JP2001189536A - Wiring substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high-density wiring by forming a metal core with a material having a low thermal expansion coefficient. SOLUTION: An external layer is formed by laminating a copper-clad insulating sheet, which is formed by forming an insulating layer on a copper foil, to a single side or both sides of a metal-core copper-clad laminate, on which circuits have been formed on its single side or both sides. The copper foil in unnecessary regions of the external layer is removed by etching. The insulating layer in specified regions are removed, and via holes are formed, through which electrical continuity is made to form a metal-core multilayer laminate, on which semiconductor components are mounted. The purpose is achieved by using for the metal core a copper material compounded with copper oxide which is a material having a low thermal expansion coefficient or a clad material which is formed by laminating the copper material compounded with copper oxide to adhere to an iron-nickel alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring board, and more particularly to a wiring board having a metal core having a low coefficient of thermal expansion.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic devices, wiring boards used for them have also been required to be smaller, denser, lighter, and more reliable. There is an increasing demand for miniaturization and high reliability of through holes and via holes. Of these, for the wiring width and wiring gap, photosensitive etching resists and etching solutions have been developed, and in order to reduce the thickness of conductive foils and insulating layers, for example, a method of manufacturing a printed wiring board described in JP-A-59-155994 Various technologies have been proposed.

In addition, as switching power supplies used in electronic equipment, DC / DC converters, inverters, and the like have become lighter and smaller, and these switching power supply DC / DC converters and inverters have semiconductor chips mounted thereon. Conventionally, a metal core substrate such as an aluminum core substrate has been used to radiate a large amount of heat generated from the semiconductor chip.

As a metal core copper-clad laminate using such a metal core substrate, a single-sided printed wiring board has been generally used. When using both sides, a non-through-hole printed wiring board is conceivable.

[0005] For example, in the case of a double-sided through hole, a hole is previously formed in a portion where a through hole is formed in a metal plate serving as a core, and then a copper foil is hot-pressed on both surfaces of the metal plate via a prepreg. By laminating, a double-sided copper-clad laminate is formed. As a result, the prepreg is filled in the holes formed in the metal plate. Next, in the center of the hole filled with the prepreg, a hole having a smaller diameter than the hole processed in advance is machined, copper plating is performed in the hole and the entire copper foil surface, and then the outer layer copper foil is etched and the outer layer is etched. The metal core multilayer wiring board is completed by forming the circuit.

[0006]

However, the conventional metal core wiring board has a large thermal expansion coefficient and a large difference in thermal expansion coefficient from the semiconductor element mounted on the wiring board, so that the reliability of bare chip mounting is not high. There is a problem that high-density mounting cannot be performed.

The present invention has been made in view of the above circumstances, and has as its object to provide a metal core multilayer wiring board having a low coefficient of thermal expansion.

[0008]

According to the present invention, there is provided a wiring board having a metal core, wherein the metal core is made of a metal material having a low thermal expansion coefficient.

More specifically, one side or both sides of a metal core copper-clad laminate having a circuit formed on one or both sides,
An outer layer is formed by laminating a copper-clad insulating sheet having an insulating layer formed on a copper foil surface, and a predetermined portion of the copper-clad insulating sheet is etched and removed, and a predetermined portion of the insulating layer is removed to form a via hole. In the metal core copper-clad laminate formed by forming and obtaining conduction, the metal core is a metal core multilayer wiring board made of a metal material having a low coefficient of thermal expansion. Further, as the metal core material having a low coefficient of thermal expansion, a copper material compounded with copper oxide, or a metal formed of a clad material formed by laminating and bonding the copper material compounded with copper oxide on both surfaces of an iron-nickel alloy It is a core multilayer wiring board.

In the present invention, since the metal core is made of a metal material having a low coefficient of thermal expansion, the coefficient of thermal expansion of the metal core multilayer wiring board can be reduced, and the ratio of the metal core to the metal core multilayer wiring board can be controlled. Thus, the coefficient of thermal expansion of the metal core multilayer wiring board can be set arbitrarily, so that the reliability of bare chip mounting, which was difficult with the conventional metal core wiring board, is obtained, and high-density mounting is possible.

[0011]

Embodiments of the present invention will be described below. Note that the present invention is not limited to these examples. Although the following examples relate to a multilayer wiring board having a circuit in an inner layer, the present invention relates to the manufacture of a copper-clad laminate having copper foil on both sides, a single-sided wiring board having a circuit on only one side, and the like. It can also be applied to

Embodiment 1 FIG. 1 shows a manufacturing process of a multilayer wiring board in this embodiment.

First, a copper foil 2 having a thickness of about 18 μm and an insulating resin layer 3 having a thickness of about 80 μm are formed on both sides of a metal core substrate 1 having through holes formed at predetermined positions by etching.
(Epoxy-based)) and a resin-coated copper foil 11 were laminated and bonded to obtain a laminate 12 (FIG. 1A).

Next, an etching resist 7 (etching resist)
After laminating JSR FDR-2500), baking and developing the pattern, removing unnecessary copper foil with ferric chloride, forming the first layer wiring 4, and irradiating a predetermined position with a carbon dioxide laser. , Dissolve / vaporize the insulating resin layer
It was decomposed to form a through hole 5. Next, after performing a resin residue removal treatment on the inner wall of the through hole 5 by the potassium permanganate method, the inner wall of the through hole 5 is immersed in a catalyst for electroless copper plating. The plating catalyst 6 was attached (FIG. 1 (b)). Note that an alkaline palladium catalyst was used as the catalyst liquid. Activator Neogant 834 manufactured by Atotech can be mentioned as a commercially available catalyst liquid.

Subsequently, an etching resist 7 (FDR-2500 manufactured by etching resist JSR) is laminated on portions of the multilayer laminated board which will be the wirings and lands (FIG. 1C), and the pattern is baked, developed and unnecessary. The copper foil was removed with ferric chloride, and the plating catalyst 6 adhering to the copper at that location was also removed. The etching resist and the etching solution used at this time may be commercially available. The etching resist JDR FDR-2500 has a high resolution, and when it is used, both the wiring width and the wiring interval can be reduced to 25 μm or less.

Next, a copper plating film 8 is deposited by thick-film electroless copper plating, and the first layer wiring 4 on the front surface and the first layer wiring 4 on the back surface are deposited.
At the same time as forming a via hole for connecting the layer wiring 4 'so as to be conductive, the thickness of the wiring pattern and the copper foil of the land were increased. Subsequently, the etching resist 7 was removed (FIG. 1D). Further, the above steps are repeated, and the second
After forming the layer wiring 10 and forming a via hole for connecting the first layer wiring 4 and the second layer wiring 10 in a conductive manner, a solder resist 9 (USR-2G manufactured by Tamura Seisakusho) is formed in a desired portion.
FA-58-300) (FIG. 1 (e)). This allows
Multilayer wiring board 13 having via holes for interlayer connection
Could be obtained.

The multilayer wiring board 1 manufactured according to this embodiment
No. 3 shows that when a composite material of copper oxide and copper is used for the metal core, the thermal expansion coefficient can be reduced to 10 μm / m · ° C., and the composite material of copper oxide and copper is formed on both surfaces of the iron-nickel alloy in the metal core. When a clad material formed by laminating and bonding was used, the coefficient of thermal expansion was extremely reduced to 6 μm / m · ° C. Also,
Further, a plurality of through holes can be formed in the through holes formed in the metal core, thereby realizing high-density wiring. Further, since the catalyst at an unnecessary portion was removed before the electroless copper plating step, high insulation reliability was exhibited in the wiring gap, and good electrical connection was made in the hole. In addition, when a semiconductor element is mounted on the multilayer wiring board 13 and sealed with a resin to produce a resin-sealed semiconductor device, a good product having excellent connection reliability can be obtained in any case. Was.

<Embodiment 2> In this embodiment, as shown in FIG. 2, multi-layer wiring is performed in the same procedure as in Embodiment 1 except that the processing order of solder resist coating and electroless plating is reversed. A substrate was produced (FIGS. 2A to 2C).

In the present embodiment, the first
After the layer wiring 4 was formed and the catalyst 6 attached to the copper at the etching location was also removed, a solder resist 9 was applied to a predetermined location (FIG. 2D). Next, a via hole was formed by depositing a copper plating film 8 by electroless copper plating, and the wiring pattern thickness was increased (FIG. 2E).

According to this manufacturing method, in the electroless copper plating step, the contact between the wiring gap and the plating solution can be completely cut off by the solder resist 9 and the plating growth direction in the wiring pattern can be limited. . In this embodiment, a multilayer wiring board 14 having more excellent electrical insulation reliability between the conductor wirings than in the first embodiment was obtained. The cost and the wiring density were the same as in the first embodiment.

<Embodiment 3> In this embodiment, a resin residue removal treatment is performed on the inner wall of the through hole 5 by a sand blast method instead of a resin residue removal treatment by a potassium permanganate method. A multilayer wiring board was manufactured in the same manner as in Example 1 and Example 2.

In this embodiment, a multi-layered wiring board can be obtained at a lower cost than in the first and second embodiments because a sandblasting device, which is a general-purpose device, is used in the resin removing step. The obtained multilayer wiring board had the same high-density wiring as in the above example, and exhibited high insulation reliability at wiring intervals and good electrical connection reliability at the hole.

<Embodiment 4> In this embodiment, a conductive resin paste is filled into the through holes 5 by screen printing, and the first layer wiring 4 on the front surface, the first layer wiring 4 'on the rear surface, and the first layer wiring are formed. A multilayer wiring board was manufactured in the same manner as in Examples 1 to 3, except that the connection between the wiring 4 and the second layer wiring 10 was formed.

In this embodiment, since a screen printing device, which is a general-purpose device, is used in the interlayer connection step, a multilayer wiring board can be obtained at a lower cost than in the first to third embodiments. The obtained multilayer wiring board had the same high-density wiring as in the above example, and exhibited high insulation reliability at wiring intervals and good electrical connection reliability at the hole.

According to the metal core multilayer wiring board shown in the above embodiment, a copper core having an insulating layer formed on a copper foil surface is provided on one or both sides of a metal core copper clad laminate having a circuit formed on one or both surfaces. An outer layer was formed by laminating a clad insulating sheet, and a copper foil of a required portion of the copper-clad insulating sheet was removed by etching, and a predetermined portion of the insulating layer was removed to form a via hole, thereby obtaining conductivity. In the metal core copper-clad laminate, a metal material having a low coefficient of thermal expansion (a copper material compounded with copper oxide, or
The thermal expansion coefficient of the metal core multilayer wiring board can be reduced by using a clad material formed by laminating and bonding a copper material composite of the copper oxide on both surfaces of a nickel alloy,
By controlling the ratio of the metal core to the metal core multilayer wiring board, the coefficient of thermal expansion of the metal core multilayer wiring board can be set arbitrarily. And high-density mounting was achieved.

[0026]

According to the present invention, the reliability of bare chip mounting can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a manufacturing process of a metal core multilayer wiring board in Example 1 of the present invention.

FIG. 2 is an explanatory view showing a manufacturing process of a metal core multilayer wiring board in Embodiment 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal core board 2 ... Copper foil 3 ... Insulating resin layer 4 ... First layer wiring on the front surface 4 '... First layer wiring on the back surface 5 ... Through-hole (laser processing) 6 ... Plating catalyst 7 ... Etching resist 8 ... None Electrolytic copper plating film 9 ... Solder resist 10 ... Second layer wiring 11 ... Copper foil with resin 12 ... Laminated body 13 ... Multilayer wiring board 14 ... Multilayer wiring board

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takehiko Hasebe 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Hitachi, Ltd. Production Research Laboratory (72) Inventor Kiyomitsu Suzuki 7-1-1 Omikacho, Hitachi City, Ibaraki Prefecture No. 1 F-term in Hitachi Research Laboratory, Hitachi, Ltd. (Reference) 5E315 AA05 AA11 BB01 BB04 BB05 BB06 BB14 GG07

Claims (3)

[Claims] 1. A wiring board having a metal core, wherein the metal core is made of a metal material having a low coefficient of thermal expansion. 2. The wiring board according to claim 1, wherein said metal core is made of a copper material in which copper oxide is compounded. 3. The wiring board according to claim 1, wherein said metal core is made of a clad material formed by laminating and bonding a copper material compounded with copper oxide on both surfaces of an iron-nickel alloy.