JP2005136051A - Manufacturing method of wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a wiring board which is superior in flatness and has high reliability. <P>SOLUTION: The manufacturing method of a wiring board includes a boring step of providing a through hole on an insulating layer 3 containing at least resin; a through-conductor forming step of forming a through-conductor 7 in the through hole; a transfer step of aligning the insulating layer 3 having the through-conductor 7 formed with a wiring circuit layer 5 preformed on a support substrate 9 in position, thermocompression-bonding the insulating layer 3, the wiring circuit layer 5 and the support substrate 9 in the laminated direction, embedding the circuit layer 5 in the insulating layer 3, and removing the support substrate 9; a coating step of applying heat and pressure to the insulating layer 3, having the wiring circuit layer 5 and the through conductor 7 formed, and forming a coat film 11 coating at least part of the surface 5a of the circuit layer with a component of the insulating layer 3 on the surface 5a; and a removing step of removing the coat film 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wiring board used for various types of AV equipment, home appliances, communication equipment, computers, and peripheral equipment, and more particularly to a method for manufacturing a wiring board having excellent flatness and high reliability. Is.

  Conventionally, a wiring board for forming a hybrid integrated circuit in which a predetermined electronic circuit is formed by mounting a large number of active components such as semiconductor elements and passive components such as capacitance elements and resistance elements is usually made of epoxy resin on a glass cloth. A through-hole is vertically formed in the impregnated insulating layer by a drill, and a plurality of wiring boards in which a plurality of wiring circuit layers are 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 functionality, high quality, and high reliability, as represented by mobile communication devices. Has shifted to surface mounting of chip parts.

  As shown in FIG. 6A, the conventional wiring board is configured such that a through conductor 42 is provided in an insulating layer 41 and a wiring circuit layer 45 is provided on the surface of the through conductor 42 or on the surface of the insulating layer 41. . However, in such a configuration of the wiring board 49, there is a step between the insulating layer 41 and the wiring circuit layer 45 on the surface of the wiring board 49. Therefore, when a semiconductor element or a capacitor is mounted on the wiring board 49, an electronic component Could tilt and cause poor soldering.

  Further, as shown in FIG. 6B, even if the wiring circuit layer 45 is pressed to embed the wiring circuit layer 45 in the insulating layer 41, the side surface of the wiring circuit layer 45 and the insulating layer 41, a gap is generated between the side surface of the wiring circuit layer 45 and the insulating layer 41, and the thermal decomposition product residue of the flux contained in the solder during component mounting remains in the gap. Deterioration could occur.

In order to solve such problems, there has been proposed a wiring board 49 in which holes 43 are provided in an insulating layer 41 made of an aramid-epoxy sheet as shown in FIG. In such a wiring board 49, as shown in FIG. 7B, when the wiring circuit layer 45 is embedded in the insulating layer 41, the holes 43 of the holes 43 provided in the insulating layer 41 become smaller, and the insulation is reduced. By reducing the apparent volume of the layer 41, the wiring circuit layer 45 is embedded in the insulating layer 41, and the smoothness of the surface of the wiring substrate 49 is improved (see Patent Document 1).
Japanese Patent No. 3173249

  However, in the method of reducing the porosity of the insulating layer 41 and embedding the wiring circuit layer 45 as in Patent Document 1, since the holes 43 are provided in the insulating layer 41, the periphery of the wiring circuit layer 45 is When there is a hole 43 in the surface, the adhesiveness at the interface between the insulating layer 41 and the wiring circuit layer 45 becomes weak, and there is a possibility that the interface peels off.

  The present invention has been devised in view of the problems of the prior art, and an object of the present invention is to improve the adhesion between the wiring circuit layer and the insulating layer in a wiring board in which the wiring circuit layer is embedded in the insulating layer. It is another object of the present invention to provide a method of manufacturing a wiring board that can satisfactorily form a metal such as plating or solder that contacts the wiring circuit layer on the surface of the wiring circuit layer.

  The method for manufacturing a wiring board according to the present invention includes a perforating step of providing a through hole in an insulating layer containing at least a resin, a through conductor forming step of forming a through conductor in the through hole, an insulating layer formed with the through conductor, A wiring circuit layer formed in advance on a supporting base material is aligned, the insulating layer, the wiring circuit layer, and the supporting base material are thermocompression bonded in the stacking direction, and the wiring circuit layer is used as the insulating layer. A transfer step of burying and removing the supporting base material, and heating and pressurizing the insulating layer on which the wiring circuit layer and the through conductor are formed, so that the wiring is formed on the surface of the wiring circuit layer with a component of the insulating layer. A coating step of forming a coating film that covers at least a part of the surface of the circuit layer, and a removal step of removing the coating film are provided.

  In addition, the method for manufacturing a wiring board according to the present invention includes a perforating step of providing a through hole in an insulating layer containing at least a resin, a through conductor forming step of forming a through conductor in the through hole, and an insulating layer formed with the through conductor And a wiring circuit layer formed in advance on a supporting base material, the insulating layer, the wiring circuit layer, and the supporting base material are thermocompression-bonded in a stacking direction, and the wiring circuit layer is insulated. A transfer step of burying in a layer and removing the support substrate, the insulating layer in which the wiring circuit layer produced in the transfer step is embedded, the perforating step, the through conductor forming step, and the transfer step Laminating step of laminating a plurality of other insulating layers produced through the above, heating and pressurizing the other insulating layer in which the wiring circuit layer and the through conductor are formed, on the wiring circuit layer surface, A component of the insulating layer A coating step of forming a coating film that covers the least part, characterized by comprising, a removal step of removing the coating film.

  In the method for manufacturing a wiring board according to the present invention, it is desirable to remove the coating film by plasma treatment in the removing step.

  In the method for manufacturing a wiring board according to the present invention, it is desirable to remove the coating film by a polishing process in the removing step.

  In the method for manufacturing a wiring board of the present invention, it is desirable to remove the coating film by chemical treatment in the removing step.

  In the method for manufacturing a wiring board of the present invention, it is desirable that the surface roughness (Ra) of the wiring circuit layer after the removing step is 0.05 to 0.5 μm.

  Moreover, as for the manufacturing method of the wiring board of this invention, it is desirable that a part of said insulating layer is a thermosetting film.

  In the method for manufacturing a wiring board according to the present invention, it is preferable that a part of the insulating layer is a composite of a fiber and a resin.

  In the method for manufacturing a wiring board according to the present invention, it is preferable that a part of the insulating layer is a composite of an inorganic filler and a resin.

  In the method for manufacturing a wiring board according to the present invention, a part of the insulating layer is composed of a three-layered structure of first to third layers, and the second layer sandwiched between the first layer and the third layer is It is desirable that the thermoplastic resin has a glass transition point higher than those of the first layer and the third layer.

  The wiring board of the present invention is manufactured by the manufacturing method described above.

  By using such a manufacturing method, the resin of the insulating layer can sufficiently flow, and the resin can be supplied to the side surface of the wiring circuit. Thereafter, the component of the insulating layer covering the wiring circuit layer surface is removed. As a result, the adhesion between the wiring circuit layer and the insulating layer is improved, the wettability with the metal is good when plating or solder mounting, and the wiring substrate is excellent in the flatness of the substrate surface.

  A method for manufacturing a wiring board according to the present invention comprising: a step of heating and pressing an insulating layer to cover at least a part of the outer surface of the wiring circuit layer with a component of the insulating layer and removing the coating film. Therefore, in the covering step, the insulating layer component is sufficiently embedded by burying the insulating layer in the insulating layer at such a pressure or temperature that the resin of the insulating layer covers at least part of the surface of the wiring circuit layer. Since the resin can be supplied also to the side surface of the wiring circuit layer, there is no gap between the side surface of the wiring circuit layer and the insulating layer. Adhesion can be improved. And since the coating film which coat | covered the surface of a wiring circuit layer consists of a part of insulating layer, it has insulation, and it can obtain electrical connection with a wiring circuit layer through a coating film. Although not desired, it is possible to obtain electrical connection with the wiring circuit layer by removing the coating film from the surface of the wiring circuit layer.

  The outer surface of the wiring circuit layer is not completely flat, and the surface of the heating plate that pressurizes and heats the wiring circuit layer and the insulating layer is not completely flat. Therefore, even when both are brought into contact with each other and heated under pressure, a slight gap is formed between them. Then, a component of the insulating layer flows into the slight gap, so that a coating film is formed on the outer surface of the wiring circuit layer.

  In addition, for example, when the insulating film in the portion where the wiring circuit layer is not formed is removed together with the coating film covering the wiring circuit layer, the flatness of the wiring board surface can be improved. it can.

  In the present invention, it is easy to make the insulating layer multi-layered, and it goes without saying that the same effect as described above can be obtained.

  Also, the coating film can be easily removed by removing the coating film by plasma treatment, and subsequent processes such as roughening of the wiring circuit layer, plating of the wiring circuit layer, etc. can be performed stably. it can.

  Further, since the plasma treatment is a dry treatment, the resin of the insulating layer does not come into contact with water at all, so that the water absorption of the resin is suppressed, and the swelling of the substrate at the time of solder reflow can be prevented.

  Moreover, since it can process by a conveyor type by removing a coating film by grinding | polishing process, productivity can be made high and processing cost can also be made low.

  In addition, when the coating film is removed by chemical treatment, it can be processed by a conveyor system in the same manner as the polishing treatment, so that the productivity is high and the processing cost can be reduced.

  Further, by setting the surface roughness (Ra) of the wiring circuit layer after the removal step to 0.05 to 0.5 μm, for example, when forming a solder resist on the wiring board of the present invention, or the wiring of the present invention When a build-up wiring substrate is manufactured using the substrate as a core substrate, the adhesion between the build-up layer and the insulating layer can be increased, and a wiring substrate having excellent reliability can be manufactured.

  In addition, when a resin film is used as the insulating layer, the viscosity of the resin film can be easily adjusted by adjusting the molecular weight of the molecules constituting the resin film. It can be used suitably for the manufacturing method of this, and reliability can be improved.

  In addition, a flexible wiring board having a small thickness can be manufactured.

  In addition, by using a composite of fiber and resin as the insulating layer, characteristics such as strength, rigidity, and thermal expansion coefficient of the insulating layer can be easily changed. For example, the rigidity of the insulating layer can be increased by impregnating the glass fiber with a resin using a woven or non-woven fabric of E glass or S glass having high rigidity as the fiber. As a result, it is possible to manufacture a wiring board that has a high rigidity and can easily mount electronic circuit components.

  In addition, by using a composite of an inorganic filler and a resin as the insulating layer, characteristics such as the thermal conductivity and the thermal expansion coefficient of the insulating layer can be easily changed. For example, when an inorganic filler having a high thermal conductivity is used, the thermal conductivity of the insulating layer can be adjusted to an arbitrary value by adjusting the amount. In addition, when an inorganic filler with a low thermal expansion coefficient is used, the thermal expansion coefficient of the wiring board can be brought close to that of the electronic component mounted on the wiring board, and a wiring board having excellent mounting reliability with the electronic component can be obtained. Can be produced.

  In addition, the insulating layer is formed from a three-layer laminate of the first to third layers, and the second layer sandwiched between the first layer and the third layer has a higher glass transition than the first layer and the third layer. For example, even when the second layer is made of a thermoplastic resin having a high glass transition point made of a liquid crystal polymer or the like, the first and third layers sandwiching the second layer are formed from the second layer. However, since the laminating property of the insulating layer is improved even if the laminating property of the second layer is low as the low glass transition point, insulating layers having various characteristics can be used.

  By using the method for manufacturing a wiring board according to the present invention described above, the resin of the insulating layer flows sufficiently, and the resin can be supplied also to the side surface of the wiring circuit. Thereafter, the component of the insulating layer covering the wiring circuit layer surface is removed. As a result, the adhesion between the wiring circuit layer and the insulating layer is improved, the wettability with the metal is good when plating or solder mounting, and the wiring substrate is excellent in the flatness of the substrate surface.

  As shown in FIG. 1, the wiring board 1 of the present invention connects an insulating layer 3 containing at least a resin, a wiring circuit layer 5 formed on the main surface of the insulating layer 3, and the wiring circuit layer 5. And a through conductor 7 formed through the insulating layer 3. In FIG. 1, the insulating layer 3 has been described as one layer, but it goes without saying that it may be a multilayer product.

  Such a wiring board 1 can be manufactured by a method as shown in FIGS. 2 (a) to 3 (d), for example.

  First, as shown in FIG. 2A, a through hole is formed in the insulating layer 3 using a laser, and a conductive paste is embedded in the through hole by a screen printing method to form a through conductor 7.

  Next, the film 10 for metal foil transfer which prepared by adhere | attaching the metal foil 5 which consists of copper on the film 9 which is the support base material 9 via the adhesive agent (not shown) is prepared. Next, the metal foil 5 of the metal foil transfer film 10 is etched into a pattern using a subtractive method using a known photoresist.

  Then, the metal foil transfer film 10 and the insulating layer 3 are aligned and temporarily laminated.

  Next, as shown in FIG. 2 (b), the metal foil 5 of the metal foil transfer film 10 is hot-pressed for 3 minutes to 1 hour under the conditions of a temperature of 100 to 200 ° C. and a pressure of 0.5 to 10 MPa. Then, the metal foil 5 to be the wiring circuit layer 5 is embedded in the insulating layer 3 by thermocompression bonding.

  Next, the wiring circuit layer 5 can be formed on the insulating layer 3 by peeling off and removing the film 9 as the supporting base material 9 and transferring the metal foil 5 to the surface of the insulating layer 3.

  Next, a pressure heating plate (not shown) is brought into contact with both surfaces of the insulating layer 3 on which the wiring circuit layer 5 and the through conductor 7 are formed, and the temperature is 150 to 300 ° C. and the pressure is 0.5 to 10 MPa. Completely harden by hot pressing for 30 minutes to 24 hours under the conditions.

  In the method of manufacturing the wiring board 1 according to the present invention, as shown in FIG. 3C, in this curing step, the resin component of the insulating layer 3 or the like removes at least a part of the outer surface 5a of the wiring circuit layer 5. It is important to form the coating film 11 on the outer surface 5 a of the wiring circuit layer 5 by flowing the resin as it is coated. Thereafter, as shown in FIG. 3D, it is also important to remove the coating film 11 covering at least a part of the outer surface 5a of the wiring circuit layer 5.

  In FIG. 3C, the covering film 11 is shown to be relatively easy to understand, but in actuality, a slight gap is formed between the wiring circuit layer 5 and the pressure heating plate (not shown). Since it is formed, it is a very thin film with a thickness of around 1 μm. Naturally, this thickness varies depending on the surface roughness of the wiring circuit layer 5 and the pressure heating plate.

  Needless to say, a film or the like may be interposed between the wiring circuit layer 5 and the insulating layer 3 and the pressure heating plate during the pressure heating.

In the method for manufacturing the wiring substrate 1 of the present invention, it is desirable to remove the coating film 11 by plasma treatment. As the plasma treatment, any one of reduced pressure and normal pressure can be used, and known gases such as CF ₄ , O ₂ , H ₂ and Ar can be used as the reaction gas. Further, the removal rate of the coating film 11 is preferably 50 to 500 nm / min. As the processing time, although it depends on the thickness of the coating film 11, it can be satisfactorily removed in 1 to 20 minutes.

Further, in the method for manufacturing the wiring board 1 of the present invention, as another method for removing the coating film 11, it is desirable to remove by a polishing process. As the polishing treatment, a method of rotating a cylindrical brush can be applied. The material of the brush is nylon, SiC, Al ₂ O ₃ , the brush count is # 100 to # 2000, and the rotation speed of the brush is 1000 to 3000 r. p. m. Is desirable.

  Moreover, in the manufacturing method of the wiring board 1 of this invention, it is desirable to remove by chemical treatment as still another method of removing the coating film 11. As the chemical treatment, an aqueous solution of potassium permanganate, sodium hydroxide or the like can be used, and either a spray method or an immersion method can be used, but the spray method can remove the coating film 11 more efficiently. This is more desirable.

  As described above, the resin flows such that the resin component of the insulating layer 3 covers at least a part of the surface 5a of the wiring circuit layer 5 in the covering step, so that the side surface of the wiring circuit layer 5 and the insulating layer 3 are strong. After that, the covering film 11 covering at least a part of the surface 5a of the wiring circuit layer 5 is removed, so that the adhesion between the insulating layer 3 and the wiring circuit layer 5 is remarkably increased. For example, when the wiring circuit layer 5 is plated, or when other components are mounted on the wiring circuit layer 5 via a metal such as solder, the wiring circuit layer 5 is plated or soldered. Therefore, it is possible to easily form the wiring substrate 1 with extremely high reliability.

  The insulating layer 3 of the wiring board 1 is preferably formed of the resin film 3, such as a thermosetting resin (for example, epoxy resin, cyanate resin, resin in which various functional groups are bonded to polyphenylene ether), heat, or the like. A film of a plastic resin (for example, a liquid crystal polymer, a polyimide resin, a polyphenylene ether resin, a polyether ether ketone, or the like) can be used. According to this configuration, a thin and flexible wiring board 1 can be easily manufactured.

  The resin film 3 has a water absorption rate of 0.5% by mass or less, desirably 0.3% by mass or less. By setting the water absorption rate to 0.5 mass% or less, it is possible to prevent the resistance of the through conductor 7 from increasing due to the influence of moisture.

The insulating layer 3 has a relative dielectric constant (εr) of 5.3 or less, preferably 4.3 or less, and a dielectric loss tangent (tan δ) of 350 × 10 ⁻⁴ or less, preferably 300 × 10 ⁻⁴ or less. By setting the relative dielectric constant (εr) to 5.3 or less, the signal transmission speed can be within a practically no problem range, and by setting the dielectric loss tangent (tan δ) to 350 × 10 ⁻⁴ or less, signal transmission loss. Can be reduced.

  In this embodiment, the resin film 3 is used as the insulating layer 3, but in addition to this, a composite of fibers and resin can be used. In this case, first, a precursor sheet of the insulating layer 3 is formed. For example, when forming a glass fiber impregnated prepreg, a resin slurry in which viscosity is adjusted by adding a solvent such as toluene, butyl acetate, or methyl ethyl ketone to an epoxy resin, a cyanate resin, or a resin in which various functional groups are bonded to polyphenylene ether. Is made. For example, a woven or non-woven fabric of E glass or S glass is immersed in the produced resin slurry, and the glass is impregnated with the resin. Thereafter, the precursor sheet is prepared by heating and drying at 40 to 100 ° C. for 0.5 to 5 hours.

  According to this configuration, the wiring board 1 having high rigidity and easy to mount electronic circuit components can be easily manufactured.

  Further, as the insulating layer 3, a composite of an inorganic filler and a resin may be used. When producing the insulating layer 3 with a resin sheet containing an inorganic filler, the composition comprising the resin and the inorganic filler is sufficiently mixed by means such as a kneading machine or three rolls, and this is rolled, extruded, or injected. After molding into a sheet by a doctor blade method or the like, the resin is semi-cured to prepare a precursor sheet. For semi-curing, when the resin is thermoplastic, the mixture mixed under heating is cooled. In the case of a thermosetting resin, the temperature may be lower than a temperature sufficient for complete curing.

  Inorganic fillers used include aluminum oxide, silicon oxide, titanium oxide, barium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, for adjusting the thermal expansion coefficient and improving mechanical strength. Fillers such as silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate, aluminum borate, barium stannate, barium zirconate, strontium zirconate, etc. A coupling agent such as a silane coupling agent or a titanate coupling agent for improving the bondability and mechanical strength may be contained.

  According to this configuration, the thermal expansion coefficient and the thermal conductivity of the wiring board 1 can be adjusted to arbitrary values, and the wiring board 1 on which electronic circuit components can be easily mounted can be manufactured.

  The insulating layer 3 may be a three-layered laminate of first to third layers, and the first layer and the third layer may be a sheet that is softened by heating and can be bonded. With such a configuration, the wiring circuit layer can be easily embedded in the insulating layer 3 in the wiring circuit layer embedding step or the curing step. As a result, the adhesion between the insulating layer 3 and the wiring circuit layer 5 can be improved.

  The insulating layer 3 preferably includes a liquid crystal polymer layer. Since the liquid crystal polymer layer has characteristics of high heat resistance, high elastic modulus, high dimensional stability, and low hygroscopicity, it is possible to form a rigid insulating layer 3 without using a reinforcing material such as glass cloth. It becomes possible. As a result, it is possible to manufacture a highly reliable wiring board 1 with less through-conductor flow in the wiring circuit layer embedding step.

  When using a liquid crystal polymer layer having a relatively high glass transition point, the wiring circuit is formed by sandwiching the liquid crystal polymer layer with a thermoplastic resin having a glass transition point lower than that of the liquid crystal polymer layer. The insulating layer 3 having high adhesion to the layer 5 can be obtained.

In addition, as a method of forming a through hole for forming the through conductor 7, a method of processing the through hole by irradiating laser light such as CO ₂ , YAG laser, excimer laser, femtosecond laser, etc. Desirable in terms of productivity.

  The through conductor 7 of the wiring board 1 of the present invention can be produced by a method of filling the through hole provided in the insulating layer 3 with a conductive paste containing metal powder, or a method of forming by plating. it can. In consideration of water absorption of the insulating layer 3, environmental load, and cost, it is preferable to fill the former conductive paste. The through conductor 7 contains at least a low-resistance metal selected from gold, silver, copper, and aluminum, and a resin, and particularly contains a low melting point metal selected from tin, bismuth, and indium as a conductor component. The reliability of the penetrating conductor 7 against severe environments such as high temperature, high humidity, and heat cycle can be improved, and deterioration of electrical resistance can be prevented.

  Further, the wiring circuit layer 5 is formed by depositing a metal foil 5 made of copper, for example, formed by patterning by a subtractive method using a known photoresist on the insulating layer 3 in which the through holes are formed, by a transfer method or the like. It is preferable to form by this.

  Specifically, a metal foil transfer film 10 in which a metal foil 5 made of copper is bonded to a film 9 as a support base material 9 through an adhesive is prepared, and then the metal foil 5 on the film 9 is publicly known. Etching into a pattern using a subtractive method using a photoresist.

  As the film 9, known materials such as polyethylene terephthalate, polyethylene naphthalate, polyimide, polyphenylene sulfide, vinyl chloride, and polypropylene can be used. The thickness of the film 9 is suitably 10 to 100 μm, preferably 25 to 50 μm. When the thickness of the film 9 is less than 10 μm, the wiring circuit layer 5 formed by deformation or bending of the film 9 is likely to break, and when the thickness exceeds 100 μm, the flexibility of the film 9 is lost and the film 9 is difficult to peel off. Tend to be. Moreover, in order to adhere the electrolytic metal foil 5 to the surface of the film 9, a known adhesive such as acrylic, rubber, silicon or epoxy may be used.

  Further, the wiring circuit layer 5 has a roughened surface 5b on the side embedded in the insulating layer 3 by a process such as buffing, blast polishing, brush polishing, or chemical treatment in order to improve adhesion to the insulating layer 3. It is preferable to keep it.

  FIGS. 4A to 5D are process diagrams showing another embodiment of the method for manufacturing a wiring board according to the present invention.

  The wiring board of the present invention comprises, for example, an insulating layer 23 containing at least a resin, a through conductor 27, and a wiring circuit layer 25 embedded in the insulating layer 23, as shown in FIG. Thus, a plurality of insulating layers 23 are laminated.

  Such a wiring board 21 can be manufactured as follows, for example.

  First, an insulating layer 23 made of an epoxy resin film is prepared. Next, a through hole is formed in the insulating layer 23 using a laser, and a conductive paste is embedded in the through hole by a screen printing method to form a through conductor 27.

  Next, a metal foil transfer film is prepared by bonding a metal foil 25 made of copper onto a film 9 as a support base 9 (not shown) with an adhesive. Next, the metal foil 25 on the film is etched into a pattern using a subtractive method using a known photoresist.

  Then, this metal foil transfer film is aligned with a resin film to be the insulating layer 23 and temporarily laminated.

  Next, the patterned metal foil 25 made of copper, for example, is hot pressed for 3 minutes to 1 hour under conditions of a temperature of 100 to 200 ° C. and a pressure of 0.5 to 10 MPa to insulate the wiring circuit layer 25. Embedded in layer 23.

  Next, the film 9 which is the support base material 9 is peeled and removed, and the metal foil 25 is transferred to the surface of the insulating layer 23, thereby forming the wiring circuit layer 25 on the insulating layer 23.

  Next, a plurality of insulating layers 23 each including the wiring circuit layer 25 and the through conductors 27 manufactured as described above are stacked as shown in FIG.

  Next, as shown in FIG. 4B, the insulating layer 23 including the wiring circuit layer 25 and the through conductor 27 is thermocompression-bonded in the stacking direction, and the insulating layer in which the wiring circuit layer 25 and the through conductor 27 are formed. As shown in FIG. 5C, the outer surface 25 a of the wiring circuit layer 25 is covered with a part of the insulating layer 23 to form a covering layer 31.

  Next, as shown in FIG. 5D, the wiring substrate 21 can be manufactured by removing the covering layer 31 that covers the surface 25 a of the wiring circuit layer 25.

  In the method of manufacturing the wiring board 21 according to the present invention, in the curing step, the resin flows as the resin of the insulating layer 23 covers at least part of the surface 25a of the wiring circuit layer 25 as shown in FIG. It is important to let Thereafter, it is important to remove the covering layer 31 covering the wiring circuit layer 25 as shown in FIG.

  By such a manufacturing method, the highly reliable multilayered wiring board 21 can be easily manufactured as with the single-layer wiring board 1.

  Needless to say, the various conditions for forming the multilayered wiring board 21 are the same as those for producing the single-layer wiring board 1.

  Next, using the method for manufacturing the wiring board 1 of the present invention, the following samples were manufactured and evaluated for reliability.

  First, four types of insulating layers 3 were prepared.

  First, a resin varnish whose viscosity was adjusted by adding a solvent such as toluene, butyl acetate or methyl ethyl ketone to a resin having various functional groups bonded to epoxy on the upper surface of the PET film was applied by the doctor blade method. An epoxy resin precursor sheet in a dry state of about 100 μm was produced.

  As the second insulating layer 3, a glass woven fabric was impregnated with the varnish containing an epoxy resin and then dried to prepare a precursor sheet. The content ratio was 50% by volume of epoxy resin and 50% by volume of woven glass cloth.

  As the third insulating layer 3, spherical fused silica having an average particle size of 0.6 μm is added to the epoxy resin so that the content thereof is 50% by volume, and a catalyst for further promoting the curing of the resin is added, The varnish was prepared by mixing for 1 hour, and the varnish was applied to the upper surface of the PET film by a doctor blade method to produce a dry epoxy resin precursor sheet having a thickness of about 100 μm.

  As the fourth insulating layer 3, the surface of the liquid crystal polymer layer having a thickness of about 50 μm and a melting point of 320 ° C. is subjected to plasma treatment and roughened to Ra = 0.7 μm. The varnish containing the epoxy resin was applied by a doctor blade method to form a dry epoxy resin layer having a thickness of about 20 μm. And the epoxy resin layer was similarly shape | molded also to the lower surface of this liquid crystal polymer layer, and the precursor sheet | seat used as an insulating layer was manufactured.

  A through-hole having a diameter of 65 μm was formed in these precursor sheets by a UV-YAG laser, and a through-conductor 7 was formed by embedding a conductive paste containing copper powder and an organic binder in the through-hole by screen printing.

  Next, the transfer support film 9 with the copper foil 5 having a thickness of 12 μm formed in a circuit shape and the precursor sheet to be the insulating layer 3 on which the through conductor 7 is formed are aligned, and a vacuum laminating machine After pressurizing with a pressure of 3 MPa for 300 seconds to embed the wiring circuit layer 5 in the precursor sheet 3, the transfer support film 9 was peeled off.

  Finally, the precursor sheet 3 on which the wiring circuit layer 5 was formed was heat-treated at a temperature of 200 ° C. for 5 hours at the pressure shown in Table 1 to form the surface 5a coating layer 11 of the wiring circuit layer 5, The coating layer 11 was removed by plasma treatment, polishing treatment, and chemical treatment.

  As a comparative example, the precursor sheet 3 on which the wiring circuit layer 5 was formed was heat-treated at a temperature of 200 ° C. for 5 hours under a pressure of 0.3 MPa to be completely cured. In this case, the coating layer 11 was not formed.

First, plasma treatment conditions were as follows: under reduced pressure of 40 Pa, the reaction gas was O ₂ , the removal rate of the coating layer 11 was 200 nm / min, and the treatment time was 2 to 20 min. The surface roughness (Ra) of the wiring circuit layer 5 was changed as shown in Table 1 by changing the processing time.

  Also, the polishing conditions were nylon as the brush material, # 1000 for the brush count, and 1500 r. p. m. As a result, the covering layer 11 covering the surface 5a of the wiring circuit layer 5 was removed.

  Moreover, it processed for 1 minute by the spray system using potassium permanganate aqueous solution, and the coating layer 11 which coat | covered the surface 5a of the wiring circuit layer 5 was removed chemically.

  The surface roughness (Ra) of the wiring circuit layer 5 of the wiring board 1 was measured with an atomic force microscope (AFM). The flatness of the wiring board 1 was measured using a laser three-dimensional measuring device.

  The adhesion state between the wiring circuit layer 5 and the insulating layer 3 of the wiring substrate 1 was calculated from the load of the wiring circuit layer 5 formed on the surface of the insulating layer 3 by peeling it off at 90 °. Further, a solder heat resistance test at 260 ° C. for 30 seconds was performed 5 times on the wiring board 1, and when the wiring circuit layer 5 was peeled off from the insulating layer 3, it was determined to be defective. The number of tests was performed on 20 wiring boards.

  In the solder wettability test, a non-defective product was obtained by immersing the wiring circuit layer 5 having a diameter of 200 μm in a solder bath at 260 ° C. and adhering the entire surface of the wiring circuit layer 5 to a non-defective product. Note that the number of tests was 20.

Table 1 shows the results.

  From the results shown in Table 1, the sample No. in which the coating layer 11 which is outside the scope of the present invention was not provided. In 8-10, it turns out that the defect has generate | occur | produced in about half of the samples by the solder heat test, and it has difficulty in reliability.

  Moreover, although the coating layer 11 which is outside the scope of the present invention was provided, the sample No. 1 in which the coating layer 11 was not removed. 5, 14, 16 and 18, since the coating layer 11 is present on the surface 5a of the wiring circuit layer 5 formed on the surface of the wiring substrate 1, regardless of the form of the insulating layer 3, the surface circuit layer 5 is wetted by the solder. In the solder wettability test, defects occurred in 14 to 16 samples out of 20.

  On the other hand, after hardening the wiring board 1 of the present invention, a coating layer 11 was provided on the outer surface 5a of the wiring circuit layer 5, and then the coating layer 11 was removed. The wiring boards 1 of 1-4, 6, 7, 11, 13, 15, and 17 had high peel strength, and the wiring circuit layer 5 did not peel off even after the solder heat resistance test, indicating good reliability.

  And sample No. which changed the surface roughness of the wiring circuit layer 5 in the range of Ra0.05-0.5 micrometer. In each of 1-4, good results were obtained in peel strength, solder heat resistance test, and solder wettability test.

  In addition, the sample No. 1 in which the removal method of the covering layer 11 was changed. In Examples 2, 11, and 12, good results were obtained in peel strength, solder heat resistance test, and solder wettability test.

  And the sample No. which changed the form of the insulating layer 3 was used. In 2, 13, 15, and 17, good results were obtained in peel strength, solder heat resistance test, and solder wettability test. In particular, as the insulating layer 3, a sample No. using a thermosetting film was used. 11 and sample No. using a mixture of fiber and resin. In No. 13, high peel strength was obtained.

It is sectional drawing which shows one form of the wiring board manufactured by the manufacturing method of the wiring board of this invention. It is process drawing which shows the manufacturing method of the wiring board of this invention. It is process drawing which shows the manufacturing method of the wiring board of this invention. It is process drawing which shows the manufacturing method of the multilayered wiring board of this invention. It is process drawing which shows the manufacturing method of the multilayered wiring board of this invention. It is a schematic cross section which shows the conventional wiring board. It is a schematic cross section which shows the conventional wiring board.

Explanation of symbols

1, 21... Wiring board 3, 23... Insulating layer 5, 25... Wiring circuit layer, metal foil 5 a, 25 a. .Support base materials 11, 31 ... coating layer

Claims (11)

A perforating step of providing a through hole in an insulating layer containing at least a resin; a through conductor forming step of forming a through conductor in the through hole; an insulating layer formed with the through conductor; and a wiring formed in advance on a support substrate The circuit layer is aligned, the insulating layer, the wiring circuit layer, and the supporting base material are thermocompression bonded in the stacking direction, the wiring circuit layer is embedded in the insulating layer, and the supporting base material is removed. A transfer step, and heating and pressurizing the insulating layer on which the wiring circuit layer and the through conductor are formed to cover at least a part of the surface of the wiring circuit layer with a component of the insulating layer on the surface of the wiring circuit layer A method for manufacturing a wiring board, comprising: a covering step for forming a covering film; and a removing step for removing the covering film. A perforating step of providing a through hole in an insulating layer containing at least a resin; a through conductor forming step of forming a through conductor in the through hole; an insulating layer formed with the through conductor; and a wiring formed in advance on a support substrate The circuit layer is aligned, the insulating layer, the wiring circuit layer, and the supporting base material are thermocompression bonded in the stacking direction, the wiring circuit layer is embedded in the insulating layer, and the supporting base material is removed. A plurality of transfer processes, the insulating layer in which the wiring circuit layer manufactured in the transfer process is embedded, the perforation process, the through conductor forming process, and other insulating layers manufactured through the transfer process. Laminating step of laminating and heating and pressurizing the other insulating layer on which the wiring circuit layer and the through conductor are formed, and the wiring circuit layer surface is coated with a component of the insulating layer on the surface of the wiring circuit layer. Forming a coating film that covers at least a portion That the coating process and method of manufacturing a wiring board and removing step, characterized by comprising removing the coating film. 3. The method of manufacturing a wiring board according to claim 1, wherein the coating film is removed by plasma treatment in the removing step. 3. The method of manufacturing a wiring board according to claim 1, wherein the covering film is removed by a polishing process in the removing step. 3. The method of manufacturing a wiring board according to claim 1, wherein the covering film is removed by chemical treatment in the removing step. 6. The method for manufacturing a wiring board according to claim 1, wherein the surface roughness (Ra) of the wiring circuit layer after the removing step is 0.05 to 0.5 [mu] m. A part of said insulating layer is a thermosetting film, The manufacturing method of the wiring board in any one of the Claims 1 thru | or 6 characterized by the above-mentioned. The method for manufacturing a wiring board according to claim 1, wherein a part of the insulating layer is a composite of a fiber and a resin. The method for manufacturing a wiring board according to claim 1, wherein a part of the insulating layer is a composite of an inorganic filler and a resin. A part of the insulating layer is composed of a three-layered structure of first to third layers, and the second layer sandwiched between the first layer and the third layer is higher than the first layer and the third layer. The method for manufacturing a wiring board according to claim 1, wherein the wiring board is a thermoplastic resin having a glass transition point. A wiring board manufactured by the manufacturing method according to claim 1.

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