even high temeratures to almost 220C and since the solder paste melts at 180C I was thinking that I might be able to make a 3D printed negative PCB with channels that are used for where the solder paste is put into and melted.The first thing I need to do is make a PETG type of prototype, but of course my 3D printer is having problems with higher temps then 210C, so I've decided to finally change out the mother board and do some upgrading.Anyways, the prototype will be a SOIC-8 breakout board to DIP pins.Here is a picture of what I intend to make after the 3D printer is repaired. The extruder nozzle for this print will require a 0.2mm type.

author: station240
author_rank: Unknown
timestamp: October 24, 2018, 06:36:33 pm
content: Let me know how you go with this, got to be more useful than trying to 3D print circuits using conductive ink.

author: Fusion916
author_rank: Regular Contributor
timestamp: October 24, 2018, 08:12:30 pm
content: Just order a chinese pcb for $5 shipped

author: sourcecharge
author_rank: Regular Contributor
timestamp: October 28, 2018, 03:00:47 pm
content: Quote from: station240 on October 24, 2018, 06:36:33 pmWell, I just got done upgrading my 3dP and I now have auto bed leveling.I printed out the breakout board, but the slic3r software seems to be less qualified than cura, at least in my experience.1 side of the PETG breakout was almost flawless, but the other side had wall problems. Although, I am reletively a noob with slic3r, the two sides seems to be showing the diference between the actual gcode.After I took some pictures, I tried using some solder paste, and the hot air unit at 300C. The breakout board melted and the walls of the traces didn't stand a chance.I have included some pics to show my 1st results, but I am not going to stop here as it was the first try.

author: sourcecharge
author_rank: Regular Contributor
timestamp: October 28, 2018, 03:10:31 pm
content: Quote from: Fusion916 on October 24, 2018, 08:12:30 pmWhere are you getting 5 dolla pcbs? The last 2 ucurrent boards I had printed were 90 + shipping.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 28, 2018, 03:25:51 pm
content: Getting $5 PCBs is easy as long as they're two layers and <= 10x10cm. Then again, the shipping prices exploded lately.Like you pay $5 for ten 10x10cm PCBs at Elecrow or Seeedstudio but then the cheapest shipping is $12 or so where it was around $6 one year ago.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 28, 2018, 07:55:28 pm
content: There are a lot of places that can do really, really cheap PCBs. Small designs where the postage costs more than 5-10 PCBs in a couple designs. PCBShopper will do a basic comparison shop for you for a bunch of places, worth checking out.While this seems like an interesting approach.... I sort of fundamentally question the use of solder paste for it. When the solder liquefies, surface tension dominates the forces that give it a shape - while wells can help control it, it's not like casting a big block of metal when you're dealing with very small channels. Even if the plastic held up to the temperature fine, I would expect this sort of series of solder balls to be there on at least some traces in EVERY heat cycle because without the solder sticking down to anything, the surface tension will just make it stick to itself more than anything and isolate to little bubbles of solder instead of in a long string like a trace. If the trace is large and wide enough, sure, but then it's largely useless (and is very expensive) as a PCB replacement. Also worth mentioning that by volume, the solder paste has a significant portion of flux (for good reason), but this means you actually want your wells to be deeper than you want them to finish as, because when heated the paste will reduce in size considerably to leave the solder deposited.If you want to get traces on a substrate, you need to get them to stick down, and it needs to be enough that when you apply solder to it (provided it's a traditional design where solder is used), so they don't immediately peel up.

author: Whales
author_rank: Super Contributor
timestamp: October 28, 2018, 08:28:02 pm
content: I have a few wacky ideas here myself, but I've only written about some of myolder ones.Suggestion: use a mix of powdered carbon and silicone, see if you can get the track resistances acceptable. I was planning something along the lines of partially-plated through holes (multiple drilling processes) and this material as a method of making resistors; resistance decided by the footprint chosen.(Attention: everyone who brings up the fact PCBs are cheap nowadays incurs a fine, payable to sourcecharge, for a criminal lack of curiosity. This law will be enforced via tracing your footprints.)