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Ferric Chloride removal pattern on circuit board. Tin plating solution ?

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
The circuit board was in plastic tube and the tube was rocked back and forth. Always the etch ends with a circle in the center? WHY?
The board was etched away in phases. At the end of a 5min etch/agitation the board was rinsed and dried. Then instrument lacquer was
brushed over the completed traces from that phase. Repeat. Some of the outside traces have bleed the black dye I used to touch up the
traces before the first etch. But the underlying copper is sealed from further etching. Keeps under-cut from happening to the outside
traces as I wait for the inside parts to get done.

DSC_1063.jpg

Tin plating solution works by just soaking circuit board in solution for 3-5 minutes. What is this layer of white sand at the bottom of the container.
It's about 1/4 inch deep. I poked a dowel into the sand and tried to mix it into solution. Some of it did break apart but what is still left at the
bottom will not mix into the solution any more. WHY?

DSC_1064.jpg
 
It looks like someone touched the board with their bare hand as there is a thumb print in the center of your "spot". Wear nitrile gloves and keep the board clean and that probably won't happen.

FWIW

-Ron
 
The circuit board was in plastic tube and the tube was rocked back and forth. Always the etch ends with a circle in the center? WHY?
The board was etched away in phases. At the end of a 5min etch/agitation the board was rinsed and dried. Then instrument lacquer was
brushed over the completed traces from that phase. Repeat. Some of the outside traces have bleed the black dye I used to touch up the
traces before the first etch. But the underlying copper is sealed from further etching. Keeps under-cut from happening to the outside
traces as I wait for the inside parts to get done.

View attachment 318970

Tin plating solution works by just soaking circuit board in solution for 3-5 minutes. What is this layer of white sand at the bottom of the container.
It's about 1/4 inch deep. I poked a dowel into the sand and tried to mix it into solution. Some of it did break apart but what is still left at the
bottom will not mix into the solution any more. WHY?

View attachment 318971

Hem's sake, Ron?

Heavy-industry manufacturing board, and you are not up to Seventh-Grade Science class?

Where to start?

Did you fail College chem, HS Chem, home cooking, fluid mechanics, READING, hygiene?

Or "all of the above"?

And where, if not the center, would you expect the wave fronts to coincide when "rocked back and forth"?

"Plastic tube?" Shed that!

Get you an ignorant Pyrex baking tray.

Get lovely PCB's. ONE go! No f****g around.

Even win a School Science fair.

Nineteen fifty-seven was it?
XXXP 2 oz. clad paper/phenolic. FR4 and G10 weren't "there yet"

Nary even a ONE ugly PCB since, either!

It just isn't that hard.

"RTFM" Any hobbiest article since the 1950's is good enough.

Pee Ess:

You have the real-estate.

Wider traces resist lift-off from soldering better. They can survive the odd spot of damage or corrosion better than uber-skinny traces. Curves are permissable, even advantageous.

Wider traces, thinner lands etch faster with less metal to be removed. Mitel had the volume to recover the metal to economic advantage. You do not.

Even FASTER you but wrap one or both of power and ground planes everywhere you can.

The metal is already paid-for. The cost of time and chemistry can be reduced.

And wider traces don't give a damn about modest "undercut".

I did say "No f**king around?" What is your rationale for nickel plate, anyway?

Self-fluxing conformal coatings been banned?

Modern PCB, you don't SEE the metal. Neither does Oxygen. Nor OTHER "gas borne" hostiles. There's good reason for that.

It JFW.

Read more. Save time. Get fewer disappointments.

IF/AS/WHEN your "reading" catches up to 1970, instead of the 1950's?

Well 1970 is about the last year I ever used Ferric Chloride!
Cupric Chloride was easily regenerated. That paid-off for R&D's chronic, but unpredictable needs.

There have been other and widely sold in convenient portions, commercial chemistry for etchants for easily fifty years!

There is even a Kitchen DIY brew that works a treat, too!

Read more..... etc.
 
It looks like someone touched the board with their bare hand as there is a thumb print in the center of your "spot". Wear nitrile gloves and keep the board clean and that probably won't happen.

FWIW

-Ron

Your statement is non sequitar. Illogical since that center spot is demonstrating a dissolve pattern and will eventually be eroded away.

(I learned about non sequitar from Star Trek's M5 or whatever that robot was called...)
 
Please ask a question.

I also answered it. The plating solution might accumulate residuals if the solution is poured back into the main container.
Might have to use an intermediate container and wait for that to lose strength. Or if strength has nothing to do with it then...
I do know that since I un-clumped the white rock stuff at the bottom of the plating solution container, it has not re-formed.

DSC_1069.jpg

Looking at this posted picture makes the boards look worse. Although under a 5x mag the jagged edges from a chemical etch are visible.
But consistent jagged edges are the best this system can achieve. There are a few areas that still have copper. I used a flash so that probably
brought that out. I have a few trim operations on the dimensions of the boards so I might as well etch the problem areas and plate where needed.
The reason for the post was partly due to doubts about the plating solution. It takes 3 to 5 minutes as stated on the container. I used 5 minutes.

I almost forgot. All the holes are drilled with a drill press. Getting those two runs of 25 holes (.0260) to line up was a lot of fun...
I will show the pictures of the finished top sides with silk screens.
 
I finally liked something out of your ass ...

Wellllll. I actually value YOUR input.

At least you don't QUIT easily.

Not even when you SHOULD!

:)

Sort of sets a boundary marker.

That a person CAN TOO do any tasking on Planet-Earth the hardest way possible ...

.. and somehow not get struck by lightning, laid-low by food-poisoning, shot by a jealous husband of indeterminant sex, run-over by a beer truck, nor starve quite all the way to death!

Guess there is hope for the "new normal" in America, after all?

DON'T quit!

"Press on, regardless!"

I don't even have an antenna hooked-up to watch day time Tee Vee - let alone a "cable" package!

:D

BTW.. if you but read the labels on the materials you utilized?

School daze chemistry will tell you what those white salts that precipitated had to be. They didn't sneak in under the door.

Not a lot more work, and you can be aware of what solute concentration levels and temperatures the precipitation itself signalled. "Molal" was not an Eyetalian Coal miner after all.

Even whether is was a good idea or a bad one to mess with trying to get them to redissolve.

Chemistry thing.

It only gets to be a pain in the nose when you have to make your own concentrated Nitric acid as a precursor to making Trinitrophenol. Didn't have access to Toluene as a curious kid.

Coal and coal chemistry town, phenol was easier.

You'd have to know Koppers and Pittsburgh?

:D
 
I have done a bit of PCB etching at home and at work and they mostly came out well. '

You say it was "in plastic tube". Does that mean a closed container? That may have prevented the etching solution from being evenly moved around the board. Tilt it one way and it only flows a fraction of an inch. Tilt it the other way and it moves a fraction of an inch the other way. There were no traces in the center so the solution there became weaker faster than around the sides and it was not effectively stirred due to your tube.

I always used a pyrex dish. If it was a cold day, it always helped to heat the etching solution before placing the board in it. Then, a plastic spoon or other implement could be used to stir the solution so that it moved from the center to the edges and vice-versa. And there should be a good amount of the solution, at least a half inch depth above the board and an inch or more around the edges. The stuff does get weaker as more copper is etched.

I never had to mask over areas of a PCB that were already etched to prevent undercutting while finishing the center areas. Just keep the solution moving. Stir every ten of fifteen seconds or so.

As for the tin plating solution, it just works. Use it until it stops working and then get a new bottle.



The circuit board was in plastic tube and the tube was rocked back and forth. Always the etch ends with a circle in the center? WHY?
The board was etched away in phases. At the end of a 5min etch/agitation the board was rinsed and dried. Then instrument lacquer was
brushed over the completed traces from that phase. Repeat. Some of the outside traces have bleed the black dye I used to touch up the
traces before the first etch. But the underlying copper is sealed from further etching. Keeps under-cut from happening to the outside
traces as I wait for the inside parts to get done.

View attachment 318970

Tin plating solution works by just soaking circuit board in solution for 3-5 minutes. What is this layer of white sand at the bottom of the container.
It's about 1/4 inch deep. I poked a dowel into the sand and tried to mix it into solution. Some of it did break apart but what is still left at the
bottom will not mix into the solution any more. WHY?

View attachment 318971
 
I have done a bit of PCB etching at home and at work and they mostly came out well. '

You say it was "in plastic tube". Does that mean a closed container? That may have prevented the etching solution from being evenly moved around the board. Tilt it one way and it only flows a fraction of an inch. Tilt it the other way and it moves a fraction of an inch the other way. There were no traces in the center so the solution there became weaker faster than around the sides and it was not effectively stirred due to your tube.

I always used a pyrex dish. If it was a cold day, it always helped to heat the etching solution before placing the board in it. Then, a plastic spoon or other implement could be used to stir the solution so that it moved from the center to the edges and vice-versa. And there should be a good amount of the solution, at least a half inch depth above the board and an inch or more around the edges. The stuff does get weaker as more copper is etched.

I never had to mask over areas of a PCB that were already etched to prevent undercutting while finishing the center areas. Just keep the solution moving. Stir every ten of fifteen seconds or so.

As for the tin plating solution, it just works. Use it until it stops working and then get a new bottle.

Should have worded it as plastic square tube like for a sandwich. I did move the liquid around the same way I did for the tin plate solution.
The observation is that decomposition is position dependent and composition is uniform. I can watch the copper change to tin because the solution is clear enough.

I'm looking at lines that are .015 wide. I like the edges to be sharp. At 5x I can see things to improve.
It might also be the laser jet ink transfer to the board. A photo-sensitive board would probably give better edges.
Or should I always agitate briskly. Up to now I just move the solution a little and tip the board up to see the progress,
then soak for a few random seconds and repeat
until enough copper has been removed.
 
The etchant should be kept moving for best results; some build an eccentric-roller or similar with a small motor to rock the dish.

I found that bubble-etching produced sharp results; I had a tank like this;





with a small aquarium air-pump.

Warm etchant works better than cold; I used an aquarium heater like this;





but just warming before etching begins should help.

Ammonium persulphate gives sharper edges than does FeCl but it doesn't keep and can be expensive for one-off jobs.
 
Do it exactly according to my recommendation. I got lots of experience with that issue (not bragging).

I assume that you use photosensitive board (pre-laminated)

1) print the artwork so the print side touches PCB
2) make an envelope of the artwork. Remember - ink inside !
3) prepare material, cut to size.
4) Remove protective film
5) NEVER TOUCH THE BOARD SURFACE. Only edges. FORGET THE GLOVES !
6) Shine the UV light
7) Remove the excess (un-cured) film with fresh solution of potassium carbonate (K2CO3). Use always fresh solution. Agitate well, dont let the board sit in the bath. Temperature - about 40' Celsius
8) DONT TOUCH THE SURFACE !
9) Etch in SODIUM PERSULPHATE. Its cheap, make fresh solution. Use aquarium bubbler and heater, about 40' C. Dont expect to get normal results without agitation !
10) After etching, rinse with water
12) remove the photomaterial with Sodium Hydroxide (or Potassium Hydroxide) solution. About 40'C, no air agitation, only move the board. Use pliers, don touch solution.
13) Drill the board Use only carbide drills ! Use underlay material (hard laminated paper, like the backside of IKEA shelves)
14) Under running water, sand the board with abrasive wool (no sandpaper !!)
15) If the board is shiny, then shake excess water and dry with warm air.
16) STILL YOU CANT TOUCH THE BOARD !!!
17) Coat the board from two sides with aerosol flux and let it dry. FORGET ABOUT chemical tin solution. Its toxic and harmful and mostly useless !

18) Assemble the board, test, etc.
19) If all is ok, remove the flux coating with isoprop, rinse with dist water, dry with warm air.
20) Coat with plastic spray from both sides.
21) Ready


Do not experiment with "better solutions" otherwise you just get frustration.
 
Do it exactly according to my recommendation. I got lots of experience with that issue (not bragging).
With PLIERS involved?

Of course not. One would not.

:)

20 to 40 thousand a year. Each about the size of a kidney bean.

Done up in hundreds per each full-sized sheet of FR4. Precision sheared into long-axis strips, one unit wide.

As many as 26 holes at ago, ten and 12 thou diameter pins in a triple-progressive punch press die at the full gallop.

"Drills" are for onesies and low-volume production.

Or at least they were back around the dawn of the 1970's, the punch presses already old before FR4 had displaced XXXP.

LONG before we could just order-up a custom IC ... and have a whole hearing aid on one die "surface-mount" yet. NO holes!

Or necessarily any longer even the overhead of an obsolete "PCB".

Didja know what the first two commercial products were to ever use a transistor?

MAICO Hearing Aid. Radioear about two weeks later. Sam was so pissed at being beaten by MAICO, he hired MAICO's Engineer into Radioear... and deviled him for the better part of 20 years!

Y'all need a "PCB"? D'yah ken just HOW obsolete your materials and methods?

May as well be hand-carving toothpicks!

ORDER IT!

There are EXPERTS at anything from an R&D onesie, change revisons to follow several times a DAY.. to multiple MILLIONS of units a YEAR, same-same for ten years in a row.

What yer doing is akin to trying to publish a dictionary once you get the hand-set metal type sorted!

Not-even a laser copier/printer.

"Catch up in the back".

Find the experts. Cut a Purchase Order. Get to the desired END.

Before the components you are using have gone out-of-production-obsolete, anyway.

Fast moving industry, y'see.

I did say "1970's"

Half a CENTURY ago if you can't be bothered to do the math.

Terry kitted-out that Ogdensburg, NY plant for Mitel stuff I needed around 1987 or 1988? Tape-magazine-fed component stuffers were still the rage.

And that is now over thirty-five years.

Modern circuitry isn't MADE that way nowadays.

Not even by "kitchen table experimenters" doing onesies.

CNC router will proto-board yah faster. I DID say no NEED to remove all the Copper?

Laser printer will lay it directly.

Want to mess with chemistry for the artistry in it?

Rent a flat in Montmarte, take up Absinthe and genuine Wormwood.

You don't even have to have short legs. Yer putz will serve well-enough.

If you haven't worn it CLEAR OFF ... playin' wit' yerself over PCB's anyway.

:D
 
While all you write is correct, its completely not relevant.
Original poster asked about home-made PCBs. And thats why I recommend the things I recommended.
As im not native english-speaker, I have to correct pliers to TWEEZERS.
And plastic tweezers are available from every corner-shop I guess. Although metal tweezers can be used in alkaline solutions.

So, the answer like "order it" is not the spirit of the forum. And one should be realistic about the possibilites of home shop. Otherwise, of course, we can recommend like "put the pcbs in titanium rack" and "rock them in 200litres of solution" but it does not help much i guess :)

I've got a small professional PCB shop, not much acres made annualy but I'm familiar with all the process.
 
So, the answer like "order it" is not the spirit of the forum.
PM is not the Cub Scout seventh-grade merit badge forum. Nothing remotely "manufacturing" related to see, here.

Ron may as well be re-painting his bathroom wall and bitching the paint is raising blisters any place were soap film was not fully removed.

But it is all OK. He didn't mention a hobby-only Chinese machine.

I've got a small professional PCB shop, not much acres made annualy but I'm familiar with all the process.

Tweezers, tongs, pliers, chopsticks, forceps, pitchforks, the point was you described a MANUAL one-board-at-a-time process.

Good on yah. I had nearly forgotten the ones that ancient!

Kinda like making custom jewelry boxes, snakeskin boots, Savile-row suits, cased blackpowder dueling pistols, and decorative leather belts and saddles, then?

There's usually a niche market for hand-made goods of high enough quality.

INDUSTRY was already outrunning that hand-processing thing the year the "PCB" was first invented.

Ron could LEARN FROM modern industry.

Modern Industry, to turn that about, doesn't waste a great deal of time looking 50 or 60 years into their own rear-view mirror.

He doesn't have anything the Grown Ups Actually NEED.

Least of all a clear grasp of what he is trying to do, and whether it is even a viable idea.
 
Dont be so angry at amateurs. Ordering PCB needs gerbers etc.
But actually, I have one more suggestion when making simple boards fast. (i.e. 3 relays with 3 connectors and diodes)

* mark the holes on grid-paper (Printable Graph Paper with ten lines per inch and heavy index lines on letter-sized paper). Most components have 2.54mm pitch. Draw the artwork on paper
* put the paper on PCB (bare copper)
* mark the holes with punch
* remove paper
* draw the artwork ON PCB with nitrous enamel paint. You need a special pen - Ruling Pen (comic tools). Its awkward to use but couple hours of practice and clean tip and youre fine
* etch
* remove paint with solvent
* Drill (you have marks) and sand

I did boards like that 25 years ago, tens or hundreds. No computer needed at all :) And if youre skilled, you can make simple board in 1 hour. Dirt cheap too. (that was the reason, 25 years ago ordering PCBs around here was about weeks pay for one order, people were poor around here)
 
Dont be so angry at amateurs.
Amateurs in this case are but history re-enactors dressing up in the uniforms of Prinz Eugen of Savoy or Gustavus Adolphus era and armed with "period correct" edged weapons.

I did boards like that 25 years ago, tens or hundreds.
And you were already 25 years out of date 25 years ago. I was using contact film and MacBeth arc lamps. For onesies. Protoyping. It was faster that way. 1973. A dozen or so years later, (Sir) Terry Matthews and HIS team did that FOR us.

The circuit Ron has is otherwise perf board, raw components, wire, solder, directly for quick and dirty. Done in ten minutes first one, half that time, later as practice makes it so. Even wire-wrap was automated.

PCBS are for magazine-fed stuffing machinery where the components on the tape were run off the same tape through automated incoming QC, the boards wave soldered, leads, if any, lawnmowered, then onto the bed of nails tester.

Not a HUMAN even inside the same room.

Or so it was in the 1980's

It has gotten better and faster, since. That's why Donguan County is poor no more and Karjala getting poorer.

Dinosaur thing. Living museums pay poorly.

Adapt ... or milk reindeer and make interesting foodstuffs.

Come to a "Manufacturing Technology Forum"? Expect seasoned Manufacturing Managers to share what it takes to... ta da would you believe?

"Manufacture".

Screwing around with toys in the kitchen or loo is still free.

But boring.

Where's the CUSTOMER in his "product", anyway, that he needs even TWO?
 








 
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