Homebrew PCBs

On Wed, 14 Feb 2007 03:17:34 +0100, Ben <bhleavi@...> wrote:

>
> I have to agree that positive photo method if far easier and better
> than TT.  I read on here what some seem to go thru to do the TT
> method to get good results.  I find the positive photo method much
> much easier.  I guess if you don't do this much TT might be a way to
> go but if you do boards very often and have a place you can setup a
> exposure frame and a etching tank you can produce boards very easily
> with better results.  For most it seems that TT method is hit and
> miss on getting a good board as can be seen in the photo of that one
> post.  I know that there or some on here that seem to really have
> the TT method down and have good results, but I have a idea that it
> took them a while to get to that point too.
> Ben


I have spent more time trying, with little success, to get decent  
photoboards than TT, the problems work the other way around too.
I do know what some of the mistakes were, and i have no doubt i could have  
gotten it right if i put in more effort.

For your situation photoprocess may well be better, but there are several  
strong points in favour of TT:

Low cost of PCB material (or no cost and effort of sensitizing).
No shelf-life limit of PCB stock, i do few boards (a couple a week) and  
prefer to buy bulk.
Speed of production (not even with a professional exposure frame and  
developer tank was i able to make small boards faster).
No inkjet required (for me maintaining an inkjet is a nightmare, the major  
annoyance with direct inkjet printing).
No chemicals other than water and etchant required.
Photo paper is only about the same cost as transparencies.
Component legend capability (90% or more of my boards have component  
legend, how would i make that with photo?).

Both processes are reliable, and produce good results. I don't think one  
can reliably predict where someone would have more trouble. You can make  
mistakes with both. The right tools must be used, and the right materials,  
and the right procedure, then both will work just fine, if you do not do  
that both processes will fail just as miserably.

I don't think one should decide which process to use by following a single  
opinion, it is well established here that both methods work and none is  
always easier. I think one should look at the needs (quantity, one-offs or  
series, space, investment, ... many more) and then decide which method is  
more suitable. It does IMO not make much sense to try to get by without  
minimal gear (for example working with a clothes iron is just as  
unreliable as not using a proper exposure device), so one should set up  
properly from the start. Look at it in detail, decide which is more  
suitable for yourself, and then stick with it and get it to work. I don't  
think there is any excuse for not getting either process to work reliably,  
because there are just too many people using them with good results. In  
other words, if it didn't work, it's your fault and not the process. One  
should decide on the merits of the one or the other, not on some worry it  
might not work, both _WILL_ work with enough attention to detail.

ST