pcb suggestions

ThePenguinMaster

ok guys heres the scoop..

im working on a setup for my car.. ive talked about it before. its going to be an mp3 player that runs off of a hard drive and wifi..

i bought an sta013 chip and a 8 pin dac for audio. they are both surface mount. so what i want to do is make my own boards to break out the pins for thease chips.. design isnt a problem but im thinking of a procegure that might work out pretty well..

im drawing the layout in a CAM program, im planning on cutting a mask for the board. im going to cut out the traces, removing the material where i want the chemical resist to be placed. i work on a wire edm machine at work so i can cut as small as 0.012' with acuracy of .00005. so i should be able to produce an acurate mask.

what im thinking is i can take this mask and place it onto a copper clad board and spray some kind of resist onto it. preferabally something i can pickup at a local store for a small price.

the chemiocal to erode the copper is easily purchased at radio shack, so i can get ahold of that. my problem is what do i use as a resist? would regular spray paint work? i know sharpy marker will work, but i cant spray that. i would like to be able to do this because this way i can make a lot of thease boards veary easily and quickly. so what do you guys think about the idea? im also laying out a program to cut a breakout board for the surface mount propeller.

Phil Pilgrim (PhiPi)

I don't have an answer to the resist question but, when mulling it over, these considerations came up:

1. Any sprayed resist has to dry on contact. Otherwise, capillary action will suck it between the mask and copper.

2. It has to clean off easily, without using a solvent that attacks the epoxy substrate.

3. If you plan to make more than one board, you have to clean it off of the mask, too.

4. If the board is to be one-off, why not use the wire edm directly on the copper-clad?

5. A mechanical mask might be better suited for exposing photosensitive copper-clad to a UV lamp than for applying a liquid resist.

-Phil

floodhound

Well if you want to make the surface mount chip into a dip type package you can purchase a surf board. This will allow you to make a proto type using DIP IC's and a proto-board.

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My web site -- > www.floodhound.com <-- take a look if you like

Paul Baker

Unless you are doing this as a learning experience, it is much cheaper to get a ready made conversion board:
http://www.sparkfun.com/commerce/product_info.php?products_id=496
http://www.sparkfun.com/commerce/product_info.php?products_id=494

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

ThePenguinMaster

yes, it is partially a procegure check to determine if i can use it for the rest of the project. im going to need to construct a board that can interface to an ide harddrive. right now im using a breadboard and a radioshack perfboard. so its a little bit big of a setup just to connect to the harddrive.. ill post pics later on anther thread.

I cant wire through the copper board compleatly because with wire edm, the electrified wire which dose the cuting passes through the part that needs to be cut. so i can only do features that pass compleatly through the part. as for the issue of the resist leaking under the mask, i believe a fine spray or a few coats of a fine spray like when your painting a car, should keep it from leaking.. but im not sure about that... it is a possibility.

my problem is that i dont have the money for photo resist and i dont know where to get the equipment. well at least i dont want to spend large amounts of money on something that is just an experimental idea.. if i decide to go and start a business in electronics manufacturing then maybe i can go that direction.. but not untill i have a garauge to work in and i get real serious about it.

i do have a spray to remove di-chem and i think its made not to harm plastics and apoxy.. actually maybe i can use di-chem for a resist? it dose dry on contact like your saying.. but im not sure how it will react with other chemicals, and that could be a deadly mistake.

good pointers.. any other ideas for a resist?

Forrest

There's a simpler method - you can use the toner transfer method discussed in this thread http://forums.parallax.com/showthread.php?p=648429

The toner method involves printing your circuit image onto inkjet photopaper with a laser printer (or a photocopier)

ThePenguinMaster

ok so heres my boards, i think im going to do the laser printer for the prototype and maybe ill also do the masking..

let me know what you guys think about the design!