Method of packaging fuses

Details Method of packaging fuses Method of packaging fuses

1999-09-07

2001-07-03

Lee, Eddie C. (Department: 2815)

Semiconductor device manufacturing: process

Packaging or treatment of packaged semiconductor

Metallic housing or support

C438S333000, C438S132000, C257S081000

Reexamination Certificate

active

06255141

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to methods of packaging integrated circuit devices, such as flip chip dice, with externally mounted but integrally packaged fuses. More particularly, the fuses are formed using lead frame lamination techniques.
In a number of electrical components it is desirable to provide fuses to protect against electrical surges. There are currently a number of commercially available fuse styles. One available type of fuse is known as a positive temperature coefficient fuse. A representative positive temperature coefficient (PTC) fuse is illustrated in FIGS.
1
(
a
) and
1
(
b
). As seen in FIG.
1
(
a
), the representative PTC fuse
50
has a top plate (top contact pad)
52
and a bottom plate (bottom contact pad)
54
that are separated by a positive temperature coefficient resistor material
56
. The contact pads
52
and
54
each have tabs
57
,
59
which are bent down to form wings that define a cavity
61
beneath the bottom contact pad
54
.
A die
64
, such as a flip chip packaged Zener diode is then attached to the bottom surface of the bottom contact pad within the cavity
61
as best seen in FIG.
1
(
b
). Solder posts
67
are formed on the tips of bent down tabs
57
,
59
. With this arrangement, the fuse can be mounted on a printed circuit board (or other appropriate substrate) by soldering the tab tip solder post
67
and the die's solder bumps
66
to appropriate landings on the printed circuit board.
The described PTC fuses are used in a number of applications. However, they are generally relatively expensive to package. Accordingly, there are continuing efforts to develop improved methods for packaging such fuses.
SUMMARY OF THE INVENTION
To achieve the forgoing and other objects and in accordance with the purpose of the invention, an improved method of packaging external fuses together with integrated circuit devices is described. A pair of frame strips are provided that each have an associated set of contact pads. A resistor paste is applied to one of the contact pad sets and the frame strips are laminated together by curing the resistor paste. The contact pads sets are aligned with one another with the resistor paste there between to form a plurality of fuses. Dice are then mounted on the opposite side of one of the contact pad sets to form integrated circuit devices having integrally packaged external fuses. The packaged devices are eventually singulated for use.
In some embodiments, the contact pads each have downturned tabs that form wings on opposite sides of their associated die. When the dice are flip chips, a device may be attached to a substrate board by soldering bumps on the singulated die and soldering the tab wing tips to the substrate board.
In a preferred embodiment, the resistor paste is a positive temperature coefficient resistor paste.


REFERENCES:
patent: 3784948 (1974-01-01), Johnston et al.
patent: 3925801 (1975-12-01), Haitz et al.
patent: 4627151 (1986-12-01), Mutholland et al.
patent: 401133315 (1989-05-01), None

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