UPduino 2.0 - first aid after broken USB socket pad - Page 1
Forum section: electronics / repair

author: iMo
author_rank: Super Contributor
timestamp: March 10, 2021, 01:35:18 pm
content: Frankly, I do not like those tiny USB connectors..So after maybe 10 insertions in total the usb socket casing's fin broke off the pad - after a re-soldering and subsequent insertion the pad copper broke off the pcb..The usb socket casing solder pad is something like 1x1mm large on this board..As I like the module I decided to save its life somehow fast - the first aid I have applied is similar to a front line surgery, howeverI cleaned up the pcb around the pads and put larger tin blobs to fasten the socket casing firmly to the copper.I fired up the module and burned my finger.. NOT a good idea..After some studying the pcb layout in the Eagle I recognized the upper fill is actually +3.3V so I shortened it against GND.Thus I decided to cut the the 3.3V parts off the socket casing pads - see the final cuts below - two on the top, and one on the bottom side.Now it works somehowagain..

author: Ian.M
author_rank: Super Contributor
timestamp: March 10, 2021, 01:47:35 pm
content: You seem to be mighty proud of your gratuitous bodgery. IMHO when mechanical fixing pads start peeling off a more considered approach is required.<snark>Have you ever heard of Epoxy glue?</snark>

author: iMo
author_rank: Super Contributor
timestamp: March 10, 2021, 01:56:03 pm
content: There was/is already the epoxy glue - between the fiber glass and the copper foilA beefy tin blob holds better than an epoxy glue drop, imho

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 10, 2021, 01:57:29 pm
content: they don't care about ground soldering (I mean the external connector casing) for those connectors, that's why all the mechanical resistance comming from those 2 spots is my first soldering job when I get some cheap pcb like this.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 10, 2021, 01:59:55 pm
content: Quote from: Ian.M on March 10, 2021, 01:47:35 pmusually on other side you got also GND fill, if you make 2 holes and add wire from connector case to the other side of that pcb, no gluewhat did you expect, french are cheap bastards

author: iMo
author_rank: Super Contributor
timestamp: March 10, 2021, 02:06:48 pm
content: Frankly, the way how those tiny smd usb sockets are actually mounted on the pcbs isa tragedy..On the other hand it supports the intention towards the "planned obsolescence"..

author: Ian.M
author_rank: Super Contributor
timestamp: March 10, 2021, 02:22:11 pm
content: Clear and white ceramic filled epoxies are non-conductive when cured. You can therefore reinforce round the sides and rear of the connector with a fillet of glue giving a much larger surface area for board adhesion than the poorly designed pad, which never had a chance once it was overstressed, probably cracking its bond to the PCB, then resoldered, letting hot flux under its edges to attack the remaining bond. Depending on the connector you may also be able to epoxy bond its underside to the board without risking epoxy penetration into its interior. When epoxy bonding, cleanliness is not next to godliness, its *FAR* more important as proper surface preparation is crucial. Any flux residue will guarantee failure.Its known to be difficult to reliably epoxy bond copper. IMHO its a near miracle that our familiar copper PCB tracks and pads adhere as well as they do, especially during soldering. Seehttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC6384627/for a review of the extremely complex chemistry required to get a reliable bond between copper foil and FR4 prepeg.@perieanuo,Yes, I thought about mentioning the use of an added thru-hole wire reinforcing hoop over the connector, but as Imo had already said the pad was only 1mm with a directly adjacent 3.3V plane, I thought it was unlikely to be practical.

author: iMo
author_rank: Super Contributor
timestamp: March 10, 2021, 02:39:22 pm
content: Even the insertion forces with the latest usb connectors are higher, imho, (ie. than with the usb socket stuff we used to use 10y back) the pcb mounting becomes more and more fragile.. Some time back I only ordered ie. Bluepills and other boards having the smd usb sockets with through hole mounting fins.Epoxy would help, but it must be applied before the soldering - between the copper and the socket, and then UV cured.

author: iMo
author_rank: Super Contributor
timestamp: March 10, 2021, 03:37:23 pm
content: Quote from: Ian.M on March 10, 2021, 02:22:11 pmThus the best pcb material was manufactured till early 90ties..