NSE8-037.PDF part of NOKIA NSE8-037 NSE8-037.PDF, NOKIA Mobile Phone Nokia

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CONFIDENTIAL 1 (1)

Nokia Mobile Phones Service Bulletin No. SB-037/20.04.00
Technical Support, Europe & Africa

NSE-8

COBBA UNDERFILLING

In some cases when NSE-8 is exposed to mechanical stress (dropped etc)
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solder-balls and the pads on the PCB. Typical symptoms are dropping calls,
loosing service or signal indicator is unstable on the display.

As underfilling for COBBA is solution for those cases it has been taken in use
in production since IMEI: 449143/10/716000/x.

Note: It is not possible to rework or replace an underfilled COBBA
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In case of phones without underfilling of COBBA:

1. 5HPRYH WKH &2%%$ %*$ XVLQJ D %*$ &63 UHZRUN VWDWLRQ
2. Inspect the number of oxidised pads "black pads" on the PCB under
COBBA (dark coloured pads). If there are more than 6 black pads then
scrap the PCB. Less than 7 black pads will ensure high reliability of
reworked component.
3. Remove carefully excessive solder from the COBBA solder pads
4. Apply flux to the COBBA solder pads (use a strong no-clean flux to
remove oxides)
5. Mount a new &2%%$ FRGH XVLQJ D %*$ UHZRUN VWDWLRQ 'R
not mount the removed COBBA!!)
6. Re-build the phone IMEI and re-initialise the SIM locks
7. Test and tune the phone's RF performance (COBBA stores RF A/D
values)

NSE-8 SB-037