Flip Chips

Flip Chips

Flip Chip describes the method of electrically connecting the die to the package carrier. The package carrier, either substrate or leadframe, then provides the connection from the die to the exterior of the package. The interconnection between die and carrier in flip chip packaging is made through a conductive bump that is placed directly on the die surface. The bumped die is then flipped over and placed face down, with the bumps connecting to the carrier. After the die is soldered, underfill is applied between the die and the substrate, around the solder bumps. The underfill is designed to contract the stress in the solder joints caused by the difference in thermal expansion between the silicon die and carrier.

UBM is the Al/NiV/Cu (under bump metallization) covering about 1% of the wafer which is under the bumps only. Nitride passivation is an invisible glass-like protective coating over 99% of the wafer, except under the bumps. The bumps will not stick to the Nitride, only the UBM. Nitride coating is standard for all Flip Chip wafers.

Flip Chips

Part Numbers:



Die Size

200 x 200 mils
400 x 400 mils

200 x 200 mils
400 x 400 mils

Bump Pitch

254 µm, 10 mil

203 µm, 8 mil

Passivation Via

80 µm

73 µm

UBM Diameter

102 µm

95 µm

Bump Height

120 µm

98 µm

Bump Diameter

135 µm

120 µm

No. of Bumps



Final Metal Pad Size
Thickness Type

127 x 127 µm

115 x 115 µm

Metal Composition

98/1/1 Al/Cu/Si

98/1/1 Al/Cu/Si


Uncut Wafer*

5" Wafer
200 x 200 mils (344Die)
400 x 400 mils (86 Die)

5" Wafer
200 x 200 mils (344 Die)

400x400mil (86 Die)


Sawed 5" Wafer
36 per tray 200 x 200
9 per tray 400 x 400
Waffle Pack

Sawed 5" Wafer
36 per tray 200 x 200
9 per tray 400x400
Waffle Pack

Tape and Reel

Call For

Call For


* * Die count represents expected yield per wafer.

* All die is packaged in waffle pack trays unless otherwise specified.

* All test wafers are currently 5" diameter and are 0.635mm thick. Passivation is one-micron thick plasma Nitride with round via openings.

* The potential multiple is the number of die repeats on the wafer. With the wafer orientated flat down, a right hand coordinate system applies.

* Die size is from scribe line to center-to-center. Scribe width is 0.05mm passivated. Each bump is electrically connected to one other bump and isolated from all others to facilitate electrical test.

* Bump pitch is defined as center-to-center distance between passivation openings.

* Bump height is defined as silicon surface to the top of the bump.

* Bump diameter is defined as the maximum diameter.

* UBM = Under Bump Metallurgy

* Lead-free parts are available with 95.5% Sn/ 3.5% Ag/ 1.0% Cu alloy.

* Unbumped wafers are available upon special request.

Part Number System


* Add "WR" to end of part number for Wafer Cut and left in Seal Ring.

* Add "TR" to end of part number for die on Tape and Reel.

* Add "EUT" to end of part number for Eutectic.

* Add "LF2" to end of part number for Lead-Free.

* Add "W" to end of part number for Uncut Wafer.

* Add "unbumped" to end of part number for unbumped wafer/die.

FCT Bump Structure


IPC Validation Services

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Technical Center

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