JP2001284806A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer wiring board having both rigidity and tenacity. SOLUTION: This multilayer wiring board is provided with insulating layers 16-20 composed of organic polymer resin, circuit layers 21-25 and metal core members 6-10 of (n) layers (n is an integer of at least 3). As to the metal core members 6-10 of the (n) layers, thickness is increased in the outer layers of the metal core members 6, 7, 9, 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board having excellent rigidity used for mounting electronic parts and the like.

[0002]

2. Description of the Related Art With the recent miniaturization and high performance of electronic devices, semiconductor devices constituting the electronic devices and printed wiring boards on which the semiconductor devices are mounted are required to be small, thin, high performance and high reliability. ing. In response to these demands, the mounting form has been progressing from a pin insertion type package such as DIP to a surface mount type package such as SOP, and further to an area array type external terminal such as CSP and MCM. In many of these area array type mounting forms, as is well known, a semiconductor chip and an interposer or MC
The package is formed in a so-called primary mounting process in which an M substrate and the like are electrically connected and undergo a sealing process. After that, usually
Solder balls are attached to the back surface of this package in an area array, and the secondary mounting is completed by performing metal bonding between the solder balls and the mother board electrode pads by IR reflow or hot air reflow. Since the yield of the mounted board obtained in this way depends on the yield of each component and the yield of individual steps, an inspection step is appropriately incorporated and a defective portion is repaired each time.

In the above-mentioned CSP and MCM, the connection between the chip and the primary mounting substrate is not a wire bonding method but a flip chip using a conductive paste or a metal bump as a bonding material, for the purpose of design for further miniaturization. Preferably, the bonding is performed.

[0004] Furthermore, it is uneconomical to dispose of the entire mounting substrate because the primary mounting product is defective due to a defect in the chip or the primary mounting process, and the primary mounting substrate is expensive like an MCM substrate. In this case, the chip needs to be repaired. The wire bonding method is not suitable for repair because bonding and fixing of the chip to the substrate are required before bonding. On the other hand, in the flip chip bonding method, repair can be performed relatively easily before the sealing step of injecting the underfill. For this reason, only electrical contacts are bonded and inspected by a method combining metal bumps or this and conductive paste, and after defective products are repaired and judged as good products,
Sealed.

[0005]

However, in this method, the mechanical strength of the electrical contacts at the time of inspection is low,
The deformation of the substrate when the electrode pins for inspection are pressed against the substrate causes a problem that the electrical contacts are broken. For this reason, a ceramic substrate having excellent rigidity may be used. However, there is a problem that the substrate itself is broken by a load at the time of inspection due to brittleness, and a problem that the substrate is expensive.

The present invention has been made in view of such circumstances, and has as its object to provide a multilayer wiring board having both rigidity and toughness.

[0007]

In order to achieve the above object, a multilayer wiring board according to the present invention comprises an insulating layer made of an organic polymer resin, a wiring conductor, and an n-layer (n ≧ 3 integer) metal core layer. Wherein the thickness d of the outermost metal core layer (when the thicknesses of both outermost metal core layers are different, the thickness of the thinner metal core layer is represented by d) is the thickness of all metal core layers. , The following equation (1) is satisfied.

[0008]

[Formula 2] d> D / n (1)

In general, an organic polymer substrate has a drawback that it is rich in toughness but lacks rigidity compared to ceramic.
One way to compensate for this drawback is to use a metal core material. However, the use of a metal core material is problematic because the thickness and weight of the substrate itself increase. Further, it is indispensable that the substrate such as the MCM is multilayered in order to secure a margin of the wiring density. Generally, a well-known metal core substrate has a structure in which a circuit layer is laminated on a metal core material via an insulating layer as described in JP-A-61-212096. However, such a metal core substrate has a structure in which materials having different coefficients of thermal expansion are laminated completely asymmetrically in the cross section of the substrate, so that a multilayer wiring board may be warped or rigidity may be sufficiently obtained for the thickness of the metal core material. Or not. Also,
Even when the thickness of the metal core material is evenly distributed in the substrate as in JP-A-11-163522, the rigidity is not sufficient.

The present inventors have conducted intensive studies to obtain a multilayer wiring board having both rigidity and toughness. As a result, the metal core layers constituting the multilayer wiring board were dispersed into three or more layers, and the three or more metal core layers were formed. The thickness d of the outermost metal core layer of the metal core layer (when the thicknesses of both outermost metal core layers are different, the thickness of the thinner metal core layer is represented by d) is the total thickness D of all metal core layers. When the above expression (1) is satisfied, the rigidity is increased, whereby the increase in thickness and the increase in weight can be suppressed, and a multilayer wiring board having both rigidity and toughness can be obtained. And arrived at the present invention. In the present invention,
The thickness d of the outermost metal core layers is preferably the same, but is not limited thereto. Further, in the present invention, the insulating layer, regardless of the presence or absence of an adhesive function,
It means one composed of an organic polymer resin.

In the present invention, when the outermost metal core layers are formed thicker than any other metal core layers, the rigidity of the multilayer wiring board is reduced by the outermost metal core layers. A multilayer wiring board having excellent rigidity and toughness can be obtained because the strength is higher at the outer part than at the center of the wiring board.

In the present invention, when the outer metal core layer is formed so as to be thicker, the rigidity of the multilayer wiring board is gradually increased from the central portion to the outer portion of the multilayer wiring board. Therefore, a similar effect can be obtained. In the present invention, “the outer core metal core layer is formed so as to be thicker” means that the metal core layer of the central layer (the metal core layer of the central layer is the central metal core layer when there are an odd number of metal core layers). (In the case of an even number of metal core layers, it indicates the two metal core layers in the center.) In the upper or lower part, the outer metal core layer is thicker than the inner metal core layer. It is a meaning including.

Further, in the present invention, when the plurality of metal core layers are disposed so as to be vertically symmetrical in thickness, external force acts on the multilayer wiring board from either the upper or lower direction. However, equivalent rigidity and toughness can be exhibited.

Next, the present invention will be described in detail.

First, the material of the metal core material constituting the metal core layer is made of Fe / Ni alloys such as 36 Alloy, 42 Alloy, Super Invar, SUS alloy, T
i and the like. These are commercially available as metal foils at relatively low cost and are suitable.

On the other hand, when fabricating the multilayer wiring board of the present invention, there is a partial restriction in that it includes a metal core layer. That is, since the metal core layer itself does not have an adhesive function, adhesive layers are required on both front and back surfaces. Therefore, a method of integrating a plurality of double-sided circuit boards and a metal core layer via an adhesive layer, and further integrating a double-sided circuit board prepared on both front and back surfaces of the metal core layer via an adhesive layer via an adhesive layer. Methods, a method of appropriately bonding a metal core layer via an adhesive layer during the build-up method, a method of appropriately combining these, and the like are possible. In any of the methods, at a portion where the IVH and the through hole penetrate the metal core layer, an opening is provided in the metal core layer in advance, and the surface is insulated with an adhesive or the like. By filling or plating through holes, conduction between the upper and lower circuit layers can be ensured.

Here, as a material for forming the adhesive layer or the insulating layer, a conventionally well-known material can be appropriately used. That is, thermoset or thermoplastic phenol, epoxy, polyester, polysulfone,
Polyetherimide, polyetherketone, polyimide resin and the like can be used. Further, paper, glass cloth, glass mat, glass nonwoven fabric, Kepler fiber and the like can be used in combination as needed.

[0018]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the multilayer wiring board of the present invention. In the figure, reference numerals 1 to 5 denote double-sided circuit boards.
The 10-layer wiring board is formed by laminating through 9. Each of the double-sided circuit boards 1 to 5 has a metal core material (metal core layer) 6 to 10 and an insulating layer 16 to 6 bonded to both front and back surfaces of the metal core material 6 to 10 via adhesive layers 11 to 15, respectively. 20 and circuit layers (wiring conductors) 21 to 25 provided on the surfaces of the insulating layers 16 to 20 (see FIG. 2, which shows the double-sided circuit board 3). That is, in the 10-layer wiring board shown in FIG.
10 to 10 are included. Then, each of the metal core materials 6
The thickness of the metal core material 8 of the double-sided circuit board 3 provided at the center is formed to be the thinnest, and the thickness of the double-sided circuit boards 2 and 4 provided above and below the double-sided circuit board 3 The metal core members 7 and 9 have the same thickness and are formed to be thicker than the metal core material 8 of the double-sided circuit board 3 disposed at the center. The thickness of the metal core members 6, 10 of the upper and lower outermost double-sided circuit boards 1, 5 is the same, and
It is formed thicker than the metal core members 7, 9 of the double-sided circuit boards 2, 4 inside thereof. For this reason, the metal core materials 6 and 10 having the upper and lower outermost layers have a thickness of 5 layers.
It is larger than the average value of the total thickness of 10 to 10. In addition,
In FIG. 1, electrical connection portions for electrically connecting the circuit layers 21 to 25 (that is, interlayer connection portions between the double-sided circuit boards 1 to 5 and connection portions within the layers of the double-sided circuit boards 1 to 5) are illustrated. Not shown.

As described above, in this embodiment, the thickness of the upper and lower outermost metal core materials 6, 10 is larger than the average of the total thickness of the five metal core materials 6 to 10. Moreover,
The five-layer metal core materials 6 to 10 are vertically symmetrical in thickness, and are formed to be thicker toward the outer layer, and are extremely excellent in rigidity and toughness.

FIG. 3 shows another embodiment of the multilayer wiring board of the present invention. In this embodiment, in the multilayer wiring board shown in FIG. 1, the thicknesses of the metal core members 6 to 10 of the double-sided circuit boards 1 to 5 are different from each other (however,
The thickness of the upper and lower outermost metal core materials 6 and 10 is formed larger than the average value of the total thickness of the five metal core materials 6 to 10). Other parts are the same as those of the above-described embodiment, and the same parts are denoted by the same reference numerals. Also in this embodiment, since the thickness of the metal core members 6 and 10 of the upper and lower outermost layers is larger than the average value of the total thickness of the metal core members 6 to 10 of the five layers, the rigidity and the toughness are excellent.

Next, examples will be described together with comparative examples.

[0023]

EXAMPLES AND COMPARATIVE EXAMPLES The thickness of the insulating layer 31 is 13 μm.
A two-layer substrate 33 composed of a polyimide and a rolled copper foil 32 having a thickness of 18 μm;
6Alloy and a 35 μm-thick polyimide-based thermoplastic adhesive 35 for bonding and integrating them were thermocompression-bonded by a press (see FIG. 4) to produce a 10-layer model substrate for evaluation (see FIG. 5). Then, in this evaluation model substrate, the thickness of the metal core material 34 was set as shown in Table 1 below.
By setting the values shown in Table 2, nine evaluation model substrates (Examples 1 to 5 and Comparative Examples 1 to 4) were produced.

Each model board for evaluation is 30 mm wide.
Cut into pieces, distance between fulcrums 20mm, head speed 5m
The bending elasticity at m / min was measured according to JIS-K6911. However, the bending elasticity is the initial elasticity of the SS curve, and is represented by a value obtained by dividing the load value (N) itself by the displacement amount (mm). In Tables 1 and 2 below, the first layer is the lowermost metal core material 34, and the second to fourth layers are the second, third, and fourth metal core materials from the lower side. In FIG. 34, the fifth layer is the uppermost metal core material 34, and the thickness of each metal core material 34 is as shown in Table 1 below.
It is shown in Table 2. In Tables 1 and 2 below,
The column indicated by "-" indicates that the metal core material 34 is not provided. However, the comparative examples 1 and 2 are comparative examples with respect to the products of Examples 1 to 4, and the comparative examples 3 and 4 are comparative examples with respect to the product of Example 5.

[0025]

[Table 1]

[0026]

[Table 2]

As is clear from Tables 1 and 2, the products of Examples 1 to 5 are different from Comparative Examples 1 to 4 in initial elasticity.
It is superior to the product and has excellent rigidity.

[0028]

As described above, according to the multilayer wiring board of the present invention, the metal core layers constituting the multilayer wiring board are dispersed into three or more layers, and the outermost metal core layer of the three or more metal core layers is dispersed. (If the thicknesses of the outermost metal core layers are different, the thickness of the thinner metal core layer is d
) Satisfies the above expression (1) with respect to the total sum D of the thicknesses of all the metal core layers, so that the rigidity is increased, whereby the thickness increase and the weight increase can be suppressed low. A multilayer wiring board having both rigidity and toughness can be obtained.

In the present invention, when the outermost metal core layers are formed thicker than any other metal core material, the rigidity of the multilayer wiring board is reduced by the outermost metal core layers. A multilayer wiring board having excellent rigidity and toughness can be obtained because the strength is higher at the outer part than at the center of the wiring board.

In the present invention, when the outer metal core layer is formed so as to be thicker, the rigidity of the multilayer wiring board is gradually increased from the central portion to the outer portion of the multilayer wiring board. Therefore, a similar effect can be obtained. In the present invention, “the outer core metal core layer is formed so as to be thicker” means that the metal core layer of the central layer (the metal core layer of the central layer is the central metal core layer when there are an odd number of metal core layers). (In the case of an even number of metal core layers, it indicates the two metal core layers in the center.) In the upper or lower part, the outer metal core layer is thicker than the inner metal core layer. It is a meaning including.

Further, in the present invention, when the plurality of metal core layers are arranged so as to be vertically symmetrical in the thickness, external force acts on the multilayer wiring board from either the upper or lower direction. However, equivalent rigidity and toughness can be exhibited.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a double-sided circuit board.

FIG. 3 is a sectional view showing another embodiment of the multilayer wiring board of the present invention.

FIG. 4 is an explanatory view showing a method of manufacturing a model board for evaluation.

FIG. 5 is a cross-sectional view showing the evaluation model substrate.

[Explanation of symbols]

 6-10 Metal core material 16-20 Insulation layer 21-25 Circuit layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Inoue 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Takuji Okei 1-1-2 Shimohozumi, Ibaraki-shi, Osaka No. Nitto Denko Corporation (72) Inventor Kei Nakamura 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 5E346 AA03 AA06 AA32 CC10 EE12 FF45 GG28 HH11

Claims (4)

[Claims] 1. A multilayer wiring board having an insulating layer made of an organic polymer resin, a wiring conductor, and an n-layer (n.gtoreq.3) metal core layer, wherein the outermost metal core layer has a thickness d (both outermost metal core layers). If the thickness of the outer metal core layer is different,
Wherein the thickness of the thinner metal core layer is represented by d) with respect to the total thickness D of all metal core layers, and satisfies the following expression (1). Formula 1 d> D / n (1) 2. The two outermost metal core layers are formed to be thicker than any other metal core layer.
The multilayer wiring board as described in the above. 3. The multilayer wiring board according to claim 1, wherein the outer metal core layer is formed to have a larger thickness. 4. The multilayer wiring board according to claim 1, wherein the metal core layer is disposed so as to be vertically symmetrical in its thickness.