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Document Number 71681

03-Mar-06

Vishay Siliconix

AN822

PowerPAK 1212 DUAL

To take the advantage of the dual PowerPAK 1212-8’s

thermal performance, the minimum recommended

land pattern can be found in Application Note 826,

Recommended Minimum Pad Patterns With Outline

Drawing Access for Vishay Siliconix MOSFETs. Click

on the PowerPAK 1212-8 dual in the index of this doc-

ument.

The gap between the two drain pads is 10 mils. This

matches the spacing of the two drain pads on the Pow-

erPAK 1212-8 dual package.

This land pattern can be extended to the left, right, and

top of the drawn pattern. This extension will serve to

increase the heat dissipation by decreasing the ther-

mal resistance from the foot of the PowerPAK to the

PC board and therefore to the ambient. Note that

increasing the drain land area beyond a certain point

will yield little decrease in foot-to-board and foot-to-

ambient thermal resistance. Under specific conditions

of board configuration, copper weight, and layer stack,

experiments have found that adding copper beyond an

ment in thermal performance.

REFLOW SOLDERING

Vishay Siliconix surface-mount packages meet solder

reflow reliability requirements. Devices are subjected

to solder reflow as a preconditioning test and are then

reliability-tested using temperature cycle, bias humid-

ity, HAST, or pressure pot. The solder reflow tempera-

ture profile used, and the temperatures and time

duration, are shown in Figures 2 and 3. For the lead

(Pb)-free solder profile, see http://www.vishay.com/

doc?73257.

Ramp-Up Rate

+ 6

°C /Second Maximum

Temperature at 155 ± 15

°C

120 Seconds Maximum

Temperature Above 180

°C

70 - 180 Seconds

Maximum Temperature

240 + 5/- 0

°C

Time at Maximum Temperature

20 - 40 Seconds

Ramp-Down Rate

+ 6

°C/Second Maximum

Figure 2. Solder Reflow Temperature Profile

Figure 3. Solder Reflow Temperatures and Time Durations

210 - 220 °C

3 ° C/s (max)

4 ° C/s (max)

10 s (max)

183 °C

50 s (max)

Reflow Zone

60 s (min)

Pre-Heating Zone

3° C/s (max)

140 - 170 °C

Maximum peak temperature at 240 °C is allowed.