A few months ago we started a private PCB website so our team can get cheap PCBs from a fab in China. Someone spilled the beans, and it hit Hack a Day, Hacker News, etc. We almost shut it down, but it was too much fun to hack and refine the process. Dirty Tuesday is a weekly post about our misadventures accidentally starting a PCB service. As a design shop with Seeed Studio doing fulfillment, we’ve never been on this side of the fence and want to share the terrifying experience.
One of the current HAXLR8R groups is designing a desktop PCB printer and asked for DirtyPCB stats to better understand the market. This Dirty Tuesday we break out PHPMYADMIN and pulled out a bunch of mostly meaningless but still grok-worthy stats. These apply to shipped, 2 layer board orders only.
SELECT count(*), `stencil` as v FROM `pcbs` WHERE `status` =’Shipped’ OR `status`=’Trackable’ GROUP BY v
A paltry 5% of orders want a steel stencil. Most want a simple steel stencil (4.9%), though a few manufacturers do buy our dirt cheap framed stencil as they are 4-10x cheaper than many other options.
SELECT DAYNAME(timestamp) day_of_week, count(*) order_count FROM `pcbs` WHERE `status`=’Shipped’ OR `status`=’Trackable’ GROUP BY day_of_week ORDER BY DAYOFWEEK(timestamp)
Are you working through the weekend? Monday is the most popular time to submit boards. In fact more than twice as many boards roll in Monday than on Saturday.
When all PCB colors are free, most people abandon boring green boards. Red is the favorite (32%), though also the default setting. Black boards, we hate then because it’s hard to see the traces and ground fill when building and debugging, are a full quarter of our orders. Blue comes in a strong third (18%). Least loved are yellow boards (6%).
“Protopacks” have 8-12 copies of a PCB, and come in two sizes. A 5x5cm protopack is for any PCB with maximum 5x5cm dimensions. A 10x10cm protopack is for any PCB with maximum 10x10cm dimensions. It’s a roughly even split between protopack sizes purchased. Around 6% of boards are a custom size, usually larger than 10cm in one dimension.
DirtyPCBs has a range of board thicknesses, all but 2.0mm are free. 1.6mm, bog standard, is still the favorite of most. 1.2mm comes in second, likely because it’s the default setting intended to shed weight and lower delivery costs.
ENIG, a high quality gold-based surface coating, is lovely to work with. We think surface mount components are way easier and more fun to solder on an ENIG board. Unfortunately it’s also an expensive addition for a small batch so only 3% have requested.
Most of these stats are only a curiosity, but a few things stand out. Color matters. Given the choice, most people don’t want a plain green board. Also, the time invested to add tons of options: ENIG, stencils, different thicknesses, and larger sizes had only minor returns. It took weeks to revamp the code, but the extra features only capture a few corner cases. That’s time that could have been spent improving other parts of the site.
PCB fab tour pics PLEASE!
By the way, is there any site that offers a metal stencil by itself, without making a PCB at the same time?
Shoot me an email, we can do it. It is just hard to take through the site though.
Thanks for the reply Ian. My idea was to abuse a solder stencil process to make a radial star pattern in metal to use in an optical rotary encoder. But now I found you can get complete, working 600 pulse per turn quadrature shaft encoders around $15 (ebay: “photoelectric rotary encoder”), so there’s little point in making my own. Oh well!
Which volume these statistics are based on?
I’m not ready to release those numbers yet :) It is based on 6 months of sales.
I tend to only order ENIG boards once I’ve proven out a design, so the first prototypes will almost always be HASL. 2nd revision will tend to switch to ENIG.