bc41b143a07 ETC-unknow, bc41b143a07 Datasheet - Page 89

• Manufacturer Part Number: bc41b143a07
• Description: Single Chip Bluetooth
• Manufacturer: ETC-unknow

12 PCB Design and Assembly Considerations
12.1
This section lists recommendations to achieve maximum board-level reliability of the 6 x 6mm VFBGA 84-ball
package:
CS-101564-DSP12
Non solder mask defined (NSMD) lands (that is, lands smaller than the solder mask aperture) are preferred
because of the greater accuracy of the metal definition process compared to the solder mask process. With
solder mask defined pads, the overlap of the solder mask on the land creates a step in the solder at the land
interface, which can cause stress concentration and act as a point for crack initiation.
Ideally, via-in-pad technology should be used to achieve truly NSMD lands. Where this is not possible, a
maximum of one trace connected to each land is preferred and this trace should be as thin as possible –
taking into consideration its current carrying and the radio frequency (RF) requirements.
35µm thick (1oz) copper lands are recommended rather than 17µm thick (0.5oz). This results in a greater
standoff which has been proven to provide greater reliability during thermal cycling.
Land diameter should be the same as that on the package to achieve optimum reliability.
Solder paste is preferred to flux during the assembly process because this adds to the final volume of solder
in the joint, increasing its reliability.
Where a nickel gold plating finish is used, the gold thickness should be kept below 0.5µm to prevent brittle
gold/tin intermetallics forming in the solder.
6 x 6mm VFBGA 84-Ball Package
Production Information
© CSR plc 2003-2007
PCB Design and Assembly Considerations
Page 89 of 97