High speed flip-chip dispensing

Details High speed flip-chip dispensing High speed flip-chip dispensing

1998-08-14

2001-03-27

Vo, Peter (Department: 3721)

Package making

Methods

Applying a partial cover

C414S416060, C029S743000, C221S074000

Reexamination Certificate

active

06205745

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to techniques and related apparatus for semiconductor chip handling and more specifically to methods for transferring chips from chip carrier tapes to other processing stations.
BACKGROUND OF THE INVENTION
A variety of systems for conveying finished integrated circuit (IC) chips from the IC singulation operation to the IC packaging operation are available commercially. Many of these systems use an apertured punched plastic carrier tape with a pressure sensitive adhesive backing, hereinafter referred to as carrier tape, as more particularly described in Industry Standard, EIA/IS-747, published by the Electronic Industries Association, Arlington, Va. Chips are mounted in the apertures with a pick and place tool, and are retained in the apertures by the pressure sensitive adhesive backing, hereinafter referred to as adhesive backing. A widely used carrier tape system uses two parallel rails of adhesive backing which extend along the underside of the apertured plastic tape, hereinafter referred to as the plastic carrier. See, e.g. U.S. Pat. No. 5,203,143, issued Apr. 20, 1993. After the carrier tapes are loaded, the tapes can be conveyed directly to the next assembly operation, or more typically, are reeled for temporary storage. Tapes are then unreeled and the chips are picked from the carrier tape to be placed in a package assembly machine. With conventional pick and place tools the chips, which are carried circuit side up on the carrier tape, are seized on the circuit side by the vacuum head of the pick and place machine, and inserted circuit side up in the next assembly station. For normal surface mount and wire bonded packages the circuit side up position of the chip is the orientation desired. However, for flip-chip packages, this orientation is upside down.
Various methods have been employed to adapt carrier tape systems for flip-chip packaging. One of these is the Bare Die Dispensing System available from Tempo Electronics, Los Angeles, Calif. In this equipment, an inverter arm is used to pick the die from the carrier tape in the usual way, i.e. circuit side up, swing the arm of the pick tool through a 180° arc, then pick the die with a second pick tool from the first pick tool, this time with the circuit side down. While this method is satisfactory, the use of two pick operations slows the chip handling operation and contributes error to chip position repeatability at the pick point. Other solutions for adapting carrier tape systems to flip-chip packaging are needed.
SUMMARY OF THE INVENTION
We have designed a carrier tape system for flip-chip assembly where the chip can be loaded on the carrier tape circuit side up in the usual manner, and can be picked from the carrier tape and placed circuit side down in a single pick operation. In one embodiment the system uses essentially the same equipment used in the conventional arrangement, and uses essentially the same carrier tape. In other embodiments, the carrier tape has a new design specifically intended for this invention, and in yet other embodiments the apparatus is modified to create the new carrier tape in situ. The feature that is common to all embodiments, according to the invention, is to pick the chip from the back side of the carrier tape. The vacuum head of the pick tool then contacts the back side of the IC chip, and dispenses the chip circuit side down without any additional handling. To facilitate back side dispensing, or through-tape dispensing, the adhesive backing of the tape is advantageously modified by providing discrete apertures at the chip sites in place of the continuous dual rail adhesive backing.


REFERENCES:
patent: 4494902 (1985-01-01), Kuppens et al.
patent: 5203143 (1993-04-01), Gutentag
patent: 5319846 (1994-06-01), Takahashi et al.
patent: 5-32217 (1993-02-01), None
patent: 5-132021 (1993-05-01), None

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