JP5780831B2 - Thermoplastic polyurea, and laminate and wiring board using the same - Google Patents

Description

  The present invention relates to a thermoplastic polyurea excellent in heat resistance, electrical characteristics, insulation and metal adhesion, and a laminate and a wiring board using the same.

  In recent years, with the rapid increase in communication information, there has been a strong demand for miniaturization, weight reduction, and speeding up of communication devices, and there is a demand for an electrically insulating material that can cope with this. In addition, radio waves used in portable mobile communications such as car phones and digital cellular phones and satellite communications are in the high frequency band from megahertz to gigahertz. In the rapid development of these communication devices, miniaturization and high-density mounting of substrates and electronic elements have been attempted.

  In the electronic element circuit, energy loss in the transmission process called dielectric loss occurs, and heat is released. This dielectric loss is caused by a change in the electric field of the dipole caused by dielectric polarization in the low frequency region, and is caused by ion polarization or electronic polarization in the high frequency region. The dielectric loss is proportional to the product of the dielectric constant and the dielectric loss tangent of the material, and both the dielectric constant and the dielectric loss tangent increase as the frequency increases. Therefore, in order to reduce the dielectric loss of the insulating material in the electronic element circuit as much as possible, it is necessary to use a material having a small relative dielectric constant and dielectric loss tangent. By using an electrically insulating material with a low dielectric constant and dielectric loss, heat generation in the electronic device circuit is suppressed, and as a result, signal malfunctions are reduced. It is strongly desired.

  As materials having such electrical insulation and low dielectric loss, polyolefins, wholly aromatic liquid crystal polyesters, polyphenylene ethers, fluororesins, polyimide resins, epoxy resins, cyanate resins, and the like have been proposed.

  However, polyolefins such as polyethylene and polypropylene are excellent in insulation and electrical properties (relative dielectric constant, dielectric loss tangent), but have a low allowable heat resistance of less than 130 ° C and are deformed when soldering. There's a problem. Moreover, since it is inferior to metal adhesion, in order to laminate | stack with a metal layer, it is necessary to provide a contact bonding layer separately.

  In addition, wholly aromatic liquid crystalline polyesters are excellent in insulation, electrical properties (dielectric constant, dielectric loss tangent), heat resistance, and chemical stability, but because of their remarkable orientation, they are easily torn by ordinary film forming methods. There is a problem that only a film can be obtained, a very special film forming method is required, and the cost is high.

  Epoxy resins satisfy the required performance in terms of insulation and heat resistance, but have a problem that the relative dielectric constant is relatively high at 3 or more.

  Patent Document 1 discloses a technique for forming a polyurea film having a low dielectric constant by vapor deposition polymerization of aromatic diamine and diisocyanate, which is based on polymerization of a monomer having a substituent having a large steric hindrance in the side chain. However, since it cannot be melt-molded, it is limited to film formation by a special technique such as vapor deposition polymerization. Moreover, there is a problem that the relative dielectric constant of the obtained polyurea is as high as 4 or more.

Japanese Patent Laid-Open No. 9-326388

  The present invention solves these problems, and is to provide a thermoplastic polyurea excellent in heat resistance, electrical properties, insulation and metal adhesion.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the gist of the present invention is as follows.
(1) A thermoplastic polyurea for an electrical insulating material represented by the general formula (1) and having a melting point of 200 to 320 ° C. (However, the thermoplastic copolyurea copolymerizing the diamine represented by the general formula (2) is excluded.)
(In the formula, R is an aliphatic or alicyclic divalent group and has 5 to 15 carbon atoms.)
(In the formula, R ₁ and R ₂ are hydrogen or an alkyl group.)
(2) A laminate comprising a metal layer and a resin layer, wherein the polyurea according to (1) is used as the resin layer.
(3) A wiring board using the laminate according to (2).

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in heat resistance, an electrical property, insulation, and metal adhesiveness, and can provide thermoplastic polyurea suitable as an electrical insulation material. In addition, a laminate comprising a resin layer and a metal layer using the polyurea of the present invention generates little heat from the resin layer, and can be suitably used for applications such as wiring boards in the high-frequency communication field.

The present invention is described in detail below.
The polyurea of the present invention is a resin represented by the general formula (1).

  R in the general formula (1) is an aliphatic or alicyclic divalent group and needs to have 5 to 15 carbon atoms. When the number of carbon atoms is 4 or less, the ratio of urea bonds per unit mass in polyurea is increased, and the relative dielectric constant is increased, which is not preferable. On the other hand, when the number of carbon atoms is 16 or more, the heat resistance is lowered, which is not preferable. Examples of the diamine that gives an aliphatic divalent group having 5 to 15 carbon atoms include 1,5-diaminopentane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, and 1,7-diamino. Examples include heptane, 1,8-diaminooctane, 1,8-diamino-2-methyloctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane and the like. . Examples of the diamine that gives an alicyclic divalent group include cyclohexanediamine, cyclopentanediamine, bisaminomethylcyclohexane, bisaminomethylcyclopentane, and bisaminomethylnorbornane. Among these, diamines having 5 to 12 carbon atoms are preferable, and from the viewpoint of raw material procurement, 1,5-diamino-2-methylpentane, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine and 1,12-dodecanediamine are more preferred. R in the general formula (1) may be one type or two or more types. By selecting the type of R, the melting point, relative dielectric constant, and dielectric loss tangent of polyurea can be controlled. The relative permittivity and dielectric loss tangent tend to increase as the ratio of urea bonds per unit mass in polyurea increases, and tend to decrease as the ratio of urea bonds decreases.

  R in the general formula (1) may contain a divalent group other than an aliphatic or alicyclic divalent group as long as the characteristics of the present invention are not impaired. Examples of diamines that give divalent groups other than aliphatic and alicyclic divalent groups include aromatic diamines such as phenylenediamine, diaminodiphenyl ether, xylylenediamine, biphenylenediamine, dichlorobenzidine, dimethylbenzidine, diaminodiphenylmethane, and naphthalenediamine. And a both-end diamine type polyalkylene oxide, a both-end diamine type polydimethylsiloxane, and the like.

  The polyurea of the present invention is a linear resin. Therefore, it is thermoplastic and can be easily molded. In contrast, conventional polyureas are obtained by polymerization of diamine and diisocyanate, are thermosetting, and are difficult to mold. Conventional polyurea is known as a two-component mixed reactive adhesive and has been used in applications such as building materials. Such polyureas are known to have excellent heat resistance, mechanical strength, and chemical resistance. However, in the method using diamine and diisocyanate as raw materials, polymerization reactivity is too high, and it is difficult to pelletize polyurea by melt polymerization, resin molding, film formation, fiberization, etc. at a temperature above the melting point. Also in the polymerization method using a solvent at a low temperature, it is necessary to use a strong acid or a fluorine compound as a solvent in order to dissolve a highly crystalline polyurea suitable for processing applications, and industrial utilization is difficult. It is possible to pelletize by polymerizing diamine and diisocyanate in a low-temperature solid state, and then crushing, melting, etc., but even in this case, the formation of a branched structure due to the reaction of urea bond and isocyanate causes gel generation. As a result, not only did polyurea become low quality, but operability during melt processing was low.

  The melting point of the polyurea of the present invention is required to be 200 to 320 ° C, and preferably 250 to 320 ° C. When the melting point of polyurea is less than 200 ° C., it is not preferable because it cannot withstand the soldering operation. On the other hand, when the melting point of polyurea exceeds 320 ° C., the melting point and the decomposition temperature of the urea bond are close to each other.

  The weight average molecular weight of the polyurea of the present invention is preferably 5000 or more, more preferably 10,000 or more, and further preferably 15000 or more. By setting the weight average molecular weight to 5000 or more, the strength of the polyurea resin layer can be secured, and the metal adhesion is further improved.

  The polyurea of the present invention can have a relative dielectric constant of 3.0 or less and a dielectric loss tangent of 0.020 or less in a frequency band of 1 MHz or higher, particularly in a frequency band of 60 MHz to 10 GHz. Since the polyurea of the present invention has a low relative dielectric constant and dielectric loss tangent, it can be suitably used in the high-frequency communication field as described above.

  The polyurea of the present invention is excellent in insulation, and its dielectric breakdown voltage is 20 kV / mm or more. If the dielectric breakdown strength is 20 kV / mm or more, it can be sufficiently used as an insulating layer of a wiring board.

  The method for producing the polyurea of the present invention is not particularly limited. For example, after introducing a diamine compound into a reaction vessel, carbon dioxide is introduced and heat polymerization is performed, or the reaction vessel is filled with carbon dioxide, A method in which a diamine compound is added to the polymer and heated to polymerize is mentioned. Of these, the former method is preferred. In these methods, urea, ethylene carbonate, phosgene, carbon monoxide or the like may be used instead of carbon dioxide. Moreover, what is necessary is just to select the diamine compound to be used suitably according to the polyurea to produce.

  In the method of introducing carbon dioxide after introducing the diamine compound into the reaction vessel and performing heat polymerization, the polymerization pressure is preferably 1 to 10 MPa, more preferably 5 to 10 MPa, and the polymerization temperature is 160. It is preferable to set it as -260 degreeC, and it is more preferable to set it as 180-220 degreeC. The polymerization time is preferably 1 hour or longer after reaching the polymerization temperature, more preferably 5 hours or longer, and even more preferably 10 hours or longer. In addition, it is preferable to make it 1-10 Mpa using a carbon dioxide, after dropping the pressure in reaction container and distilling water out of the system in the middle of superposition | polymerization. By distilling off water during the polymerization, hydrolysis by water can be efficiently suppressed and the progress of the polymerization can be promoted.

  Moreover, you may add terminal blocker and an additive as an auxiliary material. Examples of the end-capping agent include monoamines such as hexylamine, octylamine, cyclohexylamine and aniline, and monocarboxylic acids such as acetic acid, lauric acid and benzoic acid. These may be used alone or in combination of two or more. The addition amount of the terminal blocking agent is not particularly limited, but is preferably 5 mol% or less with respect to the diamine compound. Examples of the additive include an antioxidant, an antistatic agent, a flame retardant, a flame retardant aid, and a heat stabilizer.

  The polyurea of the present invention can be processed into various molded articles by known molding methods such as injection molding and extrusion molding. Moreover, it can process into various films by well-known film forming methods, such as a T-die method, an inflation method, and a hot press method.

  The polyurea of the present invention can be used as a laminate comprising a metal layer and a resin layer. As described above, the polyurea of the present invention is suitable for an insulating layer because of its high dielectric breakdown voltage. The method for producing the laminate is not particularly limited. For example, a method of laminating a polyurea film on a metal foil, a method of forming a metal film on a polyurea film by vacuum deposition, and an organic solvent on the metal foil. A method of forming a polyurea film by applying and drying dissolved polyurea can be mentioned. The thickness of the metal layer is preferably 5 to 35 μm, and the thickness of the resin layer is preferably 10 to 1000 μm. Examples of the metal foil include copper foil and aluminum foil. In order to give mechanical strength to the resin layer, a reinforcing filler may be added. Examples of the reinforcing filler include silica powder, alumina powder, and precipitated barium sulfate powder. The reinforcing filler may be used alone or in combination of two or more. The reinforcing filler content in the resin layer is preferably 10 to 70% by mass in the resin layer.

  The laminate of the present invention can be used for a wiring board. At this time, for example, a circuit can be formed on the resin layer by etching the metal layer. In addition, when forming a circuit on a resin layer, you may form a circuit by pattern printing using a metal nanoparticle ink on a resin layer. In addition, a multilayer substrate can be manufactured by heat-sealing two or more wiring substrates so that resin layers and metal layers are alternately overlapped. Since the polyurea of the present invention has good metal adhesion, a multilayer substrate can be easily produced.

  Since the polyurea of the present invention is excellent in heat resistance and insulation, and has a low relative dielectric constant and dielectric loss tangent, it can be used as a support for resonators, housings for various substrates or electronic components (for example, antenna rod housings), casings, etc. Can be used. Moreover, it can also be used as a coverlay by making it into a film shape and fusing with substrate resin. Furthermore, what laminated | stacked the film and metal foil and was heat-laminated can be used also as a coverlay which had the shielding effect by metal foil.

  Moreover, since the wiring board using the polyurea of the present invention can be used as a rigid printed wiring board and a flexible printed wiring board, it is expected to be used as an alternative to the conventional glass epoxy wiring board. Specifically, as high frequency electronic devices (for example, on-board substrates for component mounting, circuit-embedded substrates, etc.) and various substrates for electronic components (for example, resonators, filters, capacitors, inductors, antennas, etc.), as chip components Filter (for example, a C filter which is a multilayer substrate) or a resonator (for example, a triplate resonator). Moreover, if a heat dissipation process is performed on a wiring board, it can be used for an on-board board for a CPU for a high frequency band of 100 MHz or higher.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The physical properties were measured by the following method.

(1) Number average molecular weight, weight average molecular weight The number average molecular weight and weight average molecular weight in terms of polymethyl methacrylate (manufactured by Polymer Laboratories) were measured using gel permeation chromatography (GPC).
<Measurement conditions>
Refractometer: RI-8010 manufactured by Tosoh Corporation
Column: 1 TSKgel GMH _HR- H manufactured by Tosoh Corporation Solvent: 10 mM sodium trifluoroacetate-containing hexafluoroisopropanol Flow rate: 0.4 ml / min Measurement temperature: 40 ° C

(2) Melting point The melting point was measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer. The sample amount is 10 mg, the temperature is raised from 10 ° C. to 350 ° C. at 20 ° C./minute, held for 5 minutes, then cooled to 500 ° C./minute to 25 ° C. The temperature rose. The melting temperature peak at the second temperature increase was taken as the melting point.

(3) Dielectric constant, dielectric loss tangent Examples 1 to 5 and Comparative Examples 1, 2, and 4 were molded using an injection molding machine (EC-100 type manufactured by Toshiba Machine Co., Ltd.), and the length was 100 mm × width. A molded piece of 100 mm × thickness 1 mm was produced. The cylinder temperature was (melting point + 20 ° C.), and the mold temperature was 80 ° C.
For Comparative Example 3, an equimolar mixture of 1,4-phenylene diisocyanate and 1,4-diaminobenzene was heated at 100 ° C. in a vacuum deposition apparatus at an internal pressure of 3 × 10 ⁻³ Pa and deposited on a silicon wafer. Further, after removing the silicon wafer from the vacuum deposition apparatus, heat treatment was performed at 400 ° C. to produce a film having a thickness of 50 μm. Thereafter, the film was peeled off from the silicon wafer.
Using the obtained molded piece or film, PNA-L network analyzer N5230A manufactured by Agilent Technologies, Inc., and cavity resonance perturbation method (CP431 manufactured by Kanto Electronics Application Development Co., Ltd.) at 23 ° C. and 50% RH atmosphere at 1 GHz. Measured. The relative dielectric constant was based on JIS L1094 B method, and the dielectric loss tangent was based on ASTM D150.

(4) Dielectric breakdown voltage It measured based on JIS C2110 using the molded piece produced by (3).

(5) Metal adhesion For Examples 1 to 5 and Comparative Examples 1, 2, and 4, the resin was melted at (melting point + 20 ° C.), extruded from a T-die onto a cooling roll set to 50 ° C., and the thickness was A 50 μm film was prepared.
For Comparative Example 3, the film was pressed at 185 ° C. and 3 MPa for 5 minutes to produce a film having a thickness of 50 μm.
Thereafter, the obtained film and a copper foil having a thickness of 50 μm were hot-pressed at (melting point + 10 ° C.) at 3 MPa for 5 minutes to prepare a laminate.
An adhesive tape (F-12 manufactured by Nichiban Co., Ltd.) was attached to the resin surface of the laminate, and the degree of peeling of the resin layer when the tape was peeled was visually evaluated according to the following criteria.
○: No peeling at all or the peeled area was less than 5% of the whole.
X: The peeled area was 5% or more of the whole.

Example 1
550 g (3.2 mol) of 1,10-decanediamine and 58 g (3.2 mol) of water were placed in a reaction vessel having an internal volume of 4 L, the air in the vessel was replaced with carbon dioxide three times, and the inside was sealed. Heating was performed so that the temperature became 240 ° C., and carbon dioxide was allowed to flow into the reaction vessel so that the pressure became 3 MPa. Thereafter, the pressure in the reaction vessel was maintained at 3 MPa to carry out stirring polymerization. However, five times after 10 to 10 hours from the start, the pressure in the reaction vessel was lowered to 0.1 MPa, water was distilled out of the system, and the pressure of carbon dioxide was increased to 3 MPa. After polymerization for 15 hours, the pressure in the reaction vessel was lowered to 0.1 MPa, stirring was stopped, and the mixture was allowed to stand for 30 minutes. Thereafter, the bottom drain valve was opened, and the content was discharged in a strand form with a gear pump. After cooling with water, the content was cut with a strand cutter to obtain a pellet-like polyurea.

Examples 2-5, Comparative Examples 1-3
Except changing the used raw material as shown in Table 1, the same operation as in Example 1 was performed to obtain polyurea.

  Table 1 shows the raw materials and resins used and their characteristic values.

  The resins of Examples 1 to 5 have a low relative dielectric constant and dielectric loss tangent, are easy to perform molding processes such as injection molding and film formation, and are excellent in heat resistance and insulating properties, and therefore suitable for use as an electronic insulating material. Can be used. Moreover, since the polyurea of this invention is excellent also in metal adhesiveness, it can be used suitably also as an insulating layer of a wiring board.

Since the resin of Comparative Example 1 had a carbon number of R in the general formula (1) smaller than the range of the present invention, the relative dielectric constant and dielectric loss tangent were high, and it was not suitable for an electronic insulating material.
Since the resin of Comparative Example 2 had a larger number of R carbon atoms in the general formula (1) than the range of the present invention, the resin had low heat resistance and was unsuitable for use as an electronic insulating material.
The resin of Comparative Example 3 was unsuitable for use as an electronic insulating material because R in the general formula (1) was composed only of aromatic hydrocarbons, so that the relative dielectric constant and dielectric loss tangent were high.
In Comparative Example 4, polypropylene was used, but the heat resistance was low and it was unsuitable for use as an electronic insulating material.

Claims (3)

A thermoplastic polyurea for an electrical insulating material represented by the general formula (1) and having a melting point of 200 to 320 ° C. (However, the thermoplastic copolyurea copolymerizing the diamine represented by the general formula (2) is excluded.)
(In the formula, R is an aliphatic or alicyclic divalent group and has 5 to 15 carbon atoms.)
(In the formula, R ₁ and R ₂ are hydrogen or an alkyl group.) A laminate comprising a metal layer and a resin layer, wherein the polyurea according to claim 1 is used as the resin layer. A wiring board using the laminate according to claim 2.