Hi,
I think I've posted this in the right forum / section? Forgive me if I haven't!
Anyway, a little background info first:-I make my own PCBs at home. I used to etch single sided boards using the Toner Transfer method ironed directly on to the board or as transparencies for UV Photo Resist Film.
Last year I purchased a CNC3040 Milling and Engraving machine and now I do all of my PCBs on that. I mastered single sided milling pretty quickly and just recently, together with a friend, we're just getting to grips with milling double sided boards using FLATCam and the alignment pins method.
Two days ago, I milled out my first ever double sided board and with the exception of the top side milling a tad bit too deep, the board was a complete success. I don't yet have Z height mapping so I have to set my cutting bit at a compromise so some areas of the board go a tad deeper than others but nothing major.
Now that I'm getting to grips with double sided milling, I am able to produce more complex boards that are smaller in size than their single sided counterparts. The only problem now is when it comes to VIAS and Through Hole Plating in general to ensure good connectivity between top and bottom layers / traces.
The double sided PCB I've just milled out must have a couple of dozen VIAS which I'm not looking forward to hand soldering and because I've got to hand solder them, I've had to make compromises such as using VIAS right near headers so I can connect top and bottom pads where I can't get in to solder the top pads. This is all well and good on relatively simple designs but not so much fun for more complex ones.
ENTER Through Hole Plating by Electrolysis ....I've been doing some research into Copper Plating Through Holes and Vias at home and have found some great resources / methods / techniques so I jumped on eBay today to order what I need.
For the Electrolyte Solution, I picked up a liter of 38% Sulfuric Acid (
Battery Top Up), a liter of 35% Hydrochloric Acid (Muriatic Acid) and 1Kg of High Grade Copper Sulphate Pentahydrate (
99.9% Pure).
To activate the holes for plating, I've got two techniques to try. One involves waterproof Ink and Graphite while the other involves a chemical process which requires a long hot bake. I plan to try the Ink method first before getting into more chemicals for the latter.
The ONLY thing missing from my shopping list which I can't find in the UK for a decent price by volume is Polyethylene Glycol (PEG 200)
This is used as a brightening agent which helps to give a nice shiney flat coating and prevents the build up of large copper crystal clusters leaving a rough ugly finish.
In the videos I've watched and in the write ups I've read, everyone seems to use MiraLax but here in the UK that stuff seems to be near on the price of Gold Dust by weight.... I would ideally like a cheaper source but I can't find any.
The pricing of this stuff makes no sense. I can get 5 liters for £20 but if I want a small quantity, the price gets stupid. I only want half a liter of the stuff max but I can't find it anywhere that's cost effective. I would buy the 5 liters but I wont ever get through that much so it's a waste. I think the Polyethylene Glycol makes up about 1 - 2% of the final plating solution so 5 liters would last an eternity and would probably reach its shelf life before I got through it.
So, after a very long winded explanation, does anyone know where I can get a small quantity, say 500ml for a reasonable price? Or does anyone know of anything I can use as a substitute / equivalent???
Thanks!