JP2003218520A - Build-up board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a build-up board, in which there is no trouble due to the generation of a crack in an insulating layer in the case of a high temperature in the build-up board with the insulating layer formed by impregnating glass cloth with a resin, and its manufacturing method. <P>SOLUTION: In the build-up board in which wiring patterns 2 are formed in multilayers through the insulating layers 4 and 6 formed by impregnating the glass cloth 4a and 6a with the resins 4b and 6b and the wiring patterns 2 in upper layers and lower layers are connected electrically through through- holes 10 formed to the insulating layers 4 and 6 or conductor sections 8 formed in via holes 12, cutting sections 16 are formed near the through-holes 10 or the via holes 12 of the glass cloth 4a of the insulating layer 4 adjacent to the insulating layers 4 and 6, to which the through-holes 10 or the via holes 12 are formed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a build-up board and a manufacturing method thereof.

[0002]

Resin is generally used as a material for an insulating layer of a build-up substrate. However, recently, in order to increase the strength of the build-up substrate, a material in which a glass cloth is impregnated with a resin has been tried. An example of a conventional build-up substrate using a material obtained by impregnating glass cloth with a resin for an insulating layer will be described with reference to FIG. Figure 3
In (a), B is a partial cross-sectional view of a conventional build-up substrate. Reference numeral 6 denotes a core substrate as an insulating layer, which is formed by impregnating glass cloth 6a with resin 6b such as epoxy. Reference numeral 4 denotes an insulating layer laminated on the core substrate, and like the core substrate 6, is formed by impregnating the glass cloth 4a with a resin 4b such as epoxy. Reference numeral 2 is a wiring pattern formed in multiple layers via the core substrate 6 or the insulating layer 4. Reference numeral 10 denotes a through hole formed in the core substrate 6, and the wiring patterns 2 and 2 formed on the front and back of the core substrate 6 are electrically connected to each other through a conductor portion 8 provided in the through hole 10. There is. Reference numeral 12 denotes a via hole formed in the insulating layer 4, and the upper and lower wiring patterns 2 and 2 of the insulating layer 4 are electrically connected to each other through a conductor portion 8 provided in the via hole 12. The wiring patterns 2 and the conductor portions 8 are generally made of copper.

The multilayered build-up substrate B having the insulating layers 6 and 4 including the glass cloths 6a and 4a has a high physical strength. Therefore, for example, when wire bonding is performed on the wiring pattern 2 on the build-up substrate B, the phenomenon that the resin of the insulating layer 4 laterally escapes due to the pressure of pressing the wire against the insulating layer 4 is unlikely to occur, and the wire bonding work speed It has the advantage of being able to raise

[0004]

However, as described above, by using a material obtained by impregnating glass cloth with resin for the insulating layer of the build-up substrate, it is exposed to high temperature in the steps such as wire bonding and solder reflow. When
There is a new problem that cracks may occur near the lands of insulating layers 4 and 6 (ends of through holes 10 and via holes 12). When a crack occurs in the insulating layer, air is introduced into the crack and the expansion and contraction are repeated due to a temperature change to spread the crack, which often leads to a failure of the build-up substrate B.

The present invention has been made to solve the above problems, and an object thereof is a build-up substrate having an insulating layer formed by impregnating glass cloth with a resin, and cracks occur in the insulating layer at high temperature. It is an object of the present invention to provide a build-up board and a method for manufacturing the build-up board, which are free from failures.

[0006]

The inventors of the present invention have found that when the build-up substrate is at a high temperature, the difference in the coefficient of thermal expansion between the resin and the glass cloth causes stress in the insulating layer, causing the cracks in the vicinity of the land. The present invention has been completed through intensive studies and thought that it would occur. The present invention has the following configuration in order to solve the above problems. That is, a wiring pattern is formed in multiple layers via an insulating layer formed by impregnating glass cloth with a resin, and a conductor portion provided in a through hole or a via hole in which the upper and lower wiring patterns are formed in the insulating layer. A build-up board electrically connected via
A cut portion is formed in the glass cloth of the insulating layer adjacent to the insulating layer in which the through hole or via hole is formed, in the vicinity of the through hole or via hole. Further, the method for manufacturing a buildup substrate according to the present invention has the following configuration. That is, a step of forming a through hole or a via hole communicating with a wiring pattern of a lower layer of the insulating layer in the insulating layer, and a step of providing a conductor portion connecting the upper layer and the lower layer of the insulating layer in the through hole or the via hole. And a step of forming a wiring pattern on the surface of the insulating layer, and at least a glass cloth of a prepreg formed by impregnating a glass cloth with a resin is arranged according to the arrangement of the through hole or the via hole formed in the insulating layer. A step of forming a cut portion by aligning the cut portion formed on the glass cloth of the prepreg with the through hole or via hole of the insulating layer, and stacking the prepreg on the upper layer of the insulating layer. Including.

The reason why the above structure can prevent the occurrence of cracks is considered as follows. The build-up board B is 240-
It reaches a high temperature of about 250 ° C., and the resin 4b of the insulating layers 4 and 6
Exceeds the glass transition point of 6b. Particularly, when using a lead-free solder which has been recently recommended in consideration of the environment, it is exposed to a further high temperature such as about 270 ° C. during solder reflow. When an epoxy resin is used as the resins 4b and 6b, the expansion coefficient of the resins 4b and 6b when the glass transition point is exceeded is 200 ppm per 1 ° C.
It will be about. On the other hand, the coefficient of expansion of copper used for the wiring pattern 2 and the conductor portion 8 is about 16 ppm per 1 ° C., and the coefficient of expansion of the glass cloths 4a and 6a is also very small.

Therefore, the buildup substrate B is deformed as shown in FIG. 3B when the temperature rises above the glass transition point. The resin 4b, 6b of the insulating layers 4, 6 is the conductor portion 8 in the through hole 10 and the via hole 12.
Since it is sandwiched between the wiring patterns 2 and 2 (copper) connected by (copper), when the resins 4b and 6b expand, the sandwiched insulating layers 4 and 6 resist the expanding force. A stress 90 is applied. Further, the stress 90 is applied to the insulating layer 4 adjacent to the sandwiched insulating layers 4 and 6 with respect to the sandwiched insulating layer 4,
It works as a pulling force to the 6 side. Further, due to the stress 90, the glass cloth 4 a of the insulating layer 4 adjacent to the sandwiched insulating layers 4 and 6 has a through hole 10 and a via hole 1.
Although the glass cloth 4a is pulled to the 2nd side, the stress 92 that acts to restore the glass cloth 4a to its original shape acts because the expansion coefficient of the glass cloth 4a is low. As described above, it is considered that the stress 90 and the stress 92 in opposite directions act on the vicinity 14 of the land of the through hole 10 and the via hole 12 of the insulating layer 4 to cause cracks in the resin 4b of the insulating layer 4. .

Therefore, by adopting the configuration of the present invention, the cut portion of the glass cloth weakens the tension of the glass cloth when the resin of the insulating layer expands, and the stress 92 is reduced. Therefore, it is considered that the load applied to the vicinity 14 of the land of the insulating layer is reduced and the occurrence of the crack is suppressed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a build-up substrate and a method of manufacturing the same according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a part of a build-up board according to the present invention. In the build-up board A of FIG. 1, the same members as those of the conventional build-up board B are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1A, the build-up substrate A according to the present invention has an insulating layer 4 adjacent to the insulating layers 4 and 6 having through holes 10 or via holes 12 formed therein.
The cutting portion 16 is formed at a position overlapping the through hole 10 or the via hole 12. The cut portion 16 has a shape of a hole penetrating the insulating layer 4 in the thickness direction, and the through hole 10 is formed.
Alternatively, the diameter is smaller than that of the via hole 12. In addition,
The shape of the hole as the cutting portion 16 may be any shape such as a circular shape or a rectangular shape.

Here, the cutting portion 16 does not always have to be the insulating layer 4.
Does not have to penetrate in the thickness direction, and may be formed on at least the glass cloth 4a. Also, the cutting unit 1
6 does not necessarily have to be formed in a hole shape, and may have any shape as long as it is formed by cutting the fibers of the glass cloth 4a.

FIG. 1 (b) shows this build-up board A.
However, for example, in the process of solder reflow, the insulating layers 4, 6
2 shows a state when heated to a temperature equal to or higher than the glass transition point of the resin constituting the. In this case, the resin of the insulating layers 4 and 6 expands as in the case of the conventional buildup board B. Then, similarly, the stress 90 acts on the insulating layers 4 and 6. Further, the stress 90 causes the glass cloth 4 a to be pulled toward the through hole 10 and the via hole 12. At this time, the stress 92 that causes the glass cloth 4a to return to its original shape by the cutting portion 16 becomes extremely small. Therefore, the insulating layer 4
Is flexibly deformed according to the stress 90, a strong tensile force does not act on the vicinity 14 of the through holes 10 and the via holes 12 of the insulating layers 4 and 6, and it is possible to prevent the occurrence of cracks.

Next, a method for manufacturing the buildup substrate A will be described with reference to FIG. In FIG. 2A, 6 is a core substrate as an insulating layer, which is formed by impregnating glass cloth 6a with resin 6b such as epoxy, and copper foils 24 are attached to the front and back. In the first step, the copper foil 24 is etched and the core substrate 6 is irradiated with the laser beam 18 at predetermined positions of the core substrate 6 to form the through holes 10 penetrating the front and back of the core substrate 6 and connecting them.

In the subsequent second step, as shown in FIG. 2B, both surfaces of the core substrate 6 and the through holes 10 are
Apply electroless plating of copper. Further, the electroless plated layer is energized to form an electrolytic plated layer on the surface of the electroless plated layer. As a result, the conductor layer 20 composed of the copper foil 24 and the copper plating layer is formed on both surfaces of the core substrate 6, and the conductor portion 8 connecting the conductor layers 20 on the front and back sides of the core substrate 6 in the through holes 10. Is formed.

In the subsequent third step, as shown in FIG. 2C, the conductor layer 20 is selectively etched using a known technique to form the wiring pattern 2 on the front and back surfaces of the core substrate 6. Form.

In the subsequent fourth step, as shown in FIG. 2D, a hole portion 22c as a cut portion is formed in the prepreg 22 in accordance with the arrangement of the through hole 10. The prepreg 22 includes a glass cloth 22a and a resin 2 such as epoxy.
2b is a sheet-shaped member formed by impregnation with 2b, and the resin 22b is cured to the B stage.
It is a material of the insulating layer 4 which is laminated to cover the front and back surfaces of the core substrate 6 on which is formed. As a method of forming the holes 22c, a method of irradiating the prepreg 22 with a laser may be adopted. Alternatively, the hole 22c may be formed by punching the prepreg 22. Whichever method is used, the hole 22c is formed by cutting at least the fibers of the glass cloth 22a. In addition,
The fourth step may be performed separately from the first to third steps or in parallel.

In the subsequent fifth step, as shown in FIG. 2E, the hole 22c is aligned with the through hole 10 and the prepreg 22 is laminated on each of the upper and lower layers of the core substrate. The laminated prepreg 22 is heat-cured by heat treatment to become the insulating layer 4 (not shown).

Thereafter, in order to form the wiring pattern 2 in multiple layers, the same steps as above are repeated. That is, the via hole 12 is formed in the insulating layer 4 by a laser beam, the front and back surfaces of the insulating layer 4 and the inside of the via hole 12 are plated, and the plating layer on the surface of the insulating layer 4 is etched to form the wiring pattern 2, and the prepreg 22 A hole portion 22c is formed in accordance with the arrangement of the via hole 12 formed in the insulating layer 4, the hole portion 22c is aligned with the via hole 12, and the prepreg 22 is laminated on the surface (upper layer) of the insulating layer 4. The cycle of the process of forming the different insulating layer 4 is repeated many times.

By doing so, the wiring pattern 2 is formed in multiple layers via the insulating layers 4 and 6 formed by impregnating the glass cloth 4a with a resin as shown in FIG.
The upper and lower wiring patterns 2 are electrically connected to each other through a through hole 10 formed in the insulating layers 4 and 6 or a conductor portion 8 provided in a via hole 12, and the through hole 1
0 or the through hole 10 of the glass cloth 4a of the insulating layer 4 adjacent to the insulating layers 4 and 6 in which the via hole 12 is formed.
Alternatively, it is possible to obtain the buildup substrate A in which the cut portion 16 is formed in the vicinity of the via hole 12.

As the method of manufacturing the build-up board A, in this embodiment, the core board 6 having the copper foil 24 attached beforehand was used, but electroless plating is applied to the core board having no conductor foil such as the copper foil 24. Alternatively, a method of forming the conductor layer 20 by performing electrolytic plating may be adopted. Further, as the prepreg 22, the one having no conductor foil such as copper foil attached to the front and back surfaces was used, but a method of laminating one having a conductor foil such as copper foil attached to one side can also be adopted.

[0022]

According to the build-up substrate having the insulating layer formed by impregnating the glass cloth with the resin and the method for manufacturing the same according to the present invention, when the insulating layer expands at a high temperature, the tension of the glass cloth causes It is possible to obtain a build-up substrate that does not have a failure due to the generation of cracks in the insulating layer.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a build-up substrate according to the present invention, in which (a) shows a room temperature state and (b) shows a temperature state exceeding a glass transition point of a resin of an insulating layer.

FIG. 2 is an explanatory view showing a method for manufacturing a build-up board according to the present invention, in which (a) shows a state in which through holes are formed in the core board, and (b) shows the surface of the core board and the inside of the through holes. A state in which a conductor layer and a conductor portion are formed, (c)
Shows a state where a wiring pattern is formed, (d) shows a state where a cut portion is formed in a prepreg, and (e) shows a state where a prepreg is laminated on an insulating layer.

FIG. 3 is a cross-sectional view of a part of a conventional build-up substrate, in which (a) shows a state at room temperature and (b) shows a state at a temperature exceeding a glass transition point of a resin of an insulating layer.

[Explanation of symbols]

A Build-up substrate of the present invention B Conventional build-up board 2 wiring pattern 4 insulating layers 4a glass cloth 4b resin 6 core substrate 6a glass cloth 6b resin 8 conductor 10 through holes 12 beer hall 16 cutting part 22 prepreg 22a glass cloth 22b resin 22c Hole (cutting part) 24 copper foil

Continued front page    F term (reference) 5E317 AA24 BB02 BB12 CC31 CD31                       GG05                 5E346 AA01 AA12 AA15 AA32 AA38                       AA43 BB01 CC02 CC08 CC31                       DD02 DD31 EE33 FF04 GG15                       GG17 GG28 HH11

Claims (2)

[Claims] 1. A wiring pattern is formed in multiple layers with an insulating layer formed by impregnating glass cloth with a resin, and wiring patterns of upper and lower layers are provided in through holes or via holes formed in the insulating layer. A build-up substrate electrically connected via a conductor part, wherein a cut portion is formed in the vicinity of the through hole or via hole of the glass cloth of the insulating layer adjacent to the insulating layer in which the through hole or via hole is formed. A build-up substrate characterized by being formed. 2. A step of forming a through hole or a via hole connecting the front and back of the insulating layer in the insulating layer, and a step of providing a conductor portion connecting the upper layer and the lower layer of the insulating layer in the through hole or the via hole. A step of forming a wiring pattern on the surface of the insulating layer, and at least a glass cloth of a prepreg formed by impregnating a glass cloth with a resin, in accordance with the arrangement of the through hole or the via hole formed in the insulating layer. And a step of forming a cut portion, aligning the cut portion formed on the glass cloth of the prepreg with the through hole or the via hole of the insulating layer, and laminating the prepreg on an upper layer of the insulating layer. A method for manufacturing a build-up board, comprising: