JPH05343820A - Circuit board for multichip module - Google Patents

Abstract

PURPOSE:To obtain always high-speed and stable propagation characteristic of an electric signal by a method wherein the characteristic impedance of an interconnection is increased easily by a comparatively simple means or without a need for a complicated operation or the like. CONSTITUTION:This circuit board is provided with followings: a wiring pattern layer 4; and mesh ground patterns which have been arranged and installed integrally, via insulating layers 3a, 3b, on main-face sides of the wiring pattern layer 4. Each mesh opening part of the mesh ground patterns 6a, 6b is shaped to be a hexagon which is provided with two sides which are parallel to the direction of adjacent interconnections 4a of the wiring pattern layer 4, or each mesh pitch of the mesh ground patterns 6a, 6b is selected and set in such a way that each mesh pitch which is parallel to the direction of the adjacent interconnections 4a of the wiring pattern layer 4 is smaller than each mesh pitch which is perpendicualr to the direction of the interconnections 4a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board for a multi-chip module, and more particularly to a circuit board for a multi-chip module suitable for a high speed operation type module configuration.

[0002]

2. Description of the Related Art Multi-chip modules each having a semiconductor element or the like capable of high-speed operation mounted and mounted are being used in various electronic devices such as computers. A circuit board having a structure shown in cross section in FIG. 6 is generally used for the construction of this type of multi-chip module. That is, the thick film multilayer wiring board 1, the ground layer 2a made of a metal layer integrally arranged on the surface of the thick film multilayer wiring board 1, and the insulating layer integrally arranged on the surface of the ground layer 2a. Wiring pattern layer 4 composed of 3a and a metal layer (film) integrally arranged and formed on the surface of the insulating layer 3a
And an insulating layer 3b integrally arranged on the surface of the wiring pattern layer 4 and a ground layer 2b made of a metal layer integrally arranged on the surface of the insulating layer 3b. Is configured (formed). In the wiring pattern layer 4, required wirings are generally formed so as to be orthogonal to each other via an insulating layer, and via holes are provided in the inserted insulating layer at predetermined intersections. And a required signal wiring circuit is formed. by the way,
When such a circuit board is used in the construction of a multi-chip module that operates at high speed, in order to secure high-speed and stable electrical signal propagation characteristics, the characteristic impedance of each wiring forming the wiring pattern layer 4 is kept constant. It is important to match the input impedance of the semiconductor chip.

In response to such a request, the ground layer
By using a mesh structure in which square openings are provided in 2a and 2b, a means for controlling the characteristic impedance of the wiring 4a forming the wiring pattern layer 4 without increasing the film thickness of the insulating layers 3a and 3b has been tried. , Has also received a lot of attention. For example, as shown in FIG. 7 (a) in a perspective / planar manner and in FIG. 7 (b) in a sectional view (line AA ′ in FIG. 7 (a)), each ground layer is aimed at the characteristic impedance 75Ω of the wiring 4a. Thickness of 2a and 2b is about 6μm, aperture ratio of mesh ground is 51.4%, wiring
Thickness of 4a is about 6μm, width of wiring 4a is about 25μm, insulation layer
When the characteristic impedance value of each cross section with respect to the wiring direction l of the wiring 4a ₃ was calculated in the circuit board for the multi-chip module in which the film thickness of 3a was set to about 46 μm and the film thickness of the insulating layer 3b was set to about 20 μm, Curve a in FIG.
It was as shown in. Here, the mesh ground is a square with a mesh pitch of 300 μm, and the adjacent wiring
They are arranged obliquely with respect to the direction of 4a. In this characteristic calculation, the line BB 'in FIG. 7 (a) was set to l = 0.

As described above, by using a mesh having a relatively coarse mesh pitch as the ground layers 2a and 2b, the selection range of the characteristic impedance (average value) of the wiring 4a is widened, and the semiconductor element mounted on the circuit board is provided. Even when the input / output impedance of the (chip) is relatively high, reliable impedance matching is possible.

[0005]

However, when the mesh pitch is 300 μm, which is relatively coarse,
The circuit board for a multi-chip module configured as the ground layers 2a ′ and 2b ′ has a shape of the through hole 5 as shown in FIG. 9 in plan view when a through hole for connection is formed on the circuit board. Due to the installation, some of the square mesh ground layers 2a ', 2b' become so-called islands, and the required ground potential cannot be exhibited, and the characteristic impedance of the wiring 4a fluctuates significantly, achieving the initial purpose and function. Often the impossible case occurs.

It is possible to reduce the mesh pitch to, for example, 150 μm in order to solve the problem in the structure in which the ground layers 2a 'and 2b' are formed of the rectangular mesh having a relatively coarse mesh pitch. From such a viewpoint, as shown in FIG.
In the configuration shown in (b), the mesh pitch is 150 μm.
The characteristic impedance value of each cross section of the wiring 4a ₃ with respect to the wiring direction l was calculated in the same manner as described above for the circuit board for a multi-chip module having the same configuration except that, as shown by the curve b in FIG. It can be seen that the characteristic impedance value of the wiring 4a ₃ tends to decrease.

That is, the characteristic impedance of the lossless line is

[0008]

【formula】

(In the formula, L = inductance, C = capacitance, and the mesh ground layers 2a ′, 2 with the mesh pitch of 150 μm.
The mesh pitch is 300 when the b ′ is arranged.
Compared with the structure in which the μm mesh ground layers 2a ′ and 2b ′ are arranged, a structure closer to the wiring 4a ₃ is adopted. Therefore, the capacitance C for the wiring 4a ₃ increases, the characteristic impedance Z decreases, and it is difficult to achieve the required application and retention of the characteristic impedance. In this configuration, as a means for improving the characteristic impedance, it is conceivable to improve the aperture ratio of the mesh ground layers 2a ′ and 2b ′, in other words, to set the mesh line width (thickness) to be small. processing,
Alternatively, manufacturing of a circuit board for a multi-chip module becomes complicated, which is impractical in terms of productivity and economy. In the configuration of the circuit board for a multi-chip module, the insulating layers 3a and 3b are made relatively thick,
It is possible to increase the characteristic impedance,
It is not practical in terms of manufacturing process and electrical characteristics. The present invention has been made in response to the above circumstances, and is a relatively simple means or without requiring complicated operations,
An object of the present invention is to provide a circuit board for a multi-chip module, in which the characteristic impedance of the wiring can be easily increased, the characteristic impedance setting range can be expanded, and the electrical signal propagation characteristics can always be kept stable at high speed.

[0009]

A circuit board for a multi-chip module according to the present invention comprises a wiring pattern layer and a mesh ground pattern integrally disposed on the main surface side of the wiring pattern layer via an insulating layer. The mesh opening shape of the mesh ground pattern is a hexagon having two sides parallel to the wiring direction of the adjacent wiring pattern layers, or the mesh pitch of the mesh ground patterns is adjacent to each other. The mesh pitch parallel to the wiring direction of the wiring pattern layer is selected and set smaller than the mesh pitch orthogonal to the wiring direction.

[0010]

In the circuit board for a multi-chip module according to the present invention, regarding the configuration and arrangement of the mesh grounds provided, the shape of the openings of the mesh has six sides having two sides parallel to the wiring direction of the adjacent wiring pattern layers. The configuration is either rectangular or the mesh pitch is selected and set so that the mesh pitch parallel to the wiring direction of the adjacent wiring pattern layer is smaller than the mesh pitch orthogonal to the wiring direction. With this configuration, the mesh ground pattern makes it possible to widen the setting range of the characteristic impedance required for high-speed and stable electrical signal propagation characteristics, and the input / output impedance of the semiconductor element mounted on this circuit board. Ensure the matching of impedance values with.

[0011]

Embodiments of the present invention will be described below with reference to FIGS.

Embodiment 1 FIGS. 1 (a) and 1 (b) are perspective and plan views (FIG. 1 (a)) of a main part of a circuit board for a multi-chip module, and FIG.
These are shown in cross section (Fig. 1 (b)) along the line AA 'in (a). In FIGS. 1 (a) and 1 (b), 1 is a thick film multilayer wiring board 1 and 6a is a hexagonal shape of openings of meshes integrally arranged on the surface of the thick film multilayer wiring board 1 A mesh ground layer, 3a is an insulating layer 3a integrally arranged on the surface of the mesh ground layer 6a, and 4 is a wiring pattern composed of a metal layer (film) integrally arranged and formed on the surface of the insulating layer 3a. Layer, 3b is an insulating layer integrally arranged on the surface of the wiring pattern layer, and 6b is the insulating layer
This is a mesh ground layer in which the shape of the openings of the mesh integrally arranged on the 3b plane is a hexagon. Here, in the wiring pattern layer 4, generally, required wirings 4a are formed so as to be orthogonal to each other via an insulating layer, and at a predetermined intersection, a via hole connection is made to the inserted insulating layer. Is provided to form a required signal wiring. Also,
The mesh ground layers 6a and 6b in which the openings of the mesh are hexagonal are parallel to the wiring pattern of the adjacent wiring pattern layer 4 in the direction of the wiring of the preceding wiring pattern layer 4, that is, orthogonal to each other via the insulating layer. Each wiring arranged as
The hexagonally opened mesh is arranged so that two sides thereof are parallel to each other in the extending direction of the wiring of 4a.

In the above structure, the thickness of each mesh ground layer 6a, 6b is about 6 μm, the aperture ratio of the mesh ground is 58.2%, the thickness of the wire 4a is about 6 μm, and the characteristic of the characteristic impedance of the wire 4a is 75 Ω. Width of about 25 μm, wiring
The pitch of 4a is about 75 μm, the thickness of the insulating layer 3a is about 46 μm,
In the circuit board for the multi-chip module with the thickness of the insulating layer 3b set to about 20 μm, the wiring 4a ₃
When the characteristic impedance value of each cross section with respect to the wiring direction was calculated, it was as shown by the curve c in FIG.
Here, the mesh ground layers 6a and 6b have a mesh pitch 225 μm parallel to the wiring direction of the wiring 4a, a mesh pitch 150 μm orthogonal to the wiring direction of the wiring 4a, and a side length 37.5 parallel to the wiring direction of the wiring 4a. It has a hexagonal aperture of μm. In addition, in this characteristic calculation, the line BB ′ in FIG.
It was set to 0.

The characteristic impedance value (curve c in FIG. 8) of the cross section of the wiring 4a _{3 in} the wiring direction is 71.3Ω, and the characteristic impedance of the cross section of the wiring 4a _{3 having} the configuration shown in FIG. 6 for the value (curve b in Figure 8)
It was increased compared to 9.7Ω. In other words, in this configuration, the AA 'line area in Fig. 1 (a) forms the maximum part of the characteristic impedance, but the parallel sides of the mesh ground layers 6a and 6b that are hexagonally open must be adjacent. By
The area of the maximum characteristic impedance value is expanded.

In this embodiment, the mesh ground layer 6a,
Set the length of the side parallel to the wiring 4a of the mesh opening of 6b to 37.5.
μm is used, but when this value is changed variously (when the mesh pitch of the wiring 4a is changed in the wiring direction), the characteristic impedance of the wiring 4a is measured, respectively, as shown in FIG. The following relationship exists between the ground mesh pitch x μm in the wiring (progression) direction and the length d μm of the side of the mesh opening parallel to the wiring 4a.

X = 2 × d + 150 Incidentally, the point of x = 150 μm in FIG. 2 corresponds to the case of the conventional example (mesh ground of 150 μm pitch) shown in FIG. 9, and the point of x = 225 μm is Figure 1 (a)
This value is equivalent to the case of d = 37.5 μm shown in Fig.

As described above, the mesh opening is formed in a hexagonal shape having two sides parallel to the traveling direction of the wiring 4a, so that the pitch of the mesh ground layers 6a and 6b on the side orthogonal to the wiring 4a is about 150 μm. The characteristic impedance can be increased without making process difficulty such as reducing the mesh (ground) line width or increasing the thickness of the insulating films 3a and 3b while keeping the mesh ground pitch small.
Further, when the wiring pattern layer 4 is composed of two types of layers (x-ray layer and y-ray layer) orthogonal to each other, the mesh ground layers 6a and 6b closer (adjacent) to each wiring layer are
Since the influence on the wiring capacitance is large, the ground mesh ground layers 6a and 6b on the side close to (adjacent to) each wiring layer are
The opening may have a hexagonal mesh shape having sides parallel to the wiring 4a.

Embodiment 2 FIGS. 3 (a), 3 (b) and 3 (c) are sectional views (FIG. 3 (a)) of FIG.
(a) One wiring pattern layer 4 ″ shown in the figure is transparent and planar (FIG. 3 (b)), and the other wiring pattern layer 4 ′ shown in FIG. c)), and in Fig. 3 (a), (b), (c), 1
Is a thick film multilayer wiring board 1, 7a, 7b, the mesh pitch integrally arranged on the surface of the thick film multilayer wiring board 1 is the wiring direction (advancing direction) of one adjacent wiring pattern layer 4 '.
The mesh ground layer which is different depending on the oblique direction, 3a is integrally arranged on the surface of the mesh ground layer 7a, and the insulating layers 3a and 4 ″ are integrally arranged and formed on the surface of the insulating layer 3a. The other wiring pattern layer made of a metal layer (film), 3b is an insulating layer integrally arranged on the wiring pattern layer 4 ″ surface, and 7b is a mesh pitch integrally arranged on the insulating layer 3b surface. Is a mesh ground layer which is different depending on the oblique direction with respect to the wiring direction (advancing direction) of the adjacent wiring 4a. Here, in the wiring pattern layers 4 ′ and 4 ″, required wirings 4 are generally formed so as to be orthogonal to each other via an insulating layer 3 c (formed in a grid pattern), and at predetermined intersection points, A via-hole connection is provided in the inserted insulator layer to form a required signal wiring circuit.

In the above structure, the thickness of each mesh ground layer 7a, 7b is about 6 μm, the aperture ratio of the mesh ground is 51.4%, the thickness of the wire 4a is about 6 μm, and the wire 4a is aimed at the characteristic impedance of the wire 4a of 75Ω. Width of about 25 μm, wiring
The pitch of 4a is about 75 μm, and the total thickness of the insulating layers 3a and 3c is 46
When the characteristic impedance value of each cross section in the wiring direction of the wiring 4a ₃ was calculated in the circuit board for the multichip module in which the thickness of the insulating layer 3b and the thickness of the insulating layer 3b were each set to about 20 μm, the curve d in FIG. It was as shown in. Here, the mesh pitch is 4a ′, 4
The mesh ground layers 7a and 7b, which are different depending on the oblique direction with respect to the wiring direction (traveling direction) of a ″, are arranged in the wiring direction of the wirings 4a ′ and 4a ″ that form the adjacent wiring pattern layers 4 ′ and 4 ″. In contrast, the mesh pitch in the orthogonal direction is 300 μm
The mesh pitch in the parallel direction is selected and set to about 150 μm (mesh line width 42.5 μm).

As can be seen from the curve d in Fig. 8, in this embodiment, the required average characteristic impedance can be easily and reliably ensured for each wiring 4a ', 4a ". That is, the mesh pitch is 300 µm. Select and set to about
The circuit board for a multi-chip module having a structure in which the mesh ground layers 2a ', 2b' opened in a square shape (mesh line width 60 μm) are arranged can be made almost the same as the case (see the curve a). This not only provides or retains the characteristic impedance required for each wiring 4a ', 4a "in propagating a stable electric signal at high speed, but also via-hole connection between the wiring pattern layers 4', 4". This means that it is possible to facilitate the wiring and also to improve the density of the wirings 4a ′ and 4a ″, and it can be said that this brings many practical advantages.

In the above, the wiring pattern layers 4 ', 4 "are used.
An example is shown in which the wiring is insulated, separated, and separated. For example, as shown in FIG. 4 (a) in plan view and FIG. 4 (b) in cross section, the wiring pattern layer 4 has a single layer structure. If
Alternatively, as shown in plan view in FIG. 5, even if the mesh ground layers 7a and 7b having rectangular openings (mesh pitch is narrow with respect to the wiring direction) are arranged, similar to the case of the above example. , It was possible to widely deal with the setting of the characteristic impedance required for each wire to propagate a stable electric signal at high speed.

[0022]

As described above, according to the circuit board for a multi-chip module of the present invention, even if the mesh pitch of the mesh ground is set to be relatively small, there is no difficulty in the process and the characteristic impedance of the wiring is The setting range can be expanded or the characteristic impedance can be increased. That is, by selecting and setting the opening shape of the mesh ground adjacent to and arranged in the electrical signal wiring pattern and the positional relationship with respect to each wiring (forming the electrical signal wiring pattern) as described above, the wiring is surely grounded and each wiring is formed. Since a more reliable characteristic impedance control of
When mounted to form, for example, a high-speed computer module, the required functions can be sufficiently and reliably exhibited.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a main part configuration of a circuit board for a multi-chip module according to the present invention, in which (a) is a perspective plan view,
(b) is a sectional view.

FIG. 2 is a curve diagram showing the relationship between the pitch of the mesh grounds having hexagonal openings and the characteristic impedance provided in the circuit board for a multi-chip module according to the present invention.

3A and 3B show another example of the main part configuration of the circuit board for a multi-chip module according to the present invention, in which FIG. 3A is a sectional view, FIG. 3B is a perspective plan view of one wiring pattern layer portion, c) is a perspective plan view of the other wiring pattern layer portion.

4A and 4B show another example of the configuration of the main part of the circuit board for a multi-chip module according to the present invention, in which FIG. 4A is a perspective plan view and FIG. 4B is a sectional view.

FIG. 5 is a perspective plan view showing another configuration example of the main part of the circuit board for a multi-chip module according to the present invention.

FIG. 6 is a cross-sectional view showing a main part configuration of a conventional circuit board for a multi-chip module.

7A and 7B show a main part configuration of a conventional circuit board for a multi-chip module having a mesh ground, wherein FIG. 7A is a perspective plan view and FIG. 7B is a sectional view.

FIG. 8 is a curve diagram showing a comparison of characteristic impedance examples in each cross section of the wiring with respect to the wiring (traveling) direction in the circuit board for a multichip module according to the related art and the present invention.

FIG. 9 is a perspective plan view showing another configuration of a main part of a conventional circuit board for a multi-chip module having a mesh ground.

[Explanation of symbols]

1 ... Thick film multilayer wiring board 2a, 2b ... Ground layer 2
a ′, 2b ′… Mesh glands 3a, 3 with square openings
b, 3c ... Insulating layer (film) 4, 4 ', 4 "... Wiring pattern layer 4a ... Wiring 5 ... Through hole 6a, 6b ... Hexagonally opened mesh ground layer 7a, 7b ... Mutual mesh pitch is different Mesh ground layer

Claims (2)

[Claims] 1. A wiring pattern layer, and a mesh ground pattern integrally provided on the main surface side of the wiring pattern layer with an insulating layer interposed therebetween, wherein the mesh opening patterns of the mesh ground pattern are adjacent to each other. A circuit board for a multi-chip module having a hexagonal shape having two sides parallel to the wiring direction of the wiring pattern layer. 2. A wiring pattern layer, and a mesh ground pattern integrally disposed on the main surface side of the wiring pattern layer via an insulating layer, wherein the mesh pitches of the mesh ground patterns are adjacent to each other. A circuit board for a multi-chip module, wherein the mesh pitch parallel to the wiring direction of the pattern layer is selected and set smaller than the mesh pitch orthogonal to the wiring direction.