JPH07101775B2 - Multilayer printed wiring board - Google Patents

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 used for mounting various so-called semiconductor chips or other chip parts. This multilayer printed wiring board is applied to packages such as chip carriers and pin grid arrays.

[0002]

2. Description of the Related Art In recent years, the degree of integration of electronic parts called semiconductor chips and the like has become very dense, and therefore the printed wiring boards for mounting these parts must also be highly dense. There is. A multi-layer printed wiring board was developed to cope with this situation.

In this multilayer printed wiring board, a conductor circuit is formed in advance on a plurality of substrates constituting the multilayer printed wiring board, and these boards are bonded to each other so as to cope with mounting of highly integrated electronic components. . An example of such a multilayer printed wiring board is disclosed in Japanese Patent Laid-Open No. 59-201449.
There is a "semiconductor chip carrier package" disclosed in the publication.

This carrier package has a "first insulating layer,
Means for forming perforations in the first insulating layer, a chip connecting layer bonded to the surface of the first insulating layer, means for forming a chip holding recess in the chip connecting layer, and the chip connecting layer An integrated circuit chip mounted in the recess, wherein the base is made of a heat conductive material and extends at least partially across the recess underneath A base configured to contact,
A contact array extending from the chip connection layer and outside the recess ”. However, there is no disclosure of how to "mount" the integrated circuit chip, or electronic component, within the recess.

In general, the electronic components bonded to the respective conductor circuits are inferior in mechanical strength as they are and are weak against moisture and the like, so that the periphery thereof must be sealed. Moreover, the encapsulation should not be so thick when the multilayer printed wiring board is completed. This is because the packaging density of this type of multilayer printed wiring board must be increased as the density of electronic components increases.

[0006] Such encapsulation is usually done by dropping a suitable resin or the like around the electronic components bonded to the conductor circuits. However, the amount of this dropping varies, and The rear surface is not always flat. If it is not flat, it may be an obstacle when incorporating various other electronic components into the completed multilayer printed wiring board. This is because the space for mounting electronic components on the multilayer printed wiring board is limited.

However, the above-mentioned Japanese Patent Laid-Open No. 59-201.
There is no disclosure in Japanese Patent Publication No. 449 that meets such a demand. Further, Japanese Patent Laid-Open No. 60-57999 discloses that "a part of each surface of a wiring board having a conductor pattern provided on an insulating plate and laminated is exposed stepwise, and the exposed portion is connected to the conductor pattern. A multilayer wiring board characterized in that it is provided with a conductive pad. However, none of the above problems and their solutions are shown.

[0008]

As described above, in a multilayer printed wiring board, it is necessary to mount various electronic components in a limited space. Therefore, in high-density mounting, the protrusion of the sealing resin when encapsulating an electronic component is a serious problem.

In view of the above conventional problems, the present invention has a simple structure and can effectively use a limited space.
An object of the present invention is to provide a multilayer printed wiring board that can sufficiently realize high-density mounting.

[0010]

According to the present invention, by laminating at least one substrate on which an opening and a conductor circuit corresponding to the mounting portion are formed, on a substrate on which a mounting portion for mounting an electronic component and a conductor circuit are formed. In the multilayer printed wiring board that is formed and has an electronic component mounted inside the mounting portion and the periphery of the electronic component is sealed with a sealing resin, the multilayer printed wiring board is located at the outermost layer of the respective substrates. the substrate, on the surface side positioned near the opening has an opening stepped portion for sealing resin outflow preventing constructed from <br/> stepped end
In the multilayer printed wiring board, wherein a call.

What is most noticeable in the present invention is that the above-mentioned opening step is formed on the surface of the substrate located in the outermost layer in the vicinity of the opening.
In addition, the sealing resin is filled up to the opening step portion as needed.

The multilayer printed wiring board according to the present invention comprises 1
Alternatively, it is composed of a plurality of substrates. Each of these substrates is mainly made of resin, but ceramics or the like can be used if necessary. When a resin is used, it is excellent in workability. In addition, a predetermined conductor circuit is formed on each of the substrates forming the multilayer printed wiring board. Then, the respective substrates are alternately laminated via the adhesive layer and then pressure-bonded to form the multilayer printed wiring board.

Of these substrates, the one located at the lowermost end has a mounting portion for mounting electronic components formed in its substantially central portion. At the central portion of each substrate laminated on the substrate having the mounting portion, an opening corresponding to the mounting portion and gradually increasing in size as it is positioned above is formed.

[0014] opening stepped portion has a larger opening area than the opening of the substrate having an opening step portion of this. As a result, the opening step portion is continuous with the opening portion and forms a continuous space with the board mounting portion located at the lowermost end. Further, by forming such an opening step portion which is continuous with the opening portion, substantially stepwise end portions are formed in the substrate.

After forming such an opening step portion, an inverted pyramid-shaped recess is formed as a whole in the central portion of the multilayer printed wiring board, but electronic parts are placed in the mounting portion located at the lowermost end. After mounting, the electronic component and each conductor circuit are connected by a bonding wire, and sealing resin is dropped into the recess for sealing. The multilayer printed wiring board according to the present invention may be a pin grid array substrate having a large number of conductor pins electrically connected to each conductor circuit.

When forming the opening step portion having the stepped end portion, as shown in the embodiment, for example, the following steps are performed. (A) A substrate having a mounting portion for mounting electronic components and a conductor circuit, a substrate which is disposed on the upper side of this substrate and serves as an outermost layer, and the mounting portion which is interposed between these substrates as necessary. Pressure-bonding at least one intermediate substrate having an opening and a conductor circuit corresponding to each other to each other through an adhesive layer; (b) forming a through hole penetrating each pressure-bonded substrate. And then plating the through holes; (c) forming a conductor circuit on the surface of the outermost substrate; (d) mounting the conductor circuit on the surface of the outermost substrate. A step of forming an opening and an opening step for communicating the part to the outside.

[0017]

[Operations and Effects] In the multilayer printed wiring board having the above-mentioned structure, the electronic parts are first mounted in the mounting portion.
Next, after electrically connecting the electronic component and each conductor circuit with a bonding wire, a sealing resin is dropped and filled in the recess of the inverted pyramid shape.

At this time, the excess sealing resin is used as an opening.
The surface tension acts on the step, and it rises.
However, this opening step is the above stepped end.Have
The opening step is lower than the surface of the substrate.
Therefore, the upper edge of the raised encapsulation resin is above the substrate surface.
There is no way to get to the top.

The sealing resin remains in the opening step portion and does not come out from the surface of the substrate.

Further, not only when the sealing resin is simply dropped to complete the resin sealing, but when the sealing plate is further placed thereon to completely prevent the sealing resin from protruding, The stepped end is convenient. That is, when the surface of the substrate is flattened by the sealing plate, this sealing plate only needs to be locked to the opening step portion, so that the mounting thereof becomes very easy.

As described above, even if there is a surplus portion in the sealing resin, this surplus portion is absorbed by the opening step portion and therefore does not protrude from the surface of the substrate.
Further, therefore, it is possible to complete the resin sealing work without paying much attention to it.

As described above, in the multilayer printed wiring board according to the present invention, the opening step portion constituted by the stepped end portion is formed on the substrate located at the outermost layer. Therefore, when sealing the mounted electronic parts with resin,
Excess sealing resin does not protrude from the surface of the substrate.

Further, the measure for preventing the protrusion of the sealing resin is also a simple structure. Therefore, according to the present invention, it is possible to provide a multilayer printed wiring board that can effectively use a limited space with a simple structure and can sufficiently realize high-density mounting.

[0024]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 shows a plan perspective view of a multilayer printed wiring board 100 according to this embodiment. The multilayer printed wiring board 100 in this embodiment is composed of a total of four substrates 10 as shown in FIG.

Each of these substrates 10 is mainly made of resin, but ceramics or the like can be used if necessary. When a resin is used, it is excellent in workability.

Further, a predetermined conductor circuit 15 is formed on each substrate 10 which constitutes the multilayer printed wiring board 100. The multilayer printed wiring board 10 is formed by alternately stacking the substrates 10 and the adhesive layer 14 and then pressure-bonding the substrates.
0 is formed.

As shown in FIG. 2, one of these substrates 10 located at the lowermost end has a mounting portion 11 for mounting the electronic component 20 at the substantially central portion thereof. An opening 12 is formed in the central portion of each substrate 10 sequentially stacked on the substrate 10 having the mounting portion 11 so as to correspond to the mounting portion 11 and increase in size as it is positioned above. I am doing it.

The substrate 10 constituting the multilayer printed wiring board 100 as shown in FIG. 2 and located at the outermost layer.
On the surface located in the vicinity of the opening 12 of the above, an opening step portion 13 forming the main part of this embodiment is formed.

As shown in FIG. 2, the opening step portion 13 has a larger opening area than the opening portion 12 of the substrate 10 having the opening step portion 13. The opening step portion 13 is continuous with the opening portion 12 at a substantially right angle by the stepped end portion 13c.
In addition, the opening step portion 13 forms a space continuous with the mounting portion 11 of the substrate 10 located at the lowermost end.

The opening portion 1 having such an opening step portion 13
2 forms an inverted pyramid-shaped recess as a whole in the central portion of the multilayer printed wiring board 100. Then, as shown in FIG. 7, after the electronic component 20 is mounted in the mounting portion 11 located at the lowermost end, the electronic component 20 and each conductor circuit 15 are mounted.
Are connected by a bonding wire 21. After that, the sealing resin 22 is dropped into the recess for sealing.

The multilayer printed wiring board 100 is a pin grid array substrate and has a large number of conductor pins electrically connected to each conductor circuit 15. Each of these conductor pins 17 has a large number of through holes 16 formed in a predetermined portion of the multilayer printed wiring board 100.
After the conductor layer 16a is formed in 6 by plating, the support portion 17a is fixed to the multilayer printed wiring board 100 by, for example, forcibly fitting.

Next, a method of manufacturing the above-mentioned multilayer printed wiring board 100 will be described. This manufacturing method mainly includes the following steps (a) to (d). (A) First, as shown in FIG. 3, a substrate 10 having a mounting portion 11 for accommodating electronic parts and a conductor circuit 15, a substrate 10 disposed on the upper side of the substrate 10 and serving as an outermost layer, and At least one substrate 10 having an opening 12 corresponding to the mounting portion 11 and a conductor circuit 15 interposed between both substrates 10 as necessary, and an adhesive layer 14 formed on the back surface or the like of each substrate 10. There is a step of pressure-bonding to each other via.

Of course, the substrate 1 other than the substrate 10 which is the outermost layer
As for 0, the respective mounting portions 11 and the opening portions 12 are formed so as to be sequentially increased from bottom to top. As a result, the electronic component 20 and each conductor circuit 15
The connection with the bonding wire 21 can be easily performed.

The adhesive layer 14 for each substrate 10 is
It is also possible to apply it on the back surface of each substrate 10 in advance, but a sheet-like material corresponding to the adhesive layer 14 is prepared separately, and this sheet is interposed between the substrates 10 and pressure-bonded. You may do it.

(B) Then, a large number of through holes 16 are formed at the same time so as to penetrate through each substrate 10 thus pressure-bonded, and the through holes 16 are plated to form conductor layers 16a in the through holes 16. To form.

(C) The conductor circuit 15 is formed on the surface of the substrate 10 which is the outermost layer of the substrates 10 having the through holes 16 formed therein. (D) On the surface of the substrate located on the outermost layer of each substrate 10 on which the necessary conductor circuits 15 are formed by joining as described above,
The opening 12 and the opening step 13 are formed. There are various methods for forming the opening step portion 13, but the following was carried out in implementing the present invention.

That is, as shown in FIG. 3, first, the groove portion 13a is formed in the substrate 10 having the portion to be the opening step portion 13, and thereby the protrusion portion 13b protruding in the substrate 10 is formed. Is formed. The substrate 10 thus formed is laminated so that the protrusion 13b faces the mounting portion 11 or the opening 12 of each substrate 10 on which the protrusions 13b are already laminated. Thus, the protrusion 1 after the stacking is completed.
The protrusion 13b is removed from the substrate 10 having 3b by counterboring or the like.

As described above, the opening 12 and the opening step 1
The step of forming 3 is performed after the conductor circuit 15 is formed on the surface of the substrate 10 located at the outermost layer, because when the conductor circuit 15 is formed, a large opening is formed on the surface of the substrate 10. The reason is that the etching solution or the like enters through this opening and the mounting portion 11 and the like cannot be held in a desired state.

(E) After forming the opening 12 and the opening step 13 as described above, the conductor pin 17 is forcibly fitted into the through hole 16 plated with nickel and gold and is planted. Then, the multilayer printed wiring board 100 according to this embodiment as shown in FIG. 2 is completed.

Next, the operation of this example will be described. First, in the multilayer printed wiring board 100 configured as described above, the electronic component 20 is mounted in the mounting portion 11 and the bonding wire 21 electrically connects the electronic component 20 to each conductor circuit 15. . After that, the sealing resin 22 is dropped and filled in the recess of the inverted pyramid shape. The surplus portion of the dropped sealing resin 22 is in a state as shown in FIG.

That is, the surplus sealing resin 22 is
Surface tension acts on the stepped end portion 13c of the opening stepped portion 13, and rises from the stepped end portion 13c as a starting point. However, since the stepped end portion 13c is located at a position lower than the surface of the substrate 10, the raised upper end of the sealing resin 22 does not go above the surface of the substrate 10.

When the sealing resin 22 becomes excessive, a part of the sealing resin 22 may get over the stepped end portion 13c as shown in FIG. Since the step portion 13 is an opening sufficiently larger than the opening portion 12, a part of the sealing resin 22 remains in the opening step portion 13 and does not come out of the surface of the substrate 10.

Further, not only when the sealing resin 22 is simply dropped to complete the resin sealing, but also when the sealing plate 23 is further placed thereon to completely prevent the sealing resin 22 from protruding. Moreover, this opening step portion 13 is convenient. That is, as shown in FIG. 8, when the surface of the substrate 10 is flattened by the sealing plate 23, the sealing plate 23 only needs to be locked to the opening step portion 13, so that the mounting is very easy. It will be easier.

As described above, even if there is a surplus portion in the sealing resin 22, this surplus portion is not covered by the opening step portion 13.
Therefore, it does not project from the surface of the substrate 10. Further, therefore, it is possible to complete the resin sealing work without paying much attention to it.

[0045] Next above describing effects of the present embodiment, as described in detail, in the multilayer printed wiring board 100 according to this embodiment, the substrate 10 positioned on the outermost layer, the stepped end 13 c or Ranaru is formed an opening step 13. Therefore, when sealing the mounted electronic component 20 with resin,
The surplus sealing resin 22 does not project from the surface of the substrate 10.

Further, the measure for preventing the protrusion of the sealing resin has a simple structure. Therefore, according to this example, with a simple structure,
It is possible to provide a multilayer printed wiring board 100 that can effectively use a limited space and can sufficiently realize high-density mounting.

[Brief description of drawings]

FIG. 1 is a front perspective view of a multilayer printed wiring board according to an embodiment.

FIG. 2 is a partially enlarged vertical sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view showing each step of the manufacturing method according to the embodiment.

FIG. 4 is a sectional view showing each step of the manufacturing method according to the embodiment.

FIG. 5 is a sectional view showing each step of the manufacturing method according to the embodiment.

FIG. 6 is a sectional view showing each step of the manufacturing method according to the embodiment.

FIG. 7 is a cross-sectional view showing a state in which an electronic component is sealed with a sealing resin in the example.

FIG. 8 is a cross-sectional view showing a state in which a sealing plate is further covered on the sealing resin in the example.

FIG. 9 is a partial sectional view corresponding to FIG. 7, showing another state in the embodiment.

[Explanation of symbols]

 10. ． ． Substrate 100. ． ． Multilayer printed wiring board, 11. ． ． Mounting part, 12. ． ． Opening, 13. ． ． Opening step, 13c. ． ． Stepped end, 14. ． ． Adhesive layer, 15. ． ． Conductor circuit, 16. ． ． Through hole, 20. ． ． Electronic components, 21. ． ． Bonding wire, 22. ． ． Sealing resin, 23. ． ． Sealing plate,

Claims (3)

[Claims] 1. A mounting board for mounting an electronic component and a board having a conductor circuit formed thereon, and at least one board having an opening and a conductor circuit corresponding to the mounting section formed on the board. In a multilayer printed wiring board in which an electronic component is mounted inside the part and the periphery of the electronic component is sealed with a sealing resin, the opening in the board located in the outermost layer of each of the boards parts on the surface side located in the vicinity, a multilayer printed wiring board characterized that you have an opening stepped portion for sealing resin escape prevention which is more configured stepped end. 2. The multilayer printed wiring board according to claim 1, wherein each of the substrates is made of resin. 3. The multilayer printed wiring board according to claim 1 or 2, wherein the multilayer printed wiring board is a pin grid array substrate.