Homebrew PCBs

For small boards, I wonder if anyone has explored placing the board in a
well-sealed, clear glass or plastic food container, or perhaps something
more elaborate, half-filled with etchant, and then having some vigorous
shaking or rotating arrangement.

I think one of the benefits of the spray approach is that it
preferentially erodes the copper which is directly exposed, without so
much undercutting of the copper under the edge of the photoresist.

I guess shaking, tumbling or ultrasonic agitation would not have this
directional effect.

As I mentioned in a post an hour or so ago, muriatic acid (HCl) may
allow greater visibility of the board, which would help in a clear
container which used shaking, turning over etc. rather than spraying.
However, Edinburgh Etch (ferric chloride and citric acid) is claimed not
to leave any residue, thereby (I guess) reducing the need for agitation
or spraying.

I am currently using a sponge with Edinburgh Etch.

   - Robin         http://www.firstpr.com.au/pcb-diy/

On 23/08/12 12:49, Robin Whittle wrote:
> For small boards, I wonder if anyone has explored placing the board in a
> well-sealed, clear glass or plastic food container, or perhaps something
> more elaborate, half-filled with etchant, and then having some vigorous
> shaking or rotating arrangement.
>
> I think one of the benefits of the spray approach is that it
> preferentially erodes the copper which is directly exposed, without so
> much undercutting of the copper under the edge of the photoresist.
>
> I guess shaking, tumbling or ultrasonic agitation would not have this
> directional effect.
>
> As I mentioned in a post an hour or so ago, muriatic acid (HCl) may
> allow greater visibility of the board, which would help in a clear
> container which used shaking, turning over etc. rather than spraying.
> However, Edinburgh Etch (ferric chloride and citric acid) is claimed not
> to leave any residue, thereby (I guess) reducing the need for agitation
> or spraying.
>
> I am currently using a sponge with Edinburgh Etch.

Circulation would still be good to carry away saturated chelated citric acid.

I think an air-exposed system of etchant dripped or sprayed onto the pcb and 
rotating sponge rollers would be the fastest setup. The airation should help 
creating a copper-chloride etchant. I'd add some HCl to aid that process and see 
if it works.

The rollers are just to create fast fluid movement withing microns of the 
surface, which is otherwise slow due to laminar flow.

I once heard that some pcb fab houses use plastics to cover plated through holes to avoid erosion of copper layer.

--- 12年8月23日，周四, Robin Whittle <rw@...> 写道：


发件人: Robin Whittle <rw@firstpr.com.au>
主题: [Homebrew_PCBs] Etching by shaking, tumbling, turning over, ultrasonics . . .
收件人: Homebrew_PCBs@yahoogroups.com
抄送: "Derward Myrick" <wdmyrick@...t>
日期: 2012年8月23日,周四,上午10:49



  



For small boards, I wonder if anyone has explored placing the board in a
well-sealed, clear glass or plastic food container, or perhaps something
more elaborate, half-filled with etchant, and then having some vigorous
shaking or rotating arrangement.

I think one of the benefits of the spray approach is that it
preferentially erodes the copper which is directly exposed, without so
much undercutting of the copper under the edge of the photoresist.

I guess shaking, tumbling or ultrasonic agitation would not have this
directional effect.

As I mentioned in a post an hour or so ago, muriatic acid (HCl) may
allow greater visibility of the board, which would help in a clear
container which used shaking, turning over etc. rather than spraying.
However, Edinburgh Etch (ferric chloride and citric acid) is claimed not
to leave any residue, thereby (I guess) reducing the need for agitation
or spraying.

I am currently using a sponge with Edinburgh Etch.

- Robin http://www.firstpr.com.au/pcb-diy/








[Non-text portions of this message have been removed]

I have a question on this subject if I may. On U-Tube I saw a video of a bubble etchant tank simular to Pulsar Pro's.
version. If I spend the time and money to build one, heated, fish store pump, hose & valves ect. with your etchant advise will it be a tank that is worthy of building of the future. It will not be a cheep design but one I can use with Pulsar Pro's system for a professional type board, & box for a long time. I am new to this and shake up etchant
by rocking heated & temp. monitered to sucess but need advise only from experienced people. I plan on positive method with a lasar printer and am viewing your talk about paper, etchant types also. Thanks Kevin


________________________________

 From: Russell Shaw <rjshaw@....au>
To: Homebrew_PCBs@yahoogroups.com 
Sent: Wednesday, August 22, 2012 10:13 PM
Subject: Re: [Homebrew_PCBs] Etching by shaking, tumbling, turning over, ultrasonics . . .
 

  
On 23/08/12 12:49, Robin Whittle wrote:
> For small boards, I wonder if anyone has explored placing the board in a
> well-sealed, clear glass or plastic food container, or perhaps something
> more elaborate, half-filled with etchant, and then having some vigorous
> shaking or rotating arrangement.
>
> I think one of the benefits of the spray approach is that it
> preferentially erodes the copper which is directly exposed, without so
> much undercutting of the copper under the edge of the photoresist.
>
> I guess shaking, tumbling or ultrasonic agitation would not have this
> directional effect.
>
> As I mentioned in a post an hour or so ago, muriatic acid (HCl) may
> allow greater visibility of the board, which would help in a clear
> container which used shaking, turning over etc. rather than spraying.
> However, Edinburgh Etch (ferric chloride and citric acid) is claimed not
> to leave any residue, thereby (I guess) reducing the need for agitation
> or spraying.
>
> I am currently using a sponge with Edinburgh Etch.

Circulation would still be good to carry away saturated chelated citric acid.

I think an air-exposed system of etchant dripped or sprayed onto the pcb and 
rotating sponge rollers would be the fastest setup. The airation should help 
creating a copper-chloride etchant. I'd add some HCl to aid that process and see 
if it works.

The rollers are just to create fast fluid movement withing microns of the 
surface, which is otherwise slow due to laminar flow.

 

[Non-text portions of this message have been removed]