Newbie PC board fab questions

Discussion in 'General Electronics Chat' started by spinnaker, Feb 8, 2010.

  1. spinnaker

    Thread Starter AAC Fanatic!

    Oct 29, 2009
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    Putting together my first fairly major project I am quickly realizing that if you are not extremely careful in planning, a perf board can get very messy very quickly.

    I was thinking that planning out with a PCB designer might be a good way to at least help somewhat in component placement.

    But I think instead of rebuilding what I have, I might rather spend the time making a PCB.

    Just some questions.


    I am working with ExpressPCB. They have a 1.5 Amp bridge rectifier component. One of the pads are square, the others round. What does the square pad supposed to represent? It looks to me like one of the AC inputs but that does not make much sense to me.


    Am I better off just sticking with 1 layer for my first project (a bench power supply)?

    And this last one could probably be answered if I do some searching but what is the best way to cut the board to size?
     
  2. BMorse

    Senior Member

    Sep 26, 2009
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    square pads on components usually represent pin 1 of the device....

    If you were going to do the etching yourself, I would suggest sticking to a single sided PCB, since connecting layers by hand is a pain.... but if you are going to order these boards from expresspcb, then double, triple, or quad layers really doesn't matter.... But it does cost less to order a single sided PCB :)....

    for cutting PCB's to size, all depends on the thickness, for something like a single sided .0625" (1/16" thick) you can actually score the PCB with a razor utility knife and snap it along the line, you might have to make several passes with the razor..... you can then use some sand paper or a sanding block to smooth out the edges of the PCB. For thinner PCB boards I have used an industrial type manual paper cutter :) .....

    If what you are cutting off is just waste material or excess, then some tin snips will also do the trick.... In the past I have used several items to cut it (Basically whatever is handy to cut laminated fiberglass with).... if you are thinking of fabricating several PCBs in one and then cut it apart after, then a scroll saw / band saw with a fine toothed blade would also work.... just remember to wear eye protection and some kind of respirator, since most PCB material is fiberglass and could pose potential health risks being exposed to it's dust....

    My .02
     
    Last edited: Feb 8, 2010
  3. spinnaker

    Thread Starter AAC Fanatic!

    Oct 29, 2009
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    Thanks for the response!


    The component is a W10G. bridge rectifier. What is the usual pin 1 on that? Every datasheet I have seen does not really designate a pin 1.
     
  4. sgardner025

    Active Member

    Nov 5, 2009
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    You can lay it out how you want, pin numbers won't be too crucial on the rectifier as long as you get the routing done correctly. You will most likely end up having to make your own components as well. Look in the help files. I've been using ExpressPCB for a while and it's a great program in my opinion.
     
  5. spinnaker

    Thread Starter AAC Fanatic!

    Oct 29, 2009
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    Thanks. That is what I figured. The question was pretty much curiosity then anything else.
     
  6. BMorse

    Senior Member

    Sep 26, 2009
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    :rolleyes: But if you look at the components shape, and you look at the footprint for the PCB, which one do you think will be pin 1 on the rectifier?? They usually do this even for components without pin number designations, to make it easy for someone to replace the component if a repair is needed and would show component placement... the orientation of the rectifier is critical to line up the + and - outputs, if you flipped it around, you would swap those 2...
     
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