JPH0730254A - Multilayer printed circuit board and semiconductor device - Google Patents

Abstract

PURPOSE:To provide a multilayer printed circuit board and a semiconductor device in which there are no defects such as warp due to heat, etc., during manufacture and use, and which permit high density wiring and high density mounting. CONSTITUTION:The multilayer printed circuit board 20 is made of several interconnection wiring layers 2, 10, 12, 14, 16, and 18 respectively on both surfaces. The semiconductor device is formed by mounting semiconductor chips on both sides of the multilayer printed circuit board 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board for high density wiring and a semiconductor device having a semiconductor chip mounted on the multilayer printed wiring board.

[0002]

2. Description of the Related Art High-density wiring and high-density mounting technology for printed wiring boards have been required in response to the recent rapid increase in functionality, multifunctionality, and miniaturization of electronic equipment.

Conventionally, various improvements and developments have been made on the high-density wiring and high-density mounting technology of printed wiring boards, but recently, surface wiring printed circuit boards aiming at realization of high density and low cost. (SLC) has been proposed (Electronic Materials, April 1991, pp. 103-108). This SLC is a multi-layer surface wiring layer (S
In this structure, a surface wiring structure having an LC layer) is formed, and a photo via hole is used for interlayer connection instead of a through hole formed by a mechanical drill. The SLC proposed here uses double-sided copper clad glass epoxy substrates as the substrate.

[0004]

However, the above S
LC has the following problems.

(1) Since the SLC layer having a coefficient of thermal expansion different from that of the substrate exists only on one side of the substrate, the substrate is warped when heat is applied during manufacturing or during use.

(2) At the time of manufacturing, in a normal plating process for a printed wiring board, patterns on both sides are plated at the same time. However, if the SLC layer is on only one side of the substrate, for example, 4
Four plating steps must be performed to form the patterned layer of layers. Similarly, even in the step of forming a photo via hole in the insulating layer, the step of exposing both surfaces at the same time cannot be taken, and the number of steps increases, such as exposing once for each insulating layer formed. .

(3) As proposed in the above-mentioned surface wiring printed circuit (electronic material, 1991.4, pp. 103-108), copper-clad glass epoxy substrates on both sides are used as substrates, and SLC layers are provided. There is a conventional technique of forming a power supply layer on the surface opposite to the layer provided, but when manufacturing such a thing,
The surface opposite to the surface on which the SLC layer is provided needs to be protected from plating twice or more, which increases the number of steps. If it is not protected, thick plating is formed every time pattern plating of the SLC layer is performed, and the etching accuracy is deteriorated when a heat escape land or the like is formed in the power supply layer. In addition, when thick plating is formed on only one side, warpage occurs when heat is applied.

(4) In the SLC layer, unevenness occurs due to the presence or absence of the pattern provided in the lower layer, making it difficult to maintain the surface smoothness. That is, when the insulating layer is provided on the pattern layer,
The insulating layer on the portion where the pattern exists becomes a convex portion. This phenomenon becomes remarkable as irregularities are accumulated as the number of layers increases. If the surface is not smooth, it will be difficult to evenly plate. It is possible to obtain smoothness by a method of forming an insulating layer with a thick thickness and polishing the insulating layer, but since the polishing must be sufficiently performed every time, the work is complicated.

(5) Since the SLC layer is only on one side and the wiring is concentrated on one side, the wiring pattern connected to the ground layer becomes long, the connection becomes difficult, and noise from other signal patterns etc. Will also have a greater effect. This is due to the following technical background and causes. 2. Description of the Related Art In recent years, the speed of electronic devices has been increasing, as represented by the increase in communication speed of communication devices. Along with this, higher speed is also required for electronic parts. Therefore, high integration is achieved, wiring length is shortened, and propagation efficiency is increased. In a high-speed circuit, noise often causes the operation, and reducing the noise is an important technical issue. Stabilizing the ground potential is one of the measures against noise. Further, it is also practiced to provide a ground pattern above, below or around the signal line to improve the shield effect. Stabilization of the ground potential is also carried out in the IC chip. Therefore, in recent IC chips, the number of ground terminals has increased along with the increase in the number of pins.

As described above, with the increase in the number of ground terminals and ground patterns of the IC, the number of patterns connected to the ground layer has dramatically increased, and therefore the chances of interfering with the wiring of signal patterns have increased. In addition, the pattern length until connecting to the ground layer is often long, and it has been difficult to obtain a stable ground potential.

(6) Since the SLC layer is only on one side and the semiconductor chip can be mounted on only one side of the substrate, there are large restrictions on the mounting position.

(7) Since the external connection terminals are provided on only one surface of the substrate, there are large restrictions on the external connection terminal positions and external connection patterns. Further, since it is necessary to provide via holes only for connecting to the external connection terminals, the number of via holes becomes large, which becomes an obstacle when wiring other patterns.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to solve the above-mentioned conventional problems and to enable a high-density wiring / high-density mounting and a multilayer printed wiring board and a semiconductor. To provide a device.

[0014]

In order to achieve the above object, the multilayer printed wiring board of the present invention has a wiring layer formed by a plurality of build-up methods on both surface sides of a substrate made of a rigid material. The insulating layer between the wiring layers is made of the same material.

Further, the semiconductor device of the present invention has wiring layers formed by a plurality of build-up methods on both sides of a substrate made of a rigid material, and the insulating layers between the wiring layers are made of the same material. It is characterized in that semiconductor chips are mounted on both surfaces of a multi-layered printed wiring board.

Further, the invention is characterized in that each of the both sides of the substrate has a ground layer. In this case, it is preferable to set the pattern corresponding to the outer layer of the rigid substrate as the ground layer in order to control the impedance. A plurality of ground layers may be provided on both sides of the rigid substrate, or may be provided as an outer layer of the buildup layer.

The board is a multi-layer wiring board.

Further, it is characterized in that terminals for external connection are provided on both surfaces of the multilayer printed wiring board.

Further, at least a part of the insulating layer at the end of the multilayer printed wiring board is cut out, and the external connection terminal provided in the lower layer is exposed from the cutout. .

[0020]

The present invention has a wiring layer formed by a plurality of build-up methods on both sides of a substrate made of a rigid material, and since the insulating layer between the wiring layers is made of the same material, the substrate Both sides have substantially the same expansion coefficient due to heat and humidity, and warpage due to heat and humidity does not easily occur. Also, since wiring layers are formed on both sides of the substrate, the number of layers per side is half compared to the case of forming on only one side, so the process of maintaining the surface smoothness can be simplified, and plating on both sides Since the exposure process for the insulating layer is performed only once, the entire manufacturing process can be greatly shortened.

Further, according to the present invention, since the semiconductor chips are mounted on both sides of the printed wiring board, the mounting position and the degree of freedom of pattern wiring are increased as compared with the case where the semiconductor chips are mounted on one side.
The mounting position of the semiconductor chip can be determined in consideration of the wiring, which enables high-density wiring and high-density mounting.

Further, according to the present invention, since the substrate made of a rigid material has the ground layers on both sides, the substrate made of the rigid material can be connected to the ground layer without straddling the substrate.
Moreover, by providing the ground layer on the side closer to the outer layer of the build-up layer or on the outer layer, the shield effect against noise from external equipment can be enhanced.

Further, according to the present invention, by using a substrate made of a rigid material as a multilayer wiring board, an important signal pattern can be wired in an inner layer of the rigid substrate and a high shielding effect can be obtained. Further, by providing a ground layer on the inner layer of the rigid substrate, the ground potential can be further stabilized.

Furthermore, according to the present invention, by providing the external connection terminals on both surfaces of the multilayer printed wiring board, it is not necessary to draw out the wiring so as to straddle the rigid substrate when the external connection with the lead frame or the like is made. Get smaller. That is, since the rigid board has the patterns on both sides and the terminals for external connection are provided on both sides, the degree of freedom of wiring is improved when the external connection is performed.

Then, at least a part of the insulating layer at the end of the multilayer printed wiring board having wirings and terminals for external connection as described above is cut out, and the insulating layer is provided in the lower layer from the cutout. Further, since the external connection terminals are exposed, it is possible to directly connect to the outside from the inner layer of the multilayer printed wiring board, and it is not necessary to provide the via hole and once draw it to the outer layer to make the outer layer connection. Therefore, the number of via holes and the number of exterior wirings can be reduced, and the wiring density can be improved.

[0026]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

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

As is apparent from FIG. 1, the multilayer printed wiring board 20 of this embodiment has a first wiring layer 2, a second wiring layer 10 and a second wiring layer 10 on one surface side of the rigid substrate 1. A third wiring layer 12 is formed in order through the first insulating layer 3 and the second insulating layer 11, a protective layer 13 is formed on the surface, and the other surface side of the substrate 1 is also similarly formed. The first wiring layer 14, the second wiring layer 16, and the third wiring layer 1
8 are sequentially formed via the first insulating layer 15 and the second insulating layer 17, and the protective layer 19 is formed on the surface.

The rigid substrate 1 used in the present invention is not particularly limited as long as it is a rigid material. For example, it may be a double-sided copper-clad laminate obtained by impregnating glass fiber with a varnish made of epoxy resin or the like and copper foil laminated on both sides, or various copper-clad laminates or ceramic substrates.

In the multilayer printed wiring board 20 of this embodiment, wiring layers are formed on both surfaces of the rigid substrate 1 by a so-called build-up method.

A method of manufacturing the multilayer printed wiring board 20 by the build-up method will be described with reference to FIG.

For example, a double-sided copper-clad laminate in which copper foil having a thickness of about 12 μm is attached to both surfaces of a substrate 1 made of glass fiber and epoxy resin having a thickness of about 0.2 mm is patterned by photolithography, The first wiring layer 2 is formed (see FIG. 11A). When forming a through hole that extends over the base material 1, through hole drilling is performed and then through hole plating is performed.

Next, it is preferable to perform a blackening treatment in order to improve the adhesion between the wiring layer 2 thus formed and the first disconnection layer 3 formed thereon. For the blackening treatment, for example, an aqueous solution of sodium chlorite, an aqueous solution of potassium persulfate, or the like is used. In this example, NaOH 21 g / l,
Na ₃ PO ₄ · 12H ₂ O 17 g / l, NaClO ₂ 43
It was immersed in a 90 ° C. aqueous solution containing g / l for 270 seconds.

Next, the first insulating layer 3 is formed (see FIG. 3B). The insulating layer can be used without particular limitation as long as it has a high insulating property and a low dielectric constant, but it is preferable to use a photosensitive resin such as a photosensitive epoxy or a polyimide resin because fine processing can be easily performed. preferable. In this example, Pro-Vimmer 52 (manufactured by Nippon Ciba Geigy Co., Ltd.) was formed by curtain coating.

Next, after drying, the mask 4 on which a desired via hole pattern is formed is overlapped, and exposure 5 is performed.
The development is performed to form the recess 6 reaching the first wiring layer (see (c) and (d) of the same figure).

Subsequently, the mask 4 is removed, baking is performed, the surface is polished with a buff or the like to improve the smoothness of the surface, and then immersion treatment is further performed with a potassium permanganate solution or the like. In this example, the sample was immersed in an aqueous solution of 55 g / l potassium permanganate for 5 minutes. This is to finely roughen the surface of the insulating layer and increase the adhesion of plating.

Subsequently, a copper thin film 7 is formed on the entire surface including the inside of the recess 6 by electroless copper plating, and a copper plating film 8 is formed to a constant thickness by electrolytic copper plating (see FIG. ), (F)). Although the thickness varies depending on the use of the wiring board, it is 20 μm in this embodiment.

After that, the copper plating film 8 is patterned by the photolithography method to form the second wiring layer 10 and the via hole 9 (see FIG. 9G).

In this way, a printed wiring board having two wiring layers is completed. By repeating the above steps, a further multilayer printed wiring board as shown in FIG. 1 can be manufactured. In FIG. 1, the rigid substrate 1
Through holes 27 are provided for connecting patterns extending over both surfaces of the.

In the above description, the one side of the rigid substrate 1 is mainly described for the sake of convenience. However, in practice, it is necessary to form both sides of the rigid substrate 1 at the same time and sequentially form each layer from the bottom. Is desirable because it can be significantly shortened. Further, at this time, it is preferable that the insulating layers on both surfaces are formed of the same material so that the printed wiring board does not warp due to a difference in expansion coefficient.

As described above, the multilayer printed wiring board 20 of this embodiment has a plurality of wiring layers on both sides of the rigid substrate 1, but it is particularly desirable that the number of layers on both sides is the same. Further, when there are two or more signal layers on one side of the substrate 1 among the plurality of wiring layers, it is particularly desirable that the number of signal layers on the one side is even. Since the wiring is formed by the combination of the X and Y directions, the wiring density on one side of the substrate 1 can be increased particularly in the above case, and the number of through holes for connection extending across the substrate 1 can be reduced.

The multilayer printed wiring board 20 of this embodiment is also used.
Can have ground layers on both sides of the rigid substrate 1. When the ground layers are provided on both surface sides of the substrate 1 in this way, it is possible to connect to the ground layer without straddling the rigid substrate 1 and to shorten the pattern length until the connection to the ground layer. It is sufficiently compatible with recent electronic circuits, which have become highly functional and the number of patterns for connecting to the ground layer has dramatically increased. The position of the ground layer is not particularly limited, but when the ground layer is preferably provided in the outer layer or a layer close to the outer layer, the shield effect is enhanced, and the inner signal layer is less likely to be affected by noise from the external device.

As described above, it is important that the ground layer has a stable ground potential. for that purpose,
It is necessary for the ground layer to have a large area without being divided by through holes provided for connecting signal patterns between layers or being cut out to have a complicated shape. Is.

However, in a recent printed wiring board with high-density wiring, it is unavoidable that the number of through holes increases, and it is difficult to keep the above-mentioned state. Therefore, although the present invention also proposes providing the ground layers on both sides of the rigid substrate 1, a plurality of ground layers may be provided on both sides. As a result, it is possible to compensate for the ground layers having a complicated shape and obtain a stable ground potential.

FIG. 3 is a sectional view showing the structure of an embodiment of the semiconductor device of the present invention.

As is apparent from FIG. 3, the semiconductor device 23 of this embodiment is one in which semiconductor chips 22 are mounted on both surfaces of the above-mentioned multilayer printed wiring board 20. Since the semiconductor chips 22 are mounted on both sides of the multilayer printed wiring board 20, the degree of freedom of the mounting position is greater than that of the composite mounting on one side, and the semiconductor chip 2 is considered in consideration of wiring.
The mounting position of 2 can be determined, and high-density mounting becomes possible.

Further, as shown in FIG. 3, the above-mentioned rigid substrate 1 can have a structure of a multilayer wiring board 21. When the substrate has a multi-layered structure as described above, a particularly important pattern can be wired in the inner layer of the multilayer wiring board 21 to obtain a high shielding effect. In addition, a ground layer can be provided on the inner layer of the multilayer wiring board 21, which can further stabilize the ground potential.

FIG. 4 is a sectional view showing a state in which the multilayer printed wiring board or semiconductor device of the present invention is connected to a lead frame.

External connection terminals 24 are provided on both surfaces of a semiconductor device 23 having the above-mentioned multilayer printed wiring board 20 or semiconductor chip 22 mounted thereon, and the terminals 24 are used to connect to the inner leads 25 of the lead frame. To connect to the outside. By thus providing the external connection terminals 24 on both surfaces of the multilayer printed wiring board 20 and the like, restrictions on the positions where such external connection terminals are provided are reduced. Further, as shown in FIGS. 4 and 5, at least a part of the insulating layer at the end portion is cut out (cutout portion 26), and the external connection terminal 24 can be provided in the lower layer. There is no need to provide via holes only for connecting to external connection terminals by drawing them out to the outer layer, and the number of via holes can be reduced to reduce obstacles when wiring other patterns.

[0050]

As described in detail above, according to the present invention, the wiring layers formed by a plurality of build-up methods are provided on both surface sides of the substrate made of a rigid material, respectively.
Since the insulating layers between the wiring layers are made of the same material, the two surfaces of the substrate have substantially the same coefficient of expansion due to heat and moisture, and warpage due to heat and moisture does not easily occur. Since it is formed, the number of layers per side is half compared to the case of forming only on one side, so the process of maintaining the smoothness of the surface can be simplified, and the plating on both sides,
Since the exposure process of the insulating layer is performed only once, the entire manufacturing process can be greatly shortened.

Further, according to the present invention, by mounting the semiconductor chips on both sides of the printed wiring board, the degree of freedom of the mounting position and the pattern wiring is increased, so that high-density wiring and high-density mounting are possible.

Further, according to the present invention, since the ground layer is provided on both sides of the substrate made of a rigid material, the connection to the ground layer is facilitated, and the ground layer is closer to the outer layer of the buildup layer or the outer layer. By providing it, it is possible to enhance the shield effect against noise from external equipment.

Further, according to the present invention, by using a substrate made of a rigid material as a multilayer wiring board, an important signal pattern can be wired in an inner layer of the rigid substrate to obtain a high shielding effect. Further, by providing a ground layer on the inner layer of the rigid substrate, it is possible to further stabilize the ground potential.

Furthermore, according to the present invention, by providing the external connection terminals on both surfaces of the multilayer printed wiring board, it is not necessary to draw out the wiring so as to straddle the rigid substrate when the external connection is made with the lead frame or the like. Get smaller. That is, since the rigid board has the patterns on both sides and the terminals for external connection are provided on both sides, the degree of freedom of wiring is improved when the external connection is performed.

Then, as described above, at least a part of the insulating layer at the end of the multilayer printed wiring board having wiring on both sides and having external connection terminals is cut out, and the insulating layer is provided in the lower layer from the cutout. The exposed external connection terminals allow direct connection to the outside even from the inner layer of the multilayer printed wiring board, and there is no need to provide via holes and once pull out to the outer layer to make external connection.
Therefore, the number of via holes and the number of outer layer wirings can be reduced, and the wiring density can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a multilayer printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing an example of a method for manufacturing a multilayer printed wiring board according to the present invention.

FIG. 3 is a sectional view showing an embodiment of a semiconductor device of the present invention.

FIG. 4 is a cross-sectional view showing a state in which the multilayer printed wiring board of the present invention is connected to a lead frame.

FIG. 5 is a diagram showing a state in which a part of an end is cut out in the multilayer printed wiring board according to the present invention.

[Explanation of symbols]

 1 Substrate 2, 14 First Wiring Layer 3, 15 First Insulating Layer 4 Mask 5 Exposure 6 Recesses 7, 8 Copper Plating Film 9 Via Hole 10, 16 Second Wiring Layer 11, 17 Second Insulation Layers 12 and 18 Third wiring layer 13, 19 Protective layer 20 Multilayer printed wiring board 21 Multilayer wiring board 22 Semiconductor chip 23 Semiconductor device 24 External connection terminal 25 Inner lead 26 Insulating layer cutout portion 27 Through through hole

Claims (10)

[Claims] 1. A multi-layer comprising a substrate made of a rigid material, and wiring layers formed by a plurality of build-up methods on both sides of the substrate, and an insulating layer between the wiring layers being made of the same material. Printed wiring board. 2. The multilayer printed wiring board according to claim 1, further comprising ground layers on both sides of the substrate. 3. The multilayer printed wiring board according to claim 1, wherein the substrate is a multilayer wiring board. 4. The multilayer printed wiring board according to claim 1, wherein external connection terminals are provided on both surfaces of the multilayer printed wiring board. 5. The multilayer printed wiring board is characterized in that at least a part of an insulating layer at an end portion is cut out, and an external connection terminal provided in a lower layer is exposed from the cutout portion. The multilayer printed wiring board according to claim 4. 6. A double-sided multilayer printed wiring board having wiring layers formed by a plurality of build-up methods on both sides of a substrate made of a rigid material, and insulating layers between the wiring layers made of the same material. A semiconductor device comprising a semiconductor chip mounted on. 7. The semiconductor device according to claim 6, wherein grounding layers are provided on both surface sides of the substrate, respectively. 8. The semiconductor device according to claim 6, wherein the substrate is a multilayer wiring board. 9. The semiconductor device according to claim 6, wherein external connection terminals are provided on both surfaces of the multilayer printed wiring board. 10. A multilayer printed wiring board is characterized in that at least a part of an insulating layer at an end portion is cut out, and an external connection terminal provided in a lower layer is exposed from the cutout portion. The semiconductor device according to claim 9.