Product description

AN4208

2/16

DocID023948 Rev 1

1

Product description

Flip Chips are manufactured with a wafer level process that STMicroelectronics has

developed by attaching solder bumps on I/O pads of the active wafer side, thus allowing

bumped dice to be produced. The I/O contact layout can be either matrix shape or set in

periphery. No redistribution layer is used. This allows parasitic inductances coming from the

redistribution metal tracks to be minimized.

Lead-free bump composition is 96.5% Sn, 3% Ag, 0.5% Cu. This is fully compatible with

standard lead-free reflow processes. The bump dimension (175 µm bump diameter) allows

the pick and place process to be compatible with existing equipment (in particular with

equipment used for Ball Grid Array - BGA packages) and makes it also compatible with the

PCB design rules used for standard ICs.

Optional coating on the flat side of the package is available.

These components are delivered in tape and reel packing with the bumps turned down

(placed on the bottom of the carrier tape cavity). The other face of the component is flat and

allows picking as in the standard SMD packages.

Devices are 100% electrically tested before packing. The product references are marked

on the flat side of the device.

2

Mechanical description

Mechanical dimensions of Flip Chips are provided through a product example in Figure 2.

Bumps are lead-free. Bump composition is 98.25% Sn, 1.2% Ag, 0.5% Cu, 0.05% Ni alloy

with a near eutectic melting point of 218 to 227 °C. Die size and bump count are adapted to

the connection requirements.

Figure 2. Mechanical dimensions of a 2 x 2 bump matrix array.

Note:

The package height of 0.605 mm (0.650 mm for optionally coated packages) is valid for a

die thickness of 0.48 mm.

172 µm

645 µm ± 30 µm

175 µm ± 20 µm

120µm

300 µm ± 30

605 µm ± 55