Among such high density packages, the QFP has proven to be the right choice when it comes to combine high functional integration with excellent connection reliability. With its gull-wing shaped lead feet surface mount, QFP is most tolerant towards vibration, flexing, warping and other stress applied to the PCB. This mechanical reliability has been the reason why QFP is the first choice for industries that are operating in harsh conditions such as automotive.
With the highly reliable double lead foot contact, it is easy to understand the success of Yamaichi’s Open Top Socket Series IC357 when it comes to connecting QFP packages for various test and burn-in applications.
Beside of the connection reliability, issues like heat dissipation and RF property often require test sockets to be equipped with components that can handle cooling and grounding. Under-standing this important necessity, Yamaichi has furnished its test and burn-in sockets with a variety of ground pin and heat slug options. In particular the IC357 series offers no less than five different solutions to ground the QFP’s exposed pad either electrically or thermally or both in combination.
The additional exposed pad connection however has brought a new challenge to socket design: a spring loaded center pin – a common solution – mainly pushes the package away from its ideal insertion plane during loading. Possible counter measures often add technical complexity to auto load handler resulting in manual load capable sockets only.
To overcome this problem, Yamaichi Electronics has applied a new design to the ground pin in its IC357 series socket. The revolutionary design allows the center pin to actuate in conjunction with the movement of the push cover. While the push cover is being hold down, the center pin retracts completely to allow the package to be guided into its position. When the push cover is released, lead foot contacts are actuated first holding the package firmly in its plane before the center pin comes into action. This two step actuation ensures that the IC357 series remains auto load capable and reliable for all future test and burn-in applications.