Two basic questions from a newbie

Archive BatchPCB
1

First off, let me say what a great site this is, and the forums are fantastic ideas!

I’ve made lots of analog circuits, but always used point to point so I’m new to making pcbs…

  1. Would love recommendations as to the basics of pcbs – (not the diy etching process) – so I can learn i.e. what’s a solder mask/what’s it used for? 2 sided pcb?

  2. Are there standard gerber files available that have VERY basic “circuits” – specifically something like a 48 pin TQFP to DIP (or if not DIP then spreading the leads out over a larger area on the board to make hand solfering easier)? I know sparkfun has a similar product for SSOP. I will eventually learn Eagle, but but for now I think why re-invent the wheel?

Thanks!

2

rif -

I’ll attempt to answer as many questions as I can, but you really are better off using google and then learning a specific layout program.

There are a couple of different common layers involved with PCBs, the most common are:

  • Copper (layers that have traces, copper pours, fills, etc…)

  • Solder Mask (board treatment so that solder will not adhere to the board, often a very green color, but can really be any color. Typically how you get different colored boards)

  • Silk Screen (Text layers)

  • Assembly (Layers that are used for assembly of the board, you don’t send these layers in)

With that said, there are only two copper layers on a 2sided board, the top and the bottom. However, on a 4 layer board, there would be 2 inner layers in addition to the top and bottom.

There are always only two silkscreen layers (some manufactures actually won’t do bottom silkscreen).

There are always only two soldermask layers corresponding to the top and the bottom.

Quick advice when you are getting ready to start laying out your boards, check the design rules. This particular manufacture uses 8 mil for traces and 8 mil for spaces. That means that you cannot have any traces smaller than 8mil and traces must be at least 8 mils apart. (Also note, in PCBs, mill is not the same as mm!!! mill = 1/1000 in, mm = 1/25.4 in)

Standard gerber files for breakout boards? Probably, but I haven’t seen them. Digikey and other vendors sell these breakout boards, but they can get VERY VERY pricey quickly. I remember looking into purchasing an odd breakout board a couple of months ago and was amazed at the 45.00$ cost. You are really better to just do the layout yourself.

3

Thank you for the detailed reply!

I just re-read my post and meant to ask for recommendations for sources of info. but I appreciate the time you spent explaning it.

I’ll most likely use pcb in linux or Eagle in windows, since I’ll be creating “full” boards sometime in the future