home pcb production

[daedalus]

Hi,

Im just starting out getting all the equiptment to etch my own boards at home, im planning to do a set of double sided through hole and smt boards.

I have a uv lightbox, but its only single sided, so how do i produce double sided boards with it? Do i expose both sides one at a time, then develop and etch in one go, or do i develop each side one at a time?

Does anyone have any good tips for how to make sure the artwork is matched up on both sides properly?

what kind of design rules should i be using when making board designs? how thin tracks / spacings am i going to be able to do consistently on this kind of setup (im using a heated bubble etch tank)?

is there any way to apply soldermask and component names to board at home cheaply?

What is the difference between cheap copperclad board and the more expensive types? is there a good reason for paying more?


Also part of what i want to do involves doing smt boards at home, and to that end ive picked up a second hand hot air rework station. Can i get away with using this to reflow solder paste, or do i need to preheat the pcb as well? if i do could i get away with putting pcb on an electric hotplate?

sorry for all the questions, but im new to this.

[H500]

I do all my smt work with a temperature controlled soldering iron. Even .5mm pitch chips are no problem. Just wick off the excess.

For diy boards, I don't pay attention to the specs. I use whatever is cheap. Soldermask is not req'd for hand soldering.

[daedalus]

well i guess i will know more when the stuff arrives and i can have a go, im just trying to figure what else kit wise i need to aquire. I thought considered getting a fine pitch iron, but i thought a hot air gun would be easier.

another question, how long do chemicals like etchant, developer, tinning compound, photoresist stripper etc last? What i mean is i need to order enough chemicals to keep me going for a while, but am unsure how many times you can use em, how much to buy, etc..

[BobWarfield]

Daedelus, I'm not board maker, but the double sided problem seems an issue of building a jig to let you ensure that when you flip the board over it is precisely registered to the same position. Seems like all you need is a raised corner that stays put relative to the UV lamp. Build it into the base of the lamp. Align the board with say the raised edges, expose, flip, align again, and expose. You will want to make the corner moveable, so maybe it is something you clamp in place before beginning based on the size board you are exposing.

Best,

BW

[audioandy1762]

Hi Daedalus I have made a few double sided boards, I found the best way for me was to place my first mask ontop of the board and pick about four of the solder pads and drill them first, expose the drilled side to the UV only, then use a resistor leg to pass through the drilled hole's and use it to align your second mask hope this helps good luck.

[daedalus]

thanks andy, that sounds like a good approach. Just to clarify, do you uv expose one side, develop, drill then expose other side, or do you drill through the unexposed board, and develop both sides at the same time?

[audioandy1762]

Hi Daedalus the board I used was pre coated with the photo resist so the board is covered with a sticky back removable cover. I placed my "first" mask on top of the sticky back plastic drilled my holes, then removed the plastic aligned my "first" mask with drill holes exposed this side only to the UV, then remove the sticky back cover from the other side of your board align your "second" mask with the drilled holes then expose that to the UV, I covered the first side with a cloth to reduce the risk of over exposure then and only then do you develop the board, then you can start the etch procedure when all the unwanted copper has desolved expose the remaining track to the UV dip into the developer again and wash off this should now leave you with the copper track. If you are still not sure send me a PM and I will give you my phone number

[daedalus]

thats cleared everything up for me, thanks again.