User Guide

RH-10
System Module CCS Technical Documentation
Page 26 Nokia Corporation Confidential Issue 1 09/2002
areas. Target is that any ESD pulse faces ground area when entering the phone (e.g.,
between mechanics covers).
All holes in PWB are grounded and plated through holes (with the exception of LED
holes, which cannot be grounded).
LCD
ESD protection for LCD is implemented by connecting the metal frame of LCD to gnd.
Connection is only on one side, at the top of the LCD, and that is not the best solution.
Due to SAR issues, the C-cover metallization is cut in the middle, just under the display,
making the whole engine more sensitive to ESD. Software protects against LCD crashing.
Microphone
Microphone metal cover is connected to gnd and there are spark gaps on PWB. Micro-
phone is an unsymmetrical circuit, which makes it well protected against EMC.
EARP
EARP is protected with the C-cover metallization and with plastic-fronted earpiece.
Buzzer
PWB openings with C-cover metallization protect the buzzer from ESD.
Battery Connector Lines
BSI and BTEMP lines are protected with spark gaps and RC circuit (10k & 1n) where resis-
tors are size 0603.
M-bus F-bus
The opening in the protective metal deck underneath the battery is so small that ESD
does not get into M-bus and F-bus lines in the production test pattern.