Tried/tested small solder bridge shapes? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: July 06, 2018, 11:26:51 am
content: Despite removing the 'solder mask', and despite having exposed tinned pads only 0.2mm apart, I find small solder bridge shapes don't work well. They are hard to bridge.It will relate to the fact I'd like small 'SMD scale' bridges (0805 scale or less) so there is not much space for solder to stick anyway.Apparently, good designs work 'with' the surface tension?

author: Benta
author_rank: Super Contributor
timestamp: July 06, 2018, 11:39:05 am
content: They're called 0 ohm resistors and come in all shapes (leaded, 0805, 0603 etc.)

author: 741
author_rank: Frequent Contributor
timestamp: July 06, 2018, 02:09:16 pm
content: Yes, I have considered these as an alternative already.Additional noteThey are certainly a possiblity.The application is a prototyping board, and there might be a lot of these 'links'. I think solder blobs are easier to change (i.e.remove) than a 0-Ohm link, and faster to create. Also, they self-document (easy to see they are simply 'wire', not a resistance).On the other hand, the ready-made link is neat and repeatable.I don't know what other arguments there are for/against - I am unsure which method to use at present.I do note that 'solder bridges' still make an appearance on prototyping boards from (eg) TI, Microchip.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: July 06, 2018, 02:57:37 pm
content: I use this, which is about 0805 footprint.

author: tooki
author_rank: Super Contributor
timestamp: July 06, 2018, 03:01:59 pm
content: Quote from: 741 on July 06, 2018, 11:26:51 amI haven't tried them out, but I saw some jumper pads on a board recently where the gap is chevron-shaped. I would expect that this provides a much better foundation for a blob of solder than parallel lines. I found a picture online that looks like what I saw, attached.While googling, I also saw some that use nested parallel pads, also attached. (The one at top right seems like the usual hard-to-use jumpers, while the others are nifty.)

author: Zero999
author_rank: Super Contributor
timestamp: July 06, 2018, 03:17:11 pm
content: Quote from: Benta on July 06, 2018, 11:39:05 amOr a thin piece of wire. I don't know why people use solder blobs to connect anything. It's not the right way to do it!

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: July 06, 2018, 03:38:09 pm
content: Quote from: Hero999 on July 06, 2018, 03:17:11 pmIt looks like the crufty 1980s way to set some sort of parameter that doesn't change often enough for a DIP switch.Ah, nostalgia.

author: DaJMasta
author_rank: Super Contributor
timestamp: July 06, 2018, 04:34:16 pm
content: I like the idea of using solder blobs, but modern solder mask just does its job too well..... you have to heat the board up considerably and put on a lot of solder to be able to bridge even and standard 0603 footprint.... so I've just moved to resistors. Looks a tiny bit cleaner than bits of wire and honestly, for the small amount of time it takes to strip a bit of wire and makes 100 jumper links.... 100 zero ohm resistors is still cheaper than the value of the time. I bought myself a reel of 0603 zero ohm resistors for like $5 and will be set for life.

author: 741
author_rank: Frequent Contributor
timestamp: July 09, 2018, 11:19:36 am
content: I noticed the chevron shape somewhere also, looks good (and simple to create)

author: 741
author_rank: Frequent Contributor
timestamp: July 09, 2018, 11:22:51 am
content: The solder blob is (perhaps) not so physically secure as a wire, but I think the overall resistance would perhaps be simialar to a wire jumper.Part of the reason to 'blob' is space restrictions.

author: sleemanj
author_rank: Super Contributor
timestamp: July 09, 2018, 11:39:19 am
content: I can't imagine I'm the only one who always has trouble getting a bridge when you WANT a bridge, but no trouble at all getting a bridge when you don't.Anyway I just use a couple half circle pads like this...---(| |)---minimum space between them, nothing fancy.As for why to use them, just for configuration stuff, so it can be changed without needing to dig out a 0 Ohm link or whatever.

author: SeanB
author_rank: Super Contributor
timestamp: July 09, 2018, 04:50:49 pm
content: For configuration changes, where you are going into a MCU pin or some other logic level, just use a low value resistor you already have on the board. Cheap enough, and no need for a feeder extra, and as an added bonus if you need to quickly during test force a logic level change a resistor over 330R will survive 5V applied to it allowing this. Bonus is the extra resistance reduces the chances an ESD event can drive the chip into latch up.Another advantage is that you can have solderless opening of the configuration by simply crushing the resistor.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 09, 2018, 05:08:31 pm
content: Half discs are fine for solder jumpers. If properly spaced, they are very easy to bridge manually, provided that you use the right solder wire diameter. Of course too fine a wire (and soldering tip) will not work right and you will want to scream, so the key really is the solder wire and the right tip.One thing to consider when designing those solder jumpers' footprints is to try and make cutouts for solder mask in between the pads. If there is solder mask in between, they will be a lot harder to bridge.