日本語
So i have a acrylic tank about 1.5x10x10 inches that I use for bubble etching. I pipe in air using a nail-station thing I bought, its basically a quiet little compressor, which I connect to some PEX tubing with a buncha holes drilled in i, which sits on the bottom of the tank. I just have some heating strips that are adhesived to the side of the tank and I use a variac for temperature control.
I have seen spray-etching machines.
I am interested in small geometries, like TDFN parts and such, in designed mixed with large geometries (i.e. to-220, DIP, DDPAK) to make full pcbs that have power and (large) signal stages. I am also interested in home made RF/microwave PCBs.
I noticed that getting the etch right with the 0.5mm pin pitch on a big PCB is kind of difficult, on a large PCB I don't have confidence the process will work. Sometimes I need like 3 attempts, careful baby sitting, and sometimes I put masking half way during the etch to prevent excessive erosion. The boards I work with are like 6x9 inches.
I do my exposure using sodium silicate, NaOH and water on MGchemicals PCB.
I don't have a light box and I was instead putting it under a bench magnifier fluorescent ring light. I plan on building a exposure box with some LED strips (will warm white LED work?), but I also have seen some designs for rotary or spray etch machines.
The other upgrade I have planned is to make the bubbles smaller, using something like a 0.3mm drill, right now the holes are probobly made with something like a 1mm drill bit.
Do spray etchers offer significantly better performance in this situation? Are they worth the trouble? I have not been able to find side by side comparisons of bubble eched vs spray etched pcb.
I don't care how long it takes, just which method has higher quality* I mean so long I don't get undercutting
- Comments(1)
A****min
Oct 10.2019, 14:44:27
Thickness of the copper matters. It is more difficult to get fine pitch correct when the copper is thicker. This is a lesser known reason why high current stuff and bitty fine pitch stuff are often put on separate pcb, rather than just separated with the appropriately wide gap on the same pcb.
It sounds like you have identified two problems with your process.
1. The exposure is not even to the edges. Can't help, here. Fix your setup?
2. The etching is not occurring evenly, and you are having to manually intervene to prevent over-etching of spots.
I have no idea what that etchant is like or what other things you might do to improve it. But you brought up the bubbler being a bit crude. And you mentioned a nail thingy, which I assume you mean a nail gun compressor?
Google "fish tank bubble wall." It's an airstone shaped like a porous plastic tube... very roughly 3/8" OD, I suppose. It seems to come in lengths of about 14". If you put enough air/psi it produces lots and lots of super fine bubbles. Not sure if it is ok with your etchant, mind you. It is not particularly useful, IMO, using a fish tank pump. It would not work in my tank for very long before the thing clogged and no air bubbles are made, at all. But with higher psi and air like you would get with a nail gun compressor, it is super impressive how very very small, consistent, and numerous are the bubbles that this makes. I'm not sure of the psi, needed. It's probably less than 20. You would need an air pressure regulator, which a nail gun compressor usually has, built in. Just don't leave it hooked up when it's not running. With cupric, at least, you will corrode the regulator.
If you are talking about some little thing to dry nails after your manicure, then buy a nail gun compressor. From your other posts, it sounds like you could use one. Along with an 18 gauge brad nailer and an air blow gun. Air nailer and hammer and nail are like two different things, altogether. The air nailer teleports the nail into place without shifting anything, and the hold is way higher for the gauge of nails. Maybe because they are square and have rough edges?
