Datasheet

TPA2039D1

SLOS652A –DECEMBER 2009–REVISED JUNE 2010

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PRINTED CIRCUIT BOARD LAYOUT

In making the pad size for the WCSP balls, it is recommended that the layout use nonsolder mask defined

(NSMD) land. With this method, the solder mask opening is made larger than the desired land area, and the

opening size is defined by the copper pad width. Figure 32 shows the appropriate diameters for a WCSP layout.

Figure 32. Land Pattern Image and Dimensions

SOLDER PAD SOLDER MASK COPPER STENCIL

COPPER PAD STENCIL OPENING

(6)(7)

DEFINITIONS OPENING

(5)

THICKNESS THICKNESS

Nonsolder mask 1 oz max 0.275 mm x 0.275 mm Sq.

0.23 mm 0.310 mm 0.1 mm thick

defined (NSMD) (0.032 mm) (rounded corners)

1. Circuit traces from NSMD defined PWB lands should be 75 mm to 100 mm wide in the exposed area inside

the solder mask opening. Wider trace widths reduce device stand off and impact reliability.

2. Best reliability results are achieved when the PWB laminate glass transition temperature is above the

operating the range of the intended application.

3. Recommend solder paste is Type 3 or Type 4.

4. For a PWB using a Ni/Au surface finish, the gold thickness should be less 0.5 mm to avoid a reduction in

thermal fatigue performance.

5. Solder mask thickness should be less than 20 mm on top of the copper circuit pattern

6. Best solder stencil performance is achieved using laser cut stencils with electro polishing. Use of chemically

etched stencils give inferior solder paste volume control.

7. Trace routing away from WCSP device should be balanced in X and Y directions to avoid unintentional

component movement due to solder wetting forces.

Figure 33. Layout Snapshot

An on-pad via is not required to route the middle ball B2 (PV

) of the TPA2039D1. Just short ball B2 (PV

) to

ball B1 (V

) and connect both to the supply trace as shown in Figure 33. This simplifies board routing and

saves manufacturing cost.

Product Folder Link(s) :TPA2039D1