Trace Width along the path to next component - Page 1
Forum section: electronics / beginners

author: Falcon69
author_rank: Super Contributor
timestamp: September 04, 2014, 12:04:20 am
content: Can the trace on a pcb be lessened in width as it goes down it's path to the next component?Or does it need to stay the same? I wouldn't think it would have the same current going through it from one component to the next.Something like, the first trace between ground (or power) and component one (for example) would be 1.3mm, then between one and two would be 1mm, then between two and three would be 0.7mm, then between three and four would be 0.4mm, etc. This of course would be if each component, like a resistor, was the same value and had the same voltage/current draw.

author: kizzap
author_rank: Unknown
timestamp: September 04, 2014, 12:20:47 am
content: the resistance of the trace is going to increase as you decrease the width. That will mean that you might increase heat at a certain point, and all that nasty stuff.If you have any significant current flowing, I would suggest not thinning down the trace, but giving as much allowance as possible/reasonable as you can.

author: Falcon69
author_rank: Super Contributor
timestamp: September 04, 2014, 12:26:46 am
content: The trace carries a max of 2.06A when all 8 components are on. thus, each branch will carry roughly 258mA of power.I asked this, because I was trying to save circuit board space.

author: tautech
author_rank: Super Contributor
timestamp: September 04, 2014, 12:34:17 am
content: By all means if as you say the current diminishes ~250 mA per device, step trace width down accordingly as you supply each device.I have often seen this done on PCB's.

author: Falcon69
author_rank: Super Contributor
timestamp: September 04, 2014, 12:41:06 am
content: Ya, that is what I was asking tautechSomething like this.The bottom trace is power, the top is ground.According to the trace width calculator, 0.81mm width at 1oz. copper is suffice for 2.06A. I have the trace at the start drawn at 0.95mm and reduces as it goes down it's path.

author: Rudane
author_rank: Regular Contributor
timestamp: September 04, 2014, 12:45:40 am
content: There is nothing wrong with this. Each trace should be as large as possible within reason. I always look at the current expected on the trace to determine if my width is adequate. I start with big traces in my power supply and decrease them appropriately.Edit: From looking at your design, are you really saving board space?

author: andtfoot
author_rank: Unknown
timestamp: September 04, 2014, 12:48:47 am
content: Just an example of how I read it for clarificationedit: bugger... didn't see the picture in the reply above... Redundant post now.

author: Falcon69
author_rank: Super Contributor
timestamp: September 04, 2014, 12:48:56 am
content: awesome, thank you guys. I will design accordingly.I understand about the heat thing, but these traces won't see a continuous current go through them, except for may just a few seconds. Plus, I have made them larger then they need to be. I may even opt for 2oz. copper boards, just to reduce the voltage drop that may happen.

author: Falcon69
author_rank: Super Contributor
timestamp: September 04, 2014, 12:49:44 am
content: more or less andtfoot. Just like that.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 04, 2014, 11:14:29 pm
content: Quote from: Falcon69 on September 04, 2014, 12:26:46 amsaving space but wasting time and echant. i've done this kind of theoritical thing many2 years ago on plumbing system.

author: tautech
author_rank: Super Contributor
timestamp: September 04, 2014, 11:26:21 pm
content: Quote from: Mechatrommer on September 04, 2014, 11:14:29 pmAnd Tradesman plumbers from another era always did this.The best still do.I have many Km's of piping on my farm and the main piping runs are all large with small feeders supplying the individual loads/troughs.Electrical mains supply networks are no different.PCB's often have power planes....the same principle applies, does it not?When needed, it is good design IMO.