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Keeping Pace with Device Programming
December 31, 1969 |Estimated reading time: 2 minutes
MUNICH, Germany — At Productronica last November, Bill White, CEO and president of Houston-based BP Microsystems talked about his company's approach to device programming.
White founded the company, along with a classmate partner, while still a senior majoring in computer sciences at Rice University in 1985. At that time there were only 67 different types of devices to program, with a heavy emphasis on EPROMs. Their newly formed business supported all of them. "Today, after 19 years in this industry, there are 19,200 parts for programming and we still can do them all," said White.
(L-R) Bill White and Lyman Brown.
BP works closely with 139 semiconductor manufacturers, updating algorithms at least every six weeks to keep up with software updates. White estimates that 70 percent of all chips undergo revision during their product lives. As devices become more complex, including microcontrollers, microBGAs, FPBGAs and FLASH, the speed at which SMT lines pick-and-place has increased while programming requires longer time segments. To avoid possible bottlenecks, BP Microsystems' programmers work off-line. "Boundary scan and other types of test systems are often built into the device," said White. "So why not program at test?"
One programmer, such as the company's 4700, can program a variety of devices. This has proven to be popular worldwide. At present BP has more than 90 employees.
Exploring new possibilities has always sparked White's creative side, and that remains. He recently appointed Lyman Brown as executive vice president and chief operating officer to run day-to-day operations. "This allows me to concentrate on introducing the product innovations we are known for," he added.
— Gail Flower
Flip Chip Surface Finish
SUNNYVALE, Calif. — "Flip Chip Package Surface Finish and its Impact on Solder Joint Reliability" was presented by Matthew Kaufmann of Broadcom at IMAPS' Northern California luncheon on October 1.
Kaufmann focused on finishes used on the build-up flip chip substrate, but these must be compatible with PCB coatings. For example, he discussed use of an electroless Ni/immersion Au (ENIG) finish with thin gold for fine pitch substrates that tends to be sufficiently reliable on Ni/Au-coated PCBs but not on OSP- or HASL-coated boards. Kaufmann recommended using solder on pad (SOP) technology on the BGA side of the board (SOBGAP) as well as the flip chip side.
The SOBGAP process is gaining traction since it was first implemented with a Broadcom chip on a Kyocera substrate two years ago, but is not yet standard or widespread. According to Kaufmann, SOBGAP showed similar ball shear and temperature cycling results as ENIG and twice the intermetallic strength, but it is not compatible with ENIG-coated PCBs. The solder coating typically is eutectic SnPb, but a SnAgCu coating could be used for lead-free applications.
Dongkai Shangguan of Flextronics attended the IMAPS luncheon and expressed some concerns about process control in the SOBGAP process in a conversation with SMT. The solder coating is not flat, potentially making ball placement more difficult. Shangguan suggested printing additional solder paste to form solder balls, as is done on wafer-level CSP processes.
Kaufmann mentioned immersion Ag and immersion Sn as alternatives to NiAu coatings. Immersion Ag has been under evaluation for some years now but is "just beginning to gain more momentum now," according to Shangguan, as PCB suppliers move away from ENIG finishes to improve reliability. It remains to be seen whether immersion Ag will replace the dual-finish process (OSP for solder pads plus ENIG for contact pads) used in some applications and whether SOBGAP will take off for BGA components.
— Julia Goldstein, Ph.D.