Photoresist etching - Page 2 - diyAudio
Go Back   Home > Forums > Design & Build > Construction Tips

Construction Tips Construction techniques and tips

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 13th May 2013, 01:09 AM   #11
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I will redo the transparencdies tomorrow, double up on final version, then do test strips. THe more I think about it, the more I think it might be the transparency not being dark enough. I have pretty much tried every exposure time possible.

nigelwright,
do you have a contact. I currently use OshPark.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 13th May 2013, 01:13 AM   #12
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by buzzforb View Post
nigelwright,
do you have a contact. I currently use OshPark.
sales@sitopway.com

Send your pcb files for a quote.
Min order is around 5.
  Reply With Quote
Old 14th May 2013, 08:56 PM   #13
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Hang on, if all your resist dissolves away in the developer then you've over exposed it. At least that's the way the stuff I use works - exposed parts dissolve away and then get etched away, non exposed parts ... leave copper.
Have you tried doing a test strip ?
Chimed in to say the same: in **positive** boards light *destroys* emulsio, so you are overexposing.
Much worse, you already expose them too much *before* even exposing
Peel them only inside a room, use only a 25W yellow lamp; incandescent!! , not CFL nor Fuorescent tubes.
Tape your transparency over the PCB or the glass so you don't move it and get a piece of cardboard.
expose 1 minute, cover 1/4 of the image, then complete 3 minutes, cover an extra 1/4; then 9 minutes and finally 27 minutes, so you have 4 widely different exposed areas.
Develop.
Then repeat, splitting time between the best 2.
In a couple tests you'll have the proper time.
  Reply With Quote
Old 14th May 2013, 09:02 PM   #14
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
THanks. Will give it a try this weekend.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 15th May 2013, 12:20 PM   #15
diyAudio Member
 
jkuetemann's Avatar
 
Join Date: Dec 2010
Location: Paris, Ontario
I go to a local print shop that has an image setter and get a film made, trying to get a truly opaque layout at home is near futile. I use an unfiltered blacklight fluorescent and an 8 minute exposure through a pane of glass with the MG positive boards. Also ensue the developer isn't too strong. I get my best results at home with the photo method but the big key is absolutely opaque artwork.
__________________
---Jason Kuetemann---
When the student is ready, the master appears.
  Reply With Quote
Old 18th May 2013, 05:00 PM   #16
diyAudio Member
 
Join Date: Oct 2007
Location: Aarhus, Denmark
@buzzforb:

Hi,

I've actually had a similar "challenge" - the photoresist just disappeared when I tried to develop the board no matter how long/short I made the exposure time. Took me days to figure it out :-(

Eventually I ended up getting a different developer from the vendor and now everything works fine. FYI I was using Seno develop 110 (which for some reason didn't work) and now I use Seno 4006 (a concentrate) together with Seno positiv 100 (the photoresist lacquer). Also, I use a pre-made photoresist PCB and that works as well. According to the vendor the Seno products are also very environmentally friendly.

To expose the PCBs with UV light (needs to be UVA range) I use a Babyliss Hawaii UVA "face browner" (like this - in Danish:

http://www.dba.dk/ansigtssol-babyliss-uva/id-89392883/

which I found second-hand for about 14 Euros. Works excellently with exposure times of 35 seconds for my self-applied photoresist lacquer and about 2 minutes for the pre-made photoresist PCB.

I print out the PCB tracks on overheads with a laser printer setting it to maximum blackness (as it's done on this printer). With this setup I can easily make sharply defined TSSOP28 package tracks etc.

Hope this may help.

Best regards,

Jesper
__________________
... Being mindful about sustainability also in my audio endeavors matters to me ... paying CO2 - and a quite fair pollution compensation helps create a good listening "energy" ...
  Reply With Quote
Old 20th May 2013, 09:53 AM   #17
diyAudio Member
 
Join Date: Oct 2011
Location: Tauberbischofsheim, Germany
Does your developer havethe right concentration? 1 % will be ok, i.e. 10 grams of NaOH in one litre of water.

Best regards!
  Reply With Quote
Old 20th May 2013, 10:27 AM   #18
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I am using the MG chemicals brand. I didnt get to it this weekend, but will do a test strip tonight.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 27th May 2013, 09:17 PM   #19
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
RTFM. Avery clever acronym. Simple, solution. 10 parts water to 1 part developer I have been using straight developer.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 28th May 2013, 05:07 AM   #20
diyAudio Member
 
Join Date: Oct 2012
Quote:
Originally Posted by buzzforb View Post
RTFM. Avery clever acronym. Simple, solution. 10 parts water to 1 part developer I have been using straight developer.
I was about to post just that when I noticed you had already found the answer. MG developer needs 10:1 (water to developer), The average board needs very little to do the job. I use the cap from a can of board protector.

A few years ago I was able to obtain a Kinsten UV light box on Craigs List. It's a fantastic bit of kit. It has a vacuum system to suck the film tight on the board and a timer circuit to control top and bottom exposures. I've never needed more than 75 seconds exposure.

I do all my film on a laser printer set to 1200 dpi. It doesn't seem dark enough when you look at it and I used to double up the transparencies. This gets very difficult on double sided SMD boards and it isn't necessary. If the exposure time isn't to high then single films at 1200 dpi are fine. The photos show what you can get with a single film pre and post etch. You can easily get 5 mil traces. Notice the writing on the board.
Attached Images
File Type: jpg DTI 3.3 Pre Etch.jpg (789.8 KB, 75 views)
File Type: jpg After etching.jpg (660.4 KB, 73 views)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Toner transfer or photoresist for SMD precision PCB JanErik Construction Tips 9 18th September 2012 10:15 AM
photoresist Stefanoo Parts 21 30th April 2012 07:23 PM
Spray on Photoresist- How Successful is it. Mooly Parts 27 3rd August 2008 10:18 AM
Photoresist shivela39 Parts 3 26th March 2006 04:45 AM
wipe / rub on photoresist? bigpanda Everything Else 6 29th September 2005 10:27 AM


New To Site? Need Help?

All times are GMT. The time now is 11:53 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2