Calculating PCB Thickness

Hi there, a time ago I also had some issues trying to glue some "difficult" plastics together: you can go the hard way (which I actualy did) or call the tech department of an adhesive manufacturer: Loctite, Cianamid, Casco, etc.

After many trials (and more errors) I finally called Loctite: they sent me a couple of samples as well as an technical advisor; finally solving the problem.

I also learned that some materials need to be primed (there are may types of primers) before being glued

Best luck!

PCB material is available in standard thicknesses eg FR4-Cu double sided at 1.600mm, are you able to consider off-the-shelf materials, or is this for a custom multi-layer board?

Agreed!! FR4 is the industry standard (used for double sided boards and other multi layered boards). FR4 refers to the material (aka dielectric) used between opposite sides of the board. If you are thinking of low frequency stuff ballpark... below one GHz, I would not worry about it. (although in VHF work say 500 MHz, I do).

If you have to do 50 ohm transmission line and emulate capacitors or inductors on a PCB the dielectric constant is pretty important. In this region, I would worry little about the glue.

But in bunches of GigaHz, well... I have no opinion...

Bill

Hi

I never thought about it but technically the answer would be 'yes'...but it's *extremely* thin, even at *very* high RF frequencies (GHz), and IMHO you can neglect it.

CADCAM: Mentor is sort of a standard, but it depends on what you're doing.

RF_guy

My personal opinion would be to understand the application where the PCB is being used. If it is in a static/mild thermal environment, I would suggest sticking to stock material, but if the application is calling for encapsulating in harsh environments I would suggest understanding the thermal characteristics of the materials and use structural stress type software to determine the thickness. We use MathCAD for FEAs (Finite Effects Analysis). Hope this helps.

Hi :)

The vast majority of PCB's are 1.6mm thick, though 0.8mm, 2.4mm, 3.2mm are all common. The thickness depends on your application, if you have particularly heavy components, or a large board, then you may want to go thicker than 1.6mm.

PCBs are available with different numbers of layers - onto which copper tracks and areas are formed. The fabricator will take your PCB thickness and the number of layers and work out how thick the individual layers need to be - including prepreg/glue. You don't need to worry.

Second thought!! Do not do the design with PCB thickness as a variable. Buy off the shelf components. .0625 inches thickness is common in the states.

You can't assume it will be 0.0625 inches (~1.6 mm) even in the US. If those raw PCBs are made in Asia (very likely) and imported into the US they will be made to the international standard metric sizes.

They may be labeled in inches to satisfy the American market, but the Asians are not going to have two separate production runs, one for 95 % of the world and the other for the remnant 5 %. As long as they are stated in inches on the paperwork, no one in the US will be the wiser that they are hidden metric.

The Chinese did this with panel boards. The old 4 x 8 foot size (=1219.2 mm x 2438.4 mm) is made to a standard 1220 mm x 2440 mm. This is the new nominal size. The same type of changes to rounded metric numbers happens all of the time when products are sent to Asia to be made. Yet no one in the US is the wiser.