Puce
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POE HAT connector broken

Tue Aug 21, 2018 11:28 am

I have received the new POE HAT today.
It's working nicely but when removing it to add the mechanical spacers I noticed the small 4 pin connector stayed on the Pi.

This connector is a very weak point, see picture

Image
At least some glue should be added between SMD connector and PCB

OTH on top of the POE HAT I need to add the Sense HAT but I don't see how it could be done

Thanks.

hippy
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Re: POE HAT connector broken

Tue Aug 21, 2018 12:24 pm

Puce wrote:
Tue Aug 21, 2018 11:28 am
This connector is a very weak point
That doesn't surprise me. Any board I have ever built where pin connectors are soldered facing the other board, where there can be a large amount of force trying to rip them from their solder pads while pulling boards apart, has always failed in short order.

In my experience it is common for the solder pads to separate from the PCB; the pads departing with the connector and its soldered joint. It's simple laws of physics really; the force needed to separate the pins from the connectors is greater than the force needed to break the solder joint or detach solder pads from the PCB.

Connectors which have lugs to hold them against the other side of the board sometimes fare better but not always.

Puce
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Re: POE HAT connector broken

Tue Aug 21, 2018 12:57 pm

Note that I got both failure mode on the same connector ;)
- 2 solder joints failure
- 2 pads remove from PCB

:o

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mahjongg
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Re: POE HAT connector broken

Sun Aug 26, 2018 5:34 pm

That would happen when you won't lift the POE HAT straight up from the PI, it seems indeed the weakest link, but this header is structurally no different than the main 40-pin connector, its just that if you don't pull the board off straight, you can put a lever effect on it that rips the smaller connector right off the board.

I suggest that a drop of super glue dripped on the hole where the plastic pin sticks through the board will strengthen the mechanical connection if you plan to remove the POE HAT often, but more important is using the right way to lift off the POE HAT, I suggest putting a flathead screwdriver between the 4-pin pinheader and this connector to assist in separating both boards.

Another HAT can be put on the POE HAT, (specific details have been changed to make that possible) and how to do that is described on the BLOG.
the trick is to use a specific pin header extenders with longer pins that stick through the holes of the POE HAT 40-pin female "transparent" push-through connector. for this 4-pin connector a similar extender (type SSQ-102-01-G-D) is needed, its all described in the blog here;
https://www.raspberrypi.org/blog/introd ... t-poe-hat/

If I'm allowed to give the producers of the POE HAT a TIP, I would enlarge the solder pads for the 4-pin connector, at least to double the current size, perhaps with a few via's around them, and I would either add a drop of glue, or melt the plastic pin of the 4-pin connector, but yes it would only mitigate the problem, as it will always be possible to lever the connector off.

hippy
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Re: POE HAT connector broken

Sun Aug 26, 2018 6:40 pm

My tip would be to not use a surface mount header for the 4-pin connection, fit normal PTH headers and solder those from the top side of the board. I can't see there being many reasons why anyone would want to extend those pins to another HAT or Add-On.

And I would strongly suggest including an instruction sheet with the board explaining how to remove the PoE HAT without damaging anything if necessary.

Any instruction sheet will probably be long lost and forgotten before most people would come to take a PoE HAT off a Pi. And some people might receive a Pi fitted with a PoE HAT but without the instruction sheet. So it would be best to silk-screen a warning on the board that the instructions must be followed or damage may occur. The Product Compliance team should know the exact requirements to avoid product liability claims. Missing silk-screening can always be added using a sticker.

jamesh
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Re: POE HAT connector broken

Mon Aug 27, 2018 7:13 pm

hippy wrote:
Sun Aug 26, 2018 6:40 pm
My tip would be to not use a surface mount header for the 4-pin connection, fit normal PTH headers and solder those from the top side of the board. I can't see there being many reasons why anyone would want to extend those pins to another HAT or Add-On.

And I would strongly suggest including an instruction sheet with the board explaining how to remove the PoE HAT without damaging anything if necessary.

Any instruction sheet will probably be long lost and forgotten before most people would come to take a PoE HAT off a Pi. And some people might receive a Pi fitted with a PoE HAT but without the instruction sheet. So it would be best to silk-screen a warning on the board that the instructions must be followed or damage may occur. The Product Compliance team should know the exact requirements to avoid product liability claims. Missing silk-screening can always be added using a sticker.
Instructions on removing the POE Hat are here, and cover this point.

https://www.raspberrypi.org/products/poe-hat/
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davidclancy
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Re: POE HAT connector broken

Tue Aug 28, 2018 4:24 pm

I to have just received my POE Hat and had the same issue of the 4 pin connecter separating from the board. IMHA it should have through hole connectors to avoid this issue. I have asked for a replacement and this is not an issue, but I fear the same thing will happen again, its unavoidable. Does anyone have any suggestion’s for a DIY fix with the currant design. I am sure they will modifie the hat if enough people complain.

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mahjongg
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Re: POE HAT connector broken

Tue Aug 28, 2018 4:48 pm

Its not "unavoidable", (I don't believe that at all) as long as you are a bit careful, Maybe someone can publish a youTube video to demonstrate how to do it. But I do agree that the solder-pads with which the connector is soldered to the board are a bit small. Call it teething troubles, which will be fixed.
A pin through hole variant of this low profile connector does NOT exist, and besides there are some people who need the possibility to extend the 4 pins, so they can tap-off, or just measure, the POE voltages, (using the same method as extending the GPIO header so they can use a HAT on top of it).

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Re: POE HAT connector broken

Tue Aug 28, 2018 5:30 pm

jamesh wrote:
Mon Aug 27, 2018 7:13 pm
Instructions on removing the POE Hat are here, and cover this point.

https://www.raspberrypi.org/products/poe-hat/
It might be worth adding a clear warning that if care isn't taken it can lead to permanent damage otherwise it's quite foreseeable that advice to 'take care' may be taken to be no more important than the usual' take care' warnings which accompany any product.

IMO it's always best to point out the adverse consequences of not following the advice to better ensure people follow it. Otherwise people may tend to believe it's there "simply because Heath and Safety rules demand it" and don't realise, no, it is a far more important warning.

That was an issue in the infamous McDonald's 'Hot Coffee' case; everyone knew what "hot" meant, but no reasonable person would take that as a warning it would be as as hot as it actually was. A "Very Hot - Danger of Scalding" warning would have been more appropriate.

I would still include it on a leaflet with the PoE HAT anyway, and silk-screen a warning on the board, because most people won't refer to the manufacturer's website or documentation before fitting or removal otherwise, because there's no instinctive reason to do so. I can't remember exactly what CE rules say about product documentation and warnings but would have thought a business like the Foundation would be including some compliance documentation anyway.

But that's just my opinion.

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Re: POE HAT connector broken

Tue Aug 28, 2018 5:44 pm

mahjongg wrote:
Tue Aug 28, 2018 4:48 pm
there are some people who need the possibility to extend the 4 pins, so they can tap-off, or just measure, the POE voltages
If there is a further revision of the PoE HAT manufactured; it may be worth including "PP" test points or other solder pads on the top of the board to make it easier for people to measure voltages.

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Re: POE HAT connector broken

Mon Mar 04, 2019 2:56 pm

If you want to fix this here is what I would try.

Scrape away the soldermask from the remaining tracks/vias leading to the now missing pads.

Glue the connector to the board and re-solder the two intact pads.

Carefully solder some bits of thin (30AWG or so) wire between the remaining vias and the pins of the connector.

hippy
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Re: POE HAT connector broken

Mon Mar 04, 2019 4:36 pm

XimenaR wrote:
Mon Mar 04, 2019 11:15 am
hippy wrote:
Tue Aug 28, 2018 5:30 pm
I would still include it on a leaflet with the PoE HAT anyway, and silk-screen a warning on the board, because most people won't refer to the connectors market website or documentation before fitting or removal otherwise, because there's no instinctive reason to do so.
Interesting use of color tags there, presumably intended to hide your spamming link while deliberately misquoting what I wrote.

The post has been reported.

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Re: POE HAT connector broken

Mon Mar 04, 2019 4:50 pm

hippy wrote:
Mon Mar 04, 2019 4:36 pm
XimenaR wrote:
Mon Mar 04, 2019 11:15 am
hippy wrote:
Tue Aug 28, 2018 5:30 pm
I would still include it on a leaflet with the PoE HAT anyway, and silk-screen a warning on the board, because most people won't refer to the connectors market website or documentation before fitting or removal otherwise, because there's no instinctive reason to do so.
Interesting use of color tags there, presumably intended to hide your spamming link while deliberately misquoting what I wrote.

The post has been reported.
I have no idea how you spotted that, but thanks! Going to delete all this persons posts - the nuke from orbit, it's the only way to be sure approach.

edit: three from 5 posts had edited in links in to the quotes. I would swear now, but this is a child friendly forum.
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hippy
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Re: POE HAT connector broken

Mon Mar 04, 2019 5:20 pm

jamesh wrote:
Mon Mar 04, 2019 4:50 pm
I have no idea how you spotted that, but thanks!
I mostly use white-on-black themes and 'ignore page colour settings' in my browser - Anything people try to hide by making them blend into the background usually stands out like a sore thumb. I prefer it that way and it helps with spotting spam links on forums I admin.

Deviously hiding the link in a quote was fairly clever; one would normally assume it was in the original. They would have probably got away with it if they hadn't picked one of my posts to fake.

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