is there a liquid coating I can immerse my printed circuit board in before etching that would reinforce the etch resist marking pen marks and prevent it from dissolving during etching. www.ronaldarjune.com

 

is there a liquid coating I can immerse my printed circuit board in before etching that would reinforce the etch resist marking pen marks and prevent it from dissolving during etching. www.ronaldarjune.com

How would you keep the liquid only on the ink?

A black, basic Sharpie pen (fat with shirt clip) is very resistant to etchant. The other versions of sharpie (retractable, thin, metallic, etc) are not as good.

 

That's what I am using, a Sharpie. I am thinking about the Integrity of the ink became less dense which caused it to dissolve during the etching process before. My paranoia indicates that the virtual size of the marking pen marks expanded and reduced the density of belief and I am seeing an illusion that nothing is different. It seems that trust in reality and truth is working against me.

 

Post a picture of what you're trying to etch.

What I do is to minimize the amount of copper that needs to be removed by using fill.

 

That's what I am using, a Sharpie. I am thinking about the Integrity of the ink became less dense which caused it to dissolve during the etching process before. My paranoia indicates that the virtual size of the marking pen marks expanded and reduced the density of belief and I am seeing an illusion that nothing is different. It seems that trust in reality and truth is working against me.

If you wreck one, you wreck one. No big deal. Learn what wen wrong and try again. Expect to generate a little garbage.
Or, just make some test runs from stamp sized pieces of copper board.

 

Hi.

Don't forget to clean the board before you draw the circuit. I usually give the board a good scrub with a fine grit sandpaper, then I clean it with soap and water or acetone. When you are finished drawing, you could try to blow dry the ink with a hair dryer or heat it gently in the owen.

Good luck and it would be nice with som pictures with the end result.

 

Many years ago, I used the basic Sharpie pens in my direct-plot process. But then I began using the positive photo-etch process more often, so I stopped using them. I was able to get my hands on an old HP 7221T plotter some years back and went back to the direct-plot process for quick prototypes and proof-of-concept boards.
In the time away from using the Sharpies, it seems that they had reformulated to a water-based ink which is far more soluble in the etchant than it was previously. What I found was that the ink would dissolve off the board during etch, taking the traces with it, resulting in unusable boards. What I also found was that I needed to use the Sharpie Industrial, which has the old solvent-based ink. It works wonderfully.
Here's an example:
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Here's an example:

That looks great. When all the components are soldered on, do you use some kind of protective varnish or lacquer to protect against corroding?

 

Most often, I simply tin the traces to protect them. I put the solder on the traces prior to populating the board & remove it with solder wick, leaving them nicely tinned. It uses up a bit of solder wick, but I'm OK with that.
Here's a different board (an R-2R DAC) which shows the result.
.

 

I'm using a transparent coating from Würth.

 

Most often, I simply tin the traces to protect them. I put the solder on the traces prior to populating the board & remove it with solder wick, leaving them nicely tinned. It uses up a bit of solder wick, but I'm OK with that.
Here's a different board (an R-2R DAC) which shows the result.
.
View attachment 145271

I have an old HP pen plotter and tried it several times early in my DIY efforts with poor results because the etch resistant pens were too fat to get good results. Also, any lack of board flatness caused problems.

What printer driver do you use? Which pen and how do you mount your pen?

 

Here's a pic of the pen I use on my plotter for homebrew PCBs. It's a "Sharpie Industrial" with an "Extra Fine Point". If they made them in the "Ultra Fine Point" style I would probably use that, but they don't. You can see in the inset that the point is about 0.5mm, so that's the minimum width of trace I can make with it. The holder is an old, expired plotter pen which I gutted to hold the Sharpie. It's quite the kludge, but it works pretty well.
As I said previously, my plotter is an [old] HP 7221T. I use a mechanical CAD program [also old] to generate the HPGL data. Surprisingly, the program actually has a driver for the 7221. I would love to use EagleCad to design the PCBs, but I have no plotter driver for it. When I design a PCB to be manufactured, I use EagleCad and OSHPark.
.

 

Here's a pic of the pen I use on my plotter for homebrew PCBs. It's a "Sharpie Industrial" with an "Extra Fine Point". If they made them in the "Ultra Fine Point" style I would probably use that, but they don't. You can see in the inset that the point is about 0.5mm, so that's the minimum width of trace I can make with it. The holder is an old, expired plotter pen which I gutted to hold the Sharpie. It's quite the kludge, but it works pretty well.
As I said previously, my plotter is an [old] HP 7221T. I use a mechanical CAD program [also old] to generate the HPGL data. Surprisingly, the program actually has a driver for the 7221. I would love to use EagleCad to design the PCBs, but I have no plotter driver for it. When I design a PCB to be manufactured, I use EagleCad and OSHPark.
.
View attachment 145433

DesignSpark has pen plotter output. I did something similar with the pens but I couldn't find the industrial fine points several years ago.

I am keeping an old desktop just for the printer port.

Thanks.

 

Post a picture of what you're trying to etch.

What I do is to minimize the amount of copper that needs to be removed by using fill.

View attachment 145120

Here is a picture of the etched board. Some traces dissolved.

Post a picture of what you're trying to etch.

What I do is to minimize the amount of copper that needs to be removed by using fill.

View attachment 145120

 

Here is a picture of the etched board. Some traces dissolved.

Using copper fill to reduce etch time might help, but I don't think you're going to have much luck trying to hand draw. Drilling holes will be a nightmare without holes etched in the pads.

Other methods to consider: toner transfer, rub on transfers for the IC pins (if they still make them), manhattan, point to point wiring, stripboard, etc.

 

Using copper fill to reduce etch time might help, but I don't think you're going to have much luck trying to hand draw. Drilling holes will be a nightmare without holes etched in the pads.

Other methods to consider: toner transfer, rub on transfers for the IC pins (if they still make them), manhattan, point to point wiring, stripboard, etc.

Just board layout is a nightmare with hand drawn. The TS's board (assuming it works) had to be a real test of patience.

Methods like toner transfer, rub on, photo or even isolation routing will allow you to use software to design your traces.

 

This takes me well back into the last millennium.

What are you using as an etchant? Ferric chloride, though it is dreadful, messy stuff, seems to be gentler on organic resists than ammonium persulfate. Sulfuric acid - hydrogen peroxide etchant is quite brutal.

"Baking" the board for 20-30 minutes at moderate temperature (say 70°C - I really can't remember) can improve the bond between the ink and the laminate. As others have said, the copper must be very clean, however a brief dip in etchant may give it a bit of "tooth" that will aid adhesion of the ink. If you use ferric chloride to do this, do a first rinse in slightly acidified water so you don't get iron oxide deposits, then rinse with plain, preferably deionized or distilled water, let it drain without wiping and either allow a good deal of drying time or use a hot air blower (you do have lab hair dryer, I trust). Don't get skin oils on the copper. Either wear suitable gloves or use paper to cover part of the board to protect it while you're working. Don't let anything abrade the pattern you've already drawn.

Hints if you are using ferric chloride:
- Keep it away from stainless steel sinks. It attacks stainless quickly - and permanently stains it!
- If allowed to get to pH neutral or basic, the etchant will rapidly precipitate out iron oxide (rust), which stains everything. If you can obtain it where you live, look for pH reducer for swimming pools (I've bought it at a big grocery store & a DIY store) which may have a name like "pH Down." This is (always, in my experience, but there may be exceptions) "prills" (tiny spheres) of sodium bisulfate. In solution, it hydrolyzes to sulfuric acid. 30 grams in a litre of water (doesn't need to be precise; a couple tablespoons in a quart) makes a solution that will remove the rust stains. It works fairly slowly. If the stains are on something you can't immerse, like a plastic laminate counter (NOT wood or marble) you can use a paper towel or rag wet with the solution - leave it in place, perhaps cover to keep it from drying out. If you make up a lot so you can immerse large things, you can store it in a polyethylene bottle - same sort of thing you'd use for etchant. Keep it off you clothing. Cotton does not like acid.

 

I am using a powdered mix I purchased from All Electronics and I think it is ferric chloride. I will drill the board tomorrow with a 1/16 inch drill bit. I will then assemble the parts and see if it works. There are four 4511 decoder drivers and displays and many 1000 ohm resistors.

 

I will drill the board tomorrow with a 1/16 inch drill bit.

0.0625" is too big; there will be no pad left. You need something closer to 0.03".

The last time I did a board by hand, I used a perf board to drill the holes. Then I applied etch resist and etched. That way I didn't need pilot holes in the pad and didn't have to worry about off center holes.

 

If the etching solution is dark yellowish-brown it is ferric chloride. If it is clear and colorless it will be ammonium persulfate.

On drilling:
Solid tungsten carbide drills are the "best" drill for printed circuit boards, however they are extremely brittle and very easily broken with any lateral force. Small ones (less than about 2 mm or so) should only be used in a good drillpress. Circuit board drills all have 1/8" shanks. If you are using epoxy-glass PC laminate (usually greenish), ordinary high-speed drills will get dull very quickly. 0.035" is right for many small components. It is the size I specify most often. 0.042" is the next larger size that I use quite often.