Forgot to put thermal reliefs on Layer 2 of 4 layer PCB - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: July 10, 2022, 09:52:44 pm
content: Hi,I have done a 4 layer board with 1 oz copper, 1.6mm thickness. (2000W PFC’d LLC)There are six ECWFG2J105J film caps on it. Unfortunately I forgot to put thermal reliefs on the Layer 2 of this capacitor’s ground pin. (I remembered it for the other three layers)Pictures as attached...(and gerbers as attached)ECWFG2J105J datasheet:https://industrial.panasonic.com/cdbs/www-data/pdf/RDL0000/RDL0000C245.pdfI haven’t got the boards yet. When they arrive, will it be possible to solder these capacitors on? What is the cheapest “local heating” instrument that you can buy to heat this pin as I solder it? Some sort of mini hot-air gun sounds good?

author: jpanhalt
author_rank: Super Contributor
timestamp: July 10, 2022, 10:46:56 pm
content: I have no problem soldering TH anything to a layer without "thermal reliefs." I use my regular Edsyn Loner soldering iron, not my 80W one I used for tin flashing.

author: Faringdon
author_rank: Super Contributor
timestamp: July 10, 2022, 10:53:12 pm
content: Thanks, the Edysn Lonerhttps://www.edsyn.com/product/951SX.html...is rated to 220W. So i guess 60W (+30W) isnt going to be enough?....i suppose its only the inner layer that didnt get thermal relief'd.....so that'll be easier to heat up and keep hot......also, the spec of the PCB i chose was "1oz"...but i always thought that "1oz" 4 layer boards actually always had "1/2 oz" on the inner layers anyway?......(unless you specifically request they be plated up to 1oz?).I must admit this board is only prototype, so when i saw the price of £180 for 5 boards, i took it and didnt care whether inner layers were half or one ounce.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 10, 2022, 11:22:37 pm
content: It's temperature controlled. My 80W monster is huge and just gets hot. I have also used a 25W, Weller non-temp controlled iron on boards without thermals and on NiCd batteries without problems.

author: eugene
author_rank: Frequent Contributor
timestamp: July 11, 2022, 03:44:46 pm
content: Starting with the diode at one end, it will take a while to heat up. After that, the plane layer will be hot so the next nearest component will solder easily.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 11, 2022, 03:58:01 pm
content: For the capacitors soldering is not that bad. It could be a slight challange of the capacitors are PP or PS type and thus relatively temperature sensitive - still a good chance they would survive, as least if the leads are a little longer.For the soldering iron it is no so much about the power, but more about the tip and starting at high enough a temperature. Using leaded solder would also help.So a regular temperature controlled 40 W soldering station set to some 400 or 450 C should be OK. A cheap non regulated one may not start very hot. If you need to buy a new tool, I would look for a cheaper regulated one with a heay tip - the offers may vary locally.One may even get away with just a new tip for the existing iron. If desparate use 2 irons, one to preheat and the 2nd for the actual soldering, so starting hot and different from normal use with liquid solder on the tip.

author: Faringdon
author_rank: Super Contributor
timestamp: July 20, 2022, 06:33:06 am
content: Thanks,To let anyone know, i just soldered the cap in easily with no more than a cheap unregulated 20w iron and leaded solder.0.6mm tip...i kind of layed the flat "line" of the tip on the solder on the pad to give more "area" for heat transfer.I sometimes wonder if the IPC recomendations on thermal reliefing are a bit overdone.

author: Zero999
author_rank: Super Contributor
timestamp: July 20, 2022, 07:30:59 am
content: If it's tricky to solder, pre-heat that section of the board with a heat gun first.

author: Faringdon
author_rank: Super Contributor
timestamp: July 20, 2022, 07:36:44 pm
content: Thanks, but it ended up being simple with a 20W iron....i shouldnt have bothered with any thermal reliefing at all it seems

author: jpanhalt
author_rank: Super Contributor
timestamp: July 20, 2022, 07:55:32 pm
content: There are times I have intentionally not had thermals (Eagle) for high currents. At other times, I modify it. You are not stuck with the standard thermal. You can increase the size of the connections in Eagle.

author: Faringdon
author_rank: Super Contributor
timestamp: July 21, 2022, 05:31:15 pm
content: QuoteThanks, yes, though if you increase the thermal relief thickness for one component, it then does that increase for all components?ie, it a global increase.?