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I know this question might get closed because of being opinion depended but I couldn't find any answer from google or any other search, so I decided to ask it here.

For clarity of question I want to link this Nexys II board just as an example.

For PCB manufacturing, prices per board drops sharply at low volume intervals(when you double the quantity price per board) as the graphic below. So PCB manufacturing becomes feasible after a couple hundred of production. For example a 10cm x 10cm, 4 layer PCB costs ~8$ per board(with other settings default) at pcbwing.

But Quoting for PCB assembly seems way expensive in those production levels and I couldn't find an online quote website for high volumes to see when cost is feasible per board.

So my question is, approximately at what quantities I get similar price per board graphics for PCB assembly costs(for boards like Nexys II) ?

enter image description here

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  • \$\begingroup\$ depends a great deal on the board. at low levels some SMD stuff can feasibly be done be hand, although it is expensive. If you really have to set up a pick and place machine, that usually dominates costs at low quantity, but depends heavily on components. Whatever the setup cost is will be divided across the quantity you order, so cost per board is a bit misleading if the component cost/board is low (and that will also shrink at high quantity). \$\endgroup\$
    – danmcb
    Nov 28 at 11:31

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I went and got online quotes from two assembly houses for a simple board with 60 surface mount components (all on one side), no fine-pitch, bga, through-hole parts or connectors, and lead-free processing. Medium delivery time, neither rush or extended.

I then requested quotes for 1, 2, 5, 10, 20, 50, 100, 200 and 500 boards. Only the second house would quote over 100 boards online. Then I plopped the #'s into Excel.

Here are the prices (in $) per PCB for various quantities for the first assembly house:

enter image description here

and here are the numbers for the second house:

enter image description here

The actual figures range from $318 for one board down to $11 / board for 100 boards for the first house, and $448 for one board down to $16 / board for 500 boards for the second house. Guess which one is based in China.

What I find interesting, is although the prices are quite different, the shape of the two curves is almost identical. Prices rise from their lowest point until they double at around 20 boards, and in both cases there is a very sharp knee right at 5 boards. I had thought the knee would be much further right, i.e. having to pay a steep premium for even quantities of 10 or 15 boards, but I guess that isn't the case.

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  • \$\begingroup\$ I think the PCB house that you 'tested' are the ones that optimize for small runs. The ones that optimize for large runs won't do a < 100 run, and probably won't have an online quoting system at all. So mo guess is that for the industry as a whole the knee in the curve is frather to the right than can be observed from these two samples. \$\endgroup\$ Oct 11, 2014 at 8:13
  • \$\begingroup\$ @WoutervanOoijen Since his graph went from 1 to 100 boards, I chose the same range. But you are correct, the maximum number of PCB's either of these assembly houses can handle is 5000 at a time. And I can't get an on-line quote to compare the price @ 5000 pieces compared to the price @ 100 pieces. But obviously if you already have a 96% drop from $448/board down to $16/board, you're not going to have that kind of drop going from 100 pieces to 5000 pieces. So I think the price going from quantity 100's to the right are going to continue to slope fairly gradually. \$\endgroup\$
    – tcrosley
    Oct 11, 2014 at 9:22
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As a PCBA company, we'd like to give you some insight into the pricing. It is great, that you are trying to understand how the prices change at different production quantities.

The sharp bend in your original graph at 10 pieces is accurate in our experience. I would like to add that beyond 1000 pieces a company is not likely to achieve much more cost savings, so I'd say that approximates volume pricing for the given circuit design and the manufacturer.

There are different factors when it comes to the cost of a PCB assembly. What is important to note is, that the designer determines the price more than anything. Your component selection and technological constraints define the cost beyond what optimization any EMS company can bring to the table.

Factors for PCB Assembly Pricing include:

  • Component Selection and pricing.
  • Bare PCB price based on technology, layer count, drill sizes etc.
  • Manufacturing technologies used, such as SMD and THT assembly.

When it comes to how much the cost scales down with volume, you will see the lowest effect in THT assembly. Since this is generally a manual process, there is close no setup cost associated. There is a case to be made, that with very large volumes you could optimize the order of how things are placed or automate more of the component preparation. But as a rule of thumb, most EMS companies are probably not showing much scale effect in THT assemblies. Please note that double-sided SMD assembly with THT components on TOP or BOT can get quite expensive since those tend to be hand-soldered pin-by-pin instead of wave soldered unless the manufacturer uses selective soldering for THT. Here I found 10 cents per manual solder joint to be a good reference.

With SMD components, the design is really important. Generally, components smaller than approximately 5x5mm will have significantly higher assembly speeds compared to larger components. The sizes vary based on the manufacturer's pick and place machines, but I found 5x5mm or "smaller than SO8" to be a good reference. The assembly speeds of these small or large components vary by order of magnitude. On our standard assembly lines, we place slow components (large) with a speed of 1500 pieces per hour and fast components (small) with a speed of 7500 pieces per hour. If you figure an average pick and place line costs about half a million dollars and has an hourly rate of 200 USD with an operator, you can roughly estimate costs.

While I differentiate between large and small components when it comes to assembly speed, it is also important to note that component sizes smaller than 0603 tend to get more expensive again because of the very small size and large components can be more expensive if they are BGA or finepitch.

In addition, please keep in mind that SMD assembly requires the machines to be set up. Based on how many different components you have, this can be done in 30 minutes if the EMS company is focused on rapid prototyping or can take up to a day of machine downtime.

Summary:

  • The price of the final PCB assembly cost is determined mostly by the design and component selection.
  • THT assembly costs don't scale as much as SMD assembly cost because of setup times.
  • Quantities under 10 pieces rarely make sense from a cost perspective.
  • Quantities over 1000 pieces typically approximate volume pricing.

We do have some resources available on our Electronics Manufacturing Knowledge Base that may help you improve your product cost, such as our "Design Checklist for PCB Assembly" or our "Design Rules for Low-Cost PCB Manufacturing".

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    \$\begingroup\$ Newmatik - Welcome. Please note the site rule about promotions. Some site members flagged the first version of this answer as spam, probably due to its excessive & general links. You removed one & I have removed the other - this is why: since any link to your site will effectively be a promotion, its content must be very specific to that topic (without being specially written just for that question). It can't be a general "look around here" link, as that is very likely to cross the line in people's minds towards spam. || Also, do not include links in too many answers. TY \$\endgroup\$
    – SamGibson
    Nov 28 at 13:41
  • \$\begingroup\$ Thank you for this. We want to be good community members and appreciate guidance on how to meet the community and moderators content expectations. We will be mindful of this going forward. \$\endgroup\$
    – Newmatik
    Nov 28 at 13:54

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