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Or does it vary? This is a reference request for ridged PCB thickness. Email from a US manufacture:

This is from the board house.

Your customer has a profile (routed pcb outline) tolerance of +/- 0.05mm (+.002") which virtually unheard of, though theoretically possible if paid enough to hand sort and tweak the CNC machine in tightly controlled temp and humidty conditions which were agreed upon with customer.

The industry standard for CNC routed profies that are not held in a panel, is +/- .010"

Random other manufacturer:

Board Thickness 0.4-2.4 mm

Only at 0.944" (2.4 mm) does having a 0.01" dimensional tolerance make sense. That is 11%.

https://www.pcbway.com/pcb_prototype/PCB_Manufacturing_tolerances.html

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    \$\begingroup\$ If possible, you should share the full stackup of your board. Finished thickness tolerance depends on a huge number of factors, including the stackup. You can certainly get much better than that - think of any modern portable electronic device, .25 mm tolerance is huge. \$\endgroup\$ Apr 27, 2022 at 15:32
  • \$\begingroup\$ Now I am even more confused. Are we talking of a .25 mm thick PCB? Can you clarify the question please? \$\endgroup\$ Apr 27, 2022 at 20:19
  • \$\begingroup\$ I edited the question with an email I was given. \$\endgroup\$
    – adamaero
    Apr 28, 2022 at 16:21
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    \$\begingroup\$ Are you asking about outline, thickness, or both?? \$\endgroup\$ Apr 28, 2022 at 17:15
  • \$\begingroup\$ I believe Spehro Pefhany wrote the best answer by addressing that. \$\endgroup\$
    – adamaero
    Apr 28, 2022 at 21:08

2 Answers 2

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The email you received refers to outline (contour) tolerance, but you are referring the thickness tolerance. Here is PCBWay's tolerances for standard quick-turn PCBs (JLC is similar):

enter image description here

On thickness the tolerance is +/-10% or +/-0.1mm, whichever is larger.

Outline tolerance is 0.2mm for CNC routing. Note that's tolerance of size, not registration of CNC outline to traces.

Those are fairly low-end makers, for example ChinaPCBOne states an outline tolerance of +/-0.1mm with additional tolerances specified for V-cut remaining thickness and V-cut angle. They are clearly used to dealing with more demanding customers.

The size tolerance from your US maker is 0.254mm (0.01") which is only somewhat worse than the above-mentioned lower-end China makers. For example Sunstone quotes standard tolerance as +/-0.01" and special tolerance as good as +/-0.003" = +/-0.08mm (at some cost premium, of course).

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It varies with supplier. If they can do 1.5-mil trace and space width, the tolerances are much smaller.

More import is reducing the total cost by total volume of copper and next interconnects and special materials & processes.

Here's one estimator

Your comment link is 8 mil overall min thickness which is mainly the dielectric as 2S copper might only include 54 um with 1/4 oz Cu and 1/2 Oz plating.

Thinner is possible with FPC. Both would be very flexible but still limited in stress warp limits with vias. Thinner dielectric and thicker copper on FPC is also possible such as 2oz Cu for power but more costly. Cu void balancing is essential to avoid warp in process.

For GETEK 50 Ohms you would use track Width / dielectric thickness = 2:1

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  • \$\begingroup\$ What about for this one: goldphoenixpcb.com/html/capabilities/rpc.html I'm confused where they say minimum thickness and finish thickness... Is the true minimum thickness 0.008+0.008? \$\endgroup\$
    – adamaero
    Apr 27, 2022 at 15:26
  • \$\begingroup\$ The "Finish thickness" depends on layer count and is consistent \$\endgroup\$ Apr 27, 2022 at 17:18

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