How to cut costs when fabricating large PCBs?

Question

I've looked online at PCB fabrication companies, and they invariably price their boards according to the size of the board as the primary factor.

Why is this? The physical board itself isn't that expensive, is it? I'm guessing it's because the size of the boards dictates how many they can produce simultaneously, and that's the primary limiting factor in their profitability - Is that right?

Anyway, is there a way to keep the costs down when fabricating large (~8x10 in.) but sparsely populated (~50 components) boards (other than just ordering from the cheapest Chinese factory I can find)?

It seems silly to pay $50 for a board that's only gonna have $10 in parts on it.

Answer 1

10*8 isn't really large, but you may get only 2 per panel which will impact the cost. Panel sizes will vary from fab to fab so it is worth talking to a few - and negotiating the details - as The Photon says, you may get 4 per panel and half your price that way. And the economics of setting up a fab for small jobs dictate that buying 50 boards instead of 10 can half the price again, 100 or more even lower.

In addition to The Photon's good suggestions, use the simplest process possible for the large board. Single-sided PCB may be MUCH cheaper than 2-layer, especially since there's no through-hole plating stage, omitting silk screen and solder mask may save a little more money. Some fabs may still offer phenolic material - much cheaper than FR4 fibreglass.

You might be able to use an Arduino-sized full spec PCB to hold the complicated stuff or customization, which you then plug into a much larger single-sided board which - because it omits the personalization for a specific project - you can buy in larger quantities and re-use for multiple projects.

Answer 2

@Josh: You might be able to reduce board fab costs if you could work out a way to use a number of smaller boards to achieve your goal. For example, if you have either one long series string of LEDs, or, say, ten strings of five, and could use ten long, skinny boards (say, 8 inches x 0.25 inch). That'd reduce the material cost, and allow for a variety of panelization alternatives, but with substantial impact on total assembly cost (as you'd have to connect the small boards together electrically and mechanically).

Perhaps this illustrates a more general rule: If something seems unexpectedly expensive or difficult, see if you can look at your problem differently to see if you can find an easier or cheaper approach.

Answer 3

1. Be sure to know what size panel you are building, and design your board to fit well on that panel. For example, if you use an 18x24" panel (very common), and your vendors want 1" spacing around the edges, and 1/2" spacing between boards, a 7 x 10 board will be priced substantially lower tha 8 x 10 board because you'll fit 4 per panel rather than 2. Note the board spacing might be driven by your assembly vendor rather than your fabrication vendor.

2. Buy larger quantities. If you are buying less than maybe 10 boards at a time, you are paying a relatively large amount per board for per-lot processes (programming machines, ordering materials, ...). Your price per board will go down quickly as your lot size increases.