PCB board thickness - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: August 22, 2014, 12:31:08 pm
content: Hi Everyone,I noticed that itead gives a ton of options on pcb thickness. 0.4/0.6/0.8/1.0/1.2/1.6/2.0mm. What is the benefit to all of these? Why would they (the pcb manufacturer) want to stock and deal with all of the different sizes?Thanks,Alan

author: Ribster
author_rank: Frequent Contributor
timestamp: August 22, 2014, 01:40:12 pm
content: Most commonly is the 1.6mm one. If you want to use your board as USB stick, you can use the 2.0mm thickness.That way the pads of your pcb are the connections for USB.

author: Sebastian
author_rank: Regular Contributor
timestamp: August 22, 2014, 03:02:45 pm
content: If you are using a 2 layer board and you need transmission lines you probably have to use a thinner board to be able to achieve the characteristic impedance without unreasonably wide traces.

author: mazurov
author_rank: Frequent Contributor
timestamp: August 22, 2014, 03:06:29 pm
content: Also, thinner boards conduct heat better - could be useful for integrated power supplies and other heat-producing circuits.

author: tszaboo
author_rank: Super Contributor
timestamp: August 22, 2014, 03:16:52 pm
content: Such that Dave can make front panel from PCB. There are dozens of reasons to choose something other than 1.6mm. The 2mm one nicely fits into the 2mm standard slot hole. There are different PCB edge connectors. The 0.4mm is lighter than the others. Layers are closer to each other, so if you need a controlled impedance, than you don't need stupid wide traces.

author: alank2
author_rank: Super Contributor
timestamp: August 22, 2014, 03:23:29 pm
content: Does the strength of a pcb come into play? I have to wonder if a 0.4mm thick pcb is more prone to cracking, being weak, etc.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 22, 2014, 03:32:27 pm
content: Normal : 1.6mmNeed more rigidity (e.g. for heavy parts) : 2.4 , 3.2 or 4.8mmNeed smaller size or some flexibility : typically 0.8,0.6 or 0.4mm.Other thicknesses are also available but less common

author: DanielS
author_rank: Frequent Contributor
timestamp: August 22, 2014, 04:47:45 pm
content: Another reason for having multiple PCB thicknesses available is for composing multi-layer boards: PCB manufacturers already have 0.4/0.6/0.8mm boards in stock because you need two of those and an extra prepreg core in-between to make a four-layer board. Ex.: a 1.6mm four-layer board may have a pair of 0.4mm boards and a 0.6mm core or possibly a pair of 0.6mm boards with a 0.4mm core.

author: German_EE
author_rank: Super Contributor
timestamp: August 22, 2014, 05:55:06 pm
content: 2mm is nice for front panels.1,6mm is the standard thickness.Thinner than 1,6mm is handy if you are building something that has to be thin such as a PCMCIA card or a mobile phone.

author: Neilm
author_rank: Super Contributor
timestamp: August 22, 2014, 06:13:47 pm
content: 3.2mm thickness is often used if you are expecting high g shocks or vibrations. Quite often military stuff will be that sort of thickness. I saw a 1.2mm board going though a vibration trial - it bowed so much it snapped in half

author: Precipice
author_rank: Frequent Contributor
timestamp: August 22, 2014, 06:29:47 pm
content: If you're solving vibration issues that bad by stiffening up the PCB, odds on you're doing it wrong...Aside: You can put quite a bend into a 0.4mm PCB if you need a curve, and don't do it repeatedly (and take great care to avoid popping large components off the board). Gluing stiffeners where the chips are, and allowing flex elsewhere, is cheap and sometimes useful. Rather cheaper and less annoying than proper flex-PCBs, too.

author: SirNick
author_rank: Frequent Contributor
timestamp: August 22, 2014, 07:19:20 pm
content: Thick PCBs are also used as daughter cards. Take an enterprise router for example. There will be a vertical backplane board made of thick PCB to provide rigidity during insertion and removal, and the modules will be thick to withstand the insertion force applied to the connector on the end.

author: DanielS
author_rank: Frequent Contributor
timestamp: August 22, 2014, 08:53:41 pm
content: Quote from: SirNick on August 22, 2014, 07:19:20 pmThe multiple ground and signal planes necessary for all those custom BGAs, FPGAs, high-speed IOs, etc. plays a significant role in the thickness too: it is not uncommon for those boards to have 10+ layers. In some cases, they have to add layers simply because surface-mount capacitors and their connecting traces/vias are too inductive to get the job done on their own.

author: zapta
author_rank: Super Contributor
timestamp: August 23, 2014, 01:41:31 pm
content: I designed recently a few breakout boards (sub square inch) and with 1.6mm thickness they look overkill and disproportional. Next time I will order with thinner material.