JP2003158379A - Multi-layer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem wherein it is impossible to satisfy the high density, insulating performance, continuity reliability, and high frequency trans mitting characteristics of wiring at the same time in a multi-layer wiring board constituted of organic materials. SOLUTION: This multi-layer wiring board 4 is constituted of organic materials, and formed by laminating a plurality of insulating films 1 where a wiring conductor 2 constituted of a metallic foil is disposed on at least either the upper face or lower face, and electrically connecting the wiring conductors 2 positioned at the upper and lower parts with the insulating films 1 interposed through a feed-through conductor 3 formed in the insulating films 1. The insulating films 1 are constituted by forming coating layers 6 constituted of cyanate resin on the upper and lower faces of a liquid crystal polymer layer 5. Thus, it is possible to provide the multi-layer wiring board 4 whose insulating performance, continuity reliability, and high frequency transmitting characteristics are excellent.

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 a multilayer wiring board used in part.

[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 A through hole is formed by drilling in an insulating film formed by impregnating glass cloth with epoxy resin, and a plurality of wiring boards, each having a plurality of wiring conductors formed inside the through hole and on the surface of the insulating layer, are laminated. .

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 multi-layer printed circuit board has been proposed, and in Japanese Patent Laid-Open No. 8-293579, one side of a board is formed by laminating a liquid crystal polymer film having a circuit pattern formed on the surface via a prepreg therebetween. There has been proposed a multi-chip module in which a plurality of bare chips are mounted.

[0009]

However, the multilayer printed circuit board proposed in Japanese Unexamined Patent Publication No. 8-97565 has the following problems.
When an adhesive layer containing a liquid crystal polymer is inserted between the circuit layers or between the conductor foil layers of the circuit layers and they are bonded by thermocompression bonding, the liquid crystal polymer molecules are rigid and the molecules are regularly aligned to some extent. The molecules are difficult to move because they are densely arranged, and the liquid crystal polymer of the circuit layer and the liquid crystal polymer of the adhesive layer can only entangle only a part of the molecules on the surface, resulting in poor adhesion, and in the high temperature bias test There is a problem that the layers are peeled off to cause insulation failure. In addition, when the liquid crystal polymer is bonded by heat fusion, the liquid crystal polymer molecules cannot move easily into the fine recesses on the surface of the conductor foil, and as a result, a sufficient anchoring effect cannot be exerted. There is also a problem that the adhesiveness between the foil and the liquid crystal polymer is deteriorated, and the foil and the liquid crystal polymer are separated from each other 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. Although it can prevent moisture and improve the moisture resistance,
The liquid crystal polymer film and prepreg in contact with the circuit pattern are materials with different dielectric constants.
When transmitting a high frequency signal of 0 MHz or more, it is very difficult to perform impedance matching, and since the propagation delay time of the high frequency signal is different between the upper and lower surfaces of the circuit pattern, the signal is distorted and the transmission loss is large. It had a problem that it would become.

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]

A multilayer wiring board of the present invention is formed by laminating a plurality of insulating films made of an organic material and having wiring conductors made of metal foil arranged on at least one of upper and lower surfaces thereof. A multilayer wiring board in which the wiring conductors located above and below the insulating film are electrically connected via a through conductor formed in the insulating film, wherein the insulating film is on a liquid crystal polymer layer. It is characterized in that a coating layer made of a cyanate resin is formed on the lower surface.

Further, the multilayer wiring board of the present invention is characterized in that, in the above constitution, the coating layer contains 10 to 70% by volume of inorganic insulating powder.

Further, in the multilayer wiring board of the present invention having the above-mentioned structure, the liquid crystal polymer layer has a contact angle with water of 5 to 5.
The multilayer wiring board of the present invention is characterized in that the cross-sectional shape in the width direction of the wiring conductor disposed in the insulating film is the bottom side of the insulating film side. Has a trapezoidal shape whose length is shorter than the length of the opposite bottom side, and the angle formed by the bottom side and the side on the side of the insulating film is 95 to 150 °.

Further, in the above-mentioned structure, the multilayer wiring board of the present invention has a thickness x (of the coating layer located between the insulating films and between the bottom of the wiring conductor having a short length and the liquid crystal polymer layer. μm), where T (μm) is the distance between the upper and lower liquid crystal polymer layers and t (μm) is the thickness of the wiring conductor, 3 μm ≦ 0.5T−t ≦ x ≦ 0.5
T ≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm, 1 μm ≦ t
≦ 32 μm).

According to the multilayer wiring board of the present invention, since the insulating film is formed by forming the coating layers of the cyanate resin on the upper and lower surfaces of the liquid crystal polymer layer, the cyanate resin molecules are as rigid as the liquid crystal polymer molecules. Not again
Molecules are relatively easy to move because they do not show regular orientation, and as a result, the adhesion between insulating films is good, and there is no possibility of peeling between insulating films and causing insulation failure in the high temperature bias test. . In addition, the cyanate resin molecules can enter the fine recesses on the surface of the wiring conductor and exhibit a sufficient anchoring effect, resulting in good adhesion between the insulating film and the wiring conductor, and as a result, high temperature and high humidity between them. There is no possibility of peeling and breaking of the wiring conductor. Furthermore, since the upper and lower surfaces of the wiring conductor are in contact with the coating layers made of the same material, 100 MHz
When transmitting the above high-frequency signals, it is easy to perform impedance matching, and since the propagation delay time of the high-frequency signals is the same on the upper and lower surfaces of the wiring conductor, the signal is distorted and the transmission loss increases. It doesn't happen.

Further, according to the multilayer wiring board of the present invention, in the above structure, since the coating layer contains 10 to 70% by volume of the inorganic insulating powder, the coating layer has an appropriate elasticity, and as a result, It is possible to obtain a multi-layer wiring board with excellent connection reliability, in which displacement of the through conductor and variation in the thickness of the coating layer are small when the insulating films are laminated and pressed.

Further, according to the multilayer wiring board of the present invention,
In the above structure, the contact angle of the liquid crystal polymer layer with water is 5
Since it is set to -60 °, the active groups capable of hydrogen bonding on the upper and lower surfaces of the liquid crystal polymer layer and the coating layer can be bonded well by a strong intermolecular force, and as a result, the adhesion between them can be further improved. be able to.

Further, according to the multilayer wiring board of the present invention, in the above-mentioned structure, the width direction cross-sectional shape of the wiring conductors arranged on the insulating film is determined by the length of the bottom side on which the insulating film side is opposed to the bottom side. Since the trapezoid is shorter than that, and the angle between the bottom side and the side on the insulating film side is 95 to 150 °, the wiring conductor can be easily embedded in the coating layer and the wiring conductor is embedded. The surface of the subsequent coating layer can be made substantially flat, and as a result, air can not be caught between the insulating films when the insulating films are multilayered, and a multilayer wiring board with high insulation reliability can be obtained. .

Further, according to the multilayer wiring board of the present invention,
In the above structure, the thickness x (μm) of the coating layer located between the insulating film and the short base of the wiring conductor and the liquid crystal polymer layer is equal to the distance between the upper and lower liquid crystal polymer layers by T (μm), When the thickness of the wiring conductor is t (μm), 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦ 32 μm). The difference in the distance between the short length bottom and the liquid crystal polymer layer and the distance between the long length wiring conductor and the adjacent liquid crystal polymer layer can be reduced to less than t (μm), and the variation in the dielectric loss tangent around the wiring conductor is small. As a result, the transmission characteristics can be further improved.

[0021]

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

FIG. 1 is a sectional view showing an example of an embodiment of a hybrid integrated circuit in which electronic parts such as semiconductor elements are mounted on a multilayer wiring board of the present invention, and FIG. 2 is shown in FIG. FIG. 6 is an enlarged cross-sectional view of a main part of a wiring conductor in the width direction of the multilayer wiring board shown. In these figures, 5 is a liquid crystal polymer layer,
Reference numeral 6 denotes a coating layer, which mainly constitutes the insulating film 1. Further, 2 is a wiring conductor, 3 is a through conductor, and the insulating film 1, the wiring conductor 2, and the through conductor 3 mainly form the multilayer wiring board 4 of the present invention. The multilayer wiring board 4 of this example is formed by laminating four insulating films 1.

The insulating film 1 comprises a liquid crystal polymer layer 5 and
And a coating layer 6 formed on the upper and lower surfaces thereof, and when a multilayer wiring board 4 is formed using this, a support for the wiring conductor 2 and an electronic component 7 mounted on the multilayer wiring board 4. Has the function of.

Here, the liquid crystal polymer refers to 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. The thermotropic liquid crystal polymer which sometimes exhibits liquid crystallinity, or all of the type 1, type 2, and type 3 liquid crystal polymers classified by heat distortion temperature are included, and the liquid crystal polymer used in the present invention has temperature cycle reliability.・ A temperature of 200-400 ℃, especially 250-350 from the viewpoint of soldering heat resistance and workability.
Those having a melting point at a temperature of ° C are preferred.

As such a liquid crystal polymer, from the viewpoint of temperature cycle reliability, solder heat resistance and workability, it is 200 to 4
Those having a melting point at a temperature of 00 ° C, particularly at a temperature of 250 to 350 ° C are preferable. Further, the liquid crystal polymer layer 5 is a light stabilizer such as an antioxidant for improving thermal stability or a light stabilizer such as an ultraviolet absorber for improving light resistance, and flame retardancy within a range that does not impair the physical properties of the layer. Halogen-based or phosphoric acid-based flame retardants, antimony compounds and zinc borate for adding
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 / fluorocarbon-based surfactants for improving lubricity; aluminum oxide for adjusting the thermal expansion coefficient and / or 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 particle shape of the above-mentioned filler and the like may be substantially spherical, needle-like, flake-like, etc. From the viewpoint of filling properties, substantially spherical shape is preferable. The particle diameter is usually about 0.1 to 15 μm, which is smaller than the thickness of the liquid crystal polymer layer 5.

Further, the liquid crystal polymer layer 5 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 6. The contact angle with water is 5-60
It is preferable that the treatment is carried out so that

Water for evaluating the contact angle is JIS
K 0050 shows water purified by a distillation method or an ion exchange method defined in "General Rules for Chemical Analysis Method", or water purified by a method combining a reverse osmosis method, a distillation method, an ion exchange method and the like.

The wettability of water to the liquid crystal polymer layer 5 is
It has a correlation with the ratio of active groups capable of hydrogen bonding on the surface of the liquid crystal polymer layer 5, and when the contact angle between the upper and lower surfaces of the liquid crystal polymer layer 5 with water is set to 5 to 60 °, the coating layer 6 becomes liquid crystal. By bonding with the upper and lower surfaces of the polymer layer 5 by a strong intermolecular force,
Adhesion between the liquid crystal polymer layer 5 and the coating layer 6 can be made good, and as a result, the insulating film 1 that does not peel off between the two even in the high temperature bias test can be obtained. When the contact angle with water is less than 5 °, the coating layer 6 spreads extremely over the liquid crystal polymer layer 5 and the positional accuracy deteriorates, and a plurality of insulating films 1 are stacked and heated / pressed. When the multilayer structure is adopted, the positions of the wiring conductor 2 formed on the surface of the insulating film 1 and the through conductors 3 formed inside tend to be displaced to easily cause disconnection.
If it exceeds 50 °, the adhesion between the liquid crystal polymer layer 5 and the coating layer 6 in the high temperature bias test tends to be low, and there is a tendency for peeling between the two to easily occur. Therefore, the surface of the liquid crystal polymer layer 5 preferably has a contact angle with water of 5 to 60 °.

The liquid crystal polymer layer 5 preferably has a center line surface roughness Ra of 0.05 to 5 μm. Centerline surface roughness Ra of the upper and lower surfaces of the liquid crystal polymer layer 5
Is 0.05 to 5 μm, the upper and lower surfaces of the liquid crystal polymer layer 5 have a good anchoring effect with the coating layer 6 and have good adhesiveness, and the liquid crystal polymer layer 5 and the coating layer 6 are more firmly adhered. Can be one.

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 5 and the coating layer 6 during solder reflow, and the coating layer 6 is formed on the surface. The thickness is preferably 5 μm or less from the viewpoint of preventing the entrapment of air when forming the film. Therefore, the liquid crystal polymer layer 5 preferably has a center line surface roughness Ra of the surface of 0.05 to 5 μm.

Next, the coating layer 6 formed on the surface of the liquid crystal polymer layer 5 is made of a cyanate resin and has a function of an adhesive when the wiring conductor 2 is adhered and formed, and the insulating film 1 is used. When forming the multilayer wiring board 4, it serves as an adhesive for laminating the insulating films 1 to each other.

Here, the cyanate resin means a substance having two or more cyanato groups in the molecule and capable of forming a three-dimensional network structure by being trimerized by heating to form a cyanurate ring. For example, those having a bisphenol A or bisphenol E / bisphenol F / phenol novolac / dicyclopentadiene type resin as a molecular skeleton are mentioned.

The coating layer 6 as described above is used to improve the fatty acid ester processed product of a transition metal for promoting the curing, a metal catalyst such as a complex compound, the rubber component for adjusting the elastic modulus, and the thermal stability. Antioxidants, light stabilizers such as UV absorbers to improve light resistance, halogen-based or phosphoric acid-based flame retardants to add flame retardancy, antimony compounds and zinc borate / metaboric acid Flame retardant aids such as barium and zirconium oxide, lubricants such as higher fatty acids and higher fatty acid esters to improve lubricity, higher fatty acid metal salts and higher fatty acid metal salts, fluorocarbon surfactants, etc., adjusting thermal expansion coefficient and mechanical strength. Aluminum oxide, 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,
Fillers such as barium zirconate and strontium zirconate, or couplings such as silane coupling agents and titanate coupling agents to improve the bondability and mechanical strength of the fillers by increasing their affinity with them. You may contain an agent.

In particular, when the insulating film 1 is laminated and pressed to form the multilayer wiring board 4, the fluidity of the coating layer 6 is suppressed and the displacement of the through conductor 3 and the variation in the thickness of the coating layer 6 are prevented. From the viewpoint, the coating layer 6 serves as a filler.
It is preferable to contain the inorganic insulating powder in a volume% or more.
Also, the adhesive interface with the liquid crystal polymer layer 5 and the wiring conductor 2
The content of the filler is preferably 70% by volume or less from the viewpoint of preventing peeling during solder reflow at the adhesive interface with. Therefore, the coating layer 6 contains 10 to 70% by volume.
It is preferable to include the above filler.

The shape of the above-mentioned filling material is substantially spherical.
There are needle-like shapes and flake-like shapes, and a substantially spherical shape is preferable from the viewpoint of filling properties. The particle size is about 0.1 to 15 μm, which is smaller than the thickness of the coating layer 6.

According to the multilayer wiring board 4 of the present invention, the insulating film 1 is formed by forming the coating layers 6 made of cyanate resin on the upper and lower surfaces of the liquid crystal polymer layer 5,
Since the cyanate resin molecules are not as rigid as the liquid crystal polymer molecules and they do not show a regular orientation, the molecules are relatively easy to move, resulting in good adhesion between the insulating films 1 and between the films in the high temperature bias test. There is no possibility of peeling to cause insulation failure. Further, the cyanate resin molecules can enter into the fine recesses on the surface of the wiring conductor 2 and exhibit a sufficient anchoring effect, and the adhesion between the insulating film 1 and the wiring conductor 2 becomes good, and as a result, under high temperature and high humidity. There is no possibility that the wiring conductor 2 will be disconnected due to separation between the two. Furthermore, since the upper and lower surfaces of the wiring conductor 2 are in contact with the coating layer 6 made of the same material, when transmitting a high frequency signal of 100 MHz 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 2, the signal is not distorted and the transmission loss does not increase.

Such an insulating film 1 is manufactured by the following method. First, a liquid crystal polymer film stretched in the take-up direction and the width direction by a well-known inflation method to form a film is subjected to surface treatment with a vacuum plasma apparatus using O ₂ and CF ₄ as a working gas to obtain a contact angle with water. Liquid crystal polymer layer 5 having upper and lower surfaces of 5 to 60 °
To produce. Then, on the upper and lower surfaces, for example, the particle size is 0.
A paste obtained by adding a cyanate resin, a solvent, a catalyst, a plasticizer, a dispersant, etc. to an inorganic insulating powder of about 1 to 15 μm, such as silicon oxide, is adopted by a conventionally known sheet molding method such as a doctor blade method. To form the coating layer 6, or by forming the coating layer 6 on the surface of the liquid crystal polymer layer 5 by immersing the liquid crystal polymer layer 5 in the above paste and pulling it up vertically, the coating layer 6 is formed at a temperature of 60 to 100 ° C. It is manufactured by heating and drying for 5 minutes to 3 hours.

The thickness of the insulating film 1 is preferably 10 to 200 μm from the viewpoint of ensuring insulation reliability, and from the viewpoint of ensuring high heat resistance, low hygroscopicity and high dimensional stability. It is preferable that the thickness of the liquid crystal polymer layer 5 be within the range of 40 to 90% of the thickness of the insulating film 1.

The insulating film 1 has wiring conductors 2 adhered to at least one of the upper and lower surfaces thereof. The wiring conductor 2 has a thickness of about 2 to 30 μm and is made of a highly conductive metal foil such as copper or gold. The electronic component 7 mounted on the multilayer wiring board 4 is electrically connected to an external electric circuit (not shown). Has the function of connecting to.

Such a wiring conductor 2 is composed of the insulating film 1
From the viewpoint of preventing voids from being generated around the wiring conductor 2 when a plurality of wiring conductors are stacked, the wiring conductor 2 is buried so that at least the surface of the wiring conductor 2 and the surface of the coating layer 6 are flat. Is preferred. Moreover, when the wiring layer 2 is embedded in the coating layer 6, if the porosity of the coating layer 6 in the dry state is set to 3 to 40% by volume, resin swelling of the coating layer 6 around the wiring layer 2 does not occur. In addition to flattening, air trapped between the wiring conductor 2 and the covering layer 6 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 6 after pressurizing and heating and curing the laminated insulating films 1, and the pores adsorb moisture in the air. Therefore, it is preferable that the porosity of the coating layer 6 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 6 in the dry state is appropriately adjusted by drying conditions such as a drying temperature and a heating rate when the coating layer 6 is applied on the surface of the liquid crystal polymer layer 5 and dried. By doing so, a desired value can be obtained.

Further, the cross-sectional shape in the width direction of the wiring conductor 2 arranged on the insulating film 1 is a trapezoidal shape in which the length of the base on the side of the insulating film 1 is shorter than the length of the opposite base, and the insulating film is formed. The angle formed by the base and the side on the 1st side
It is preferably set to 95 to 150 °. The cross-sectional shape of the wiring conductor 2 arranged in the insulating film 1 in the width direction is a trapezoid in which the length of the bottom side on the side of the insulation film 1 is shorter than the length of the opposite bottom side and the bottom side on the side of the insulation film 1 By setting the angle formed with the side edges to be 95 to 150 °, the wiring conductor 2
When the wiring conductor 2 is embedded in the coating layer 6, the wiring conductor 2 can be easily embedded in the coating layer 6 so that the surface of the coating layer 6 after the wiring conductor 2 is embedded can be made substantially flat. It is possible to obtain the multilayer wiring board 4 that does not bite into and deteriorate the insulation. From the viewpoint of embedding air bubbles without biting in, it is preferable that the angle formed by the bottom side and the side side of the insulating film 1 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 6 located between the short base of the wiring conductor 2 and the liquid crystal polymer layer 5 between the insulating film 1 is between the upper and lower liquid crystal polymer layers 5. Is T (μm), and the thickness of the wiring conductor 2 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 5 is T (μm),
When the thickness of the wiring conductor 2 is t (μm), the thickness x (μm) of the coating layer 6 between the liquid crystal polymer layer 5 and the short base of the wiring conductor 2 is 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35μ
By setting m, the difference between the distance between the short base of the wiring conductor 2 and the liquid crystal polymer layer 5 and the distance between the long bottom of the wiring conductor 2 and the adjacent liquid crystal polymer layer 5 is t (μ
The thickness can be made smaller than m) and the warp of the multilayer wiring board 4 caused by the large difference in the thickness of the coating layer 6 can be prevented. Therefore, the thickness x (μm) of the coating layer 6 located between the trapezoidal upper bottom surface of the wiring conductor 2 and the liquid crystal polymer layer 5 is set to T
(Μm), where t (μm) is the thickness of the wiring conductor 2, it is preferable that the range is 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm.

Such a wiring conductor 2 is composed of the insulating film 1
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 to be the insulating film 1, 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 peeling off the film and transferring the metal foil to the surface of the precursor sheet which becomes the insulating film 1, the wiring conductor 2 having the trapezoidal upper bottom side embedded in the coating layer 6 can be formed.

The thickness x (μm) of the coating layer 6 between the liquid crystal polymer layers 5 opposed to the short base of the wiring conductor 2 is small.
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 to the coating layer 6, it is preferable that the surface of the wiring conductor 2 is roughened by a treatment such as buffing, blasting, brushing, or chemical treatment.

The insulating film 1 has a diameter of 20 to 15
The through conductor 3 having a thickness of about 0 μm is formed. Through conductor 3
Is a wiring conductor 2 located above and below the insulating film 1.
Has a function of electrically connecting to each other, and after forming a through hole by performing a drilling process on the insulating film 1 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 4 of the present invention, since the insulating film 1 has the coating layers 6 made of cyanate resin on the upper and lower surfaces of the liquid crystal polymer layer 5, the liquid crystal polymer layer 5 has high heat resistance.・ High elastic modulus, high dimensional stability, and low hygroscopicity make it possible to construct the insulating film 1 without using a reinforcing material such as glass cloth. As a result, laser drilling is easy and fine processing is possible. It is possible to form uniform through holes.

In such a multilayer wiring board 4, a through conductor 3 is formed at a desired position on a precursor sheet to be the insulating film 1 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 4 of the present invention, the semiconductor element is connected to the connection pad 8 formed of a part of the wiring conductor 2 formed on the upper surface of the multilayer wiring board 4 having the above-mentioned structure via the conductive bump 9 such as solder. Etc. while electrically connecting the electronic components 7 such as the above, and the conductor bumps 9 such as solder to the connection pads 8 formed of a part of the wiring conductor 2 formed on the lower surface of the multilayer wiring board 4.
By forming the above, it is possible to obtain a hybrid integrated circuit having a high wiring density and an excellent insulating property.

The multi-layer wiring board 4 of the present invention is not limited to the above-mentioned embodiments, but various modifications can be made without departing from the scope of the present invention. Then, the multilayer wiring board 4 is manufactured by laminating the four layers of the insulating film 1, but the multilayer wiring board 4 may be manufactured by laminating two, three, or five or more layers of the insulating film 1. Further, on the upper and lower surfaces of the multilayer wiring board 4 of the present invention, a build-up layer or a solder resist layer 10 made of an insulating film containing one, two, or three or more layers of organic resin as a main component, or the electronic component 7 is provided. After mounting, the underfill material 11 may be formed between it and the electronic component 7.

[0053]

According to the multi-layer wiring board of the present invention, since the insulating film is formed by forming the coating layers of the cyanate resin on the upper and lower surfaces of the liquid crystal polymer layer, the cyanate resin molecules are almost the same as the liquid crystal polymer molecules. Since it is not rigid and does not show a regular orientation, the molecules move relatively easily, and as a result, the adhesion between insulating films is good and peeling occurs between the films in the high temperature bias test, resulting in insulation failure. It doesn't end up. In addition, the cyanate resin molecules can enter the fine recesses on the surface of the wiring conductor and exhibit a sufficient anchoring effect, resulting in good adhesion between the insulating film and the wiring conductor, and as a result, high temperature and high humidity between them. There is no possibility of peeling and breaking of the wiring conductor. Furthermore, since the upper and lower surfaces of the wiring conductor are in contact with the coating layers made of the same material, 100 MHz
When transmitting the above high-frequency signals, it is easy to perform impedance matching, and since the propagation delay time of the high-frequency signals is the same on the upper and lower surfaces of the wiring conductor, the signal is distorted and the transmission loss increases. It doesn't happen.

Further, according to the multilayer wiring board of the present invention, in the above structure, since the coating layer contains 10 to 70% by volume of the inorganic insulating powder, the coating layer has an appropriate elasticity, and as a result, It is possible to obtain a multi-layer wiring board with excellent connection reliability, in which displacement of the through conductor and variation in the thickness of the coating layer are small when the insulating films are laminated and pressed.

Further, according to the multilayer wiring board of the present invention,
In the above structure, the contact angle of the liquid crystal polymer layer with water is 5
Since it is set to -60 °, the active groups capable of hydrogen bonding on the upper and lower surfaces of the liquid crystal polymer layer and the coating layer can be bonded well by a strong intermolecular force, and as a result, the adhesion between them can be further improved. be able to.

Further, according to the multilayer wiring board of the present invention, in the above-mentioned structure, the width direction cross-sectional shape of the wiring conductor arranged on the insulating film is determined by the length of the bottom side on which the insulating film side is opposed. Since the trapezoid is shorter than that, and the angle between the bottom side and the side on the insulating film side is 95 to 150 °, the wiring conductor can be easily embedded in the coating layer and the wiring conductor is embedded. The surface of the subsequent coating layer can be made substantially flat, and as a result, air can not be caught between the insulating films when the insulating films are multilayered, and a multilayer wiring board with high insulation reliability can be obtained. .

Further, according to the multilayer wiring board of the present invention,
In the above structure, the thickness x (μm) of the coating layer located between the insulating film and the short base of the wiring conductor and the liquid crystal polymer layer is equal to the distance between the upper and lower liquid crystal polymer layers by T (μm), When the thickness of the wiring conductor is t (μm), 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦ 32 μm). The difference in the distance between the short length bottom and the liquid crystal polymer layer and the distance between the long length wiring conductor and the adjacent liquid crystal polymer layer can be reduced to less than t (μm), and the variation in the dielectric loss tangent around the wiring conductor is small. As a result, the transmission characteristics can be further improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a hybrid integrated circuit in which electronic components such as semiconductor elements are mounted on a multilayer wiring board of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the multilayer wiring board shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulating film 2 ... Wiring conductor 3 ... Penetrating conductor 4 ... Multilayer wiring substrate 5 ... Liquid crystal polymer layer 6 ... Covering layer T: Distance between upper and lower liquid crystal polymer layers t: Thickness of wiring conductor x: Coating layer located between bottom of wiring conductor having short length and liquid crystal polymer layer Thickness

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5E343 AA02 AA16 AA33 AA38 BB05                       BB15 BB24 BB66 DD56 DD62                       EE42 ER50 ER52 GG01                 5E346 AA05 AA06 AA12 AA15 AA32                       AA38 AA43 BB01 BB15 CC02                       CC08 CC12 CC32 DD02 DD33                       EE02 EE06 EE07 EE18 EE19                       EE20 EE42 FF18 GG27 GG28                       HH07 HH08 HH11

Claims (5)

[Claims] 1. A plurality of insulating films, which are made of an organic material and have wiring conductors made of a metal foil disposed on at least one of the upper and lower surfaces, are laminated, and the insulating films are located above and below each other. A multilayer wiring board in which the wiring conductors are electrically connected to each other through a penetrating conductor formed in the insulating film, wherein the insulating film has a coating layer made of a cyanate resin on upper and lower surfaces of a liquid crystal polymer layer. A multilayer wiring board characterized by comprising the following. 2. The multilayer wiring board according to claim 1, wherein the coating layer contains 10 to 70% by volume of inorganic insulating powder. 3. The liquid crystal polymer layer has a contact angle with water of 5
The multilayer wiring board according to claim 1 or 2, wherein the multilayer wiring board has an angle of -60 °. 4. The cross-sectional shape in the width direction of the wiring conductor disposed on the insulating film is a trapezoidal shape in which the length of the base on the side of the insulating film is shorter than the length of the opposite base, and The angle between the bottom side of the film and the side is 9
The multilayer wiring board according to any one of claims 1 to 3, wherein the multilayer wiring board has an angle of 5 to 150 °. 5. The thickness x (μm) of the coating layer located between the insulating film and the short base of the wiring conductor and the liquid crystal polymer layer is a distance between the upper and lower liquid crystal polymer layers. Is T (μm) and the thickness of the wiring conductor is t (μm), 3 μm ≦ 0.5T−t ≦ x
≦ 0.5T ≦ 35μm (however, 8μm ≦ T ≦ 70μ
m, 1 μm ≦ t ≦ 32 μm), The multilayer wiring board according to claim 4, wherein