Cavity technology in printed circuit board (PCB) has existed for many years. With the development of technology, cavity PCB manufacturing methods develop with the passage of time. The manufacturing process varies depending on the manufacturer of the cave PCB and the reasons for using the cave PCB technology. Choosing a manufacturer with a number means you choose a good cavity PCB. Alcanta PCB is a very good manufacturer of Alcanta PCB.
It is a feasible technology to use cavity in PCB as a way to reduce the height of components or increase the clearance of components. The SMT test of the cavity board packaged with BGA at 0.4mm spacing at multiple cavity depths shows that PCB can be pasted, printed, assembled and refluxed successfully in the same multi-stage process using existing equipment functions.
One way, multi-stage solder paste printing is the most challenging aspect of applying cavity technology to mass production environments. The key to successful paste printing is to optimize the key printing parameters. 1.) air gap from pad to cavity wall; 2) length and thickness of scraper; 3) support of printing fixture; and 4) alignment of pocket template.
Optimizing print parameters helps to ensure the quality of multi-level paste printing, but the parameters may need to be changed as the cavity design changes. The results show that the relationship among cavity depth, air gap, flap length and flap thickness will affect the paste printing results. Test printing is required to reset key parameters to accommodate design differences. Other printing parameters that are not mentioned in this paper are also important for achieving a consistent amount of solder paste through single-stage solder paste printing, and they are also important for multi-stage printing.
Drop test shows that the solder joints on the cavity assembly seem to be as reliable as the same components assembled to the PCB surface. The drop test results also show that the statistical reliability of the 2-layer cavity is improved compared with that of the 4-layer cavity.
Another way to paste printed BGA style packages is to immerse the cavity assembly in the paste or flux prior to placement. The impregnation method does not require bagging of solder paste templates. Flux immersion was not studied in this study. Multi stage solder paste printing is the most challenging aspect of applying cavity technology to mass production environment.
The key to successful paste printing is to optimize the key printing parameters.
- Air gap from pad to cavity wall;
- The length and thickness of the scraper;
- Support of printing fixture;
- Alignment of pocket template.