Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For plural devices
Reexamination Certificate
2001-05-18
2002-08-27
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For plural devices
C257S723000, C257S666000, C257S713000, C257S675000
Reexamination Certificate
active
06441484
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and more particularly to a technique effectively applicable to packaging of semiconductor devices.
Semiconductor devices of elemental structure for use as switches in power supply-related items including power amplifiers and power source units are available-in various package structures. For instance “2.5 V-Driven Type 3rd Generation Trench Gate MOSFET” in
Toshiba Review
, Vol. 53 , No. 11 (1998), pp.45-47 , describes a semiconductor device for power supply use of a package structure known as TSSOP (Thin Shrink small Out-line Package) type. In this TSSOP type semiconductor device, as a switching element, for instance, a semiconductor chip with a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) built into it is sealed with a resin sealing body.
On the other hand, the Japanese Published Unexamined Patent Application No. Hei 7-58293 (1995) (the counterpart of the U.S. Pat. No. 5,642,252) discloses a circuit system for controlling the turning on/off of a power MOSFET built into a semiconductor chip that is controlled with a controller.
Further, the Japanese Published Unexamined Patent Application No. Hei 5(1993)-234495 discloses a semiconductor device for power supply use in which a semiconductor chip with a built-in power MOSFET and a fuse element whose fusible portion is fused by its own heat when an overcurrent flows are sealed by a single resin sealing body. The fuse element is provided to prevent trouble from occurring when the source and drain of the power MOSFET are short-circuited to each other, and is connected to the power MOSFET in series.
SUMMARY OF THE INVENTION
Incidentally, the present inventors developed a semiconductor device (module) semiconductor chip with a built-in control circuit (hereinafter to be referred to simply as a “control chip”), a plurality of semiconductor chips (hereinafter to be referred to simply as “switching chips”) each with a power MOSFET, as switching elements whose turning on/off is controlled by the control chip, and a plurality of fuse elements individually connected by these switching chips are sealed by a single resin sealing body. During their work to develop this semiconductor device, the present inventors discovered the following problems.
(1) As the amperage handled by the switching chips is high, the quantity of heat generated is high relative to that generated by the control chip. Therefore, where the plurality of switching chips are to be sealed with the control chip by the single resin sealing body, the chip arrangement should be such that heat generated by these chips can be efficiently discharged out of the resin sealing body.
(2) Where the control chip and the switching chips are to be electrically connected by bonding wires, the bonding wires should be kept as short as practicable. If the bonding wires are too long, the hanging portions of wire loops, after they have bonded the chips, are apt to invite short circuiting, and this would result in a low yield of the manufacturing process. Longer bonding wires would also invite a low yield of the manufacturing process in another way because, when resin sealing body is formed by a transfer mold process, a wire flow due to the fluidity of resin pressure-injected into the cavity of the molding die is apt to lead to short circuiting. However, depending on how the chips are arranged, some switching chips may far more distant from the control chip than other switching chips, and bonding wires for these distant switching chips become extremely long.
(3) For fuse elements whose fusible portions are fused by their own heat when an overcurrent flows, it is essential to secure stable fusing currents (breaking currents). However, where the fuse elements are sealed together with switching chips generating large quantities of heat by a single resin sealing body, the heat generated by the switching chips are transmitted via the resin of the resin sealing body to the fuse elements to destabilize the fusing currents of the fuse elements. Moreover, as the heat generated by the fuse elements escapes via the resin of the resin sealing body, the fusing currents of the fuse elements are destabilized in this respect as well. Then, selective providing hollows in the fuse element part to prevent the elements from getting in contact with the resin of the resin sealing body could restrain the effect of heat transmitted via the resin of the resin sealing body and that of heat escaping via the resin of the resin sealing body, and this contributes to stabilizing the fusing currents of the fuse elements, but it is difficult to selective form hollows in the fuse element part by the transfer mold method which is suitable for mass production.
Furthermore, for a semiconductor device requiring high heat radiation, a heat radiation plate (cooling wheel) is selected. In a package structure having a heat radiating plate, as heat generated by switching chips is more easily transmitted to fuse elements and heat generated by the fuse elements can more easily escape, the fusing currents of the fuse elements become even more unstable.
An object of the present invention, therefore, is to provide a technique capable of helping improve heat radiation from semiconductor devices.
Another object of the invention is to provide a technique capable of helping enhance the yield in semiconductor device manufacturing.
Still another object of the invention is to provide a technique capable of helping stabilize the stability of the fusing currents of fuse elements.
These and other objects and novel features of the invention will become apparent from the following description of the specification when taken in conjunction with the accompanying drawings.
Typical aspects of the invention disclosed in this application will be briefly outlined below.
(1) A semiconductor device comprising:
a first semiconductor chip having a control circuit,
a plurality of second semiconductor chips each having a switching element, and
a resin sealing body for sealing the first semiconductor chip and the plurality of second semiconductor chips, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body, and
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip.
(2) A semiconductor device comprising:
a first semiconductor chip having on one main surface a control circuit and a plurality of electrodes,
a plurality of second semiconductor chips each having on one main surface a switching element and an electrode,
a plurality of bonding wires for electrically connecting the plurality of electrodes of the first semiconductor chip and respective electrodes of the plurality of second semiconductor chips, and
a resin sealing body for sealing the first semiconductor chip, the plurality of second semiconductor chips and the plurality of bonding wires, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body, and
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip.
(3) The semiconductor device described in (1) or (2), wherein:
the plurality of second semiconductor chips are arranged symmetrically relative to the first semiconductor chip.
(4) A semiconductor device comprising:
a first semiconductor chip having a control circuit, a plurality of second semiconductor chips each having a switching element,
a plurality of fuse elements whose fusible portions are fused by their own heat when an overcurrent flows, and
a resin sealing body for sealing the first semiconductor chip, the plurality of second semiconductor chips and the plurality of fuse elements, wherein:
the first semiconductor chip is arranged in the central portion of the resin sealing body,
the plurality of second semiconductor chips are arranged on a periphery of the first semiconductor chip, and
the plurality of fuse elements are arranged on a periphery of the first semiconductor chip and outside the second semiconductor chips
Arai Norinaga
Iizuka Mamoru
Koyama Kenji
Mikami Akio
Ho Tu-Tu
Nelms David
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