JP2003101241A - Insulating film and multilayer wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem wherein an insulating film composed of an- organic material and a multilayer wiring board using the insulating film cannot satisfy the high density, the insulating property, the continuity reliability, and the high-frequency transmission characteristic of an interconnection. SOLUTION: In the insulating film, epoxy resins and coating layers 2 which are composed of an organic substance having a coefficient of elasticity lower than that of the epoxy resins are formed on the surface and the rear surface of a liquid crystal polymer layer 1, the layer 1 has a coefficient of thermal expansion in the direction of the layer of -20 to 20×10<-6> / deg.C and a tensile modulus of elasticity of 2 GPa or more, and the coating layers 2 have a tensile modulus of elasticity in the direction of the layers of 6.2 to 1.5 GPa. It is possible to obtain the insulating film whose insulating property, continuity reliability and high-frequency transmission characteristic are superior.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating film used in various kinds of electronic equipment such as AV equipment, home electric appliances, communication equipment, computers and peripheral equipment thereof, and a multilayer wiring board using the same, and particularly to a liquid crystal polymer. The present invention relates to an insulating film used in part and a multilayer wiring board using the same.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board used for a hybrid integrated circuit in which a large number of active components such as semiconductor elements and passive components such as capacitance elements and resistance elements are mounted to form a predetermined electronic circuit is usually Formed by stacking a number of wiring boards, each having a plurality of wiring conductors formed inside the through hole and on the surface of the insulating layer by forming through holes in the insulating film made of glass cloth impregnated with epoxy resin by a drill. ing.

In general, current electronic devices are required to be small, thin, lightweight, high-performance, high-performance, high-quality and highly reliable, as represented by mobile communication devices. Electronic components such as hybrid integrated circuits mounted on
There is a growing demand for higher density. And
In order to meet such demands for higher density, it has become necessary to miniaturize wiring conductors, thin insulating layers, and miniaturize through-holes also in multilayer wiring boards constituting electronic components. For this reason, in recent years, in order to miniaturize the through holes, laser machining, which enables finer machining than drilling, has come to be used.

However, the insulating film formed by impregnating glass cloth with an epoxy resin has a limit in miniaturizing the through holes because it is difficult to drill the glass cloth with a laser, and the glass cloth of There is a problem that it is difficult to form a through hole having a uniform hole diameter due to the uneven thickness.

In order to solve such a problem, an insulating film obtained by impregnating a non-woven fabric made of aramid resin fiber with an epoxy resin or an insulating film obtained by coating a polyimide film with an epoxy adhesive is used as an insulating layer. Multilayer wiring boards have been proposed.

However, an insulating film using an aramid non-woven fabric or a polyimide film has a high hygroscopic property, and when solder reflow is performed in a moisture-absorbed state, moisture absorbed by the solder reflow is vaporized to generate a gas, and However, there is a problem such as peeling off.

In order to solve such a problem, it has been studied to use a liquid crystal polymer as a material for an insulating layer of a multilayer wiring board. The liquid crystal polymer layer is composed of rigid molecules and has a structure in which the molecules are regularly arranged and the intermolecular force is strong, so high heat resistance, high elastic modulus, high dimensional stability, It has low hygroscopicity, does not require the use of a reinforcing material such as glass cloth, and has excellent fine workability. Further, even in a high frequency region, it has a characteristic that it has a low dielectric constant and a low dielectric loss tangent and is excellent in high frequency characteristics.

Utilizing the characteristics of such a liquid crystal polymer,
JP-A-8-97565 discloses that a circuit layer contains a first liquid crystal polymer, and an adhesive layer containing a second liquid crystal polymer having a melting point lower than that of the first liquid crystal polymer is inserted between the circuit layers. A multilayer printed circuit board made of is proposed, and in Japanese Unexamined Patent Publication No. 8-293579, one side of a board formed by laminating a liquid crystal polymer film having a circuit pattern formed on the surface with a prepreg interposed therebetween. There has been proposed a multi-chip module in which a plurality of bare chips are mounted.

[0009]

SUMMARY OF THE INVENTION
The multilayer printed circuit board proposed in 8-97565 is
When an adhesive layer containing a liquid crystal polymer is inserted between the circuit layers and they are bonded by thermocompression bonding, the molecules of the liquid crystal polymer are rigid and the molecules are regularly aligned to a certain degree so that the molecules are closely arranged. It is difficult to move, and the liquid crystal polymer of the circuit layer and the liquid crystal polymer of the adhesive layer can only entangle only a small part of the molecules on the surface, resulting in poor adhesion and peeling between layers during high temperature bias test, resulting in insulation failure. It had a problem that it would end up. Also, when the conductor foil of the circuit layer and the liquid crystal polymer are bonded by heat fusion, the liquid crystal polymer molecules are difficult to move and therefore cannot enter the minute recesses on the conductor foil surface, resulting in sufficient anchoring effect. However, the adhesiveness between the conductor foil and the liquid crystal polymer deteriorates, and there is a problem that the conductor foil peels off between the two under high temperature and high humidity and the conductor foil is broken.

Further, the multi-chip module proposed in Japanese Unexamined Patent Publication No. 8-293579 discloses a multi-chip module in which a prepreg is sandwiched between liquid crystal polymer films having low hygroscopicity and low moisture permeability. However, since the liquid crystal polymer film and prepreg in contact with the circuit pattern have different dielectric constants,
It is very difficult to perform impedance matching when transmitting high frequency signals of Hz or higher, and
The propagation delay time of the high frequency signal is different between the upper and lower surfaces of the circuit pattern, so that the signal is distorted and the transmission loss becomes large.

The present invention has been devised in view of the problems of the prior art, and an object thereof is an insulating film having high-density wiring and excellent in insulation reliability, conduction reliability, and high frequency transmission characteristics. And to provide a multilayer wiring board using the same.

[0012]

The insulating film of the present invention is formed by forming a coating layer made of an epoxy resin and an organic material having a lower elastic modulus than that on the upper and lower surfaces of the liquid crystal polymer layer, and the liquid crystal polymer layer is a layer. Coefficient of thermal expansion in the direction is -2
0 to 20 × 10 ^-6 / ° C and a tensile elastic modulus of 2G
Pa or more, the coating layer has a tensile elastic modulus in the layer direction of 0.
It is characterized by being 2 to 1.5 GPa.

Further, the insulating film of the present invention is characterized in that, in the above constitution, the coating layer contains 5 to 60% by volume of an organic material having a low elastic modulus.

Further, the insulating film of the present invention is characterized in that, in the above-mentioned constitution, the low elastic modulus organic material contains 20 to 80% by volume of the styrene organic material.

Further, in the insulating film of the present invention, in the above constitution, the total thickness of the coating layers is the thickness of the insulating film.
It is characterized by being 10 to 70%.

Further, the multilayer wiring board of the present invention is formed by laminating a plurality of the above-mentioned insulating films in which wiring conductors made of metal foil are provided on at least one of the upper and lower surfaces, and sandwiching the insulating films. It is characterized in that the wiring conductors located above and below are electrically connected to each other through a penetrating conductor formed in an insulating film.

According to the insulating film of the present invention, the coefficient of thermal expansion in the layer direction of the liquid crystal polymer layer is −20 to 20 × 10 ⁻⁶ /
℃, the tensile modulus of elasticity is 2GPa or more, and the tensile modulus of the coating layer in the layer direction is 0.2 to 1.5GPa. Therefore, when the insulating film thermally expands and contracts due to temperature change, the tensile modulus of the layer direction. The coating layer having a low elastic modulus of 0.2 to 1.5 GPa is constrained by the liquid crystal polymer layer having a small thermal expansion coefficient and a high elastic modulus, resulting in a small thermal expansion / contraction, resulting in a rapid temperature change. It is possible to obtain an insulating film in which a coating layer does not crack even in a temperature cycle test.

Further, according to the insulating film of the present invention, in the above structure, the coating layer contains 5 to 60% by volume of an organic material having a lower elastic modulus than that of the epoxy resin. It can be in the range of up to 1.5 GPa.

Further, according to the insulating film of the present invention,
In the above structure, since the low elastic modulus organic matter contains 20 to 80% by volume of the styrene organic matter, the styrene organic matter has a low dielectric constant and low dielectric loss tangent, and reduces the dielectric constant and the dielectric loss tangent of the coating layer. Can result in 100
It is possible to obtain an insulating film having excellent transmission characteristics even at high frequencies of MHz or higher.

Further, according to the insulating film of the present invention, in the above-mentioned constitution, the total thickness of the coating layers is calculated as the total thickness of the insulating layers.
Since the content is 10 to 70%, it is possible to obtain an insulating film having good adhesion to the wiring conductor, high heat resistance, low moisture absorption, and high dimensional stability.

Further, according to the multilayer wiring board of the present invention,
Since the multilayer wiring board is formed by using the above-mentioned insulating film, it is possible to obtain a multilayer wiring board having excellent insulation reliability, conduction reliability, and high frequency transmission characteristics.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an insulating film of the present invention and a multilayer wiring board using the same will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view showing an example of an embodiment of the insulating film of the present invention, and FIG. 2 is a multilayer wiring board formed by using the insulating film of FIG. It is sectional drawing which shows an example of embodiment of the hybrid integrated circuit which mounts components. Further, FIG. 3 is an enlarged cross-sectional view of a main portion in the width direction of the wiring conductor of the multilayer wiring board shown in FIG. In these figures, 1 is a liquid crystal polymer layer, 2 is a coating layer, and these mainly constitute the insulating film 3 of the present invention. Further, 4 is a wiring conductor, 5 is a through conductor, and the multilayer wiring board 6 of the present invention is mainly composed of the insulating film 3, the wiring conductor 4, and the through conductor 5. In addition, the multilayer wiring board 6 of this example is shown as being formed by laminating four layers of the insulating films 3.

The insulating film 3 includes the liquid crystal polymer layer 1 and
When the multilayer wiring board 6 is manufactured by using the coating layer 2 adhered and formed on the upper and lower surfaces thereof, the support for the wiring conductor 4 and the electronic component 7 mounted on the multilayer wiring board 6 is formed. Has the function of.

The liquid crystal polymer herein means a polymer exhibiting liquid crystallinity in a molten state or a solution state or a polymer having an optical birefringence property, and generally, a lyotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state or a molten polymer. It includes a thermotropic liquid crystal polymer which sometimes exhibits liquid crystallinity, or all of 1 type, 2 type, and 3 type liquid crystal polymers classified by heat distortion temperature.

In the insulating film 3 of the present invention, the liquid crystal polymer layer 1 has a coefficient of thermal expansion in the layer direction of −20 to 20 from the viewpoint of temperature cycle reliability, solder heat resistance and workability.
20 × 10 ^-6 / ° C and a tensile elastic modulus of 2 GPa
As described above, it is preferable that the melting point is 200 to 400 ° C. The liquid crystal polymer layer 1 has a coefficient of thermal expansion of −20 × 10 ⁻⁶ / ° C.
When it is less than 20%, the difference in the coefficient of thermal expansion between the liquid crystal polymer layer 1 and the coating layer 2 tends to be large, and the coating layer 2 tends to crack, and when it exceeds 20 × 10 ⁻⁶ / ° C., the insulating film 3 and the difference in the coefficient of thermal expansion between the wiring conductor 4 become large,
The coating layer 2 tends to be cracked near the wiring conductor 4. If the tensile elastic modulus is less than 2 GPa, the bending strength of the insulating film 3 tends to be low, and the insulating film 3 tends to warp when the insulating film 3 is multilayered.
Therefore, it is preferable that the liquid crystal polymer layer 1 has a coefficient of thermal expansion in the layer direction of −20 to 20 × 10 ⁻⁶ / ° C. and a tensile elastic modulus of 2 GPa or more, particularly when the electronic component 7 is mounted. From the viewpoint of connection reliability, the coefficient of thermal expansion is −
It is preferably 10 to 10 × 10 ⁻⁶ / ° C. and the melting point is 250 to 350 ° C.

The liquid crystal polymer layer 1 contains a light stabilizer such as an antioxidant for improving thermal stability and an ultraviolet absorber for improving light resistance as long as the physical properties of the layer are not impaired. Halogen-based or phosphoric acid-based flame retardants to improve flame retardancy, antimony-based compounds and zinc borate.
Flame retardant aids such as barium metaborate and zirconium oxide,
Lubricants such as higher fatty acids and higher fatty acid esters, higher fatty acid metal salts and fluorocarbon surfactants for improving lubricity, aluminum oxide for adjusting the thermal expansion coefficient and / or for improving mechanical strength, Silicon oxide, titanium oxide, barium oxide, strontium oxide,
Zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate, aluminum borate, barium stannate,
A filler such as barium zirconate or strontium zirconate may be contained.

The shape of particles of the above-mentioned filler and the like may be substantially spherical, needle-like, flake-like, etc. From the viewpoint of filling property, substantially spherical shape is preferable. Furthermore, the particle size is usually 0.1 to 15 μm.
And is smaller than the thickness of the liquid crystal polymer layer 1.

Further, the liquid crystal polymer layer 1 is subjected to buffing, blasting, brushing, plasma treatment, corona treatment, ultraviolet treatment, chemical treatment, etc. on its surface in order to improve the adhesion with the coating layer 2. Using center line surface roughness Ra
Is preferably roughened to a value of 0.05 to 5 μm. The center line surface roughness Ra is preferably 0.05 μm or more from the viewpoint of preventing separation of the liquid crystal polymer layer 1 and the coating layer 2 during solder reflow, and when forming the coating layer 2 on the surface. From the viewpoint of preventing air entrapment, the thickness is preferably 5 μm or less.

Next, the coating layer 2 has a function of an adhesive when the wiring conductor 4 which will be described later is adhered and formed, and when the insulating film 3 is used to form the multilayer wiring board 6, the insulating film 3 is used. It plays the role of an adhesive when laminating each other. It is preferable that the coating layer 2 is made of an epoxy resin and an organic material having a lower elastic modulus than that of the epoxy resin and has a tensile elastic modulus in the layer direction of 0.2 to 1.5 GPa. This is also important.

According to the insulating film 3 of the present invention, since the coating layers 2 made of an epoxy resin and an organic material having a lower elastic modulus than that of the epoxy resin molecules are formed on the upper and lower surfaces of the liquid crystal polymer layer 1, the epoxy resin molecules are liquid crystal polymer. The molecule is not as rigid as the molecule, and it does not show a regular orientation, and the molecule is relatively easy to move. As a result, even when the insulating films 3 are multilayered, the adhesion between the insulating films 3 is good,
In the high temperature bias test, the insulating films 3 are not separated from each other to cause insulation failure. Even when the wiring conductor 4 is arranged on the surface of the insulating film 3, the epoxy resin molecules can enter into the fine recesses on the surface of the wiring conductor 4 and exert a sufficient anchoring effect, so that the insulating film 3 and the wiring conductor 4 can be exerted. Adhesion to the wiring conductor 4 is improved, and as a result, there is no possibility that the wiring conductor 4 is disconnected due to peeling between the two under high temperature and high humidity. Furthermore, even when a plurality of insulating films 3 having wiring conductors 4 on the surface thereof are laminated to manufacture a multilayer wiring board 6, the upper and lower surfaces of the wiring conductors 4 are in contact with the coating layer 2 made of the same material.
When transmitting a high frequency signal of Hz or more, impedance matching is easy to perform, and since the propagation delay time of the high frequency signal is the same on the upper and lower surfaces of the wiring conductor 4, the signal is distorted and the transmission loss is large. It doesn't happen. Further, the coefficient of thermal expansion in the layer direction of the liquid crystal polymer layer 1 was −20 to 20 × 10 ⁻⁶ / ° C., the tensile elastic modulus was 2 GPa or more, and the tensile elastic modulus of the coating layer 2 in the layer direction was 0.2 to 1.5 GPa. Therefore, when the insulating film 3 thermally expands / contracts due to temperature change, the coating layer 2 having a low elastic modulus of 0.2 to 1.5 GPa in the layer direction has a small thermal expansion coefficient and a liquid crystal of high elastic modulus. The coating layer 2 is constrained by the polymer layer 1 so that the thermal expansion and thermal contraction of the coating layer 2 can be made small, and as a result, the coating layer 2 is not cracked even in the temperature cycle test involving a rapid temperature change.

As such an epoxy resin, a bisphenol A type epoxy resin, a novolac type epoxy resin, a glycidyl ester type epoxy resin or the like or a derivative thereof or a mixture thereof is used, and further, an amine compound, an imidazole compound, an acid anhydride is used. A curing agent such as a physical compound or a curing accelerator may be added and mixed.

The tensile elastic modulus of the coating layer 2 is 0.2 GP.
If it is less than a, the rigidity tends to decrease when the insulating film 3 is multilayered, and warpage tends to occur. If it exceeds 1.5 GPa, the liquid crystal polymer layer 1 will be heated at high temperature.
Tend to be difficult to restrain the coating layer 2, and as a result, the liquid crystal polymer layer 1 is stretched to increase the thermal expansion of the insulating film 3, resulting in disconnection at the connection with the electronic component 7. Tends to end. Therefore,
The coating layer 2 has a tensile elastic modulus of 0.2 to 1.5 GPa, preferably 0.
It is preferably 7 to 1.2 GPa.

The coating layer 2 preferably contains 5 to 60% by volume of an organic material having a lower elastic modulus than that of the epoxy resin.

According to the insulating film 3 of the present invention, the coating layer 2 contains 5 to 60% by volume of an organic material having a lower elastic modulus than that of the epoxy resin.
It can be in the range of 2 to 1.5 GPa. If the content of the organic material having a lower elastic modulus than that of the epoxy resin is less than 5% by volume, the effect of lowering the tensile elastic modulus of the coating layer 2 tends not to appear, and if it exceeds 60% by volume, the coating is not performed. When the tensile elastic modulus of the layer 2 becomes too low and the insulating film 3 is multilayered to manufacture the multilayer wiring board 6, the multilayer wiring board 6 becomes soft and warps, and as a result, the wiring conductor 4 is broken. Tends to end. Therefore, it is preferable that the content of the organic material having a lower elastic modulus than that of the epoxy resin of the coating layer 2 is 5 to 60% by volume, and optimally 20 to 40% by volume.

As the organic substance having a lower elastic modulus than such an epoxy resin, a resin or a rubber-like elastic body having an elastic modulus of 1 GPa or less is used, and examples thereof include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, and polysulfide. Rubber, thiochol rubber, acrylic rubber, urethane rubber, silicone rubber, shrimp chlorohydrin rubber, styrene-butadiene block copolymer (SBR)
Hydrogenated styrene-butadiene block copolymer (SE
B ・ SEBC) ・ styrene-butadiene-styrene block copolymer (SBS) ・ hydrogenated styrene-butadiene-styrene block copolymer (SEBS) ・ styrene-isoprene block copolymer (SIR) ・ hydrogenated styrene-isoprene block Copolymer (SEP) / styrene-isoprene-styrene block copolymer (SI
S) -hydrogenated styrene-isoprene-styrene block copolymer (SEPS) -ethylene propylene rubber (E
PR) / Ethylene propylene diene rubber (EPDM) /
Butadiene-acrylonitrile-styrene-core shell rubber (ABS) -methyl methacrylate-butadiene-
Styrene-core shell rubber (MBS) -methyl methacrylate-butyl acrylate-styrene-core shell rubber (MAS) -octyl acrylate-butadiene-styrene-core shell rubber (MABS) -alkyl acrylate-butadiene-acrylonitrile-styrene core-shell rubber (AABS) -butadiene Core-shell type particulate elastic bodies such as styrene-core shell rubber (SBR) and siloxane-containing core shell rubbers such as methyl methacrylate-butyl acrylate siloxane, or rubbers obtained by modifying these are used.

The organic material having a low elastic modulus may be modified with a modifier having a polar group such as maleic anhydride or epoxy. Further, these organic compounds having a low elastic modulus may be used alone or in combination of two or more.

In the insulating film 3 of the present invention, it is preferable that the low elastic modulus organic material contains 20 to 80% by volume of the styrene organic material. Insulating film 3 of the present invention
According to this, since the low elastic modulus organic matter contains 20 to 80% by volume of the styrene organic matter, the styrene organic matter has a low dielectric constant and a low dielectric loss tangent, and the dielectric constant and the dielectric loss tangent of the coating layer 2 are small. Can result in 100MHz
The insulating film 3 having excellent transmission characteristics even at the above high frequencies can be obtained.

The low-modulus organic material containing such a styrene-based organic material is an organic material having styrene as a monomer unit in its molecular structure, and particularly SBR and S
EB / SEBC / SBS / SEBS / SIR / SEP /
SIS and SEPS, or low-modulus organic substances obtained by modifying these are used.

When the content of the styrenic organic material is less than 20% by volume, the dielectric constant and dielectric loss tangent of the organic material having a low elastic modulus become large and the transmission characteristics in the high frequency region of 100 MHz or more deteriorate. If it exceeds 80% by volume, the elastic modulus of the organic material having a low elastic modulus increases, so that it tends to be difficult to set the tensile elastic modulus of the coating layer 2 in a desired range. Therefore, the content of the styrenic organic material is preferably 20 to 80% by volume.

Further, from the viewpoint of suppressing the fluidity of the coating layer 2 when laminating the insulating film 3 and applying pressure, it is possible to prevent the displacement of the through conductor 5 and the variation in the thickness of the coating layer 2 which will be described later. The coating layer 2 preferably contains 10% by volume or more of inorganic insulating powder as a filler. Further, from the viewpoint of preventing peeling at the adhesive interface with the liquid crystal polymer layer 1 and the adhesive interface with the wiring conductor 4 during solder reflow, the filler content is preferably 70% by volume or less. Therefore, it is preferable that the coating layer 2 contains 10 to 70% by volume of the filler.

The thickness of the insulating film 3 is preferably 10 to 200 μm from the viewpoint of ensuring the insulation reliability, and the total thickness of the coating layers 2 is the wiring conductor 4.
From the viewpoint of improving the adhesiveness with, it is preferably 10% or more of the thickness of the insulating film 3. Further, from the viewpoint of ensuring high heat resistance, low hygroscopicity, and high dimensional stability, it is preferably 70% or less. Therefore,
The total thickness of the coating layer 2 is 10 to the thickness of the insulating film 3.
It is preferably 70%.

Such an insulating film 3 is manufactured by the following method.

First, the coefficient of thermal expansion in the layer direction is −20 to 20 × 10 ⁻⁶ / ° C. and the tensile elastic modulus is adjusted by adjusting the draw ratio in the take-up direction and the width direction of the film by a well-known inflation method. Of 2 GPa or more is formed as the liquid crystal polymer layer 1. Then, an epoxy resin or a cyanate resin and an organic substance, a solvent, a plasticizer, a dispersant, etc. having a lower elastic modulus are added to the upper and lower surfaces of an inorganic insulating powder such as silicon oxide having a particle size of 0.1 to 15 μm and the like. Of the liquid crystal polymer layer 1 after the coating layer 2 is formed by using a conventionally known sheet molding method such as a doctor blade method, or by immersing the liquid crystal polymer layer 1 in the paste and pulling it up vertically. After forming the coating layer 2 on the surface, it is manufactured by heating and drying the coating layer 2 at a temperature of 60 to 100 ° C. for 5 minutes to 3 hours.

Next, the multilayer wiring board 6 of the present invention is formed by laminating a plurality of insulating films 3 each having a wiring conductor 4 made of a metal foil disposed on at least one of the upper and lower surfaces thereof.
Wiring conductors 4 located above and below with the insulating film 3 interposed therebetween
It is formed by electrically connecting the gaps through the penetrating conductors 5 formed on the insulating film 3.

The wiring conductor 4 has a thickness of 2 to 30 μm and is made of a metal foil having good conductivity such as copper or gold. The electronic component 7 mounted on the multilayer wiring board 6 is connected to an external electric circuit (not shown). It has a function of electrically connecting.

Such a wiring conductor 4 is composed of the insulating film 3
From the viewpoint of preventing voids from being generated around the wiring conductor 4 when a plurality of wiring conductors are stacked, the wiring conductor 4 is buried so that at least the surface of the wiring conductor 4 and the surface of the coating layer 2 are flat. Is preferred. When the wiring conductor 4 is embedded in the coating layer 2, if the porosity of the coating layer 2 in the dry state is set to 3 to 40% by volume, resin swelling of the coating layer 2 around the wiring conductor 4 does not occur. The air can be flattened and the air trapped between the wiring conductor 4 and the coating layer 2 can be easily discharged to prevent air bubbles from being trapped. When the porosity in the dry state exceeds 40% by volume, pores remain in the coating layer 2 after pressurizing and heating and curing a plurality of laminated insulating films 3, and the pores adsorb moisture in the air. Therefore, it is preferable that the porosity of the coating layer 2 in the dry state is in the range of 3 to 40% by volume because the insulating property may be deteriorated.

The porosity of the coating layer 2 in the dry state is appropriately adjusted by adjusting the drying conditions such as the drying temperature and the heating rate when the coating layer 2 is applied on the surface of the liquid crystal polymer layer 1 and dried. By doing so, a desired value can be obtained.

Furthermore, the cross-sectional shape in the width direction of the wiring conductor 4 arranged on the insulating film 3 is a trapezoidal shape in which the length of the bottom side on the insulating film 3 side is shorter than the length of the opposite bottom side, and the insulating film is formed. The angle between the bottom side and the side on the 3 side is
It is preferably set to 95 to 150 °. The cross-sectional shape of the wiring conductor 4 disposed on the insulating film 3 in the width direction is a trapezoid whose base length on the insulating film 3 side is shorter than the length of the opposing base, and By setting the angle formed by the sides with 95 to 150 °, the wiring conductor 4
When the wiring conductor 4 is embedded in the coating layer 2, the wiring conductor 4 can be easily embedded in the coating layer 2 so that the surface of the coating layer 2 after the wiring conductor 4 is embedded can be made substantially flat. It is possible to obtain the multilayer wiring board 6 that does not bite into and deteriorate the insulation. From the viewpoint of embedding air bubbles without biting, it is preferable that the angle formed by the bottom side and the side side of the insulating film 3 side be 95 ° or more.
From the viewpoint of miniaturization, it is preferable that the angle be 150 ° or less.

In addition, the thickness x (μm) of the coating layer 2 located between the short base of the wiring conductor 4 and the liquid crystal polymer layer 1 between the insulating film 3 is between the upper and lower liquid crystal polymer layers 1. Is T (μm), and the thickness of the wiring conductor 4 is t
(Μm), 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T
≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦
32 μm) is preferable.

The distance between the liquid crystal polymer layers 1 is T (μm),
When the thickness of the wiring conductor 4 is t (μm), the thickness x (μm) of the covering layer 2 between the short base of the wiring conductor 4 and the liquid crystal polymer layer 1 is 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35μ
By setting m, the difference between the distance between the liquid crystal polymer layer 1 and the short base of the wiring conductor 4 and the distance between the liquid crystal polymer layer 1 adjacent to the long bottom of the wiring conductor 4 is t (μ
It is possible to reduce the thickness to less than m) and prevent the warpage of the multilayer wiring board 6 caused by the large difference in the thickness of the coating layer 2. Therefore, the thickness x (μm) of the coating layer 2 located between the trapezoidal upper bottom surface of the wiring conductor 4 and the liquid crystal polymer layer 1 can be calculated by setting the distance between the liquid crystal polymer layers 1 to T
(Μm), where t (μm) is the thickness of the wiring conductor 4, it is preferable that the range is 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm.

Such a wiring conductor 4 is made up of the insulating film 3
It is formed by depositing a metal foil made of, for example, copper, which is patterned by a subtractive method using a known photoresist, on the precursor sheet to be formed by a transfer method or the like. First, a metal foil transfer film is prepared by adhering a metal foil made of copper on a film serving as a support through an adhesive, and then a metal foil on the film is subjected to a subtractive method using a known photoresist. Is used to etch in a pattern. At this time, the side surface on the surface side of the pattern is more likely to be etched because the side surface on the surface side is in contact with the etching solution for a longer time than the side surface on the film side, and the cross-sectional shape in the width direction of the pattern can be trapezoidal. In addition,
The trapezoidal shape allows the angle between the short base and the side to be adjusted to 95 ~ by adjusting the concentration of the etching solution and the etching time.
It can be trapezoidal at 150 °. Then, this metal foil transfer film is laminated on a precursor sheet which becomes the insulating film 3, and hot pressed for 10 minutes to 1 hour under the conditions of a temperature of 100 to 200 ° C. and a pressure of 0.5 to 10 MPa, and then becomes a support. By removing the film by peeling and transferring the metal foil onto the surface of the precursor sheet which becomes the insulating film 3, the wiring conductor 4 having the trapezoidal upper bottom side embedded in the coating layer 2 can be formed.

The thickness x (μm) of the coating layer 2 between the liquid crystal polymer layers 1 facing the short bottom of the wiring conductor 4 is opposite.
Can be set to a desired range by adjusting the pressure of the hot press at the time of transferring the metal foil. Further, in order to improve the adhesion with the coating layer 2, the surface of the wiring conductor 4 is preferably roughened by a treatment such as buffing, blasting, brushing, or chemical treatment.

The insulating film 3 has a diameter of 20 to 15
The through conductor 5 having a thickness of about 0 μm is formed. Through conductor 5
Are the wiring conductors 4 located above and below with the insulating film 3 in between.
Has a function of electrically connecting to each other. After a through hole is formed by performing a drilling process on the insulating film 3 with a laser, a conductive paste made of copper, silver, gold, solder or the like is conventionally provided in the through hole. It is formed by embedding by a known screen printing method.

According to the multilayer wiring board 6 of the present invention, since the insulating film 3 has the coating layers 2 made of epoxy resin on the upper and lower surfaces of the liquid crystal polymer layer 1, the liquid crystal polymer layer 1 has high heat resistance.・ High elastic modulus, high dimensional stability and low hygroscopicity make it possible to construct the insulating film 3 without using a reinforcing material such as glass cloth. It is possible to form uniform through holes.

In such a multilayer wiring board 6, a through conductor 5 is formed at a desired position on a precursor sheet to be the insulating film 3 manufactured by the above-described method, and then a patterned metal foil of copper, for example, is formed. , The temperature is 100-200 ℃ and the pressure is 0.
Transfer by hot pressing for 10 minutes to 1 hour under the condition of 5 to 10 MPa, stacking these, and finally hot pressing under the condition of temperature of 150 to 300 ° C and pressure of 0.5 to 10 MPa for 30 minutes to 24 hours. It is manufactured by being completely cured.

Thus, according to the multilayer wiring board 6 of the present invention, the semiconductor element is connected to the connection pad 8 formed of a part of the wiring conductor 4 formed on the upper surface of the multilayer wiring board 6 having the above-mentioned structure via the conductor bump 9 such as solder. And the like electronic components 7 are electrically connected, and at the same time, a conductor bump 9 such as solder is attached to the connection pad 8 formed of a part of the wiring conductor 4 formed on the lower surface of the multilayer wiring board 6.
By forming the above, it is possible to obtain a hybrid integrated circuit having a high wiring density and an excellent insulating property.

The multilayer wiring board 6 of the present invention is not limited to the above-described embodiments, but various modifications can be made without departing from the scope of the present invention. Then, the multilayer wiring board 6 is manufactured by laminating the four layers of the insulating films 3, but the multilayer wiring board 6 may be manufactured by laminating the insulating films 3 of two layers, three layers, or five layers or more. Further, on the upper and lower surfaces of the multilayer wiring board 6 of the present invention, a build-up layer composed of an insulating layer containing one, two or three or more layers of organic resin as a main component, a solder resist layer 10 and an underfill material 11 are provided. You may form.

[0059]

According to the insulating film of the present invention, the coefficient of thermal expansion in the layer direction of the liquid crystal polymer layer is −20 to 20 × 10 ^−6.
/ ° C., the tensile elastic modulus is 2 GPa or more, and the tensile elastic modulus in the layer direction of the coating layer is 0.2 to 1.5 GPa. Therefore, when the insulating film thermally expands and contracts due to temperature change,
The coating layer having a tensile elastic modulus in the layer direction of 0.2 to 1.5 GPa and a low elastic modulus is constrained by a liquid crystal polymer layer having a small coefficient of thermal expansion and a high elastic coefficient, and has a small thermal expansion / contraction.
As a result, it is possible to obtain an insulating film in which cracks do not occur in the coating layer even in a temperature cycle test involving a rapid temperature change.

Further, according to the insulating film of the present invention, in the above structure, the coating layer contains 5 to 60% by volume of an organic material having a lower elastic modulus than the epoxy resin, so that the elastic modulus of the coating layer can easily be 0.2. It can be in the range of up to 1.5 GPa.

Further, according to the insulating film of the present invention,
In the above structure, since the low elastic modulus organic matter contains 20 to 80% by volume of the styrene organic matter, the styrene organic matter has a low dielectric constant and low dielectric loss tangent, and reduces the dielectric constant and the dielectric loss tangent of the coating layer. Can result in 100
It is possible to obtain an insulating film having excellent transmission characteristics even at high frequencies of MHz or higher.

Further, according to the insulating film of the present invention, in the above-mentioned constitution, the total thickness of the coating layers is calculated as the total thickness of the insulating layers.
Since the content is 10 to 70%, it is possible to obtain an insulating film having good adhesion to the wiring conductor, high heat resistance, low moisture absorption, and high dimensional stability.

Further, according to the multilayer wiring board of the present invention,
Since the multilayer wiring board is formed by using the above-mentioned insulating film, it is possible to obtain a multilayer wiring board having excellent insulation reliability, conduction reliability, and high frequency transmission characteristics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of an insulating film of the present invention.

FIG. 2 is a sectional view showing an example of an embodiment of a hybrid integrated circuit in which a semiconductor element is mounted on a multilayer wiring board of the present invention.

FIG. 3 is an enlarged cross-sectional view of a main part of the multilayer wiring board shown in FIG.

[Explanation of symbols]

1 ... Liquid crystal polymer layer 2 ... coating layer 3 ... Insulation film 4 ... Wiring conductor 5 ... Through conductor 6 ... Multilayer wiring board

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 1/11 H05K 1/11 H // C08L 67:00 C08L 67:00 F term (reference) 4F006 AA35 AB05 AB34 BA01 CA08 4F100 AB01D AB01E AB33D AB33E AH00B AH00C AK01A AK12B AK12C AK53B AK53C BA03 BA05 BA10B BA10C BA25B BA25C GB41 GB43 JA02A JA11A JG04 JK02A JK02B JK02C JK07A JK07B JK07C JK14 YY00A YY00B YY00C 5E317 AA24 BB01 BB11 CC22 CC25 GG14 5E346 AA32 CC02 CC32 CC38 CC39 CC40 DD02 DD12 DD32 EE01 EE08 EE31 FF01 FF18 HH06 HH16

Claims (5)

[Claims] 1. A liquid crystal polymer layer is formed by forming a coating layer on the upper and lower surfaces of an epoxy resin and an organic material having a lower elastic modulus than the epoxy resin, and the liquid crystal polymer layer has a coefficient of thermal expansion in the layer direction of −20 to 20. × 10 ^-6 / ° C, and
An insulating film having a tensile elastic modulus of 2 GPa or more, and the coating layer having a tensile elastic modulus in the layer direction of 0.2 to 1.5 GPa. 2. The insulating film according to claim 1, wherein the coating layer contains the organic material having a low elastic modulus in an amount of 5 to 60% by volume. 3. The insulating film according to claim 1, wherein the organic material having a low elastic modulus contains 20 to 80% by volume of a styrene-based organic material. 4. The insulating film according to claim 1, wherein the total thickness of the coating layers is 10 to 70% of the thickness of the insulating film. 5. The insulating film according to claim 1, wherein a wiring conductor made of a metal foil is provided on at least one of the upper and lower surfaces, and the insulating film is laminated. A multilayer wiring board, characterized in that the wiring conductors located above and below with a pinch therebetween are electrically connected via a penetrating conductor formed in the insulating film.