Netgear GSM7224 Switch might need Reflow / Reballing

[Majestyk]

Hi there,
I have been using this nice 24 port layer 2 switch for a couple of years now. Last week it started to cause serious troubles by rebooting without any reason and by hanging at startup with all the status LEDs permanently lit.

When I press the packet-processor down gently, the booting continues and the LEDs turn off but the unit will not run stable. When pressing down the processor while it is running might cause the unit to reboot.

This looks to me like a case of faulty solderings of the BGA chip, a Marvell 98DX240-BCW. The packet-processor doesn´t have any heatsink atttached to it and gets considerably warm during operation.

The pictures show the packet-processor and it´s surroundings and the bottom side with several capacitors.

I wonder if there´s a reliable way to resolder / reflow or even reball this chip to make sure it will operate stable for another couple of years.

[stj]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

recap it first.

[Majestyk]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

Did that already. The caps on the mainboard are all new. I also checked the ones in the psu, everything´s fine there.

This must be a mechanical / contact issue since the CPU is tender to the touch.

[stj]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

normally it would take more heat than that to mess it up.
if you burned your finger on it then i'd suspect soldering or a bad chip.

[Majestyk]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

I don´t think it is getting THAT hot during normal operation. I don´t know what´s happening on hot summer days under heavy data traffic though.

I´m afraid the soldering was not made perfectly in the factory. Maybe the soldering heat wasn´t appropriate or a solder ball was faulty, maybe the flux had not been dispensed properly.
I have seen similar embedded units before that showed problems with the BGA soldering without ever running too hot. It´s just lousy manufacturing I assume.

For a professional reworking specialist it´s probably no big deal removing the chip, reball it and solder it right back to the board. But you got to have a good reworking station, the right materials plus lots of experienc which I lack unfortunately.

[stj]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

well to reflow a chip that large you need a pre-heater under the board, and a hot-air / IR heater on top.
other than that, just flux it.

[Agent24]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

It could also point to one of the ceramic capacitors being cracked or something, and pushing down on the CPU affects it since they are right under it on the other side.

[Majestyk]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

There are several capacitors and two inductors on the downside in the processor-area. I resoldered all of them carefully, but the problem persists.

I also took a look at the layout of the bga pads of the processor. Most of them are located near the edges of the chip, only a few in the center. And the right half of the rear edge is whrere the thing responds to light pressure.

It´s amazing when you search Youtube for bga reballing. There are guys in China, Pakistan and elsewhere who do this job in a small workshop very professionally and carefully, replacing notebook graphics chips and chipsets on PC-Mainboards.
I think I will ask some companies here how much reballing this chip would be just for laughs...

[stj]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

the ps3 / xbox360 guys would charge you about 50-75€

[Agent24]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

There are several capacitors and two inductors on the downside in the processor-area. I resoldered all of them carefully, but the problem persists.

The capacitors themselves might be physically damaged, resoldering won't fix that. (Unlikely though, more likely it's the BGA)

It´s amazing when you search Youtube for bga reballing. There are guys in China, Pakistan and elsewhere who do this job in a small workshop very professionally and carefully, replacing notebook graphics chips and chipsets on PC-Mainboards.
I think I will ask some companies here how much reballing this chip would be just for laughs...

Any professional company will charge big $$$ (buy a new switch)

You'd need to find someone who will do a reflow for cheap, but actually knows what they're doing. Anyone can buy a BGA rework machine on eBay, watch a few YouTube videos, and become a self-proclaimed BGA rework specialist.

[xboxhaxorz]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

^ is totally right

i had a modem with a similar issue so i took it apart and lifted the chip and wow it was totally delaminated and it kind of made sense because it was kept in the basement so moisture had entered and over time totally destroyed the pcb

while you can repair delamination, its not worth it due to a modem being around $80

[Agent24]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

Moisture by itself shouldn't cause delamination... but running a board that has been exposed to moisture for a long time through a reflow profile without baking the board for several hours at a low temperature first will.

[Uranium-235]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

unplug it, push down on the chip fairly hard (and continue to do so) and plug it in, see if the problem persists.

[chris1h1]

Re: Netgear GSM7224 Switch might need Reflow / Reballing

Sorry to revive a one year old thread, but did you get the GSM7224 working in the end? I've spotted one on eBay with the same symptoms and am wondering whether to risk it; I can replace the capacitors, but reflowing a BGA is not within my skill set.