Author Topic: Hole/Pad size - First PCB ever  (Read 4289 times)

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Online toli

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Hole/Pad size - First PCB ever
« on: September 26, 2011, 01:30:49 pm »
Hi Guys,

I've finally come around to designing my first PCB for a discrete linear regulator I've designed. I have some experience in IC layout (Cadence Virtuoso) but non when it comes to PCB's. I've decided to use FreePCB as its seems very easy to use, and I a coworker recommended it. At the moment I would like to try and stick to that program.

Now to the question:
I've got a few large capacitors I'm using, which have up to 1mm diameter of the leads. So I understand its about 40mil (39.37), right? In that case what size of hole and pad I should use? Will 45/90mil be good? I was quite surprised to see that the RAD-709 footprint (capacitor with 7.5mm LS, and 18mm dia.) available in FreePCB has 28mil/65mil hole/pad size for these large capacitors, and I can't understand how its supposed to fit them.

I'm sure I'll have some more questions once I move along, but that is all at the moment.

Thank you.
« Last Edit: September 26, 2011, 01:35:02 pm by toli »
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Offline Time

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Re: Hole/Pad size - First PCB ever
« Reply #1 on: September 26, 2011, 04:10:29 pm »
Is this going to be printed?  milled on copper clad board? Are you going to be soldering by hand?  Does the capacitor casing cover the pad on the top so you only have solder access from the bottom?

Really things like this come with trial and error.  If you are soldering by hand your best bet is to make things bigger if your design does not depend on such factors.

I suggest figuring out how to print your board to scale (1:1) and examining the layers to really get a feel for what its going to be like once made.  By print I mean on paper with ink, not PCB type printing
-Time
 

Online toli

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Re: Hole/Pad size - First PCB ever
« Reply #2 on: September 26, 2011, 04:12:21 pm »
I'm going to have the boards made, and solder it by hand.
My DIY blog (mostly electronics/stereo related):
http://tolisdiy.com/
 

Online IanB

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Re: Hole/Pad size - First PCB ever
« Reply #3 on: September 26, 2011, 10:09:23 pm »
What Time said seems like really good advice. Print your design on paper, glue it to some thin card, use a pin to make holes where the component leads go, and lay out your components to see how they fit. You will be able to check things like clearance between components, correctness of lead spacing and possible improvements to the layout.
I'm a ChemE--I know all about the flow of fluids.
 

Online toli

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Re: Hole/Pad size - First PCB ever
« Reply #4 on: October 04, 2011, 07:42:14 am »
Well my first PCB design is done :)
I've asked a couple of my co-workers who have quite a bit of experience in this to have a look and they gave me the ok to send it to manufacturing.

I've noticed iteadstudio (which I plan on using) are asking for .txt drill file, and .GBL/.GTL/etc for the layers files. I have .GRB for all layers (RS-274x format as requested) and .drl for the drill file. I can easily rename them, but I was wondering if anyone has sent these file types to iteadstudio and knows if its fine. I've sent them an email by got no response for a couple of days now.
My DIY blog (mostly electronics/stereo related):
http://tolisdiy.com/
 


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