Author Topic: General PCB Manufacturing Pros and Cons  (Read 3288 times)

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Offline ataradov

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Re: General PCB Manufacturing Pros and Cons
« Reply #50 on: August 12, 2017, 11:37:29 AM »
They just want to pad the price. In the end PCBWay is cheaper than AllPcb all around. I fell like they just want to convert AllPcb into a premium service.
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Online blueskull

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Re: General PCB Manufacturing Pros and Cons
« Reply #51 on: August 12, 2017, 11:42:54 AM »
New Allpcb.com service sounds great except they they emphasise speed, and for some bizarre reason they charge $8.695 for each BGA part you've got on the board.

Even if you don't order assembly service?

It's common in China that they charge you not only based on their cost, but also on your estimated profit from their service. Basically more BGA means higher tech, and higher tech means more profit.
By this way, they can offer lower cost to low tech DIYers to spread their name, and recoup the cost from established high tech corporate customers.
The same is for why they charge extra for combined designs in a panel.

For the controlled impedance, there's actually a physical cost. Controlled impedance means the PCB side of the copper (bonding line) must be very smooth to not to introduce extra capacitance caused by rough (increased surface area) surface, and hence controlling impedance.
These boards have an additional process, that is to polish the surface for electroplating before carbon deposition and electroplating of copper, hence the extra cost.
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Offline evb149

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Re: General PCB Manufacturing Pros and Cons
« Reply #52 on: August 12, 2017, 01:05:51 PM »
blueskull may be right about this being purely rent-seeking "market segmentation" predatory pricing because there aren't many good alternative vendors.  But it may be as suggested that there is ZERO technical justification for the cost and they just do it because they can get away with it.  The fact that they pick not only "costs extra for BGA" but ALSO "costs extra for EACH BGA" on the same PCB is really not sensible when they are not doing assembly.

On the other hand there are some POTENTIALLY good reasons they or SOMEONE could charge a modest amount extra for (relative to the most basic possible 2L PCBs).  I'd actually be happy to pay a MODEST (speaking as a hobbyist) extra cost for a higher level service if it offered many or all of the following features which are actually relevant for many (most) but not all BGA designs:

* ENIG finish.  Because planarity and ROHS solder being better to use for BGAs and SMT even for hobbyists because of better (less) flow characteristics in reflow which tends to help SMDs stay in place despite a poor DIY reflow process.

* 8mil hole / 18 mil pad mechanically drilled vias.  Usually 8mil/18mil is the only hope for a great many even quite low density (1mm / 0.8mm pitch etc.) BGA breakouts if using separate vias and no HDI processes.  Even with such small mechanically drilled holes it is still impossible to break out many low to medium-low density BGAs with full arrays as most are.

* Properly plugged and plated over "via in pad" processing which is especially relevant for any CSP or BGA packages that are low to medium low or more density.  There is literally no alternative to via in pad with proper pad plugging, plating, and planarization for MOST BGAs and basically everything but the most simple CSPs needing breakouts.

* Obviously offering low cost laser drilled microvias, blind and buried vias as well as via in planarized plated over pad would be IDEAL for almost any BGA package even higher density CSP ones.  So it would be quite attractive if manufacturers could offer such services for low enough costs to be relevant to hobbyists.  There are many CPU and SOC and FPGA and sensor and similar projects I would make as a hobbyisst if such PCBA technology was affordable to prototype and make in low quantities.  But even without full HDI processing at least with the above options you could access several low or medium low density BGAs but still probably be excluded from the possibility of MOST modern CSP BGAs without HDI / micro vias.

* Narrower minimum solder mask clearances from non-solder-mask-defined pads.  Also narrow minimum solder mask minimum web diameters between pads.  Almost any fine pitch BGA / CSP BGA even ones with only 4 pins and certainly ones with 9-dozens+ will stipulate in the recommended layout application notes that you should be able to have solder mask still present in between the BGA or CSP BGA ball pads so you will less likely have solder bridging.  The 4 mil minimum pad to mask edge clearances that are offered at low costs aren't even good enough to allow solder mask between many 0.5mm pitch QFN / QFP and similar low density SMD parts.  BGA / CSP usually impossible.

* Allowance for 3.5mil or 4mil minimum diameter track and gap sizes because it is necessary to allow running one or more tracks between CSP / fine pitch BGA balls for the recommended / necessary breakout routing patterns for the parts and for proper neck down entry to small CSP pads etc.

Those are characteristics of what I would call "ordinary" SMD manufacturing capability that properly supports CSP or fine pitch BGA packages.  That and inexpensive PCBS with 6 layers minimum and affordable also for 8 or 10 layers.
Anything much less and you will have only the most minimal percentage of CSP / fine pitch BGA parts usuable on a 4L PCB with the unsuitable 0.3mm via hole / 4mil solder mask to pad clearances / non plugged via type of design rules you see from low cost services.

So actually for a proper manufacturing process I would not mind some extra cost but when you start to see $2000-$5000 costs for just a few prototype PCBS like many companies pay for quantity 5-10 boards with 8-10 layers, CSP BGAs, etc. then it completely excludes almost every maker / hobbyist and a lot of small businesses also that can't spend thousands to make a few prototypes just for the satisfaction of making a modern and interesting circuit design.

Every hobbyist now is used to using PCBS like RaspberryPi, BeagleBone, etc. but mostly nobody besides big companies could afford to make similar products with DRAM, ARM-A CSP BGA SOCs, fine pitch FPGAs, etc. because of the PCB costs and also to some extent assembly costs / difficulties.


Even if you don't order assembly service?
Yep. Check out their new ordering page - there is a field at the bottom where you're supposed to type in number of BGAs in your design. I wonder what they were thinking when they've introduced this surcharge - I can't think of any reason to use 6-layer boards other than breaking out large BGAs...
 

Online asmi

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Re: General PCB Manufacturing Pros and Cons
« Reply #53 on: August 12, 2017, 01:07:32 PM »
They just want to pad the price. In the end PCBWay is cheaper than AllPcb all around. I fell like they just want to convert AllPcb into a premium service.
Not for 6-layer boards. Even with added costs of 4 BGAs 0.125/0.125/0.25 mm boards with 50 Ohm CI (minimum for 0.8 mm BGAs like DDR2/3/3L) are cheaper in allpcb. PCBWay pricing for that kind of board is weird - price with CI is less that without CI :o
 

Offline ataradov

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Re: General PCB Manufacturing Pros and Cons
« Reply #54 on: August 12, 2017, 01:14:58 PM »
Not for 6-layer boards.
Don't judge allpcb price by the instant quote. They will bump it by a random amount after you already paid, and ask you to pay more. At least that's what they did to me on a pretty simple board.

And oh yeah, refunds don't go back to PayPal, they go towards store credit.
Alex
 

Offline evb149

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Re: General PCB Manufacturing Pros and Cons
« Reply #55 on: August 12, 2017, 01:16:16 PM »
Yeah controlled impedance is a good feature.  And to the extent that it incurs real extra costs somewhat in fabrication but also in testing (TDR, certificate, rejection and remanufacture of PCBs out of specification) then I expect some cost addition for it.  But to suddenly increase the PCB cost by 30x or whatever just because of picking a copuple of options other than the lowest cost ones is extreme and unreasonable pricing.

For many designs I'd be happy enough with "controlled dielectric / specified stackup" service even without guaranteed per batch tested and tuned controlled impedance.

They could just offer a few standard PCB options, FR4 2L 1.6mm or 0.8mm, FR4 4L 1.6mm or 0.8mm, FR4 6L 1.6mm or 1mm-0.8mm whatever is sensible, and then for the 4L / 6L options maybe a couple of different common stackup options for core and prepreg types and spacings.

Then if they just said that you pick whichever of those few choices you want then you will know exactly the PCB material stackup, thicknesses, dielectric constants, solder mask thickness / type, etc.  And they could just send one or two sample production boards of test coupons in such stackups per year to be TDR tested to characterize the impedance.  Then based on that they can just say for our standard stackup #3 typical L1 to L2 microstrip 50 ohm line is 12mil wide, L2 to L3 stripline is 7 mil wide 50 ohms, etc. and assume that will be true to within maybe +/- 25% without actual per-design analysis and testing.  If you need better then you can pay some more for per-design controlled impedance.

But if someone offers reasonable for DIY cost controlled impedance with testing and CAM to make the impedance come out right so much the better.  It is about time.


For the controlled impedance, there's actually a physical cost. Controlled impedance means the PCB side of the copper (bonding line) must be very smooth to not to introduce extra capacitance caused by rough (increased surface area) surface, and hence controlling impedance.
These boards have an additional process, that is to polish the surface for electroplating before carbon deposition and electroplating of copper, hence the extra cost.
 
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Online asmi

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Re: General PCB Manufacturing Pros and Cons
« Reply #56 on: August 12, 2017, 01:47:27 PM »
Don't judge allpcb price by the instant quote. They will bump it by a random amount after you already paid, and ask you to pay more. At least that's what they did to me on a pretty simple board.
I used their service few times (admittedly before they've dumped subcontracting business and became a manufacturer), and what you're describing only happened once, and even then we quickly resolved situation to my satisfaction. So I can't say anything bad about them from my experience - other than they don't seem to support Gerber x2 format and work with older one.
« Last Edit: August 12, 2017, 01:51:29 PM by asmi »
 

Offline Kean

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Re: General PCB Manufacturing Pros and Cons
« Reply #57 on: August 12, 2017, 11:52:20 PM »
Additional cost per BGA could be related to e-testing.  They might have to use a higher spec flying probe machine for some BGA pad layouts.
That additional cost seems somewhat exhorbitant though.  I imagine they want to always cover costs (+ a good margin) on these more advanced designs ... while they still can.
 

Online asmi

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Re: General PCB Manufacturing Pros and Cons
« Reply #58 on: August 13, 2017, 12:37:29 AM »
Additional cost per BGA could be related to e-testing.  They might have to use a higher spec flying probe machine for some BGA pad layouts.
In this case it would be a flat fee, and I would be OK with that (as long as it's reasonable). But per-package fee is something really weird.
 

Online GreggD

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Re: General PCB Manufacturing Pros and Cons
« Reply #59 on: August 13, 2017, 01:17:08 AM »
Options for UL markings and certificate of conformance.
 

Online asmi

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Re: General PCB Manufacturing Pros and Cons
« Reply #60 on: August 13, 2017, 02:10:39 AM »
It's common in China that they charge you not only based on their cost, but also on your estimated profit from their service. Basically more BGA means higher tech, and higher tech means more profit.
By this way, they can offer lower cost to low tech DIYers to spread their name, and recoup the cost from established high tech corporate customers.
Well my profit from my boards is zero. I'm totally willing to share that profit with them if they so desire. Damn, I can give them the whole 100% of that profit! :-DD
 

Online blueskull

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Re: General PCB Manufacturing Pros and Cons
« Reply #61 on: August 13, 2017, 05:32:33 AM »
It's common in China that they charge you not only based on their cost, but also on your estimated profit from their service. Basically more BGA means higher tech, and higher tech means more profit.
By this way, they can offer lower cost to low tech DIYers to spread their name, and recoup the cost from established high tech corporate customers.
Well my profit from my boards is zero. I'm totally willing to share that profit with them if they so desire. Damn, I can give them the whole 100% of that profit! :-DD

For that case, PCBWay has an sponsorship discounting. Basically you sign an agreement with them stating your PCB work is not funded, and you agree to provide them with a photo including your acknowledgement to their service and your final physical board. They can give you a heavy discount.

Check out here: https://www.pcbway.com/project/sponsor/

There are some really cool projects.
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Online asmi

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Re: General PCB Manufacturing Pros and Cons
« Reply #62 on: August 13, 2017, 01:15:24 PM »
For that case, PCBWay has an sponsorship discounting. Basically you sign an agreement with them stating your PCB work is not funded, and you agree to provide them with a photo including your acknowledgement to their service and your final physical board. They can give you a heavy discount.

Check out here: https://www.pcbway.com/project/sponsor/

There are some really cool projects.
I looked at that, and they seem to require photos of the project before getting sponsorship. But how am I supposed to have them, if I don't have the board?
 

Online blueskull

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Re: General PCB Manufacturing Pros and Cons
« Reply #63 on: August 13, 2017, 01:26:42 PM »
I looked at that, and they seem to require photos of the project before getting sponsorship. But how am I supposed to have them, if I don't have the board?

It requires a cover picture upfront, can be anything, not exactly the finished project.
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