TOKYO Sanyo Electric Co. Ltd. has moved one step ahead in system-in-package technology with its Integrated System in Board (ISB) packaging approach.
Sanyo's solution takes multiple ICs, transistors and other passive components such as resistors and condensers, and wires them to copper foil patterns. All the components are encapsulated in resin in an ISB package without using a substrate. The elimination of a supporting substrate or a die pad makes the resultant circuitry thin and compact, and improves thermal dissipation to the package. Because the package does not use a metal mold, there is no restriction in size and shape.
"Chips in ISB packages are floating in the encapsulated resin. If the resin is melted away, the chips would be in pieces," said Junji Sakamoto, general manager of the module systems division at Sanyo Semiconductor Co., who led the ISB effort.
The copper foil pattern is 35 microns thick, with a pattern pitch of 100 microns at present. Sanyo engineers intend to narrow the pitch to 60 microns or less within a year. Only a thin copper foil borders the ICs and directly faces the outside air without a substrate, producing low-dielectric wiring. Sanyo intends to promote the packaging for high-frequency circuits.
When used with a 0.33-mm-thick chip, the ISB package is 0.6 mm thick. By comparison, existing P-LGA packages are 1.1 mm thick, and ceramic-LGA packages are 0.7 mm thick.
Thin is in
Semiconductor manufacturers are competing hard to make their packages thin and compact. "But no other manufacturer has realized a package technology which satisfies all the requirements of thinness, high heat radiation and flexible shape at once," Sakamoto said.
Sanyo has applied for 103 patents in Japan and 33 patents outside the country, but the company would not detail the technology it uses to encapsulate chips in resin with no substrate. "The first idea was to remove the supporting substrate after encapsulation," Sakamoto said, but he would say no more.
System-on-chip is only one possible solution for high integration, Sakamoto said. "We do not deny the SoC approach, but not all [function] blocks on the chip necessarily require the same fine process," he said. "With an ISB package, LSIs can have wiring in it or out of it depending on efficiency. Customers can use other vendors' blocks [combined with] in-house-designed LSIs. Once they are incorporated into one chip, the function would be the same as an SoC."
Sanyo is developing a CAD system that is tuned for the ISB approach of combining chips, functional blocks, peripherals and other circuitry in a single package, and intends to provide it to its customers in a year or so to enable them to complete designs that are ready for ISB packaging.
Sanyo will introduce its first ISB-packaged product in December, a 30-watt, two-channel audio amplifier module. Use of the ISB-packaged chip resulted in a 66 percent reduction in the number of modules in the package, according to Sanyo.