problem with pcb etching

[ArakelTheDragon]

HI guys,

I etched A pcb, but after the copper fell, when I use the multimeter, the etched part is still conductive. Can anyone help me solve this please?

 

[KlausST]

Hi,

Obviously there are copper residuals.

Surely you do know that you don't give any information that we can validate.

Klaus

 

[ArakelTheDragon]

It was hard to decide which information is needed, thats why I did not post anything. I can give you a picture if that will help, but I expected the chemicals to have removed all residues. The whole PCB is conductive as if I have not etched it at all.

 

[betwixt]

The whole PCB is conductive as if I have not etched it at all.

Clearly that is the problem. Without knowing the process you used to make the PCB we can't advise what might have gone wrong.
A photograph AND telling us the method of production is needed.

Brian.

 

[ArakelTheDragon]

Clearly that is the problem. Without knowing the process you used to make the PCB we can't advise what might have gone wrong.
A photograph AND telling us the method of production is needed.

Brian.

I understand.

0. Here is a link to the process.

1. Here is a link to the dropbox picture.

 

[betwixt]

I think you are doing this a very complicated and unreliable way. It still isn't clear which exposure process you are using as the pictures seem to show a very low resolution track layout. Are you using a transparency as shown in the article or paint/ink covering the copper directly?

Using sunlight to expose the board isn't a good idea, you want a light source with higher UV content and a shorter exposure time. Light scattering under the edges of the ink on the transparency will cause poorly defined edges and unless the black ink/toner areas are very dark, some light will still pass though. There is no substitute for a good UV source with a glass top so you can sandwich the transparency and board under pressure to eliminate any gaps. Regardless of that, after exposure and removing the photo-resist you should see a very clearly defined track layout with shiny copper showing where it is to be removed and a good layer of resist where the tracks will be.

The vinegar/hydrogen peroxide solution you are using the etch the board will be very poor and unpredictable. Get hold of some Ferric Chloride or a proprietary PCB etchant. Shop vinegar and hydrogen peroxide will not have controlled concentration. If you have to leave it for a long time in the solution, the copper will be eaten away under the edges of the resist.

Reasonable times for exposure are around 3 - 4 minutes and for etching about 15 minutes.

Brian.

 

[ArakelTheDragon]

I am using printer toner and a marker for the tracks. I don't think the "sun bath" will remove these residues?

 

[FvM]

betwixt was assuming a photosensitive PCB board, thus he's discussing UV exposure. You clarified that the etch resist pattern is a laser printer image respectively hand painted.

The photo shows that your board is not completely etched. I see a small stripe of uncovered epoxy only near the bottom border. Etch time need to be increased or more effective etchant used.

 

[ArakelTheDragon]

I will increase the etch time 24 times and check the results.

 

[ArakelTheDragon]

Result: the problem really was the etchant. It turns out that only the upper part of the copper was removed, when I scratched the PCB, I saw the rest of the copper layer. Until it turns full plastic and you can look through it, when you point it towards the sun, its not ready.

https://www.dropbox.com/s/3pi2e4q384h057c/IMG_20190927_083706.jpg?dl=0
https://www.dropbox.com/s/145vrjqgowlrr2r/IMG_20190927_084142.jpg?dl=0

 

[KlausST]

Hi,

Please read forum rules.
Don't use external servers to store picures, load them directly up to edaboard using the "insert image" button.

Klaus

 

[ArakelTheDragon]

I tried that, but it did not work.

 

[KlausST]

Give useful informations.
Why did it not work? What's the problem? Press button and follow the guidance.

Klaus

 

[ArakelTheDragon]

I got rediredted to some pic site "tumblr" or something and I have to register, cause myself problems and I don't think this is your server? There were good pics of kittens on it.

 

[KlausST]

Hi,

There are tutorials.
If you use the "insert image" button on top of the editor window you are asked to select the spurce if your file.

It seems you use the "add an image" buttom on the bottom of the editor window. I don't recommend this.

Klaus

 

[Pjdd]

One vital point that has not been mentioned yet is that the raw copper-clad board has to be kept very clean before etching. Even a fingerprint will slow down the etching process.

Clean the board thoroughly before transferring the pattern - by manual drawing, iron transfer or whatever method you use. Don't touch the board surface. Don't wipe it with cloth unless the cloth is perfectly clean.

 

[c_mitra]

I will increase the etch time 24 times and check the results.

Perhaps the Hydrogen peroxide is too weak; use a stronger solution. Etching for a longer time will get you a poorer quality.