JPH06188361A - Multichip module substrate - Google Patents

Abstract

PURPOSE:To obtain a device capable of high density mounting and application to a high speed device wherein a bare chip can be effectively cooled, by a method wherein mounting pads are arranged in a step type, two TAB chips are stacked and mounted, and heat sinks are independently formed on the surface and the rear. CONSTITUTION:Lamination boards are stacked in a state that a part of the board is hollowed out, mounting pads 5, 7 are arranged in a step type, and two TAB chips 4, 6 are stacked and mounted. A heat sink 1 is directly brought into contact with the upper TAB chip 4 and fixed. Copper pads 8, 9 are arranged just under the lower TAB chip 6 and on the surface of a substrate 13 wherein the rear side is hollowed out, and connected via a through hole. A metal slab 11 is buried in the part where the rear of the substrate 13 is hallowed out, and is connected with the copper foil pad 9 on the surface wherein the rear of the substrate 13 is hollowed out. A heat sink 12 is connected with the buried metal slab 11. For example, the upper TAB chip 4 wherein an adhesive agent 3 is spread on the rear is mounted with its face down, and the heat sink 1 is bonded to the chip 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-chip module (hereinafter abbreviated as MCM) substrate.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a conventional example.
Connect the TAB 2 to the substrate 1 with the bonding wire 5,
The metal slug 3 is embedded in the substrate 1, exposed on the back surface, and connected to the heat sink 4. The TAB 2 is sealed with the sealing resin 7.

[0003]

The conventional technique has a drawback in that the bare chip connected by wire bonding needs to be sealed with a resin, so that the repair process cannot be performed and the bare chips cannot be arranged in an overlapped manner like double-sided mounting.

[0004]

The MCM substrate of the present invention has two
Since two TAB chip LSIs are mounted on top of each other, two mounting pads are provided on the stairs, a metal slug for connecting a heat sink in the lower part, a metal pad under the TAB chip in the lower part and a metal slug embedded in the lower part. Has a through hole for connecting the TAB chip, a heat sink for cooling the TAB chip on the upper side, and a lower T via the metal slug on the lower side.
It is composed of a heat sink that cools the AB chip.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.
The substrate 13 is a ceramic substrate having an etched wiring pattern or PWB. First in advance
A pad 2 for fixing the heat sheet sink 1 for cooling the upper TAB chip 4 is provided in the layer, and a pad 5 for solder-connecting the upper TAB chip 4 is provided in the second layer. A pad 7 for soldering the lower TAB chip 6 is provided on the third layer. Further, a copper foil pad 8 is provided below the third layer lower TAB chip. A copper foil pad for contacting the metal slug 11 is also provided in the fourth layer.

Next, regarding the copper-clad laminate sandwiched between the first layer and the second layer, a part of the upper portion of the upper TAB chip mounting pad 5 is milled with a milling machine to expose the upper TAB chip mounting pad 5 to the upper side after the lamination. Cut off. Similarly, for the copper clad laminate sandwiched between the second layer and the third layer, the upper portion of the lower TAB chip mounting pad 7 is ground with a milling machine to expose the lower TAB chip mounting pad 7 to the upper side after lamination. Keep it. With respect to the copper clad laminate narrowed between the fourth layer and the fifth layer, the portion where the metal slug 11 is fitted is ground with a milling machine.

Next, regarding the copper clad laminate sandwiched between the third layer and the fourth layer, the copper foil pad 8 for contacting the lower TAB chip 6 of the third layer and the metal slug 11 of the fourth layer are contacted. After providing a plurality of through holes with a drill for connecting the copper foil pads 9 to be formed, the inside of the through holes is plated. This heats the lower TAB chip 6 with metal slag 11
This is because it escapes to the heat sink 12 via the.

Each of the copper clad laminates thus produced is pressure-heated by a laminating press to form one substrate, and then the metal slug 11 is attached to the metal slug connection pad 9 of the fourth layer by the adhesive 1
Attach 4 and then fit. Next, the TAB chip is mounted on the substrate. First, glue 15 under the lower TAB chip 6.
And then fixed to the third layer copper foil pad 8. Next, the lead of the lower TAB chip 6 is soldered to the lower TAB chip mounting pad 7 of the third layer. Next, the leads of the upper TAB chip 4 are connected to the upper TAB chip mounting pads 5 of the second layer.
Make a down face and solder connect. Adhesive 3 is attached to the back side of the upper TAB chip, and the heat sink 1
To adhere. The heat sink 1 is fixed by soldering on the heat sink fixing pad of the first layer. An adhesive 14 is attached to the metal slug fitted on the back side of the substrate, and then the heat sink 12 is adhered and fixed. The heat generated by the TAB chip is dissipated into the air through the heat sink 1 for the upper TAB chip 4, and is conducted to the heat sink 12 on the back side through the through hole 10 and the metal slug 11 for the lower TAB chip 6 before being dissipated in the air. Let

[0010]

As described above, according to the present invention, since two bare chips can be mounted in an overlapping manner, many bare chips can be mounted in a small area. Therefore, the packaging density between bare chips can be increased and the wiring length can be shortened, so that it can be applied to a higher speed device. In addition, since heat sinks can be independently provided on the front and back sides, it is possible to efficiently cool bare chips that generate high heat. Further, since the bare chips are collectively solder-connected with the TAB chips, it is more efficient than the wire bonding connection. Further, since heat is conducted between the lower TAB chip and the metal slug through the through hole, there is an effect that the wiring area between the chips which is lost can be minimized as compared with the case where the TAB chip and the metal slug are directly contacted with each other. .

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Heat Sink 2 Pad for Fixing Heat Sink 3 Adhesive 4 TAB Chip 5 Upper TAB Chip Mounting Pad 6 TAB Chip 7 Lower TAB Chip Mounting Pad 8 TAB Chip Connecting Copper Foil Pad 9 Metal Slug Connecting Copper Foil Pad 10 Through Hole 11 Metal Slug 12 heat sink 13 substrate 14 adhesive

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H01L 23/36 H05K 7/20 D 8727-4E

Claims (1)

[Claims] 1. A means for stacking a plurality of laminated plates in a hollowed-out state, providing mounting pads in a staircase shape and mounting two TAB chips in an overlapping manner, and directly fixing a heat sink to the upper TAB chip to fix it. Means, a means to connect a through hole by providing a copper foil pad on the surface of the lower side of the TAB chip and the back side of the board which are hollowed out, and a metal piece is embedded in the hollowed out part of the back side of the board, and the back side of the board is hollowed out. A multi-chip module substrate comprising means for connecting to a copper foil pad on the exposed surface and means for connecting a heat sink to the embedded metal piece.