User Guide

Nokia Customer Care System Module
Company Confidential RH-21
Issue 2 07/2004  2004 Nokia Corporation. Page 17
Test Interfaces
Production Test Pattern
Interface for RH-21 production testing is 5-pin pad layout in BB area (see figure below).
Production tester connects to these pads by using spring connectors. Interface includes
MBUS, FBUSRX, FBUSTX, VPP and GND signals. Same pads also are used for AS test
equipments such as module jig and service cable.
Figure 7: Top View of Production Test Pattern
Other Test Points
Because BB asics and flash memory are CSP components, the access to BB signals is very
poor. This makes measuring of most of the BB signals impossible. In order to debug BB at
least on some level, the most important signals can be accessed from 0.6 mm test points.
EMC
General
There are many ways to protect the phone from EMC. One form of protecting BB against
EMC is a shield to cover main components of BB — components such as UEM, UPP and
Flash. UEM has internal protection against ±8kV ESD pulse. BB shield has a removable lid
so repairing of BB is possible. Shield also improves thermal dissipation by spreading the
heat more widely.
BB Component and Control IO Line Protection
Keyboard lines
The keyboard PWB layout consists of a grounded outer ring and either a "trefoil pattern"
grid (matrix) or an inner pad. This construction makes the keys immune for ESD, as the
keydome will have a low ohmic contact with the PWB ground.
The keyboard is controlled entirely by the UPP. The rows and columns are ESD protected
by diodes and spark gaps.
PWB
The PWB has been designed to shield all lines susceptible for radiation. Sensitive PWB
3.
FBUS_RX
8.
GND
6.
VPP
7.
MBUS
2.
FBUS_T
X