JPH04356998A - Multichip module - Google Patents

Abstract

PURPOSE:To materialize high-density mounting of electronic parts by connecting a thin built-in electronic part to an inside conductor circuit besides the outside conductor circuit of a multilayer printed wiring board. CONSTITUTION:A recess 17 is made in an inner layer substrate 12 being the inside insulating layer, and a chip capacitor 16 is placed upside down, and is soldered to an inner conductor circuit 13. And two sheets of prepreg adhesive layers are stacked and pressed as inter-layer insulating materials, respectively, thus a chip capacitor 16 is built in the multilayer wiring board 10. Hereby, the overall thickness of the multilayer printed wiring board can be made thin to the utmost and besides the adhesion between the layers can be made enough, so high-density of electronic parts can be materialized.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a multi-chip module in which a large number of electronic components are mounted and mounted on a multilayer printed wiring board, and in particular, the present invention relates to a multi-chip module in which a large number of electronic components are mounted and mounted on a multilayer printed wiring board, and in particular, electronic components are built-in and connected to the internal conductor circuit in addition to the external conductor circuit. Regarding multi-chip modules.

0002

2. Description of the Related Art Conventionally, various efforts have been made to achieve high-density packaging using double-sided or multilayer printed wiring boards. It is a hybrid technology that miniaturizes electronic components and mounts them in high density. Initially, this high-density packaging technology started at the level of components such as hybrid ICs, but in recent years, this high-density packaging technology has been used for entire electronic circuits such as portable audio and video cameras, and the miniaturization of electronic devices is progressing.

On the other hand, as for printed wiring boards for high-density packaging, high-density wiring has been realized by miniaturizing conductor circuits and making substrates thinner and multilayered. Currently, 0.05m
0.1mm fine conductor circuit, a combination of a 0.1mm thick inner layer substrate and a 0.1mm thick prepreg adhesive layer.
5mm thick 4-layer boards are being mass-produced.

However, in recent years, there has been a demand for higher-density packaging, and in addition to mounting electronic components only on the surface of printed wiring boards, passive components are mainly mounted between the internal conductor circuits of printed wiring boards. It was requested that it be built-in. At first, consideration was given to inserting a resistor such as a printed carbon resistor or a nickel-plated resistor between internal conductor circuits, and attempts were also made to incorporate a capacitor. However, printed wiring boards with carbon resistors have large resistance fluctuations,
Because it was expensive to form nickel resistors and capacitors, it was difficult to incorporate it into mass production.

[0005] Further, studies have been made to incorporate chip components, which have been rapidly miniaturized in recent years. For 1005 type chip parts, 0.5 mm width and 1.0 mm length are 0.3
Chip resistors with a thickness of 5 mm are manufactured, and also with a thickness of 0.5 mm.
Chip ceramic capacitors with a width of 1.0 mm, a length of 0.5 mm and a thickness of 0.5 mm are also made. This small chip component is embedded between the layers of the printed wiring board.

However, even if 1005 type chip components are built in, the thickness is 0.35 to 0.5 mm, which is much thicker than the 0.1 mm thickness of prepreg, which is an interlayer insulating material, and it is not necessary to laminate it as a multilayer printed wiring board. In order to achieve this, it was necessary to use multiple sheets of prepreg to make it thicker. Even so, the amount of resin around the chip components may be insufficient, resulting in insufficient interlayer adhesion or voids remaining.
Additionally, the entire multilayer printed wiring board became thicker, which went against the idea of high-density packaging.

Furthermore, in order to bond the inner layer substrate and the prepreg together as a multilayer printed wiring board, blackening treatment of converting the surface of the internal conductor circuit on the inner layer substrate into cupric oxide or roughening treatment by reducing the copper oxide is necessary. must be a surface, and
This roughened surface is sensitive to high heat and is easily oxidized and reduced, and a major problem has been how to deal with the effects of heat when soldering chip components and thin packaged ICs.

[0008]

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and the problem to be solved is when a thin chip component or a thin package IC is incorporated. Another objective is to make the overall thickness of the multilayer printed wiring board as thin as possible and to ensure sufficient adhesion between the layers. An object of the present invention is to realize high-density packaging of electronic components by connecting thin electronic components not only on the external conductor circuits of a multilayer printed wiring board but also to the internal conductor circuits thereof. It is in.

[0009]

[Means for Solving the Problems] The means taken by the present invention to solve the above-mentioned problems can be explained using the reference numerals used in the embodiments. , 15 and 16, in which an electronic component 15 is mounted and mounted on an external conductor circuit 11 of a multilayer printed wiring board 10, and a thin chip is mounted between an internal insulating layer 12 of the multilayer printed wiring board 10. In the multi-chip module 100 in which the electronic components 14 and 16 are mounted and electrically connected to the internal conductor circuit 13, a recess or opening 17 is formed in the internal insulating layer 12 to accommodate the thin electronic components 14 and 16. In addition to providing
A multi-chip module 1 characterized in that the gap between a recess or opening 17 and thin electronic components 14 and 16 is filled with a prepreg adhesive of a multilayer printed wiring board 10.
00. ”.

0010

[Operation] Multi-chip module 1 configured as above
00, a thin electronic component 14 is provided on the internal insulating layer 12.
, 16 are provided, so that the thickness of the thin electronic components 14, 16 can be absorbed. Therefore, the inner insulating layer 12
The internal conductor circuit 13 has a smooth, flat shape without a large bulge in thickness due to the built-in thin electronic components 14 and 16. Furthermore, since the gap between the recess or opening 17 and the thin electronic components 14 and 16 is filled with the prepreg adhesive of the multilayer printed wiring board 10, the thin electronic components 14 and 16 are particularly close to the inner insulating layer 12 and the internal conductor circuit 13. , 16, there are no remaining voids. And a thin electronic component 14,
Since the area around 16 is gently flat, filling with the prepreg adhesive will not result in resin shortage.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in detail according to embodiments shown in the drawings.

FIG. 1 shows one embodiment of a multi-chip module 100 of the present invention. A plurality of thin package ICs 15 are mounted on external conductor circuits 11 on both sides of the multilayer printed wiring board 10. In this embodiment, the thin package IC 15 is TAB (Tape Out).
It is a bonding package. In addition to TAB, transfer molded TSOP (
Thin Small Outline Pac
cage) is suitable for high-density, thin packaging. A thin chip capacitor 16 is placed between the internal insulating layers 12 of the multilayer printed wiring board 10 and electrically connected to the internal conductor circuit 13. In this example, a recess 17 was formed by counterbore in the inner layer substrate 12, which is an internal insulating layer, and a chip capacitor 16 with the front and back turned upside down was placed therein, and the internal conductor circuit 13 was soldered to the recess 17. Then, two prepreg adhesive layers each having a thickness of 0.1 mm were laminated and pressed as interlayer insulating materials to obtain a multilayer printed wiring board 10 with a built-in chip capacitor 16. The multilayer printed wiring board 10 obtained here with a built-in chip capacitor 16 is
There were no remaining voids in the internal insulating layer 12, and the adhesive strength was sufficient. Further, after this, electronic components 15 were mounted and connected on the external conductor circuit 11 of the multilayer printed wiring board 10 to obtain a multichip module 100.

The surface treatment of the internal conductor circuit 13 and the soldering of the electronic component 16 are preferably carried out as follows. First, as for the surface treatment of the internal conductor circuit 13, the connection terminal portion (not shown) with the electronic component 16 is plated with nickel and gold, and then blackened. Since nickel and gold plating is applied only to the connection terminals, that area is masked with a plating resist and nickel and gold plating is performed. If the blackening treatment is performed, the gold-plated portion will not be oxidized, so the blackening treatment will be performed on the internal conductor circuit 13 other than that portion.

Next, the electronic component 16 is soldered by placing the electronic component 16 in the recess or opening 17 described above, and connecting a part of the external connection terminal (not shown) of the electronic component 16 to the internal conductor circuit 13. Soldering can be performed by applying solder paste to the terminals and melting the solder by reflow. Here, it is important to note that the blackened part is sensitive to heat, and it is important not to apply high heat to the blackened part. For this reason, in reflow melting, it is desirable to use a heater block, a pulse tool, a method of partial heating using a laser beam, etc., or a low-temperature reflow using a low melting point solder paste. The low melting point solder paste is preferably bismuth solder or indium solder with a melting point of about 130 to 180°C.

FIG. 2 shows another embodiment of the multichip module 100 of the present invention. The difference between the embodiment shown in FIG. 2 and the embodiment shown in FIG. This is the point connected to the conductor circuit 13. As the thin package IC 14, the above-mentioned TAB or TSOP package is preferable. Furthermore, it is easy to use flip-chip mounting of a bare chip IC instead of the thin package IC 14. In that case, the inner layer substrate 1 which is an internal insulating layer
No opening was provided in 2, a bare chip IC was flip-chip mounted on the inner layer substrate 12, and an opening 17 was provided in the prepreg which is an interlayer insulating material in that part.

In the embodiment shown in FIG. 3, a chip component 16 such as a chip capacitor or a chip resistor and a thin package IC 14 are mixed and built in between the internal insulating layers 12, and the details will be omitted.

[0017]

Effects of the Invention As detailed above, in the multi-chip module according to the present invention, when thin chip components or thin package ICs are incorporated, the overall thickness of the multilayer printed wiring board can be made as thin as possible, and the interlayer Adhesion can be made sufficient. Therefore, thin electronic components can be built-in and connected to the internal conductor circuits of the multilayer printed wiring board in addition to the external conductor circuits, and high-density packaging of electronic components can be realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a multi-chip module according to the present invention.

FIG. 2 is a sectional view showing another embodiment of a multi-chip module according to the present invention.

FIG. 3 is a sectional view showing still another embodiment of the multi-chip module according to the present invention.

FIG. 4 is a cross-sectional view showing a conventional multi-chip module.

[Explanation of symbols]

10 Multilayer printed wiring board 11 External conductor circuit 12 Internal insulation layer 13 Internal conductor circuit 14 Thin package IC 15 Electronic parts 16 Chip parts 17 Recess or opening 100 Multi-chip module

Claims (1)

[Claims] 1. A multi-chip module in which a large number of electronic components are mounted and mounted on a multilayer printed wiring board, wherein the electronic components are mounted and mounted on an external conductor circuit of the multilayer printed wiring board, and the electronic components are mounted and mounted on an external conductor circuit of the multilayer printed wiring board. In a multi-chip module in which a thin electronic component is placed between internal insulating layers and electrically connected to an internal conductor circuit, the internal insulating layer is provided with a recess or opening for accommodating the thin electronic component, and A multi-chip module characterized in that a gap between a recess or opening and the thin electronic component is filled with a prepreg adhesive of the multilayer printed wiring board.