Homebrew PCBs

I am using a 275W Sun Lamp from GE, one of the kind that was used 
years ago to get a sun tan. It's 15 inches above the sandwich of 
positive PCB and 'flimsy' image. I tried times from seconds to 6 
minutes and each time, after having it developed in NaOH (5%) for 30s 
to 1 minute - there is no image left, all emulsion is gone. I've done 
so many tests that a test wedge method would become redundant. I 
think that since all image is gone that either the whole PCB is 
overexposed or the developer is too strong or a cobination of the 
two. Maybe you have some suggetsions. I also tried a laboratory clean 
NaOH and a new batch of PCBs- no change. The transfer method with its 
quirks of laminating, appears sweeter and sweeter.

----- Original Message ----- 

From: "mikezcnc" <eemikez@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, January 12, 2004 4:34 PM
Subject: [Homebrew_PCBs] Anybody uses successfully a sun lamp?


> I am using a 275W Sun Lamp from GE, one of the kind that was used
> years ago to get a sun tan. It's 15 inches above the sandwich of
> positive PCB and 'flimsy' image. I tried times from seconds to 6
> minutes and each time, after having it developed in NaOH (5%) for 30s
> to 1 minute - there is no image left, all emulsion is gone. I've done
> so many tests that a test wedge method would become redundant. I
> think that since all image is gone that either the whole PCB is
> overexposed or the developer is too strong or a cobination of the
> two. Maybe you have some suggetsions. I also tried a laboratory clean
> NaOH and a new batch of PCBs- no change. The transfer method with its
> quirks of laminating, appears sweeter and sweeter.

That combination seems OK to me.

I use about 10 gm of NaOH per litre for developing, usual recommendation is
7 gm but I like it quite fast. It takes about 30 seconds.

It sounds as if your artwork isn't dense enough.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

> > to 1 minute - there is no image left, all emulsion is gone. I've 
done

Hi, 

remember un exposed pcb cant normaly developed -it should stay on 
i think either you carying the pcb in the sunlight :) ore your fluid 
is to strong. 
to test that is simple just put a peace off new not exp. pcb in 
developer it must stay on. 
so you must be making somewere a mistake

i had one off those sunlights - as i remember it also had ird ceramic 
heaters!  - worked perfect 

gr. Roel

Both of you were right. I got the process under control. I am HUGE!

Will post the results later, have to do few more trials. Thank you 
for your fast response. ALways pleasure hearing from you. 

Mike

--- In Homebrew_PCBs@yahoogroups.com, "roel_cnc" <atmelletje@g...> 
wrote:
> > > to 1 minute - there is no image left, all emulsion is gone. 
I've 
> done
> 
> Hi, 
> 
> remember un exposed pcb cant normaly developed -it should stay on 
> i think either you carying the pcb in the sunlight :) ore your 
fluid 
> is to strong. 
> to test that is simple just put a peace off new not exp. pcb in 
> developer it must stay on. 
> so you must be making somewere a mistake
> 
> i had one off those sunlights - as i remember it also had ird 
ceramic 

> heaters!  - worked perfect 
> 
> gr. Roel