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Historically, choosing a design avoiding 0402 and finer pitch components was advantageous for mass production cost savings. The yields were improved and accuracy requirements for pick and place machines were reduced. This allowed vendors to choose from a larger number of manufacturing facilities and identify cost saving opportunities.

Does that kind of thinking still hold any water given that 0402s and BGAs have been popular for a long time? Are there still factories that specialize in low cost larger pitch manufacturing?

Just to be clear, I'm only talking about production volumes in the millions.

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    \$\begingroup\$ It would be interesting to hear people's experiences with lower volumes too though. A lot of electronics products are made in the 1000's of units per year. \$\endgroup\$
    – Jon
    Jul 5 '17 at 16:46
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    \$\begingroup\$ @Jon, I've used a few (fairly inexpensive) USA-based board houses for quantities of 100-500 and they didn't care about 0402 vs 0608, except that they wanted more overages of the 0402 parts... \$\endgroup\$
    – bitsmack
    Jul 5 '17 at 17:05
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    \$\begingroup\$ "Are there still factories that specialize in low cost larger pitch manufacturing?" - I expect there are but they'll likely go to the wall except for fulfilling the needs of designers of low volume stuff who have to do some proptotyping and hate shuffling bits of dust around whilst wearring telescopes on each eye (that'd be folk like me of course). \$\endgroup\$
    – Andy aka
    Jul 5 '17 at 17:06
  • \$\begingroup\$ I've had similar experiences as @bitsmack so figured any worthwhile cost savings must come at higher volumes. \$\endgroup\$
    – lm317
    Jul 5 '17 at 17:11
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Many assembly houses these days do 0402 with the same machines they do anything else, possibly using a different needle, though I'd suspect they'd be using the 0402 capable needle for 0603 and 0805 as well.

Is it still true you'll have more choices when you don't go below 0603? Sure. Most likely. There's a lot of cheap assembly houses that are cheap because they use the old equipment of the others, probably everywhere around the world. Some assembly houses may do down to 0201, but not be too happy to do the smaller stuff, because it requires extra operator attention.

However, when you go into volume, the cost of the more advanced assembly house will likely not weigh up to the cost difference for smaller circuit boards, more efficient systems and/or lower component cost. And some times using 0402 or even 0201 offers better per-component performance as well, such as lower parasitic effects.

Obviously if a 5000 unit reel of 0603 capacitors costs $15 and the 10000 unit reel of 0402 of the same value cost $20, that'll add up when you're making 10's of thousands with 10 each, but not really do much at all below using a reel per month.

Because boards are now almost always made to 5mil/5mil standard, the board won't likely be much more expensive if you make anything more compact with tiny components, but at high volumes the board space savings will start weighing as well. If a panel costs $100 and with 0603 the panel can fit 20 PCBs, but with 0402 it can fit 25 PCBs, that usually saves much more in volume than any extra cost you have at assembly in high quantities.

In all, if you want to be fully sure you'd need to do a cost estimation, including an RFQ to a few assembly houses that tickle your fancy. All the assembly/full-service houses I use are always ready to pick up the phone or answer an e-mail with questions about comparative costs. And more often than not I find the cost increase of something "unwise" 10 years ago falls into the less than a few percent now. And the same will happen later to stuff we think expensive now, so, really, you need to regularly keep asking them if things have changed if you want to be the best designer you can be.

Summarising: The only reason I don't do at least 0402 in my designs is if it's a hobby thing for me or others, where I want to be as quick as possible with replacing components, or I want others to be able to use my design as well, as I am not even noticing significant cost increase up to 160mmx160mm boards at 10 units. Over average past orders.

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  • \$\begingroup\$ I share all your thoughts. Is the disparity in BOM costs that much? I'm not on the purchasing side so don't get to see negotiated pricing. \$\endgroup\$
    – lm317
    Jul 5 '17 at 17:19
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    \$\begingroup\$ @lm317 It depends on the component, but the example is a real-world one. Or at least, as remembered. These days it even happens the 10kunit reel of 0402 is the same price or lower than 0603's 5kunits. \$\endgroup\$
    – Asmyldof
    Jul 5 '17 at 18:20
  • \$\begingroup\$ Great answer -- with the (relative) advances in components and their shrinking package sizes, even cheap consumer stuff may need 0402 to support some of the SoCs on-board. I think only the truly low, low, LOW cost CMs balk at 0402 these days... \$\endgroup\$ Jul 6 '17 at 1:33
  • \$\begingroup\$ @KrunalDesai Yes, it also depends on board size a little though. I have one fab that complains about 0402 on larger than 160x100mm, but no extra cost. And if they do start with extra cost I'll go to another, because they're not cheap enough that there's no alternatives. \$\endgroup\$
    – Asmyldof
    Jul 6 '17 at 17:28
  • \$\begingroup\$ Oh that's interesting -- what's the issue with a larger board? Something about number of components in a given area? \$\endgroup\$ Jul 6 '17 at 17:45
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In 2017, 0402 is completely standard and no contract manufacturer will blink an eye, whether in prototype or mass production quantities.

You'll start to notice minor effects on yield and availability at 0201, though those are outweighed by the board area savings in most cases. Going to 01005 will significantly impair yield and/or choice of manufacturer.

Hopefully someone else has info on the practicalities of BGAs at the production scales you're interested in. They certainly still can have yield issues and field failures, but it's not usually a placement accuracy problem - more an issue with reflow profile, board flex, underfill or lack thereof. Of course BGAs come in a range of sizes and pitches, with different implications.

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  • \$\begingroup\$ What you say is what I was hoping but I just had a vendor say I'd save 10% in assembly costs. Any idea why that might be? \$\endgroup\$
    – lm317
    Jul 5 '17 at 17:21
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    \$\begingroup\$ TIL about 01005 components \$\endgroup\$ Jul 5 '17 at 17:26
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    \$\begingroup\$ @lm317 How old school is the vendor? There's lots of little PCB houses with ancient 20-30 year old equipment that are still tooling along supporting clients with legacy products. There is a company in my area that still does very low spec 2 layer boards for a living. They don't even support RoHS, all their boards are still lead HASL. If you send a board to them requesting RoHS or more than two layers, they just send it to another board house and come back with a markup. \$\endgroup\$ Jul 5 '17 at 17:28
  • \$\begingroup\$ I don't know what this vendor's network of factories looks like but that's probably it. Good to know companies like that still exist. \$\endgroup\$
    – lm317
    Jul 5 '17 at 17:40
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I got word back from my preferred full service low volume vendor with both domestic and offshore capabilities. They said on average we could save 10% in assembly costs.

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  • \$\begingroup\$ Why are you using a low-volume vendor for a high-volume run? If you want to find the answer, you should be looking for more quotes. \$\endgroup\$ Jul 5 '17 at 17:34
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    \$\begingroup\$ I am looking for more quotes. This is just one response so far which contradicts the pricing another vendor has provided. Furthermore, if the cost saving is relevant to low volume, shouldn't it matter more at high volume? I'll try to keep this answer with updated responses from vendors I contact. \$\endgroup\$
    – lm317
    Jul 5 '17 at 17:38
  • \$\begingroup\$ There are differences in production volume driven by machinery used. High volume manufacturers regularly have production trains that are highly stable and well controlled, but take more set-up. This makes them expensive at low volume, but much, much cheaper at high volume, as making 10000 takes no intermediate re-calibrations and checks that stop the train, just random batch checks at the output. \$\endgroup\$
    – Asmyldof
    Jul 6 '17 at 17:31

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