Pcb design Parameters

Thread Starter

Dr.killjoy

Joined Apr 28, 2013
1,196
I been learning diptrace and know each PCB build house has it's own rules .. But when you PCB's how do you know how wide of a trace do you use or what pad size or guide lines ?? Is there any thread or information you could point me too ??
 

spinnaker

Joined Oct 29, 2009
7,837
There are definite guidelines that you should be able to find online. But as a hobbyist, you will most likely be using the toner transfer method. For that I try to use the widest traces and largest pads I can get away with. It makes getting a good transfer more likely. There is a verification option in diptrace that will help you determine if trace and pads are too close.

In the real world there is also copper weight to consider along with many, many other factors when designing a PCB.
 

Thread Starter

Dr.killjoy

Joined Apr 28, 2013
1,196
Ok thanks and does anyone know where pcb build house list is .. I tired looking but I can;t seem to find anything ..
 

Lestraveled

Joined May 19, 2014
1,946
I been learning diptrace and know each PCB build house has it's own rules .. But when you PCB's how do you know how wide of a trace do you use or what pad size or guide lines ?? Is there any thread or information you could point me too ??
I am not sure I understand your question. Back in the 80s and 90s the gerber plotters had fixed "apertures". It was actually a wheel with precisely cut holes that shaped the light source that exposed the PCB. You would get an "aperture list" from the board maker and use those sizes in your board design. This went away with black and white TVs. Today the size of pads and traces is almost infinite. The board maker will often state the minimum trace width or trace separation. That is about the only thing you need to consider when laying out a PCB.
 

Lestraveled

Joined May 19, 2014
1,946
............ how do you know how wide of a trace do you use or what pad size or guide lines ?.....................
Trace width is generally set based on the current drawn through the trace. There is a lot of info on this sizing around. The other concern is impedance. If you are connecting very high frequency signals the width of the trace affects its impedance. There are calculators online for that.
 

spinnaker

Joined Oct 29, 2009
7,837
My problems comes that I live in a small apartment with smalls kids and it's hard to make pcb at home with all the chemicals and having to drill the pcb with a drill press I don't have and just no room..
From what I have seen, it is not cheap to make just one. Most of the cheap places are in China. So it is going to take a while to get your boards. As a newbie you are bound to make mistakes in PCB layout. It is easy to do for someone that has done it a few dozen times too. Awfully expensive mistake in both time and money.

http://www.ebay.com/itm/Prototype-PCB-Manufacture-Etching-Fabrication-2-Layers-start-from-US-12-9-/161571651593?hash=item259e6bc009:g:~WgAAOSwQItT7xAp

Do you have a local club you can join? There is one here in Pittsburgh that has all kinds of equipment to use. I have never been but I understand it is great. They even have a CNC machine.
 

Lestraveled

Joined May 19, 2014
1,946
@spinnaker makes a good point. You are not the first person to have a space and safety problem. Look around for "maker" clubs. If you can find a place to use the toner transfer, or photographic PCB methods you could save yourself a lot of money.
 

spinnaker

Joined Oct 29, 2009
7,837
@spinnaker makes a good point. You are not the first person to have a space and safety problem. Look around for "maker" clubs. If you can find a place to use the toner transfer, or photographic PCB methods you could save yourself a lot of money.

A "maker" club will most likely have a Laserjet since it is a very common way to make PCBs for hobbyists. But they will more than likely have equipment for the photo method and CNC for milling. Plus lots of folks to help you get started.
 

Thread Starter

Dr.killjoy

Joined Apr 28, 2013
1,196
@spinnaker makes a good point. You are not the first person to have a space and safety problem. Look around for "maker" clubs. If you can find a place to use the toner transfer, or photographic PCB methods you could save yourself a lot of money.
I was going to try making smd boards at my place cause then I wouldn't have to drill alot of hole for components..But I have to pick up some iron tips for smd work.. Also it should work well with my reflow oven build but I know solder paste doesn't last very long unless refrigerated..
 

ErnieM

Joined Apr 24, 2011
8,010
I don't ever make a PCB myself, either I breadboard with wires soldered on a board, or go for a professionally made boards with plated thru holes, solder mask, silk screen, the works.

Each house is a bit picky on what minimum line width, line spacing, and hole size you can use, but these are usually only an item on very tight SMD boards.

Pick a house you can live with for price and size, and see if your board fits their limits. My guess is you will meet it.
 
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Lestraveled

Joined May 19, 2014
1,946
For quick and easy printed circuit boards I like ExpressPCB. Their schematic capture and PCB layout software is free and easy to learn. You order boards directly from their application and they are fast, typically 3 day turnaround plus shipping time. They are not the cheapest PCB house but I think they are the most streamlined. They have a "mini board" special I use often, 3 each, 2.5" X 3.8", double sided, through hole plated, 3 day turnaround, for $51 plus shipping. They keep you informed and send you a tracking number when it ships.
 

mcgyvr

Joined Oct 15, 2009
5,394
best pricing/excellent quality..
https://www.itead.cc/open-pcb/pcb-prototyping.html

Trace with is mainly dictated by the current through it.. I've done traces 1" wide or more for 100A+
pad size for SMT is dictated by the recommended pad layout in the datasheet.. Stick to it..
pad size for through hole I typically use 2x hole diameter for the pad as I just like it better to solder to.. some only do 1.5x,etc...

google search for pcb design guide or similar will give you plenty of reading/information..
 
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