EEVblog Electronics Community Forum

Electronics => Projects, Designs, and Technical Stuff => Topic started by: chrisbrown on May 23, 2014, 10:10:14 pm

Title: HF prototyping board
Post by: chrisbrown on May 23, 2014, 10:10:14 pm
I like dead-bug prototyping, and do plenty of it. But I don't like how difficult it can sometimes be to replace components, and I HATE slicing copper clad by hand. So to make my life easier, and considering how little a 10x10cm board from China costs, I made this dead-bug breadboard. Figured I'd share it in case someone else finds it useful.

http://imgur.com/a/sXVlx (http://imgur.com/a/sXVlx)
 
The board measures 99.7 mm x 99.7 mm.  The top layer has two independent power rails and ample grounding. The prototyping areas are sliced into .250" x .175" pads with 25 mil spacing. The bottom layer is a mostly-solid ground plane.

There main prototyping area is composed of four ground-encircled quadrants of 20 pads each. Four smaller auxiliary areas near the edges can be used for off-board connections, voltage regulation, and constructing inexpensive wirewound scope probe jacks.

For RF work, there are two dedicated footprints that accept standard vertical or right-angle BNC connectors, although most right-angle connector bodies will overhang past the board edge by about 1/3rd.

If you want one, the attached zip file can be submitted directly to a board house. Add your own fab notes if required.
Title: Re: HF prototyping board
Post by: T3sl4co1l on May 23, 2014, 11:33:27 pm
Not a bad idea. :-+

Don't suppose those pads happen to be a standard capacitance too?  (Even if not, once it's quantified it would be handy to use.)

For a v2.0, I wonder if it would be practical to add pads via'd to an inner layer polygon for supply rows and such?  Could add some SMT sections too (0.5 / 0.65 / 1.27 mm pitch pads in TSSOP / SO / QFP layouts), interspersed with the generic pad areas.  Dead bug?  Sure, why not, bugs die right-side-up too... ;D

Hard to say if there would be any one or few near-optimal layouts... pretty easy to go wild and then you have twenty gazillion breakouts to shuffle through!

Tim
Title: Re: HF prototyping board
Post by: chrisbrown on May 24, 2014, 02:11:13 am
Yeah it was hard enough to decide on a general layout, nevermind potential features. I'd love to add SMT pads and internal layers and maybe an extra 10 or 20 cm on each side...

Back of the envelope: pad capacitance is about 0.7pF on 1.6mm FR4 with a dielectric constant of 4.5.  -> 2.2kOhms at 100MHz.
Title: Re: HF prototyping board
Post by: Tac Eht Xilef on May 24, 2014, 02:52:13 am
Yeah, nice idea :-+

Re: smt - how about offsetting a row of pads by 1/2? That'd work for SOT-23 etc, some TO-xxx/DPAK, & similar packages.
Title: Re: HF prototyping board
Post by: chrisbrown on June 23, 2014, 08:02:56 am
Quote
Re: smt - how about offsetting a row of pads by 1/2? That'd work for SOT-23 etc, some TO-xxx/DPAK, & similar packages.
Good idea, I'll definitely do that next time.

Just got the boards back and they don't disappoint. Nearly as easy as a breadboard, and they work well above 100 MHz. Here's a basic 2 meter transmitter I'm working on: http://i.imgur.com/O9p88hl.jpg (http://i.imgur.com/O9p88hl.jpg)
Title: Re: HF prototyping board
Post by: theatrus on June 25, 2014, 05:30:29 am
Looks good!