Renesas Subsidiary Creates High-Temp QFN-Like Package

A Renesas Technology subsidiary has developed a thermal dissipation package that supports a wider operating temperature range than conventional QFN packages. The Pro.Quad package has small portions (<1>

Kenji Tsuda, Asia Contributing Editor -- Semiconductor International, 2/17/2009 7:27:00 AM

Renesas Northern Japan Semiconductor Inc. has developed a new thermal dissipation package that is size-compatible with QFN (quad flat non-leaded) packages. The Pro.Quad package features a rear-side metal in the bottom center, and a small protrusion of lead in the four sides and corners. The package attaches to a PCB more closely, leading to effective heat dissipation. The name of the new package comes from the protrusion in the four corners.

Renesas Northern Japan, a subsidiary of Renesas Technology Corp. (Tokyo), created the package with a form that is similar to QFN packages. However, the Pro.Quad package has small portions (<1>

The Pro.Quad is a QFN-like package that can withstand higher temperatures. (Source: Renesas)

Renesas provides three types of Pro.Quad packages: 6 mm square with 36 leads, 8 mm square with 52 leads, and 9 mm square with 60 leads. The lead pitch of 0.5 mm complies with the JEDEC standard, along with a mounted thickness of <1>In general, a heat dissipation metal with plastic resin in the same plane could peel away the resin or generate a gap between the resin and the metal because of a large thermal expansion coefficient difference between the metal and resin. Renesas has studied a wide variety of combinations of base resin, silica filler, mold release agent and other materials, along with the metal design. The metal sheet in the rear surface is part of the leadframe, and is the same material as the leads.

In conventional mold packages, four corners in a package can tend to concentrate stress with temperature cycles, leading to detachment of the package from the board. The new package has four corner metals that easily adhere to the board, leading to higher endurance during the temperature cycles. In a temperature cycle test of -40 to +125°C, the new package achieved >4000 cycles with no failures. Automotive electronics require up to 1500 cycles, and the company targeted double that number: 3000 cycles. In another temperature cycle test of -40 to +85°C, the new package passed 5500 cycles.

The new package also features visible solder joints, while joints in conventional QFN packages are usually invisible. That makes it possible to check the solder fillets in the Pro.Quad package after reflow soldering, Akaki said.