Space is getting smaller
BGA's give designers the capability to put even more functionality into an even smaller area. However, when these designs flow through the rest of the product development process, three problems typically arise:
- Loss of Physical Access - Using BGAs to carry signals means that there are no leads coming off the chip or through the board. This makes physical access to the device impossible.
- Solder Smearing - Assembling boards with BGAs is much more difficult than previous packaging technologies because the solder is so easily smeared. This leads to structural, interconnect and functional problems.
- Test Points - To use traditional testing methods, the designer is forced to bring out a large number of test points -- which is in direct conflict with the designer's goals to miniaturize the design.
JTAG boundary-scan tools give back the access that BGAs would otherwise take away. Test and design engineers can now access and control the signals (inputs and outputs) of a BGA package.