DocID027277 Rev 1

11/16

TN1200

Soldering assembly recommendations

16

5.2

PCB assembly guidelines

For Flip Chip mounting on the PCB. Flip Chips are fully compatible with the use of near

eutectic 95.8% Sn, 3.5% Ag, 0.7% Cu solder paste with no-clean flux. ST's

recommendations for Flip-Chip board mounting are illustrated on the soldering reflow profile

shown in Figure 10.

mounting on PCB (definitions)

Dwell time in the soldering zone (with temperature higher than 217 °C) has to be kept as

short as possible to prevent component and substrate damages. Peak temperature must

reflow, specially above 150 °C.

Flip Chips are able to withstand three times the previous recommended reflow profile to be

compatible with a double reflow when SMDs are mounted on both sides of the PCB plus

one additional repair.

A maximum of three soldering reflow are allowed for these lead-free packages (with repair

step included).

The use of a no-clean paste is highly recommended to avoid any cleaning operation. To

prevent any bump cracks, ultrasonic cleaning methods are not recommended.

on PCB (value)

Parameter

Probe

#1 PLCC 44

#2 PLCC 28

#3 SO-18

Positive temperature gradient °C/s

4.50

3.94

4.49

Time in positive gradient (min/sec)

00:17

00:13

00:16

Time from 150 to 200 °C (min/sec)

01:22

01:36

01:24

Time above 217 °C (min/sec)

02:05

01:50

02:05

Maximum temperature °C

244.0

239.9

243.6

Temperature difference °C

4.1

-

Negative temperature gradient °C/s

-3.46

-2.88

-3.97

250

0

50

100

150

200

240

210

180

150

120

90

60

30

300

270

-6°C/s

240-245 °C

2 - 3 °C/s

Temperature (°C)

-2 °C/s

-3 °C/s

Time (s)

0.9 °C/s

60 sec

(90 max)