Solder Paste Recommendation
Background
The ACPM-7886 package is a lead free package that
was proven to pass MSL3 when reflowed under lead
free solder reflow profile. The recommended lead free
solder for SMT reflow is Sn-Ag-Cu (95.5% Tin, 3.8%
Silver, 0.7% Copper) or other similar Sn-Ag-Cu solders.
This lead free solder paste has a melting point of 218°C
(423°F), the ternary eutectic of Sn-Ag-Cu system, giving
it the advantage of being the lowest melting lead free
alternative. This temperature is still low enough to
protect from damaging the internal circuitry during
solder reflow operations provided the exposure time
at peak reflow temperatures is not too excessive.
In 1999 the China Academy of Telecommunications
Technology (CATT) and Siemens proposed a new 3G
standard that would rival WCDMA and CDMA2000 data
rates. Time Domain Synchronous Code Domain Access
(TD-SCDMA) combines both CDMA and TDMA
technologies. It benefits from CDMA capacity as well
as being compatible with current GSM networks. But
unlike existing WCDMA, CDMA2000 and GSM
networks, this new standard transmits and receives on
the same frequency thus greatly increasing spectrum
efficiency. Figure 6 simplifies this explanation by
showing one TD-SCDMA frame with 7 slots and 16
channelization codes in each slot.
In certain situations, the designer may use leaded
solder paste for reflow. The recommended solder for
mounting ACPM-7886 package is Sn63 (63% Sn, 37%
Pb). It is a eutectic compound with a typical melting
point of 183°C.
ACPM-7886 Test Setup
The test setup for measuring a TD-SCDMA power
module resembles a GSM test. Specifically, it is very
important to properly configure the timing for the test
instruments and the device under test. In GSM, in order
to turn ON and OFF each time slot, a controlled pin on
the PA is triggered with a pulse period of 4.615ms and
a 12% duty cycle (577uS). This pin is usually labeled
as Vapc on most GSM PAs.
Application Information
Introduction
The ACPM-7886 amplifier module is designed for TD-
SCDMA applications in the 2010-2025MHz band. This
power amplifier is able to produce excellent results for
the emerging Chinese standard, TD-SCDMA. Typical
ACLR performance at Vdd is 41dBc with Pout of 28dBm
and 41% efficiency.
[1]
Figure 6. TD-SCDMA frame.
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AVAGO [ AVAGO TECHNOLOGIES LIMITED ]
