4

Multilayer Organic (MLO

0806 CDMA Diplexer

AUTOMATED SMT ASSEMBLY

SMT REFLOW PROFILE

The following section describes the guidelines for automated

SMT assembly of MLO

Grid Array (LGA) packages or side termination SMT pacages.

Control of solder and solder paste volume is critical for

surface mount assembly of MLO

Stencil thickness and aperture openings should be adjusted

according to the optimal solder volume. The following are

general recommendations for SMT mounting of MLO

TM

devices onto the PCB.

Common IR or convection reflow SMT processes shall be

used for the assembly. Standard SMT reflow profiles, for

eutectic and Pb free solders, can be used to surface mount

the MLO

gradient of 3°C/sec, or less, should be maintained to prevent

warpage of the package and to ensure that all joints reflow

properly. Additional soak time and slower preheating time

may be required to improve the out-gassing of solder paste.

In addition, the reflow profile depends on the PCB density

and the type of solder paste used. Standard no-clean solder

paste is generally recommended. If another type of flux is

used, complete removal of flux residual may be necessary.

Example of a typical lead free reflow profile is shown below.

Profile Parameter

Pb free, Convection, IR/Convection

Ramp-up rate (Tsmax to Tp

3ºC/second max.

Preheat temperature (Ts min to Ts max)

150ºC to 200ºC

Preheat time (ts)

60 – 180 seconds

60 – 120 seconds

Peak temperature (Tp)

260°C

Time within 5ºC of peak temperature (tp)

10 – 20 seconds

Ramp-down rate

4ºC/second max.

Time 25ºC to peak temperature

6 minutes max.

Critical Zone

Ramp-down

Ramp-up

Ts max

25

t 25ºC to Peak

Ts min

ts

Preheat

Tp

tp

Time

Figure A. Typical Lead Free Profile and Parameters