Photoresist PCB Developer

[sohel]

Dear all,

i am facing problem with pcb developing. i am using photoresist film. i can laminate film to blank pcb. and also expose with uv light. exposed track are shows brown.
i think all are ok. but when i am going to develop it with sodium hydroxide solution. after 20 sec all are ok but after 10 sec all resist (exposed and non exposed) goes off. nothing on board. i am looping at this stage.
why photoresist didnt attach on board?

thanks

[sohel]

Thanks.

I have also use sodium carbonate. but same condition. and also use Kinsten Presensitized PCB Board Developer 50g /bag. same.

[sohel]

now its work. Thanks

i use sodium carbonate. and good lamination.

[cerebronico]

What photo-resist you used?, where may i buy it?

 

[sohel]

its an negative  photoresist film role. i have collect from china. you can buy it from ebay.

Item number:   370460564054
Item location:   ShangHai, China

[Tanuki]

Here is a pretty good "How To" site for making your own PCB's.

http://www.siongboon.com/projects/2005-09-07_home_pcb_fabrication/

[sohel]

i want  to buy small  Quantity of smd parts. like diode, transistor, ic, mcu etc.

please see picture for photoresist type.

[puta]

Do you use PCB plating technique to protect the exposed copper area of the board ( eg. gold, silver...etc plating)

I always have the problem of oxidisation of the exposed copper area of the developed board.

Thanks

[sohel]

i am in learning mode. step by step. i think you can get it with chemical  tin (Sn) plating.

[Thor]

Sohel, i think, your problem is in not proper (to strong) concentration of sodium hydroxide. I use this solution all the time (about 7 grams of NaOH in 1 liter of water). For usual POSITIVE photoresist. Are you sure, that you have negative photoresist? As i see your picture, it is positive.... the negative resist remains on the surface wherever it is exposed to UV, and the developer solution removes only the unexposed portions.

[sohel]

Thanks,

I have both of them. picture was positive Presensitized PCB board.

1. Kinsten/Chiefskill Positive Acting Presensitized PCB board
2. Negative photoresist film role. its too hard to laminate with lamination machine .

http://members.optusnet.com.au/eseychell/PCB/photoresist/Wet_Lamination_of_Photoresist_for_Hobbyists.pdf

[rajudp]

i am using Negative photoersist film roll, and is giving good results

[sohel]

Dear all,

i am fail to laminate cut piece ( 3"x5") of photo resist to pcb. i have try with many process . but some air bubble come as a gift.   any one give me easy solution?

thanks

[Ichan]

Hot roll laminator is the best, but difficult for a small cut pcb.

For a non drilled blank pcb you can try wet lamination where the photoresist pre wetted with a mixture of water + alcohol. This technique is patented by Dupont, and in the DIY way it was described on www.thinktink.com but looks like not anymore. In the extreme way you can try to lay the photoresist to the pcb under the water mixture, later iron it with cloths iron with a piece of paper above the photoresist.

For a pre drilled substrate, no other way instead of hot roll laminator (not hot shoe) - maybe vacuum laminator will do, never have a chance to try it.

-ichan

[Thor]

For small PCB-s is better to use light sensitive spray. I use "Positiv 20". http://www.crcind.com/wwwcrc/tds/TKC3%20POSITIV20.PDF

[sohel]

In the extreme way you can try to lay the photoresist to the pcb under the water mixture, later iron it with cloths iron with a piece of paper above the photoresist.

I think this method is good. i will go for under sea water with film and pcb board. there will be no air bubble. 

[Ichan]

Yep, don't forget to open your cloths - you will need it later.

Have you try to google "wet lamination"?

Here is the first hit i got, be ready to get wet: http://www2.dupont.com/Imaging_Materials/en_US/assets/downloads/presentations/EIPC-YM2K_presentation.pdf

-ichan

[rtm]

To avoid bubbles I cover pcb by photoresist under water. I am using simple cold water. After that, I roll pcb with hand rubber roller. Next, I warm this pcb to 60-70 degrees centigrade for 5-6 minutes and roll it again.

Next you make UV exposition.

Another problem is to remove protective film after UV exposition and not damage photoresist. I have found a good method - putting pcb into freezer for 5-10 minutes. Protective film is removing easily after cooling.

[rajudp]

i am using normal laminating machine , giving good results
cut  photoresist larger than the copper clad, i first fix one side of photoresist to a thick paper 80gsm is also giving good results for single sided
then put it to laminating machine holding the other end oh photoresist and leave it only when i was not able to hold it ( near to laminating machine ) and giving good results

[jzaghal]

Hi,

I use normal laminator. Just make sure you clean well the pcb. result perfect at about 125C.

Cheers.