Cost difference between multi layered PCBs?

[treez]

If I have a six layer LED driver PCB of 6 layers, 2 oz copper on every layer..........

what is the approx. cost difference of having different inter layer thicknesses as follows...

0.4mm thickness interleaving board sections
0.3mm thickness interleaving board sections
0.2mm thickness interleaving board sections

 

[andre_luis]

I had noticed some PCB manufacturers ( particularly the most expensives ) providing on theirs webpage online calculator forms which allow perform a quick assesment just providing few inputs as that.

 

[FvM]

Are you talking about pre-pregs in PCB stackup? A standard 6-layer stackup uses two cores (substrates) and three pre-preg layers.

Both can be generally choosen freely within the limitations of pre-products that are available respectively stocked by a PC manufacturer. Most customers are referring to a standard 1.6 mm stackup which is usually cheaper in small quantities because the boards can be made in pool manufacturing. Once you decide for a custom stackup, the price doesn't depend much on the substrate and pre-preg selection.

Online order probably doesn't include full control over stackup details, just number of layers, overall thickness, copper weight and surface finish. You have to talk to the manufacturers.

 

[D.A.(Tony)Stewart]

6 layers of 2oz copper costs will be significant more expensive than 6 std. 0.5 oz plated to 1oz on outer layers.

In volume the biggest cost factor is all based on total copper weight and size. This is why people use selective busbars inserted as a component. DFC rules are extensive and take experience.

 

[treez]

yes I am taking about the stack up.
The thing is, most boards are double sided, so I doubt they will be able to pool our pcb onto a shared panel.

Also, a 1.6mm pcb with 6 layers of 2 oz copper ends up being 1.6mm + (6*0.07) = 2.02mm thick?

 

[D.A.(Tony)Stewart]

sounds like an opportunity for cost reduction

 

[FvM]

Also, a 1.6mm pcb with 6 layers of 2 oz copper ends up being 1.6mm + (6*0.07) = 2.02mm thick?

I overlooked the "2 oz on every layer". That's a custom stackup anyway, substrates and pre-pregs will be assembled by the PCB maker to achieve your favourite end thickness, as far as possible.

The question also suggests that you aren't familiar with the details of PCB production. Multilayer PCB making uses a construction kit of cores (substrates with doublesided copper plating), pre-pregs (half-cured glass-epoxy layers) and copper foils for the outer layers.

A possible problem is the availability of thin substrates with 2 oz copper plating, the pre-preg layers must be at least massive enough to fill the voids of the adjacent 2 oz copper layers (presumed they are not just all-over power planes).

You really should discuss the design with a PCB manufacturer.

 

[marce]

**broken link removed**

 

[candhg124]

As I know, the PCB price will be made mainly according to its layers, inner copper thickness, outer copper thickness, the finished board thickness and its surface treatment and other special requirements, like buried and blind vias. PP will be normally no problem for a PCB maker, but your stackup should be accepted by their PP stock.

If I have a six layer LED driver PCB of 6 layers, 2 oz copper on every layer..........

what is the approx. cost difference of having different inter layer thicknesses as follows...

0.4mm thickness interleaving board sections
0.3mm thickness interleaving board sections
0.2mm thickness interleaving board sections

 

[kozacy]

As far as I know. The total area of the deal(each size of pcb* the quantity ).When the whole area is more than 3 ㎡，the factory will make a fixture for electronical testing,the fee is much expensive than flying probe testing.And so it is almost the same when comes to the NRE fee.
Layers ,outer and inner copper thickness.
Surface treatment: HASL and OSP are cheap.For example ,ENIG is much expensive. And the factory have to know your requirement : the thickness of Gold. 2u" or 3u". The price is not the same.
The board thickness and the mini hole dia , the aspect ratio can be calculated from that . If your aspect ratio is more than 8 for example, it is have something to do with plating,the factory will certainly charge a higher price.
The mini track width and spacing.
The color of solder mask .Mostly it is green solder mask and white silk screen.
The hole density.
Special process: Impedance control/Gold finger/Peelable mask/Gold finger uneven /blind &buried via/via plugging.

Another important factor is base material.We use FR-4(Tg≤170℃）.

I am Roy from China. I have acted as a manufacturing engineer in the pcb industry for 2 years.
Writing in English is not that easy for me.And I will try my best.

 

[mtwieg]

I recently had a large 6L board done with 2oz copper on every layer, and went with a 3/32" overall thickness, as I was worried about bowing. When your copper becomes very thick overall, there is less solid core to keep things rigid. There is extra cost though.

 

[kozacy]

I recently had a large 6L board done with 2oz copper on every layer, and went with a 3/32" overall thickness, as I was worried about bowing. When your copper becomes very thick overall, there is less solid core to keep things rigid. There is extra cost though.

Most of the fabrication houses in China the bow and twist is controlled within 0.75%.I do not know whether it can meet your requirements.:|

 

[treez]

this is an interesting subject, because due to the omnidirectionality of leds, sometimes it would be nice to have a "bendy" pcb, ie, a single pcb with many leds on it which gets bent so that the different leds shine in different directions and therefroe illuminate the whole room...I wonder if such a bendy pcb exists?

 

[marce]

https://www.diy.com/departments/masterlite-led-12w-striplight-l5000mm/841807_BQ.prd

Just nip down to B & Q

 

[treez]

thanks I thought of those strips, but doubt theres much thermal copper on them, at least on the one's ive seen.

 

[mtwieg]

Most of the fabrication houses in China the bow and twist is controlled within 0.75%.I do not know whether it can meet your requirements.:|

I meant bowing from physical stress applied to the board (lots of heavy duty connectors), not residual stress.

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this is an interesting subject, because due to the omnidirectionality of leds, sometimes it would be nice to have a "bendy" pcb, ie, a single pcb with many leds on it which gets bent so that the different leds shine in different directions and therefroe illuminate the whole room...I wonder if such a bendy pcb exists?

Yes you can get FR4 to flex quite if it's thin and you slot it the right way. Do a google image search for "kerf bending" to get an idea. Probably not a great idea for designs with more than two layers.

 

[kozacy]

I meant bowing from physical stress applied to the board (lots of heavy duty connectors), not residual stress.

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Yes you can get FR4 to flex quite if it's thin and you slot it the right way. Do a google image search for "kerf bending" to get an idea. Probably not a great idea for designs with more than two layers.

Really good idea!
And I do not think FR-4 is flexible enough.
And Flex pcb can not sustain the shape.

 

[marce]

I meant bowing from physical stress applied to the board (lots of heavy duty connectors), not residual stress.

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Yes you can get FR4 to flex quite if it's thin and you slot it the right way. Do a google image search for "kerf bending" to get an idea. Probably not a great idea for designs with more than two layers.

Done loads of boards both fully rigid and flexi rigid with lots of connectors for both automotive and military applications with no problems, maybe going up to 2.4mm thick PCB can help.

 

[kozacy]

maybe you should make some samples and have a test on that. What do you think?

I meant bowing from physical stress applied to the board (lots of heavy duty connectors), not residual stress.

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Yes you can get FR4 to flex quite if it's thin and you slot it the right way. Do a google image search for "kerf bending" to get an idea. Probably not a great idea for designs with more than two layers.

 

[D.A.(Tony)Stewart]

about 20 yrs ago the cost of PCB's could be estimated simply as $0.05 /sq.in/0.5oz/layer
so 2 oz. is 4x 0.5 oz.

The FR4 thickness is free for 1mm but dont know about cost up to 8mm.