JPH025307A - Vertical orientation high polymer insulator - Google Patents

Abstract

PURPOSE:To relax a thermal deformation and to improve the thermal conductibility by composing an insulator layer with a group of high polymer crystalline blocks whose molecular axes are oriented vertical to conductor surfaces, and forming clearances at the borders between crystalline blocks on the plane of the conductor surface. CONSTITUTION:The molecular axes of high polymers in high polymer crystalline blocks 2 to be an insulator layer, are oriented vertical to the surface of conductors 1, and at the same time, the crystalline blocks 2 stride between the conductors 1 opposing each other. As a result, the linear expansion rate of the insulator layer in the vertical direction to the conductor surface is reduced, and the thermal conductivity is increased. Moreover, clearances are formed at the borders of crystalline blocks 2 on the plane parallel to the conductor 1 surface. Consequently, the deformation of the linear expansion of the insulator layer parallel to the conductor surface is absorbed by the clearances regardless of a large linear expansion rate of individual crystalline block, and the value of the linear expansion rate of the insulator layer is made almost same as that of the conductors.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to industries related to electronic components, which are used in environments with significant temperature differences such as extremely low temperatures and high temperatures, and where shape stability and reliability are strongly required. It relates to insulated conductors used in the field, which can alleviate thermal strain caused by the difference in coefficient of linear expansion between the conductor and the insulating layer, and which have excellent thermal conductivity between the conductors. The present invention relates to an insulated conductor whose coefficient of linear expansion is small in the direction perpendicular to the conductor surface, approximately equal to the linear expansion coefficient of the conductor in the direction parallel to the conductor surface, and whose thermal conductivity of the insulating layer is high in the direction perpendicular to the conductor surface.

[Conventional technology]

In recent years, with the increasing integration and density of electronic components, not only the internal lines of ICC chips, but also the internal wiring of IC chip mounting boards and the internal wiring of input/output cables are becoming thinner and thinner. contact failure due to slight thermal strain caused by the difference in coefficient of linear expansion of the constituent materials between the board and the input/output cable, and
An important issue is how to efficiently dissipate the heat generated by the C-chip and reduce the temperature rise of the device.

Furthermore, in the field of superconductivity, it is important to develop insulating materials with low thermal distortion and excellent thermal conductivity in order to suppress the quench phenomenon unique to superconductivity.

In general, polymer materials have a large coefficient of linear expansion, so insulating materials (substrates) are made that have a better consistency with the coefficient of linear expansion of the engineering a-chip, such as by incorporating inorganic photonic agents such as glass with a small coefficient of linear expansion. Among polymers, there are input and output cables made of polyimide, which has a relatively low coefficient of linear expansion, as an insulator.

[Problem to be solved by the invention]

However, the h deviation is not completely satisfactory,
There is a strong desire to create materials that can alleviate thermal strain caused by differences in linear expansion coefficients between different materials such as conductors and insulators, and insulating materials that have excellent thermal conductivity.

An object of the present invention is to provide an insulated conductor that can alleviate thermal strain caused by a difference in coefficient of linear expansion between different materials and has excellent thermal conductivity.

[Failure to solve the problem]

To summarize the present invention, the present invention relates to a vertically oriented polymer insulated conductor, which has a button insulating layer between opposing conductors, and the insulating layer is a vertically oriented polymer insulated conductor having a molecular axis oriented perpendicularly to the conductor surface. It is composed of an aggregate of molecular crystal clusters, each crystal cluster spans between opposing conductors, and there are voids at the boundaries of the crystal clusters in a plane parallel to the conductor plane, and there are gaps between the conductors. It is characterized by having or not having a spacer for keeping the conductor spacing at a predetermined value as required during the installed manufacturing process.

By stretching a crystalline polymer such as polyethylene or polyoxycmethylene, a polymer material in which molecular chains are oriented in the -axis direction can be easily obtained. The coefficient of linear expansion in the stretching direction of this more -axially oriented polymer rapidly decreases with the stretching ratio, and changes from zero to a negative value.1. M. Ward (Eng.

M, Ward)
t stn orientea Polymers
-1), Applied Science (Appl, Sci,
) Ltd., London (1982)), the thermal conductivity in the stretching direction increases with the stretching ratio (0.L
, Choi (0, L, ahoy) et al. [Journal
Oppolymer Science Polymer Physics
Eddie V Yong (J, Polym, Elci, Pol
ym, Phys, Frid, Volume 18, Page 1187 (1980)). For example, the coefficient of linear expansion (room temperature) of high-density polyethylene is 1.2 x 10 in the unstretched state.
-' From K-1, it becomes zero at a stretching ratio of 2 times, and becomes -1,2XlO''''sK''''1 at a stretching ratio of 18 times.Thermal conductivity (
The coefficient of linear expansion (room temperature) of αOO55"I/cnt K in the unstretched state increases significantly to 0.13 W/mK at a stretching ratio of 25 times. In polyoxymethylene, the coefficient of linear expansion (room temperature) increases from αOO55"I/cnt K in the unstretched state to 0.13 W/mK in the unstretched state. From ``''1, it becomes zero at a stretching ratio of 8 times, and becomes -1 at a stretching ratio of 20 times to -4,0×10-·. Thermal conductivity (room temperature) of unstretched state (LOO37W/c
103W/cm K at a stretching ratio of 8x from y+sK
It gets bigger. However, the coefficient of linear expansion in the direction perpendicular to the stretching direction slightly increases with the stretching ratio, and the thermal conductivity in the direction perpendicular to the stretching direction decreases.

Hereinafter, the present invention will be specifically explained based on the drawings.

FIG. 1 is a cross-sectional perspective view of an insulated conductor according to the present invention, where 1 is a conductor, 2 is a vertically oriented polymer crystal mass, and 5 is a void. As shown in FIG. 1, in the vertically oriented polymer insulated conductor of the present invention, the molecular axes of the polymer in the polymer crystal mass forming the absolute R layer are oriented perpendicularly to the conductor surface, and the crystal mass straddles between opposing conductors, so the coefficient of linear expansion of the insulating layer in the direction perpendicular to the conductor plane is small and the thermal conductivity is large. Also, since there are voids at the boundaries of the crystal clusters in the plane parallel to the conductor plane, the insulating layer in the direction parallel to the conductor plane! II expansion coefficient is the linear expansion coefficient of each crystal block, which is thick b
Nevertheless, since the strain is absorbed by the voids, the coefficient of linear expansion becomes almost equal to the coefficient of linear expansion of the conductor. Note that the thermal conductivity in the direction parallel to the conductor surface of the insulating layer is small, but since the conductor is usually made of a material with high thermal conductivity such as metal, the thermal conductivity in the direction parallel to the conductor surface of the insulated conductor is small. is also excellent.

As a method for orienting the crystalline polymer that forms the insulating layer perpendicularly to the opposing conductor plane, an electric field is applied as shown in Japanese Patent Application No. 62-305820, filed earlier by the present inventor. There are methods. In such an orientation method using an electric field, the crystalline polymer that becomes the insulating layer has a dipole moment in the direction of its molecular axis, or if it does not have a dipole moment, the crystalline polymer before polymerization has a dipole moment. Having a child moment becomes essential.

An example of a crystalline polymer having a large dipole moment in the direction of the molecular axis is polyγ-benzyl-L-, which is one of the synthetic polypeptides in which the molecular chain has an α-helical structure within the crystal.
There is glutamate (n). This PBLG has an α-helical structure at room temperature in a polar solvent such as dimethylformamide (DMF) and has a large dipole moment in the direction of the molecular axis. For example, if a DMF solution of this PBLG is filled between opposing conductors and an electric field is applied between the conductors, the PBLG will be oriented perpendicularly to the conductor surface.

If DMIF is gradually evaporated in this state, a so-called solvent cast film can be obtained, and an insulated conductor having an insulating layer of PBLG oriented perpendicularly to the conductor surface can be obtained.

Polyoxymethylene (POM), known as a general-purpose engineering plastic, has a molecular chain of 91 in the crystal.
As with the five-helical structure, the dipoles cancel each other out and are not oriented by an electric field. However, the changes in POM
Formaldehyde, one of the
Because it has a dipole moment of , it is oriented by an electric field.

The inventors discovered that if liquid formaldehyde is polymerized under an electric field, the molecular axes are oriented perpendicular to the conductor plane, and an aggregate of nine POM crystals can be obtained. This is a formaldehyde 7-layer structure oriented perpendicularly to the conductor plane.
This is because non-polar POM is also oriented in the direction of polarization due to the influence of . As shown in Figure 1, scanning electron microscopy reveals that each POM crystal cluster straddles opposing conductors, and that there are voids at the boundaries of the crystal clusters in a plane parallel to the conductor plane. That's what I found out. These voids are caused by unreacted upper particles and low molecular weight POM gathering at the boundaries of crystal clusters, which evaporate after polymerization.

In this method, in which a monomer is filled in advance between opposing conductors and then polymerized to create a polymer insulation layer, a spacer is required to maintain the distance between the conductors at a predetermined value during the manufacturing process. Various materials can be used, such as glass fibers, granular inorganic materials, plastic films such as polyimide, and stretched oriented fibers and films. In addition, in this method, if the conductor surface is made rough, the oxides can penetrate into fine pores, so that even POM, which has poor adhesiveness, can be firmly bonded due to the so-called anchor effect. In addition, the strength in the direction perpendicular to the conductor surface, that is, in the direction of the molecular axis, is extremely strong, so opposing conductors do not easily peel off or crush, and have excellent shape stability. Further, as in the case of the stretched and oriented sample, since it is oriented in one direction, brittle failure does not occur even at extremely low temperatures.

In addition to the radiation method shown in Japanese Patent Application No. 62-305820, other polymerization methods include a method in which a polymerization catalyst is added to a polymer in advance and then polymerized under an electric field, and a method in which a polymerization catalyst is added to a conductor surface in advance. There are various methods, such as a method in which a monomer is filled and polymerized under an electric field after coating, and any of these methods may be used.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 Commercially available electrolytic copper foil with a thickness of 35 μm for use in printed circuit boards with one side roughened was placed so that the rough sides faced each other, and a polyimide film (Kapton) with a thickness of 125 μm was placed as a spacer between the copper foils. .

Gaseous formaldehyde, produced by thermal decomposition of commercially available powdered paraformaldehyde, is passed through a trap cooled to approximately -20°C with salt and ice through the gap between the opposing electrolytic steel foils. After dehydration and purification, it was filled in a liquid state at -78°C. While applying an electrostatic voltage of 5 KV (electric field strength α4 MY/cm ) between opposing copper foils,
The r-ray polymerization using Co'' was carried out in a liquid phase at -78°C.The irradiation dose rate was 5x105R/h and the irradiation time was 3 hours.

After polymerization, the linear expansion coefficient and thermal conductivity of the insulated conductor with a portion of the spacer removed were measured.

The coefficient of linear expansion in the direction perpendicular to the conductor surface is zero, and the coefficient of linear expansion in the direction parallel to the conductor surface is #! Same as expansion rate 1.4
The thermal conductivity in the direction perpendicular to the conductor surface was CLO5W/anK. In addition, the opposing copper foils are strongly bonded, and the liquid nitrogen temperature (-196℃)
Even after repeated cycles between temperature and room temperature, the copper foil did not peel off, and no distortion such as deformation was observed.

Comparative Example 1 An insulated conductor was produced in exactly the same manner as in Example 1 except that the electrostatic voltage was set to zero (field strength My/-). The coefficient of linear expansion of this insulated conductor in the direction perpendicular to the conductor surface is lX10-4.
The thermal conductivity was as low as 5W/6IIK, both of which were close to the values in the unstretched state. Note that the adhesive strength between opposing copper foils was weak, and they were easily peeled off when cooled with liquid nitrogen.

〔Effect of the invention〕

As explained above, in the vertically oriented polymer insulated conductor of the present invention, the coefficient of linear expansion of the insulating layer is small in the direction perpendicular to the conductor surface, and approximately equal to the coefficient of linear expansion of the conductor in the direction parallel to the conductor surface.
However, it has the advantage that it is an insulated conductor with a high thermal conductivity of the absolute R layer in the direction perpendicular to the conductor surface. Such an insulated conductor is effective if used as an insulated conductor for wiring in a RE chip mounting board, an insulated conductor for an input/output cable/pull, or an insulated conductor related to superconducting applications.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view of an insulated conductor according to the present invention. 1: conductor, 2: vertically oriented polymer crystal mass, 3: void

Claims (1)

[Claims] 1. An insulating layer is provided between the opposing conductors, and the insulating layer is composed of an aggregate of polymer crystal blocks whose molecular axes are oriented perpendicular to the conductor plane, and each of the crystal blocks straddles between the opposing conductors. In addition, there are voids at the boundaries of the crystal clusters in a plane parallel to the conductor plane, and spacers are installed here and there between the conductors to maintain the required distance between the conductors at a predetermined value during the manufacturing process. A vertically oriented polymer insulated conductor characterized by having or not having any.