JP5287556B2 - LCP multilayer substrate and manufacturing method thereof - Google Patents

Description

  The present invention relates to an LCP multilayer substrate and a manufacturing method thereof.

  An example of a printed circuit board is described in Japanese Patent No. 3473601 (Patent Document 1). In the example shown in this document, the printed circuit board is formed by laminating a thermoplastic resin film made of a polyetheretherketone resin and a polyetherimide resin, and pressurizing while heating. In general, a printed circuit board is made for the purpose of mounting an electronic component or the like on the surface thereof, and is not easily bent and is hard. However, when a package including electronic components is disposed inside a movable part of the apparatus, the package itself may be required to have flexibility.

  An example of an IC chip package using a liquid crystal polymer film is described in Japanese Patent No. 3642885 (Patent Document 2). In this document, a liquid crystal polymer (Liquid Crystal Polymer) (hereinafter referred to as “LCP”) is melted in a short screw extruder, extruded into a film shape, and cooled to obtain an LCP film. In the LCP film of this document, the LCP molecules are randomly oriented along the plane direction.

Japanese Patent No. 3473601 Japanese Patent No. 3642885

  In the IC chip package disclosed in Patent Document 2, a conductor is disposed so as to penetrate the LCP film in the thickness direction. This conductor is hereinafter referred to as “via conductor”. The IC chip package disclosed in Patent Document 2 has the following problems.

  First, there is a problem during thermal expansion. Therefore, when the temperature of the entire LCP film is raised, a large difference in the degree of thermal expansion occurs between the via conductor and the LCP resin portion around the via conductor. As a result, peeling or cracking occurs between the via conductor and the LCP resin portion.

  Second, there is a problem of signal delay. When the electrical signal flows through the via conductor, the relative dielectric constant around the via conductor is increased, so that the signal delay in the via conductor is increased.

  Accordingly, the present invention is directed to an LCP multilayer substrate that can solve the above-described problems and a method for manufacturing the same.

  In order to achieve the above object, an LCP multilayer substrate according to the present invention is an LCP multilayer substrate in which a plurality of layers including an LCP layer in which LCP molecules are aligned in a plane direction are stacked, and at least one of the LCP layers A conductor pattern is disposed on the surface, and the LCP layer has a via conductor extending in a thickness direction so as to be electrically connected to the conductor pattern, and is in contact with an outer periphery of the via conductor. A first region in which LCP molecules are oriented in the thickness direction is provided so as to surround.

  According to the present invention, since the difference in thermal expansion coefficient between the via conductor and the LCP resin portion around the via conductor can be reduced, peeling or cracking occurs between the via conductor and the LCP resin portion. The degree can be reduced. Furthermore, the dielectric constant around the via conductor when an electric signal flows through the via conductor can be reduced, and as a result, the signal delay in the via conductor can be reduced.

It is the 1st sectional view of the LCP multilayer substrate in a reference example. It is a 2nd sectional view of the LCP multilayer substrate in a reference example. It is a partial top view of the LCP layer of the LCP multilayer substrate in a reference example. It is sectional drawing of the LCP multilayer substrate in Embodiment 1 based on this invention. It is sectional drawing of the LCP multilayer substrate in Embodiment 2 based on this invention. It is sectional drawing of the LCP multilayer substrate in Embodiment 3 based on this invention. It is a one part enlarged view of FIG. It is explanatory drawing of preferable dimension conditions. It is 1st explanatory drawing of the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention. It is 2nd explanatory drawing of the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention. It is 3rd explanatory drawing of the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention. It is 4th explanatory drawing of the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention. It is 5th explanatory drawing of the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention. It is 6th explanatory drawing of the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention. It is explanatory drawing of the example using the heat retention member with the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention.

  The inventors examined conventional problems. In the conventional LCP film, the material is formed into a film by extruding the material, so that the LCP molecules are oriented along the plane direction of the film. On the other hand, in general, in an LCP resin in which LCP molecules are oriented in a certain direction, the thermal expansion coefficient in the longitudinal direction of the LCP molecules is small, and the thermal expansion coefficient in the direction perpendicular to the longitudinal direction of the LCP molecules is large. There is. In general, a metal such as Cu or Sn / Ag is used as the material of the via conductor. Here, “Sn / Ag” means an alloy of tin and silver. In the LCP resin in which the LCP molecules are oriented in a certain direction, the thermal expansion coefficient in the longitudinal direction of the LCP molecules is smaller than that of Cu, Sn / Ag, etc., and the thermal expansion coefficient in the direction perpendicular to the longitudinal direction of the LCP molecules is Cu. Or a thermal expansion coefficient such as Sn / Ag.

  In the conventional LCP film, the peeling or cracking occurred between the via conductor and the LCP resin part. In the LCP film, the LCP molecules are oriented not in the thickness direction but in the plane direction. This is probably because the thermal expansion coefficient in the thickness direction of the LCP resin portion is large. When the temperature rises, the LCP resin portion tends to expand greatly, whereas a via conductor made of a metal such as Cu usually does not expand so much, so it is considered that peeling or cracking occurs between the two. It is done.

  In addition, in the conventional LCP film, the relative permittivity around the via conductor is increased and the signal delay is increased when an electric line of force is generated by current flowing through the via conductor. This is probably because the LCP molecules are aligned along the plane direction, so that the lines of electric force are orthogonal to the alignment direction of the LCP molecules.

  The thermal expansion coefficients of the LCP layer and the conductor are as shown in Table 1 and Table 2, respectively, depending on the temperature.

  The relative dielectric constant of the LCP layer is as shown in Table 3.

  Before describing an embodiment based on the present invention, an LCP multilayer substrate constituted by laminating a plurality of LCP layers will be described as a reference example.

(Reference example)
A cross-sectional view of the LCP multilayer substrate is shown in FIG. The LCP multilayer substrate 100 includes a plurality of LCP layers 1 in which LCP molecules are aligned in the plane direction. The LCP layers 1 included in the LCP multilayer substrate 100 may originally be independent LCP films, and the LCP multilayer substrate 100 may be integrated by pressurization after being laminated. In FIG. 1, the boundary line between the LCP layers 1 is virtually indicated by a two-dot chain line, but in reality, the adjacent LCP layers 1 may already be integrated and the boundary line may disappear. . A conductor pattern 2 is provided on the lowermost surface of the LCP multilayer substrate 100. A conductor pattern 3 is provided on the uppermost surface of the LCP multilayer substrate 100. Conductor patterns 41 and 42 are provided in the middle in the thickness direction. A via conductor 5 is provided from the conductor pattern 2 to the conductor pattern 3 via the conductor patterns 41 and 42.

  FIG. 2 shows the orientation of LCP molecules in the LCP multilayer substrate 100 expressed by short linear dots. Thus, in the LCP layer 1, since the LCP molecules are along the plane direction, all the LCP molecules appear to extend in the lateral direction in the cross-sectional view. FIG. 3 shows an arbitrary portion of the LCP layer 1 as viewed from above. When viewed from above, the orientation of LCP molecules is random.

(Embodiment 1)
(Constitution)
With reference to FIG. 4, the LCP multilayer substrate in Embodiment 1 based on this invention is demonstrated. The LCP multilayer substrate 101 is an LCP multilayer substrate in which a plurality of layers including the LCP layer 1 in which LCP molecules are aligned in the plane direction are stacked. A conductor pattern extending in the surface direction of the LCP layer is disposed on at least one surface of the LCP layer 1. In this example, conductor patterns 2, 41, and 42 exist as conductor patterns. The LCP layer 1 has a via conductor 5 extending in the thickness direction so as to be electrically connected to the conductor pattern. A first region 6 in which LCP molecules are oriented in the thickness direction is provided so as to be in contact with the outer periphery of the via conductor 5 and surround the via conductor 5. The via conductor 5 may be made of Cu, for example. Each of the conductor patterns may also be formed of Cu, for example. In FIG. 4, the boundary line between the LCP layers 1 is virtually indicated by a two-dot chain line. However, in fact, the adjacent LCP layers 1 may already be integrated and the boundary line may disappear. .

(Action / Effect)
In the present embodiment, since the LCP molecules are oriented in the thickness direction in the first region 6 that surrounds the outside of the via conductor 5 in the LCP layer 1, the thermal expansion coefficient in the thickness direction in the first region 6 is small. It has become. Therefore, even when the temperature of the entire LCP multilayer substrate 101 is raised, there is no significant difference in the degree of thermal expansion between the via conductor 5 and the surrounding LCP resin portion. As a result, it is possible to prevent peeling or cracking between the via conductor and the LCP resin portion.

  In the present embodiment, it can be said that the orientation direction of the LCP molecules in the first region 6 coincides with the direction in which the current flows in the via conductor 5. Therefore, in the LCP multilayer substrate 101 in the present embodiment, the dielectric constant is low and the signal delay is small.

(Embodiment 2)
(Constitution)
With reference to FIG. 5, the LCP multilayer substrate in Embodiment 2 based on this invention is demonstrated. The LCP multilayer substrate 102 is an LCP multilayer substrate in which a plurality of layers including the LCP layer 1 in which LCP molecules are aligned in the plane direction are stacked. A conductor pattern is disposed on at least one surface of the LCP layer 1. In this example, conductor patterns 2, 41, and 42 exist as conductor patterns. The LCP layer 1 has a via conductor 5 extending in the thickness direction so as to be electrically connected to the conductor pattern. Up to this point, it is the same as the LCP multilayer substrate 101 shown in the first embodiment. As a difference from the LCP multilayer substrate 101, the LCP multilayer substrate 102 is provided with a second region 7 in which LCP molecules are randomly oriented so as to contact the outer periphery of the via conductor 5 and surround the via conductor 5. In other words, the LCP multilayer substrate 102 in the present embodiment has a configuration in which the first region 6 of the LCP multilayer substrate 101 in the first embodiment is replaced with the second region 7.

(Action / Effect)
In the present embodiment, since the LCP molecules are randomly oriented in the second region 7 that surrounds the via conductor 5 in the LCP layer 1, the second region 7 is second in comparison with the case where it is oriented in the plane direction. In the region 7, the thermal expansion coefficient in the thickness direction is small. Since the LCP molecules are randomly oriented in the second region 7 rather than in the thickness direction, the thermal expansion coefficient in the thickness direction is larger than that in the case where the LCP molecules are oriented in the plane direction in the region just outside the via conductor 5. As a result, peeling or cracking between the via conductor and the LCP resin portion can be prevented. In addition, the dielectric constant is reduced and the signal delay is reduced as compared with the case where the LCP molecules are oriented in the plane direction in the region immediately outside the via conductor 5.

  In this embodiment, the effect is inferior to that of the configuration shown in Embodiment 1, but a certain effect can be achieved.

(Embodiment 3)
(Constitution)
With reference to FIG. 6 and FIG. 7, the LCP multilayer substrate in Embodiment 3 based on this invention is demonstrated. The LCP multilayer substrate 103 according to the third embodiment of the present invention includes the configuration of the LCP multilayer substrate 101 shown in the first embodiment, and further includes the following configuration. As shown in FIG. 6, the LCP multilayer substrate 103 is provided with a second region 7 in which LCP molecules are randomly oriented so as to surround the outer side of the first region 6. FIG. 7 shows an enlarged view of the vicinity of one layer of the via conductor 5 in the LCP layer 1 in FIG. In FIG. 7, the conductor pattern included in the LCP layer 1 is not shown. The first region 6 is also called “vertical alignment region”. The second region 7 is also called “random orientation region”. The region 8 extending outside the second region 7 is also referred to as a “lateral orientation region”. In the region 8, the LCP molecules are oriented in the plane direction. Most of the LCP resin belongs to region 8.

(Action / Effect)
In the present embodiment, the region 8 in which the LCP molecules in the LCP layer 1 are aligned in the plane direction and the first region 6 aligned in the thickness direction are not in direct contact with each other but are randomly aligned. Since the two regions 7 are interposed, the thermal expansion coefficient in the thickness direction gradually changes as the via conductor is approached. Therefore, not only between the via conductor 5 and the first region 6 but also between the first region 6 and the second region 7 and between the second region 7 and the region 8, the difference in thermal expansion coefficient is kept small. This is preferable because any load can be prevented from occurring during thermal expansion at any location.

(Preferred dimensional conditions)
In both the LCP multilayer substrate 101 in the first embodiment and the LCP multilayer substrate 103 in the third embodiment, the first region 6 surrounds the via conductor 5 so that the width on one side of the via conductor 5 is not less than 100 μm and not more than 500 μm. It is preferable that That is, the dimension D shown in FIG. 8 or the dimension D shown in FIG. 7 is preferably 100 μm or more and 500 μm or less. The diameter of the via conductor 5 is, for example, 100 μm. In FIG. 8, the conductor pattern included in the LCP layer 1 is not shown. If the first region 6, that is, the dimension D is smaller than 100 μm, the effect of preventing peeling or cracking during thermal expansion is thin, and the effect of suppressing signal delay is also thin. Conversely, if the dimension D is larger than 500 μm, the thermal expansion in the surface direction is adversely affected. Therefore, the dimension D is preferably 100 μm or more and 500 μm or less.

(Embodiment 4)
(Production method)
With reference to FIGS. 9-15, the manufacturing method of the LCP multilayer substrate in Embodiment 4 based on this invention is demonstrated. The manufacturing method of the LCP multilayer substrate extends in the thickness direction so as to be electrically connected to the conductor pattern with respect to the LCP layer in which the LCP molecules are oriented in the plane direction and the conductor pattern is arranged on one side. A first step of making a hole for installing a via conductor, and a first region in which LCP molecules are oriented in the thickness direction or LCP molecules are randomly oriented so as to surround and surround the hole. A second step of forming a second region; a third step of disposing the via conductor in the hole; and a plurality of layers including the LCP layer having undergone the second step and the third step. 4 processes and the 5th process of integrating what was laminated | stacked in the said 4th process.

  The state of the first step is shown in FIGS. The LCP layer 1 in which the conductor pattern 41 is disposed on one surface is subjected to a process for forming a hole for installing a via conductor extending in the thickness direction so as to be electrically connected to the conductor pattern 41. . This drilling can be performed, for example, by irradiation with laser light 21 as shown in FIG.

  As a result of drilling, part of the LCP layer 1 is removed and holes 22 are obtained as shown in FIG. The hole 22 is depicted as a straight vertical hole in the figure, but may actually be a tapered hole. FIG. 10 shows a state immediately after the laser beam 21 is irradiated. The LCP resin originally in the hole 22 is removed by laser irradiation, and a region 23 in which the LCP resin is melted exists in the vicinity of the inner wall of the hole 22.

  The LCP resin melted in the region 23 is re-solidified due to the slow decrease in temperature, and the first region 6 in which LCP molecules are oriented in the thickness direction is formed as shown in FIG. By controlling the pace of temperature decrease until re-solidification at this time, the first region 6 in which the LCP molecules are oriented in the thickness direction is formed, or the second region in which the LCP molecules are randomly oriented. It is possible to select whether to form the region 7. In the present embodiment, the first region 6 is formed as shown in FIG.

  As shown in FIG. 12, the via conductor 5 is disposed in the hole 22 as the third step. This can be performed by forming a film of the metal that will be the material of the via conductor 5 on the upper surface of the LCP layer 1 and then removing the excess metal film. The via conductor 5 can be made of Cu, for example.

  As shown in FIG. 13, as the fourth step, a plurality of layers including the LCP layer 1 that has undergone the second step and the third step are stacked. In addition to stacking, as shown in FIG. 14, all the LCP layers included in the laminate are integrated as a fifth step. The fifth step can be performed by heating and pressurizing.

(Action / Effect)
In the manufacturing method of the LCP multilayer substrate in the present embodiment, the first region 6 in which the LCP molecules are oriented in the thickness direction or the LCP molecules are randomly oriented immediately outside the via conductor 5 in the LCP layer 1. In addition, the structure surrounded by the second region 7 can be easily manufactured. Therefore, it is possible to easily obtain an LCP multilayer substrate that can prevent peeling or cracking between the via conductor and the LCP resin portion when the temperature is raised, and can reduce the signal delay.

  Since the second step can be performed by cooling and re-solidifying the portion melted in the first step, as described above, the second step is preferably performed simultaneously with the first step.

  The first step is preferably performed by laser irradiation on the LCP layer 1. This is because laser irradiation can melt and remove a desired region of the LCP resin quickly.

  In the first step, it is preferable that the region where the holes 22 of the LCP layer 1 are to be opened is heated, and in the second step, the cooling rate after the heating is controlled. By doing so, the orientation of the LCP molecules can be adjusted to a desired state. Heating may be performed by laser irradiation as described above, but may be performed by other methods. Various known methods can be employed for controlling the cooling rate.

  In the second step, the region where the holes 22 of the LCP layer 1 are to be opened is heated, and then the LCP layer 1 is kept in contact with the LCP layer 1 as shown in FIG. It is preferable to cool 1. Here, “contact with the LCP layer 1” means to contact with the conductor pattern provided in the LCP layer 1. When the conductor pattern is formed of a metal, the conductor pattern serves as a heat radiating member. Therefore, it is preferable to transfer heat through the conductor pattern. If the heat retaining member 24 heated from the outside is used, cooling can be performed while supplementing the heat, so that the temperature of the LCP resin in the region 23 can be lowered very slowly. As a result, the orientation of the LCP molecules can be easily changed to a desired state, which is preferable.

  The second step is preferably performed such that the longitudinal direction of the hole 22 coincides with the direction of gravity. For example, in FIG. 10 and FIG. 11, it is preferable that the vertical direction of the figure is the direction of gravity. This is preferable because the LCP molecules are aligned in a desired state by the action of gravity when the melted LCP resin in the region 23 around the hole 22 re-solidifies as the temperature decreases.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 LCP layer, 2, 3, 41, 42 Conductor pattern, 5 Via conductor, 6 1st area | region, 7 2nd area | region, 8 area | region, 21 Laser beam, 22 hole, 23 (the LCP resin melted) area | region, 24 heat insulation Element.

Claims (10)

An LCP multilayer substrate in which a plurality of layers including an LCP layer in which LCP molecules are aligned in a plane direction are stacked,
A conductor pattern is disposed on at least one surface of the LCP layer,
The LCP layer has a via conductor extending in a thickness direction so as to be electrically connected to the conductor pattern,
An LCP multilayer substrate in which a first region in which LCP molecules are oriented in a thickness direction is provided so as to be in contact with an outer periphery of the via conductor and surround the via conductor.   2. The LCP multilayer substrate according to claim 1, wherein a second region in which LCP molecules are randomly oriented is provided so as to surround a further outside of the first region.   2. The LCP multilayer substrate according to claim 1, wherein the first region surrounds the via conductor so that a width on one side of the via conductor is not less than 100 μm and not more than 500 μm. An LCP multilayer substrate in which a plurality of layers including an LCP layer in which LCP molecules are aligned in a plane direction are stacked,
A conductor pattern is disposed on at least one surface of the LCP layer,
The LCP layer has a via conductor extending in a thickness direction so as to be electrically connected to the conductor pattern,
An LCP multilayer substrate in which a second region in which LCP molecules are randomly oriented is provided so as to contact the outer periphery of the via conductor and surround the via conductor. In order to install a via conductor extending in the thickness direction so as to be electrically connected to the conductor pattern with respect to the LCP layer in which the LCP molecules are oriented in the plane direction and the conductor pattern is arranged on one side A first step of drilling holes;
A second step of forming a first region in which LCP molecules are oriented in the thickness direction or a second region in which LCP molecules are randomly oriented so as to be in contact with and surround the pores;
A third step of disposing the via conductor in the hole;
A fourth step of laminating a plurality of layers including the LCP layer after the second step and the third step;
And a fifth step of integrating the stacked layers in the fourth step.   6. The method for manufacturing an LCP multilayer substrate according to claim 5, wherein the second step is performed simultaneously with the first step.   The method for manufacturing an LCP multilayer substrate according to claim 5, wherein the first step is performed by laser irradiation on the LCP layer.   8. The heating according to claim 5, wherein in the first step, the region of the LCP layer to be perforated is heated, and in the second step, the cooling rate after the heating is controlled. Manufacturing method of LCP multilayer substrate.   In the second step, the region of the LCP layer to be perforated is heated, and then the LCP layer is cooled in a state where a heat retaining member heated from the outside is in contact with the LCP layer. A method for producing an LCP multilayer substrate according to any one of claims 5 to 8.   10. The method of manufacturing an LCP multilayer substrate according to claim 5, wherein the second step is performed such that a longitudinal direction of the hole coincides with a direction of gravity.

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