US 6,713,318 B2Granted

Flip chip interconnection using no-clean flux

AssigneeIntel Corporation

InventorsMichihisa Maeda, Kenji Takahashi

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Abstract

A flip chip method of joining a chip and a substrate is described. A thermo-compression bonder is utilized to align the chip and substrate and apply a contact force to hold solder bumps on the substrate against metal bumps on the chip. The chip is rapidly heated from its non-native side by a pulse heater in the head of the bonder until the re-flow temperature of the solder bumps is reached. Proximate with reaching the re-flow temperature at the solder bumps, the contact force is released. The solder is held above its re-flow temperature for several seconds to facilitate wetting of the substrate's metal protrusions and joining. A no-clean flux that has a volatilization temperature below the melting point of the solder bumps is utilized to minimize or eliminate the need for a post interconnection de-flux operation.

Claims12

Dependent claims

A method, comprising:

placing a substrate against a first fixture,
the substrate having deposited thereon a plurality of solder bumps and a flux, the solder bumps having a melting point at a first temperature, and the flux having a volatilization temperature at which substantially all of the constituents of the flux volatilize, the volatilization temperature being less than or equal to the first temperature,
the first fixture being maintained at a second temperature below the first temperature;
placing a chip against a second fixture,
the chip having affixed thereto a plurality of metal protrusions,
the second fixture coupled with a heater, the heater being maintained at a third temperature, the third temperature being less than the first temperature;
bringing the plurality of solder bumps into contact with the plurality of metal protrusions by moving one or both of the first and second fixtures towards each other;
rapidly increasing the temperature of the heater from a third temperature to a fourth temperature, the fourth temperature being higher than the first temperature;
and
holding a pulse heat tool approximately at or above the fourth temperature until the plurality of solder bumps have melted and wetted the plurality of metal protrusions.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/820,547Filed 28 Mar 2001
Published: US 2002/0142517 A13 Oct 2002
Granted: 30 Mar 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

H10W 72/072
Connecting or disconnecting: of bump connectors
B23K 35/262
With the principal constituent melting at less than 400°C: sn as the principal constituent
B23K 35/3618
With organic compounds as principal constituents: carboxylic acids or salts
H05K 3/3436
Leadless components: having an array of bottom contacts, e.g. pad grid array or ball grid array components