Ironwood-electronics Kelvin testing using GHz socket Manual do Utilizador descarregar pdf (Página 1)

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Kelvin Testing Using a GHz socket for MLF/QFN packages

A measurement method called Kelvin probing for measuring resistance allows very accurate

measurement of milliohm or sub-milliohm resistance. To accomplish this there are two

leads, which provide a current source across the load to be measured, and two more leads

across the load, which provide the sensing. This is shown in Fig. 1. The problem is that it

takes twice as many connections as with a two-wire measurement. There is no lead

resistance in the measurement as there is of course with the two-wire measurement. This can

easily be several tenths of an OHM, thus swamping out the milliohms that are to be

measured.

Figure 1: Test Setup.

A further complication arises when accurate measurements are required in very small

packages. Many analog functions are being packaged in MLF/QFN packages. These

devices have pitches as low as 0.4mm and lead dimensions in the range of 0.5mm x 0.25mm.

A bottom view of an MLF/QFN package is shown in Fig. 2.

1 2 3 4 5

Tel: (800) 404-0204 www.ironwoodelectronics.com Kelvin Testing Using a GHz socket for MLF/QFN packages A measurement method called Kelvin probing

Tel: (800) 404-0204 www.ironwoodelectronics.com Figure 2: MLF pad detail Ironwood Electronics, Inc. has developed a socket for MLF device, whic

Tel: (800) 404-0204 www.ironwoodelectronics.com of the bisected pad. 15.225mm±0.125mm sqr.Socket sizeOrientation MarkNon plated mounting holeNon p

Tel: (800) 404-0204 www.ironwoodelectronics.com Figure 4: Test Chip layout The MLF GHz sockets vary by package; call Ironwood Electronics, Inc.

Tel: (800) 404-0204 www.ironwoodelectronics.com 1:3 0.0112 1:21. 0.0483 1:39 0.0844 1:57 0.026 1:4 2.3584 1:22 2.409 1:4

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Ironwood-electronics Kelvin testing using GHz socket Manual do Utilizador Página 1