PCB Tab Terminal Force Relief


#1

Hi,

I have 4x 2.8mm vertical tab’s to solder onto the PCB. These are quite small and knowing what users are like they may suffer some sort of lateral force which may in turn lead to failure. I went for dual pin as one mitigating measure but I’m wondering, given I have the space, whether there is a practice to use copper tracks spreading out from the holes to increase strength?

Every little helps!

Andrew


#2

Why not just make the pads bigger. You will need a big iron to solder them anyway


#3

Yes :slight_smile: that’s one way. I take it tracks coming off them won’t make much or any difference in preventing them lifting?


#4

The only thing that helps is solder blobs at front and back really and large areas.


#5

There are horizontal versions of those ? - we have always avoided the vertical tine ones, for the exact reason you mention, of too weak in force tolerance.

Also note traces should exit on underside, or have many vias. Do not rely on plating to carry current, especially on physically stressed connections.

You could look at slots, & oval pads, to make the pins more press-fit. That reduces solder-span asks.

If you cannot use right angle ones, I see some have skewed tines on PCB top, to reduce wobble.
Including those in the solder plan, with a couple of vias might help.
Of course, physics says such a tine makes things stiffer, but also provides a fulcrum to deliver more force to the solder joint… hard to beat simple metal mass here - get the widest tines and thickest… ?


#6

PCB_Wiz,

I’m pretty new to this. Are you’re saying I should create a via (or two) and trace on the rear, is that correct? It is indeed a 4 layer board and layer 2 & 3 are linked to the pad.

There are horizontals but I can’t use them due to waterproofing issues. The ones I’m intending to use have blobs on the sides so downwards force won’t be an issue. I’ll be sure to tell users not to wiggle the buggers!


#7

Yes, multiple vias, and do not rely on tine plating to carry current, or force.
We have used a ring of vias on such “current & stress” entry points.
Bottom soldering you can rely on, so the tine-bottom pad is your main current path - vias fan-out to other layers from there.

Hehe, I like your optimism there…
Any pictures of what you must use ?


#8

Ok first the vias, thanks for that tip. I’ll add some more vias…


#9

Cleaner. :slight_smile:

Good enough?


#10

Looking better, what current is present here ?
Traces look modest for the size of the connector.
I’d use oval holes and oval pads, and use fill on top and bottom with maybe 10 vias .

I like the look of this vertical one (attached keystone 4900) which isolates any rocking effects from the PC joint, and can be top and bottom soldered.


#11

Top tip that, I found a few other places where I was tracing from a middle layer to the plating with higher current. You may have saved some headache!

The 2.8’s I have in mind are these:-

https://www.aliexpress.com/item/100pcs-lot-2-8-feet-circuit-board-insert-PCB-solder-insert-terminal-free-shippng/32813641767.html

TE doesn’t make them like that (2 legs), only for larger sizes.

The one you posted looks reasonable but also like it may fracture. AS it happens I need 2x 4.8’s so they could work for that. I do like that they can be soldered on the top!

I haven’t played with oval holes before, is that something I’ll have to run by the fab company first?

Current to the tabs is max 1.7A.


#12

The neck isolates the PCB from loom flexing, but yes, extreme flexing would fracture in an obvious place.

Just send them a test file, usually slots are quite common and have no issues.

Seems they have no definite seating on the PCB, rely on that inner radius.

These ones seat better
https://www.aliexpress.com/item/100pcs-2-8-Inserts-Plug-Spring-Terminal-PCB-Solder-lug-type-thickness-0-5mm-two-legs/32707169900.html?spm=2114.search0104.3.1.45ee6cd6ph89sa&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10151_10065_10344_10068_10342_10547_10343_10340_10548_10341_10084_10083_10618_10307_5711215_10313_10059_10534_100031_10103_10627_10626_10624_10623_10622_5711315_10621_10620_5722415,searchweb201603_41,ppcSwitch_3&algo_expid=724cdb34-7a6c-4ec0-aa5e-3922502bf5ac-0&algo_pvid=724cdb34-7a6c-4ec0-aa5e-3922502bf5ac&priceBeautifyAB=0

and there are also this design in 2.8 (keystone 4917,4916)

  • 3 legs and an angle tab (come 30’ and 60’ choices), tho higher price.
    Looks good enough to go down a paste-reflow line, if you have SMD flows ?


#13

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