JP4689263B2 - Multilayer wiring board and manufacturing method thereof - Google Patents

Description

The present invention relates to a method for manufacturing a multilayer wiring board and a multilayer wiring board, more particularly to a laminated wiring board and its manufacturing method of the liquid crystal polymer and the insulating layer.

  In recent years, demands for miniaturization and higher functionality of electronic devices have been promoted, and the same contents are also required for wiring boards as internal components thereof. Multi-layering and high density are prevalent. In addition, in such an electronic device, it is necessary to increase the frequency of a signal in order to process a large amount of information, and in recent years, development of a substrate that transmits a high-frequency signal has attracted attention.

  A conventional wiring board corresponding to multilayering and high density is formed by using a plurality of materials. For example, a multilayer wiring board uses a prepreg layer using a glass fiber and a resin as an adhesive as an insulator in order to aim at dimensional stability, and even in a wiring board having fine wiring, In order to ensure fillability, a film coated with an adhesive is used as a cover film. However, the above materials are not suitable for transmitting high frequency signals.

  On the other hand, even if the wiring board has an impedance-controlled wiring configuration to support high-speed signal transmission, if the dimensional variation is large depending on the environment used, the consistency of the impedance-controlled wiring is impaired. Because of the fear, a feature with small dimensional variation is also desired.

  In order to transmit a high-frequency signal, it is necessary to use a material having a low dielectric constant and a low dielectric loss tangent. Furthermore, if the material is a thermoplastic resin, a wiring board can be formed using a single material, and therefore the multilayer board can be made thinner.

  As such a thermoplastic resin, for example, a liquid crystal polymer can be considered. When a wiring board is formed using a thermoplastic resin such as a liquid crystal polymer, it is desirable that the layers are laminated in the vicinity of the melting point in order to obtain adhesion between the resins. However, since the resin flows in the lamination near the melting point, circuit deformation occurs. This circuit deformation may impair the impedance-controlled wiring configuration for board reliability and high-speed signal transmission.

In Patent Document 1, a heating / pressurizing step is performed by filling a conductive paste that is sintered at a lower temperature than a heating / pressurizing step that is performed to make a through hole in a thermoplastic resin and adhere the film. It is shown that when executed, the conductive paste is sintered to form a columnar support, which prevents excessive pressure from being applied and suppresses deformation of the conductor pattern. Further, in Patent Document 2, in a multilayer wiring board in which conductive bumps are press-fitted and inserted into a thermoplastic resin as an insulator layer, and through-hole type connection and non-through-hole type connection are provided via the bumps, When pressurizing to connect the wiring pattern, there is a risk of causing deformation of the wiring pattern in contact with the non-through hole portion. For this reason, it is shown that a conductive paste reinforcing layer for preventing deformation of the wiring pattern is integrally disposed on at least a part of the wiring pattern connected to the non-through hole portion to suppress deformation.
JP 2003-209356 A Japanese Patent Laid-Open No. 11-214849

  Patent Documents 1 and 2 disclose that a reinforcing structure is provided in the wiring board in order to suppress circuit deformation caused by the use of a thermoplastic resin. It becomes a hindrance to the conversion.

  A method of suppressing the deformation of the circuit by suppressing the flow of the resin by lowering the temperature of the lamination process to near the temperature at which the resin starts thermal deformation can be considered. However, sufficient adhesion between the resins cannot be obtained, which may impair the insulation required for the wiring board.

  The present invention has been made in consideration of the above-described points, and is suitable for high-speed transmission in which the dimensional fluctuation due to humidity is small, and the adhesive strength between the resins is ensured by using a thermoplastic resin having a low dielectric loss tangent and a low relative dielectric constant. An object of the present invention is to provide a high-density wiring board and a manufacturing method thereof.

In order to achieve the above object, in the present invention,
In a method of manufacturing a laminated wiring board by superimposing unit substrates each having a conductive layer provided on at least one surface of a thermoplastic resin layer,
At least one surface of each of the thermoplastic resin layers is subjected to a chemical solution roughening treatment using an alkali mixed solution as a chemical solution,
As the alkali mixed solution, a solution containing an aliphatic amine 0.5 to 5.0 mol / L, an alkali metal or alkaline earth metal hydroxide 5.0 to 10.0 mol / L, an aliphatic alcohol 4.0 to 8.0 mol / L,
The temperature of the chemical solution in the chemical treatment is in the range of 40 to 90 ° C,
The surface layer of the thermoplastic resin layer is chemically dissolved by a predetermined thickness ,
Forming a laminate having two or more layers by superimposing the treated surface on the surface of another unit substrate;
A method of manufacturing a laminated wiring board, wherein the laminated board is heated and pressurized.
Is to provide.

  According to the method for manufacturing a wiring board of the present invention, it is possible to form a dense roughened surface on the surface of the liquid crystal polymer layer without affecting the circuit formed on the surface layer of each unit board constituting the wiring board. In addition, it is possible to provide a wiring board having excellent adhesion between liquid crystal polymer layers. As a result, it can withstand high temperatures and high humidity, suppress delamination that tends to occur during bending (bending), and has excellent heat resistance, hygroscopic dimensional stability, reliability, etc. during and after the manufacturing process. It becomes.

  The obtained wiring board retains the inherent dielectric properties and characteristics of the liquid crystal polymer, and is therefore suitable for high-frequency boards and high-density mounting boards.

  In the production method of the present invention, two or more unit substrates having conductor circuits or conductor layers on one or both sides of the insulating layer are used, and these are heated and pressed to be laminated to obtain a multilayer wiring substrate. If the insulating layer is L, the conductor circuit is C, and the conductor layer D, the unit substrate is represented by L / C, C / L / C, L / D, C / L / D, and D / L / D. Some have a layered structure. These outer layers serve as adhesive surfaces, but when any of the adhesive surfaces is the conductor layer D, they cannot be adhesive surfaces.

  However, when the conductor circuit C is an outer layer, the surface on the conductor circuit C side also has an exposed surface of the insulating layer L, and therefore can be an adhesive surface. The adhesion surface refers to a surface where adhesion occurs when unit substrates are stacked and laminated. The combination and number of unit substrates to be overlapped can be arbitrarily determined, but both the adhesion surfaces between two adjacent unit substrates are prevented from being the conductor layer D.

  The unit substrate composed of the insulating layer and the metal foil as the conductor layer can be prepared by a known method, for example, by passing the prepared thermoplastic resin film and the metal foil through a pressure roll. A substrate can be manufactured.

  From the unit substrate, for example, when the metal foil is a copper foil, a photosensitive resist is pasted on the copper foil, exposed, developed, and then etched on the insulating layer by ferric chloride. The wiring circuit of the conductor by a pattern can be formed.

  In the method for producing a multilayer wiring board according to the present invention, it is desirable that a dimensional change rate (hereinafter abbreviated as a hygroscopic expansion coefficient) of a wiring board having an insulating layer made of a thermoplastic resin is 10 ppm /% RH or less. In general, an insulating layer reinforced with glass cloth or the like is used as a substrate layer constituting a multilayer wiring board, and a dimensional change rate at the time of moisture absorption is 20 ppm /% RH or less.

  However, the reinforced insulating layer causes deterioration of electrical characteristics during moisture absorption, and a small dimensional change rate and electrical characteristics are not compatible. Since the multilayer wiring board of the present invention does not use a reinforcing material or the like in order to maintain flexibility, an insulating layer that achieves both dimensional stability and electrical characteristics is required.

  Here, the hygroscopic expansion coefficient is related to the water absorption rate of the insulating layer and the amount of functional groups having an affinity for water, etc., so the water absorption rate is very small, and the insulation characteristics and electrical characteristics in the high frequency band are good. Both can be achieved by using a suitable thermoplastic resin. When the hygroscopic expansion coefficient is larger than 10 ppm /% RH, the reliability of general high-density wiring processing is lowered, and when it is small, a reinforced insulating layer must be used, and flexibility is lowered.

  The insulating layer of the wiring board constituting the multilayer wiring board is preferably a thermoplastic resin on the processed surface, and more preferably a thermoplastic resin having good high frequency characteristics. Specifically, it is desirable that the relative dielectric constant is 3 or less and the dielectric loss tangent is 0.005 or less at a frequency of 1 GHz or more.

  The relative dielectric constant is related to the propagation speed of the signal of the high-frequency circuit, and the propagation speed is improved as it is lower. The dielectric loss tangent is related to the transmission loss of the signal. The smaller the dielectric loss tangent, the lower the power and noise. Low dielectric constant and dielectric loss tangent of insulating layer are desirable, but because it is a parameter determined by the chemical structure and higher order structure of insulating layer, as a thermoplastic resin that achieves both thermoplasticity and high frequency characteristics, liquid crystal More preferably, a polymer is used.

  The liquid crystal polymer layer forms an optically anisotropic melt phase and is also called a thermotropic liquid crystal polymer. As is well known to those skilled in the art, such a polymer that forms a melt phase that forms optical anisotropy is observed in a molten sample under crossed Nicols with a polarizing microscope equipped with a heating device. Is a polymer that transmits polarized light.

  The liquid crystal polymer is not particularly limited, and examples thereof include known thermotropic liquid crystal polyesters and polyester amides synthesized from the compounds classified in 1) to 4) exemplified below and derivatives thereof. However, in order to form a polymer liquid crystal, there is an appropriate range for each combination of raw material compounds.

1) Aromatic or aliphatic dihydroxy compounds (see chemical formula 1 for typical examples)

2) Aromatic or aliphatic dicarboxylic acids (see Chemical Formula 2 for typical examples)

3) Aromatic hydroxycarboxylic acid (see Chemical Formula 3 for typical examples)

4) Aromatic diamine, aromatic hydroxyamine or aromatic aminocarboxylic acid (see Chemical Formula 4 for typical examples)

As a typical example of the liquid crystal polymer obtained from these raw material compounds, a copolymer having the structural unit shown in Chemical formula 5 can be given.

As a preferable liquid crystal polymer, there is a polyester resin containing a p-hydroxybenzoic acid unit and a 6-hydroxy-2-naphthoic acid unit shown in Chemical formula 6 as main components. In Chemical Formula 6, m and n represent a number of repetitions of 1 or more, and the p-hydroxybenzoic acid unit and the 6-hydroxy-2-naphthoic acid unit may exist as a block or may exist randomly.

  The liquid crystal polymer layer constituting the laminate is preferably a thermoplastic resin, and can be obtained by, for example, extrusion molding or coating. For example, when a liquid crystal polymer film to be a liquid crystal polymer layer is produced by extrusion molding, any extrusion molding method can be applied, but a known T-die method, laminate stretching method, inflation method and the like are industrially advantageous.

  In particular, in the inflation method and the laminate stretching method, stress is applied not only in the mechanical axis direction of the film (hereinafter referred to as MD direction) but also in the direction orthogonal thereto (hereinafter referred to as TD direction). A film with a balanced mechanical property can be obtained.

  The liquid crystal polymer preferably has a transition temperature to an optically anisotropic molten phase in the range of 200 to 400 ° C., particularly 250 to 350 ° C. in terms of heat resistance and workability. In addition, a lubricant, an antioxidant, a filler and the like may be blended within a range that does not impair the characteristics of the film.

  A preferable thickness range of the liquid crystal polymer layer of the unit substrate is 200 μm or less, more preferably 20 to 150 μm, and particularly preferably 25 to 100 μm. The type of metal constituting the conductor circuit or conductor layer of the unit substrate is not particularly limited, and examples thereof include gold, silver, copper, iron, nickel, aluminum, and alloy metals thereof.

  When manufacturing a unit board | substrate using metal foil, copper foil (including copper alloy foil which has copper as a main component) and stainless steel foil are used preferably. As the copper foil, any copper foil manufactured by a rolling method or an electrolysis method can be used. The metal foil is subjected to physical surface treatment such as roughening treatment or chemical surface treatment such as acid cleaning for the purpose of ensuring adhesion with the liquid crystal polymer film within a range not impairing the effects of the present invention. It may be.

  When using metal foil, the preferable thickness range is 5-50 micrometers, More preferably, it is the range of 8-35 micrometers. It is preferable to reduce the thickness of the metal foil from the viewpoint that a fine pattern can be formed. However, if the thickness is too thin, the metal foil may be wrinkled in the manufacturing process, and the circuit may be used as a wiring board. Even if formed, the wiring may be broken or the reliability of the wiring board may be lowered.

  On the other hand, when the thickness of the metal foil is increased, the side surface of the circuit is tapered when the metal foil is etched, which is not preferable for forming a fine pattern. In addition, the conductor circuit in a laminated board may be formed by sputtering method and a plating method.

  In the present invention, the unit substrate having a conductor circuit or a conductor layer is superimposed on the surface of the liquid crystal polymer layer, but the conductor circuit or the conductor layer may be provided only on one side thereof, or on both sides of the liquid crystal polymer layer. You may have.

  When the unit substrates are stacked, before the stacking, alkali mixing is performed on at least one surface, preferably both surfaces, of the liquid crystal polymer layer (including the conductor circuit formed on the surface) to be the stacked surface. It is necessary to perform a chemical treatment using the solution as a chemical solution or a plasma treatment. Or it is necessary to perform the roughening process of the copper foil surface which is a conductive layer. By these chemical treatment and plasma treatment, a dense roughened surface can be formed on the surface of the liquid crystal polymer layer, and the interlayer adhesion of the multilayer substrate can be improved and a highly reliable multilayer wiring substrate can be obtained. Moreover, it is possible to improve the adhesive force between a liquid crystal polymer and copper foil by a copper foil roughening process.

  The temperature of the chemical treatment is preferably 40 to 90 ° C, particularly preferably 60 to 80 ° C. Further, the alkali mixed solution contains aliphatic amine 0.5 to 5.0 mol / L, alkali metal or alkaline earth metal hydroxide 5.0 to 10.0 mol / L, aliphatic alcohol 4.0 to 8.0 mol / L and water. Use of the alkali mixed solution is suitable for forming fine irregularities on the surface of the liquid crystal polymer layer without excessively dissolving the conductor circuit. The immersion time is preferably about 1 to 3 minutes. If this processing condition is greatly deviated and the film etching becomes insufficient, the surface does not exhibit a fine roughness and the adhesion between the film layers becomes low, and if the film etching becomes excessive, the lower part of the circuit is dissolved. There is a fear.

  Preferred examples of the aliphatic amine, the alkali metal or alkaline earth metal hydroxide and the aliphatic alcohol used in the alkali mixed solution include the following compounds. Examples of the aliphatic amine include monovalent or divalent primary amines and secondary amines, and ethylenediamine, ethanolamine, propanolamine, and butanolamine are preferable, and among them, ethylenediamine is preferable. Preferred examples of the alkali metal or alkaline earth metal hydroxide include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and potassium hydroxide is more preferred. Preferred examples of the aliphatic alcohol include monohydric alcohols such as methyl alcohol, ethyl alcohol, and butyl alcohol, and ethylene glycol, propylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of about 500, and the like. Is preferred.

  Although it is conceivable to perform the chemical treatment with a single solvent, in this case, since the unevenness of the treated surface is not dense, when a multilayer wiring board is produced, the adhesion between the layers is not good. Moreover, although the method of performing surface treatment of a liquid crystal polymer layer by mechanical polishing is also considered, the unevenness | corrugation of a process surface is not dense and adhesiveness is not favorable like the case where a single solvent is used.

  The chemical solution treatment on the laminate is not limited as long as the treatment on the surface of the liquid crystal polymer layer corresponding to the laminate surface of the laminate is performed. From the viewpoint of forming fine irregularities on the entire surface of the laminated surface, the alkali mixed solution is preferably sprayed onto the liquid crystal polymer laminated surface using a spray nozzle or the like. At this time, the chemical treatment can be arbitrarily performed on one or both laminated surfaces.

  In this way, fine irregularities can be formed on the surface of the liquid crystal polymer layer by the chemical treatment, but in the present invention, the solvent contained in the chemical is removed together with or after the chemical treatment, and then overlapped. A multilayer wiring board is manufactured by laminating a plurality of laminated plates together under heat and pressure. Removal of the solvent is performed by washing with water and drying after the chemical treatment. The surface roughness (Ra) of the liquid crystal polymer layer that has been subjected to the chemical solution treatment is desirably in the range of 0.1 to 0.4 μm, and more preferably 0.25 to 0.3 μm. This is because when Ra is large, there is no dense difference in the uneven shape of the surface state and the anchor effect cannot be obtained. Conversely, when Ra is too low, the surface becomes smooth and the anchor effect cannot be obtained.

The plasma treatment is preferably a treatment method including an RIE mode in which high-frequency power is applied to a gas introduced into the apparatus to form a plasma state, and + ions generated therein are accelerated to collide with the substrate and promote an etching reaction. There are Ar, O ₂ , N ₂ , CF _4, etc. as the types of gases for performing the above, but it is particularly desirable to use Ar. The processing time is preferably about 10 to 20 minutes. If the treatment time is out of this range, a dense roughened surface is not formed on the surface if the treatment is insufficient, and if the treatment is excessive, the dense roughened state may be destroyed.

  For the roughening treatment of the copper foil as the conductive layer, there are dry roughening methods such as blasting and polishing, and wet roughening methods using chemicals, and it is particularly desirable to use blackening treatment.

  The unit substrate on which the liquid crystal polymer laminated surface is treated with a chemical solution is heated and pressurized in order to be laminated with other unit substrates. Lamination can be performed with a precision press, and the heating temperature during lamination is preferably 240 ° C. to 265 ° C., and the pressure is preferably 4.0 MPa to 6.0 MPa.

  Two or more unit substrates are used for the production of a multilayer wiring board. The liquid crystal polymer layer of the unit substrate used here has a flow start temperature of 15 ° C. or more different between adjacent liquid crystal polymer layers when the multilayer substrate is used. It is desirable. If the difference in flow start temperature is less than 15 ° C, when the unit board is used as a multilayer wiring board, the resin in each layer starts to flow simultaneously due to the pressurization at the time of lamination, and all the conductor circuits become easy to move. This is because the positioning control of the conductor circuit may be difficult.

  In view of the above, the liquid crystal polymer layer constituting the multilayer wiring board is composed of two or more layers having a flow start temperature different by 15 ° C. or more, and the flow start temperature of at least one liquid crystal polymer is set to a range of 250 to 260 ° C. In addition, the flow start temperature of at least one other liquid crystal polymer adjacent to this layer is preferably 265 ° C. or higher, particularly preferably 270 to 280 ° C. In this way, by using two or more types of liquid crystal polymer layers with different flow start temperatures as the constituent material of the multilayer substrate, there is no displacement of the conductor wiring during high-temperature precision press processing in the manufacturing process, and in a state suitable for the conductor circuit. Resin can be filled, and the substrate can be manufactured stably.

  As a configuration of the multilayer wiring board, when three liquid crystal polymer layers are stacked, it is advantageous that the core side has a high flow start temperature and both sides have a low flow start temperature. By adopting such a configuration, there is no displacement of the conductor wiring during general high-temperature precision pressing, and the conductor circuit can be appropriately filled with resin.

  In the present invention, the flow start temperature is determined by opening a 5 mm hole in a liquid crystal polymer film having a thickness of 50 μm with a punch and then changing the temperature under a fixed pressure (3.9 MPa). Refers to the first temperature at which the radius of the gas changes beyond 200 μm.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

Reference example
(a) A copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid was formed into an inflation film to obtain a film having a thickness of 50 μm. This is a liquid crystal polymer layer. The relative dielectric constant of this film at 1 GHz by the triplate line resonance method was 2.85, and the dielectric loss tangent was 0.0025.

(b) a liquid crystal polymer film comprising a unit substrate having a copper foil on both sides of a liquid crystal polymer layer having a flow start temperature of 280 ° C. and a unit substrate having a copper foil on one side of a liquid crystal polymer layer having a flow start temperature of 260 ° C. Two types of unit substrates with single-sided and double-sided copper foils made of copper foil (thickness 18 μm) were prepared.

(c) A photosensitive resist was attached to the copper foil, exposed and developed, and then the copper foil was etched with ferric chloride to form a circuit pattern. The conductor circuit laminates obtained by forming the circuit pattern are a double-sided conductor circuit laminate and a single-sided conductor circuit laminate. The hygroscopic expansion coefficient of this conductor circuit laminate was 4 ppm /% RH.

1) Measuring method of hygroscopic expansion coefficient A sample is prepared according to IPC-TM-650 2.2.4, the dimension after drying (relative humidity RH = 0%) is L0, humidity is RH (%), The dimension after humidity control can be determined by the following equation, with L1.
Hygroscopic expansion coefficient = [(L1-L0) / L0] / RH

2) Measuring method of relative dielectric constant and dielectric loss tangent As shown in FIG. 1, a microstrip structure wiring board comprising a combination of ground conductor 1 / liquid crystal polymer 2 / strip conductor 3 / liquid crystal polymer 2 / ground conductor 1 was prepared. Measured using a triplate line resonance method (loss separation method). The measuring method is as follows.

Measuring method of relative dielectric constant Resonant frequency (fr) of triplate line resonator, 3db bandwidth (δf), transmitted power ratio (at), resonance order (m) are measured, and relative dielectric constant of the dielectric in the resonator The relationship between the rate (εr) and the resonance frequency fr is obtained by the following equation.
c ² · m ²
εr =
4 (L + δL) ² · fr ²

Here, c is the electromagnetic wave velocity in free space, m is the resonance order, L is the strip conductor length, and δL is the increase in L due to the end effect.

Measurement Method of Dielectric Loss Tangent The relationship between the reciprocal (1 / Q0) of the Q value (Quality Factor) depending on all the losses in the resonator and the dielectric loss tangent (tan δ) is obtained by the following equation.
1 / Q0 = tan δ + 1 / Qc + 1 / Qe + 1 / Qr
Here, Qc is a Q value due to conductor loss, Qe is a Q value due to radiation loss at the end of the resonance line, and Qr is a Q value due to radiation loss from the side surface of the resonance line.

3) Preparation of multilayer wiring board for evaluation of interlayer adhesion and solder resistance
(a) A single-sided copper-clad laminate with an insulating layer (thickness 50 μm) made of liquid crystal polymer and a copper foil (thickness 18 μm) on one side, and the liquid polymer layer has flow start temperatures of 260 ° C. and 280 ° C. Two types of single-sided copper clad laminates (unit substrates) were prepared.

(b) The following two types of treatment were performed on the liquid crystal polymer surface of the two types of single-sided copper-clad laminates. Chemical solution A or B adjusted to a predetermined temperature was used for 1 minute, followed by washing with pure water and then drying in a hot air oven at 60 ° C. for 5 minutes. On the other hand, plasma treatment including RIE mode was performed as another treatment. Moreover, in order to confirm the adhesive force of copper foil and liquid crystal polymer, the copper foil surface of this single-sided copper clad laminated board was blackened.

(c) Thereafter, the two processed single-sided copper-clad laminates are laminated on the substrate that has been subjected to each treatment so that the treated surfaces overlap each other, and pressed with a precision press at 260 ° C and a pressure of 4.0 MPa. A laminated board, that is, a wiring board A (FIG. 2) was obtained.

4) Preparation of multilayer wiring board for bendability test
(a) A liquid crystal polymer with a flow start temperature of 280 ° C is used as the insulating layer (thickness 50 µm), and a dry film is pasted on a double-sided copper-clad substrate with copper foil (thickness 18 µm) on both sides. / S = 200μm / 200μm) after exposure and development to form a copper-clad board (double-sided conductor circuit board) with a comb-like pattern formed on both sides by etching Cu with ferric chloride, peeling off the dry film Created.

  (b) On the other hand, a liquid crystal polymer having a flow start temperature of 260 ° C. was used as the insulating layer, and a single-sided copper-clad substrate having a copper foil on one side was prepared.

  (c) Each of the laminated surfaces of the copper-clad substrates (double-sided for a double-sided conductor circuit board, or liquid crystal polymer layer surface for a single-sided copper-clad substrate) for 1 minute using a chemical solution A or B adjusted to a predetermined temperature. Processed with chemicals, then washed with pure water, dried in a hot air oven at 60 ° C for 5 minutes, and then laminated a single-sided copper-clad board on both sides of the double-sided conductor circuit board, and precision press at 260 ° C, 4.0 MPa The test piece was pressed at a pressure of.

  (d) The copper foil of the outermost layer of the prepared board was removed by etching, and this was used as a wiring board B for evaluation.

  FIG. 3 is a cross-sectional view for explaining this laminated structure. On one side of the liquid crystal polymer 7 side, the liquid crystal polymer layer side is subjected to a chemical solution treatment on both sides of a chemical solution treated double-sided conductor circuit board having a conductor circuit 9 on the surface. A structure in which a substrate 8 is laminated is shown. Here, the unevenness appearing on the laminated surface is caused by the chemical treatment.

5) Preparation of chemicals
(a) Chemical solution A: Potassium hydroxide (6.0 mol) was dissolved in water (335 mL) and then ethylene glycol (3.5 mol) and ethylenediamine (1.8 mol) were mixed to obtain an alkali mixed solution. The alkali mixed solution thus obtained was put in a plastic container, and the temperature of the alkali mixed solution was adjusted while heating and stirring with a hot plate equipped with a stirrer.

  (b) Chemical solution B: Sodium hydroxide (0.1 mol) was dissolved in water (995 mL) to obtain an alkaline aqueous solution. The liquid temperature was adjusted by the same method as the method for adjusting the chemical liquid A.

  (c) Chemical solution C: Potassium hydroxide (8.9 mol) was dissolved in water (500 mL) to obtain an alkaline aqueous solution. The liquid temperature was adjusted by the same method as the method for adjusting the chemical liquid A.

6) Measurement of flow start temperature of liquid crystal polymer The flow start temperature was measured using a liquid crystal polymer film with a thickness of 50μm, and after opening a 5mm hole with a punch, the temperature was changed under a fixed pressure (3.9MPa). The measurement was performed by a method of pressing. Measurement was performed by increasing the temperature from a low temperature by this method, and the first temperature at which the radius of the opening changed beyond 200 μm was defined as the flow start temperature.

7) Measurement of interlayer adhesion The wiring board A prepared as described above was punched into a 10 mm strip and used as a test piece. After bringing out the adhesion interface of this test piece, it was pulled in a 90 ° direction at room temperature with a tensile tester manufactured by Toyo Seiki Co., Ltd., and the load at this time was measured.

8) Measurement of solder resistance The wiring board A prepared as described above was cut to 30 × 30 mm to obtain a test piece. This test piece was immersed in a solder bath at 260 ° C. for 1 minute, and the deformation, foaming and blistering of the test piece were measured.

9) Measurement of bendability The wiring board B was cut into a 50 mm strip and used as a test piece. This test piece was bent 10 times at 180 °, and the peeling between layers was examined.

10) Measurement of chemical treatment surface (Ra) The roughness Ra (average value of absolute value deviation from the average line) of the liquid crystal polymer surface of the single-sided copper-clad substrate after chemical treatment was measured with a laser microscope (manufactured by Keyence Corporation).

Example 1
In creating a multilayer wiring board using the two types of unit substrates obtained in the reference example, a chemical solution A adjusted in advance to 60 ° C. on the liquid crystal polymer layer of the laminated surface of the double-sided copper-clad substrate as the unit substrate. Was used for chemical treatment by immersion. After the treatment, it was left for 1 minute in a vertical state and washed twice with pure water. After washing, drying was performed at 60 ° C. for 30 minutes to form dense irregularities on the surface of the liquid crystal polymer layer on the laminated surface. When the surface shape of the treated surface was observed with a laser microscope, Ra averaged 0.3 μm.

  Then, as shown in FIG. 3 which is a cross-sectional view of the laminated structure, a double-sided copper-clad substrate 5 having a conductor circuit 9 on both sides of the liquid crystal polymer layer 7 is used as a core, and the conductor circuit 9 is provided on one side of the liquid crystal polymer layer 8 on both sides. Single-sided copper-clad substrates 4 and 6 having Next, this was pressed with a precision press machine to obtain a printed multilayer wiring board.

  At this time, the pressing conditions were a temperature of 260 ° C., a pressure of 6.0 MPa, and 15 minutes. In this case, the chemical treatment of the laminated surface of the single-sided copper-clad substrates 4 and 6 was not performed. Separately, a laminated board and a multilayer wiring board having two liquid crystal polymer films having flow start temperatures of 280 ° C. and 260 ° C. as insulating layers were prepared and evaluated as described above.

Example 2
The same procedure as in Example 1 was performed except that the three laminated surfaces of the single-sided copper-clad substrates 4 and 6 as well as the double-sided copper-clad substrate 5 as the unit substrate were treated with the chemical solution A. FIG. 3 shows this stacked structure. Here, the unevenness appearing on the laminated surface is caused by the chemical treatment.

Examples 3 and 4
The same procedure as in Example 1 or 2 was performed except that the temperature condition of the chemical treatment was changed from 60 ° C to 80 ° C.

Examples 5-9
In preparing a multilayer wiring board using the two types of unit substrates obtained in the reference example, the liquid crystal polymer layer of each unit substrate was subjected to plasma treatment in advance. The gas type at the time of processing was evaluated with CF ₄ , O ₂ , Ar, and N ₂ , and Ar was evaluated by changing the processing time. Subsequent pressing was performed in the same manner as in Example 1.

Example 10
In preparing a multilayer wiring board using the two types of unit substrates obtained in the reference example, the surface of the copper foil layer of each unit substrate was blackened in advance. Subsequent pressing was performed in the same manner as in Example 1.

Comparative Example 1
The same procedure as in Example 1 was performed except that the chemical treatment was not performed at the time of lamination.

Comparative Examples 2-5
The chemical solution B was used under the respective conditions of 60 ° C. or 80 ° C. during the chemical treatment. The case where only the surface of the double-sided copper-clad substrate was treated (Comparative Examples 2 and 4) and the case where the surfaces of both unit substrates were treated were evaluated.

Comparative Examples 6-9
The chemical solution C was used at the time of chemical solution treatment at 60 ° C or 80 ° C. The case where only the surface of the double-sided copper-clad substrate was treated (Comparative Examples 2 and 4) and the case where the surfaces of both unit substrates were treated were evaluated.

Comparative Example 10
The copper foil surface was not treated, and the subsequent pressing was performed in the same manner as in Example 1. The conditions and results are shown in Table 1, Table 2, and Table 3. The two treated surfaces mean the case where only the surface of the double-sided copper-clad substrate is treated, and the four sides mean the case where the entire laminated surface of the double-sided copper-clad substrate and the single-sided copper-clad substrate is treated.

  From the results of Examples and Comparative Examples, it can be seen that the multilayer wiring board of each Example in which the laminated surface was treated with a chemical solution using a specific chemical solution is excellent in interlayer adhesion, solder resistance, and bendability.

Sectional drawing of a sample for demonstrating a dielectric constant and a dielectric loss tangent measurement. Sectional drawing for demonstrating an example of the layer structure of a multilayer wiring board. Sectional drawing for demonstrating another example of the layer structure of a multilayer wiring board.

Explanation of symbols

1 Ground conductor,
2 Thermoplastic liquid crystal polymer,
3 Strip conductor,
4 Single-sided copper-clad substrate (liquid polymer flow start temperature 260 ° C),
5 Double-sided copper-clad board (liquid polymer flow start temperature 280 ℃),
6 Single-sided copper-clad substrate (liquid polymer flow start temperature 260 ° C),
7 Liquid crystal polymer layer (liquid polymer flow start temperature 280 ° C),
8 Liquid crystal polymer layer (liquid polymer flow start temperature 260 ° C),
9 Conductor circuit,
10 Copper foil layer.

Claims (8)

In a method of manufacturing a laminated wiring board by superimposing unit substrates each having a conductive layer provided on at least one surface of a thermoplastic resin layer,
At least one surface of each of the thermoplastic resin layers is subjected to a chemical solution roughening treatment using an alkali mixed solution as a chemical solution,
As the alkali mixed solution, a solution containing an aliphatic amine 0.5 to 5.0 mol / L, an alkali metal or alkaline earth metal hydroxide 5.0 to 10.0 mol / L, an aliphatic alcohol 4.0 to 8.0 mol / L,
The temperature of the chemical solution in the chemical treatment is in the range of 40 to 90 ° C,
The surface layer of the thermoplastic resin layer is chemically dissolved by a predetermined thickness ,
Forming a laminate having two or more layers by superimposing the treated surface on the surface of another unit substrate;
A method of manufacturing a laminated wiring board, wherein the laminated board is heated and pressurized. In the manufacturing method of the multilayer wiring board of Claim 1,
The one flow start temperature of the thermoplastic resin layer is in the range of 250 to 260 ° C, the other flow start temperature of the thermoplastic resin layer in contact with this layer is in the range of 270 to 280 ° C, and the flow start temperature is A method for producing a multilayer wiring board, wherein the temperature difference of the substrate is 15 ° C. or more . In the manufacturing method of the multilayer wiring board of Claim 1 or 2,
A method for producing a laminated wiring board , comprising: roughening a conductive layer on a surface in contact with another thermoplastic resin layer at the time of lamination, and then laminating the laminated board under heating and pressure . In the manufacturing method of the multilayer wiring board of Claim 3,
The method for manufacturing a multilayer wiring board, wherein the roughening treatment is a blackening treatment . In the manufacturing method of the multilayer wiring board in any one of Claims 1 thru | or 4,
It is formed as a laminate of insulating layers made of a thermoplastic resin having a relative dielectric constant of 3 or less at a frequency of 1 GHz or more and a dielectric loss tangent of 0.005 or less, and a 90 ° peel strength at room temperature between the insulating layers is 0.5 kN / m or more. A method for producing a laminated wiring board, wherein: In the manufacturing method of the multilayer wiring board of Claim 5 ,
A method of manufacturing a multilayer wiring board, wherein a dimensional change rate due to humidity of the multilayer wiring board is 10 ppm /% RH or less . In the manufacturing method of the multilayer wiring board of Claim 5 or 6 ,
The method for manufacturing a wiring board, wherein the thermoplastic resin is a liquid crystal polymer . In the manufacturing method of the multilayer wiring board of Claim 7 ,
The method for producing a wiring board, wherein the liquid crystal polymer contains at least p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid as constituent units .

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