JP2006237241A - Printed circuit board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed circuit board ensuring excellent reliability of connection between internal wall of through-hole and through-conductor thereof, and to provide a method of manufacturing the same. <P>SOLUTION: The printed circuit board 21 comprises an insulated base material 5 including at least fiber 1 and resin 3, a through-hole 7 formed to the insulated base material 5, and a through-conductor 9 constituted of the metal phase formed to the through-conductor 7. In this printed circuit board 21, an alienating part A alienating the fiber 1 and resin 3 is opened to the through-hole 7, and a sealing conductor 11 is also formed to the alienating part A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic material-based wiring board, and more particularly to a wiring board for mounting a large-scale semiconductor (LSI), and more particularly to a wiring board excellent in connection reliability between a through-hole inner wall and a through-conductor and a manufacturing method thereof. Is.

  Conventionally, as an organic material-based wiring board for mounting electronic components such as semiconductor elements, copper foil and its upper and lower surfaces of an insulating substrate made of, for example, a glass-epoxy plate and having through holes penetrating from the upper surface to the lower surface thereof A wiring board is used in which a wiring conductor made of a plating layer applied thereon is attached and a through conductor made of a plating layer connecting the wiring conductors on both the upper and lower surfaces is attached to the inner surface of the through hole. Yes.

  For such an organic material-based wiring board, a double-sided copper-clad plate having copper foils attached to both upper and lower sides of an insulating substrate made of a glass-epoxy plate is prepared, and a through-hole penetrating through this double-sided copper-clad plate is provided. Holes are drilled, and then plated on the upper and lower copper foils by depositing a copper plating layer on the upper and lower copper foils and on the inner surface of the through holes by electroless plating and electrolytic plating. A through conductor made of a plated layer is formed on the inner surface of the through hole, and then the copper foil deposited on the upper and lower surfaces of the insulating substrate and the plated layer deposited on the copper foil are photolithography. It is manufactured by employing a technique and partially etching to form a wiring conductor.

  Moreover, a buildup wiring board is manufactured by forming a buildup resin layer and a buildup wiring layer on both surfaces of the wiring board. In such a wiring board, the through hole to which the through conductor is attached is usually filled with a filling resin such as an epoxy resin.

By the way, in such an organic material-based multilayer wiring board, in order to increase the wiring density in response to the demand for reduction in size and thickness of the electronic device, for example, the insulating substrate has a thickness of about 0.2 to 1 mm. Attempts have been made to make the hole diameter as small as 75 to 130 μm. Moreover, in order to form such a small through-hole with a diameter of about 75 to 130 μm, for example, a drilling method using a carbon dioxide gas laser is employed (see Patent Document 1).
JP 2000-91750 A

  However, even when the through hole is formed using the laser beam as described above, or when the through hole is formed by a conventional drilling process, the through hole wall surface and the through conductor cannot have sufficient adhesion strength. There was a problem.

  In particular, the adhesion between the periphery of the glass fiber and the through conductor in the insulating substrate is weak, the difference in thermal expansion coefficient between the resin and the glass fiber and the through conductor of the insulating substrate on the wall surface of the through hole due to thermal history at the time of mounting the semiconductor element, In particular, the three stress points of the three types of materials with different thermal expansion generate greater stress and peeling occurs at the interface between the through conductor and the glass fiber, which becomes a starting point and a crack between the through hole and the through conductor, There is a problem in that the through conductors for conduction between the front and back sides of the wiring board are disconnected to cause conduction failure.

  On the other hand, an object of this invention is to provide the wiring board excellent in the connection reliability of an inner wall of a through-hole, and a through-conductor, and its manufacturing method.

  The wiring board of the present invention comprises an insulating base containing at least fibers and a resin, a through hole formed in the insulating base, and a through conductor made of a metal phase formed in the through hole. In the wiring board, a separation portion where the fiber and the resin are separated is formed so as to open in the through hole, and a sealing conductor is formed in the separation portion.

  In addition, it is desirable that the length of the divergence portion increases toward the through hole side.

  Further, it is desirable that the through conductor and the sealing conductor are formed from the same metal phase.

  Moreover, it is desirable that the length of the sealing conductor is 3 to 20 μm.

  Further, it is desirable that the fiber has a wire diameter of 15 μm or less.

  Moreover, it is desirable that the fibers are glass fibers.

  The method for manufacturing a wiring board according to the present invention is characterized in that the through hole is formed by laser processing.

  Also, the method for manufacturing a wiring board according to the present invention is characterized in that the dissociation portion between the fiber and the resin is formed by allowing the through hole of the insulating base to penetrate into the roughening solution.

  The wiring board manufacturing method of the present invention is characterized in that when the through hole of the insulating substrate is infiltrated into the roughening liquid, the ultrasonic wave is permeated while being applied to the product to form a separation portion between the fiber and the resin portion. .

  Moreover, the manufacturing method of the wiring board of the present invention is characterized in that a sealing conductor is formed by a plating method.

  The wiring board manufacturing method of the present invention is characterized in that a through conductor is formed by a plating method.

  According to the wiring board of the present invention, an insulating base comprising at least fibers and a resin, a through hole formed in the insulating base, and a through conductor made of a metal phase formed in the through hole are provided. In the wiring board, the gap between the fiber and the resin is formed so as to open in the through hole, and the sealing conductor is formed in the gap, thereby forming the wall surface of the conductor and the insulating substrate. The contact area between the through conductor and the insulating substrate is increased, so that the contact strength between the through conductor and the insulating substrate on the wall surface of the insulating substrate is increased.

  Moreover, since the conductor is sandwiched between the glass fiber and the resin more firmly by providing the diameter of the peeled portion toward the through hole at that time, the through conductor on the wall surface of the through hole is further provided. In addition, the adhesion strength between the resin of the insulating substrate and the glass cloth increases.

  In addition, by making the sealing conductor and the through conductor the same metal layer, there is no boundary between the sealing conductor and the through conductor, and peeling is unlikely to occur, so that the connection reliability of the conductor that conducts the front and back is further improved. it can.

  Also, by setting the length of the sealing conductor to 3 to 20 μm, the adhesion strength between the through conductor on the wall surface of the through hole, the resin of the insulating base, and the glass cloth on the wall surface of the through hole can be increased, and at the same time, the insulation reliability It becomes a wiring board that secures. This is because when the sealing conductor is 3 μm or more, the adhesion strength is increased by increasing the area where the glass fiber and the conductor are bonded. Moreover, the insulation reliability between a through-hole and the wall of a through-hole becomes higher by making a sealing conductor into 20 micrometers or less. This is because if it is larger than 20 μm, the insulation reliability between the walls may not be sufficiently secured.

  Moreover, when forming a through-hole by making the wire diameter of a fiber into 15 micrometers or less, hole workability can be made favorable.

  Further, when the fiber is made of glass, the insulating substrate can have sufficient rigidity, and the warpage of the substrate can be reduced.

  In addition, by forming the through hole by laser processing, the glass fiber and the resin of the insulating substrate are peeled off due to the alteration of the resin in the vicinity of the glass fiber due to the thermal action during laser processing. Adhesion does not weaken. This is because the altered part of the resin is only chemically removed, so that stress such as strain between the glass fiber and the resin that are not separated does not act.

  Moreover, the dissociation part of the said fiber and resin can be formed by osmosis | permeating the roughening liquid through the through-hole of an insulation base | substrate. This is because it is possible to remove almost all the denatured residue of the resin near the glass fiber by chemically removing the resin denatured by laser processing between the glass fiber and the resin, and seal it on the denatured resin residue A conductor is formed, and the adhesion force at that portion is not reduced.

  In addition, when the penetration hole of the insulating substrate is infiltrated into the roughening liquid, it is possible to further remove the denatured residue of the resin near the glass fiber by infiltrating while applying ultrasonic vibration to the product. The sealing conductor is formed on the top, and the adhesion force at that portion is not reduced.

  Further, by forming the sealing conductor and the through conductor by plating, the plating solution can easily penetrate into the dissociated portion. Since the liquid can enter all the gaps, the gap between the glass fiber and the resin can be filled with the sealing conductor, and the adhesion between the sealing conductor plating and the through conductor can be sufficiently maintained.

  For example, as shown in FIG. 1, the wiring board of the present invention includes an insulating base 5 containing a glass cloth 1 as a fiber 1 and a resin 3, and a through-hole formed through the insulating base 5. 7, the through conductor 9 formed in the through hole 7, the sealing conductor 11 that enters the peeling portion A between the glass fiber 1 and the resin 3 on the inner wall of the through hole 7, and the insulating base 5. Core wiring layer 13, insulating layer 15 formed on the main surface of insulating base 5, via conductor 17 formed through insulating layer 15, and wiring conductor layer 19 formed on the main surface of insulating layer 15 It consists of and.

  In such a wiring board 21, the insulating substrate 5 and the insulating layer 15 are composed of the core wiring layer 13, the wiring conductor layer 19, and the through conductors 9 and vias that are provided so as to sandwich them. The conductor 17 is supported and electrically insulated.

  The core wiring layer 13, the wiring conductor layer 19, the through conductor 9, and the via conductor 17 are arbitrarily connected to each other to form a wiring circuit.

  In the wiring board 21 of the present invention, it is important to form the sealing conductor 11 at the divergence portion A formed between the fiber 1 on the inner wall of the through hole 7 and the resin 3. The sealing conductor 11 is placed on the gap A between the fiber 1 and the resin 3 on the inner wall of the through hole 7, which is one of the major factors that cause the through conductor 9 to easily peel off the wall surface of the wiring board 21 and reduce the reliability of the wiring board 21. By forming, the contact area between the sealing conductor 11 and the through conductor 9 and the insulating base 5 containing the fiber 1 and the resin 3 is increased, and the sealing conductor 11 is between the fiber 1 and the resin 3. Therefore, the adhesion strength between the sealing conductor 11 and the through conductor 9 on the wall surface of the insulating base 5 and the insulating base 5 containing the fibers 1 and the resin 3 is remarkably increased. The reliability of 21 is greatly improved. Further, since the adhesion strength between the sealing conductor 11 and the through conductor 9 and the insulating base 5 containing the fiber 1 and the resin 3 is improved, it is difficult for peeling to occur between the fiber 1 and the resin 3. The occurrence of through-holes and through-conductor cracks starting from the above can be reduced, and the connection reliability in conduction between the front and back sides of the wiring board can be improved.

  In order to form the sealing conductor 11 in the divergence portion A and to improve the adhesive strength between the sealing conductor 11 and the insulating substrate 5, the divergence portion A has a diameter that is increased toward the through hole 7. It is desirable to make it.

  Further, in order to eliminate the boundary between the sealing conductor 11 and the through conductor 9 and to prevent peeling due to thermal shock or the like in the semiconductor chip mounting, the sealing conductor 11 and the through conductor 9 are formed of the same metal phase. It is desirable.

  Further, in order to improve the adhesion strength between the sealing conductor 11 and the insulating substrate 5, it is desirable that the penetration depth of the sealing conductor 11 from the through hole 7 is 3 μm or more, particularly 5 μm or more, It is desirable to set it as 7 micrometers or more. Further, in order to improve the insulation reliability between adjacent through conductors 7, the penetration depth of the sealing conductor 11 from the through hole 7 is desirably 20 μm or less, in particular, 15 μm or less, It is desirable that the thickness be 10 μm or less.

  In addition, when the fiber 1 has a wire diameter of 15 μm or less, the through-hole 7 can be easily formed, and the detachment portion A having a desired shape can be easily formed around the fiber 1.

  Further, since the insulating base 5 can have sufficient rigidity and the warping of the wiring substrate 21 can be reduced, it is desirable to form the fiber 1 from glass and use the so-called glass cloth 1 as the fiber 1. That is, in FIG. 1, the fiber 1 is expressed linearly, but when the glass cloth 1 in which the glass fiber 1 is knitted like a cloth is used as the fiber 1, the glass fiber 1 is wavy, The insulating base 5 is formed so as to cross each other. Moreover, although the fiber 1 is expressed as the long fiber 1 in FIG. 1, it goes without saying that the fiber 1 may be a short fiber.

  Further, when the through-hole 7 is formed by laser processing, the divergence between the glass fiber 1 and the resin 3 of the insulating base 5 can be formed by alteration of the resin in the vicinity of the glass fiber due to thermal action during laser processing, It becomes easy to maintain the adhesiveness between the glass fiber 1 and the resin 3 other than the separation part. As for the laser processing conditions, it is desirable to adjust the output of energy and the number of shots in order to change the resin 3 around the glass fiber 1 around the through-hole 7 so that it can be easily removed. Specifically, it is possible to adjust the alteration of the resin 3 in the vicinity of the glass fiber 1 by using a carbon dioxide laser and setting the output per shot to 10 to 25 mJ and the number of shots to 3 to 20 shots.

  By allowing the through hole 7 of the laser-processed insulating substrate 5 to penetrate into the roughening liquid, the fiber-resin separation portion A can be formed. This is because it is possible to almost remove the denatured residue of the resin 3 in the vicinity of the glass fiber 1 by chemically removing the resin 3 denatured by the laser processing between the glass fiber 1 and the resin 3. The sealing conductor 11 is formed on the residue, and the adhesion force at that portion is not reduced. This is because the resin 3 is altered during the laser processing and only the portion that has been easily removed is chemically removed, so that the resin 3 and the glass fiber 1 that are not altered during the laser processing are newly separated. There is nothing.

  In addition, when the through-hole 5 of the insulating substrate 1 is infiltrated into the roughening solution, it is possible to more quickly remove the altered residue of the resin near the glass fiber by infiltrating the product while applying ultrasonic vibration. The sealing conductor is not formed on the resin residue, and the adhesive force at that portion is not reduced.

  In addition, when the sealing conductor and the through conductor are formed by plating, the plating solution can easily penetrate into the gap A, and the sealing conductor can easily fill the gap between the glass fiber and the resin. Adhesion between the sealing conductor plating and the through conductor can be sufficiently maintained.

  Below, the manufacturing method of the wiring board 21 of this invention for manufacturing the wiring board 21 of this invention demonstrated using FIG. 1 is demonstrated in detail. In this embodiment, an example of manufacturing a thin wiring board having a fine through hole 7 with a diameter of 75 to 130 μm and a thickness of 0.2 to 0.8 mm is shown.

  First, as shown in FIG. 2A, for example, an insulating substrate 5 having a thickness of 0.2 to 0.8 mm in which a glass cloth 1 is impregnated with a resin 3 such as an epoxy resin, a bismaleimide triazine resin, or a polyphenylene ether resin. A double-sided copper-clad plate 25 having a copper foil 23, which is a metal foil 23 having a thickness of 5 to 20 μm, is prepared on both sides. At this time, it is desirable to use glass fiber 1 having a fiber diameter of 15 μm or less as glass cloth 1.

  The insulating base 5 has a thickness of 0.2 mm or more, so that a plurality of through holes 7 are formed by penetrating the insulating base 5 and the copper foil 23, and further, the filling resin 38 is formed. It is possible to reduce the risk of warping or deformation of the wiring board 21 due to the influence of heat, external force, etc. applied to the wiring board, making it impossible to ensure the flatness required for the wiring board. By setting the thickness to 0.8 mm or less, as will be described later, when plating is applied to the inner wall of the through hole 7 to form the through conductor 9, the plating solution is less likely to enter the through hole 7. Disconnection is not likely to occur. Therefore, it is preferable to use the insulating substrate 1 having a thickness of 0.2 to 0.8 mm. In addition, the glass cloth 1 has a fiber 1 having a diameter of 15 μm or less, which facilitates processing when the through hole 7 is formed by laser processing, facilitates processing of a predetermined hole diameter, and improves the shape.

  Further, by setting the thickness of the copper foil 23 to 5 μm or more, the copper foil 23 is etched at the time of microetching performed as a pretreatment for plating after the formation of the through hole 7, thereby causing pinholes or defects in the copper foil 23. This eliminates the possibility of increasing the adhesion and adhesion of the copper foil 23 to the plating.

  Moreover, when the thickness of the copper foil 23 is 20 μm or less, when the through hole 7 is drilled by laser processing, the through hole 7 having a diameter of 75 to 130 μm can be stably formed. Therefore, it is desirable to use a copper foil 23 having a thickness of 5 to 20 μm.

  For example, the copper foil 23 has a thickness of about 8 to 40 μm adhered to the entire upper and lower surfaces of the insulating base 5 and the copper foil 23 is made of a copper etching solution such as sulfuric acid-hydrogen peroxide solution. It is formed by etching so that the film thickness becomes uniform and processing so that the thickness becomes 5 to 20 μm.

  Next, as shown in FIG.2 (b), the through-hole 7 with a diameter of 75-130 micrometers which penetrates the double-sided copper clad board 25 is drilled by laser processing.

  Thus, when the diameter of the through hole 7 is as fine as 75 to 130 μm, the through conductor 9 and the wiring conductor 13 can be arranged with high density when forming the through conductor 9 and the wiring conductor 13. Thus, a high-density wiring board can be obtained. In addition, when the hole diameter of the through hole 7 is 75 μm or more, when forming the through conductor 9 by depositing a plating metal on the inner layer of the through hole 7, a plating solution for forming the through conductor 9 is used in the through hole 7. The inside of the through hole 7 can be satisfactorily formed, and the through conductor 9 can be satisfactorily formed inside the through hole 7. On the other hand, when the thickness is 130 μm or less, the through conductor 9 and the wiring conductor 13 can be arranged with high density. Therefore, the diameter of the through hole 7 is preferably in the range of 75 to 130 μm.

  In order to form the through-hole 7 in the insulating substrate 1 and the copper foil 23, a laser processing sheet made of a resin having a black color or a color close to black, for example, which absorbs laser beam energy satisfactorily on the copper foil 23 is used. A method of applying carbon dioxide laser light from above the laser processing sheet, or roughening the surface of the copper foil 23 with an arithmetic average roughness Ra in the range of 0.2 to 2 μm, and then the copper Either of the methods in which the foil 23 is heat-treated at an oxidizing atmosphere of 150 ° C. for about 30 minutes, and the surface is irradiated with carbon dioxide laser light as a color having a color close to black, such as black or brown, which absorbs the energy of the laser light well. Using this method, a method of piercing the through-hole 7 by irradiating a predetermined position with a carbon dioxide laser beam with an output of 8 to 30 mJ with a pulse width of 40 to 240 μsec is employed.

  At this time, by setting the output of the carbon dioxide laser beam to 8 mJ or more, the through hole 7 can be drilled to a sufficient size. Moreover, the hole diameter of the through-hole 7 in the insulated substrate 1 can be accurately formed by setting it as 30 mJ or less. Therefore, it is preferable that the carbon dioxide laser beam to be irradiated has an output of 8 to 30 mJ and a pulse width of 40 to 240 μsec.

  In addition, in order to make the through-hole 7 have a shape that expands toward both the upper and lower surfaces, when drilling by laser processing, the energy per laser beam and the number of shots may be adjusted.

  When the through hole 7 is formed using laser light in such a process, a carbonized layer (not shown) is formed on the inner wall of the through hole 7 by heat. Moreover, even if it is not carbonized, the resin around the wall surface of the through-hole 7 and the fiber 3 in the vicinity of the wall surface of the through-hole 7 is altered by heat and easily removed.

  Then, the carbonized layer and the altered layer formed on the inner wall of the through-hole 7 are removed by roughening using, for example, a roughening solution composed of a potassium permanganate solution or a sodium permanganate solution, thereby removing the carbonized layer or the altered layer shown in FIG. The double-sided copper-clad board 25 from which the carbonized layer and the altered layer shown in the partial cross-sectional view are removed is obtained.

  The periphery of the fiber 1 in contact with the inner wall of the through-hole 7 of the double-sided copper-clad plate 25 is removed, and a divergence portion A is formed.

  Next, as shown in FIG. 3 (d), after removing the carbonized layer and the altered layer, the inside of the through hole 7 and the surface of the metal foil 23 are electroless plated copper plated (not shown) and electrolytic copper plated layer. (Not shown) are sequentially deposited to form the sealing conductor 11 in the divergence portion A, the through conductor 9 is formed in the through hole 7, and the thickness of the copper foil 23 is also 1 to 3 μm. The electroless copper plating layer and the electrolytic copper plating layer having a thickness of 20 to 30 μm are sequentially deposited to form a plating layer.

  Thus, since the sealing conductor 11 and the through conductor 9 can be formed of the same metal by forming the sealing conductor 11 and the through conductor 9 at the same time, a difference in thermal expansion coefficient between the sealing conductor 11 and the through conductor 9 can be obtained. Therefore, the wiring board is excellent in reliability. Also, since only one process is required, the process cost can be reduced.

  At this time, the carbonized layer 17 is removed from the inner wall of the through-hole 7, and further, the metal foil 23 at the periphery of the through-hole and the ultrathin portion of the surface layer where the adhesion strength of the insulating substrate 1 at the periphery of the through-hole is reduced are removed in advance. As a result, the through conductor 9 and the through hole 7, and the through hole peripheral wiring layer 14 and the insulating substrate 1 can be firmly bonded.

  In order to deposit the electroless copper plating layer, for example, a palladium active solution containing ammonium chloride-based palladium acetate is used to expose the inner wall of the through-hole 7, the exposed portion of the insulating substrate 1 at the periphery of the through-hole, and copper. A palladium catalyst may be attached to the surface of the foil 23, and an electroless copper plating layer may be deposited thereon using a copper sulfate-based electroless copper plating solution. At this time, since the diameter of the through-hole 7 is increased toward the outside at the opening of the double-sided copper-clad plate 15, the electroless copper plating solution satisfactorily enters the through-hole 7, and as a result, the electroless A copper plating layer can be satisfactorily deposited to a substantially uniform thickness.

  Moreover, as an electrolytic copper plating solution for depositing the electrolytic copper plating layer, for example, a copper sulfate-based electrolytic copper plating solution may be used. At this time, since the diameter of the through hole 7 is increased toward the outside at the opening of the double-sided copper clad plate 25, the electrolytic copper plating solution enters the through hole 7 favorably, and as a result, the through hole 7 The inside can be satisfactorily filled with electrolytic copper plating.

  Next, as shown in FIG. 3 (e), the embedded resin 27 is filled in the through hole 7a formed by the through conductor 9 formed in the through hole 7 and cured, and then the resin shown in FIG. ), The surface of the double-sided copper-clad plate 25 in which the hole filling resin 27 is embedded is polished and flattened.

  By this polishing, unnecessary portions of the hole filling resin 27 are removed, and the thickness of the conductor layer formed on the surface of the double-sided copper-clad plate 25 can be set to a predetermined thickness. In the polishing step, polishing and copper etching are alternately repeated a plurality of times to remove unnecessary portions of the hole-filling resin 27, and the thickness of the conductor layer formed on the surface of the double-sided copper clad plate 25 is set to a predetermined thickness. . Rather than removing unnecessary portions of the hole-filling resin 27 only by polishing and making the thickness of the conductor layer formed on the surface of the double-sided copper-clad plate 25 a predetermined thickness, polishing and copper etching are performed alternately. The working time is shortened, and the thickness of the conductor layer formed on the surface of the double-sided copper-clad plate 25 becomes more uniform. As the copper etching solution, a mixed solution of sulfuric acid-hydrogen peroxide solution or an aqueous solution of ammonium persulfate is desirable, and etching with a uniform copper thickness can be performed.

  Next, for example, as shown in FIG. 4 (f), a conductor 29 is formed by plating on the surface of the flattened double-sided copper clad plate 25. Finally, as shown in FIG. The wiring conductor 13 is formed by removing unnecessary portions of the conductor layer formed on the surface of the double-sided copper clad plate 25 by a known subtractive method, semi-additive method, or the like.

  Furthermore, when a buildup wiring board is manufactured by laminating a buildup resin layer and a buildup wiring layer on the main surface of such a wiring board, a wiring board as shown in FIG. 1 can be obtained.

  That is, according to the present invention, a highly reliable wiring board in which the through hole wall surface and the through conductor are firmly connected can be easily manufactured.

  In the above-described embodiment, the through hole 7 has a diameter of 75 to 130 μm and a thickness of 0.2 to 0.8 mm as an example. However, the present invention is not limited to the above-described embodiment. Needless to say, various modifications can be made without departing from the scope of the present invention.

  Moreover, in the above-mentioned Example, although the through-hole 7 was formed by laser processing, when the through-hole 7 is formed by drilling, it cannot be overemphasized that the same effect is acquired.

  In addition, although the example which forms the hole filling resin 27 was demonstrated, it cannot be overemphasized that it is not necessary to form the hole filling resin 27 when the inside of the through-hole 7 is completely filled by plating.

  In order to evaluate the wiring board of the present invention, a sample was prepared and the following evaluation was performed.

  The through-hole 7 was formed in the double-sided copper clad board 25 which has the copper foil 23 with a thickness of 10 micrometers on the main surface, and whose thickness is 0.4 mm with a carbon dioxide laser. Carbon dioxide laser drilling conditions were combined under the conditions of a pulse width of 160 μs, an output of 10 mJ to 25 mJ, and a condition of changing the number of shots from 4 shots to 6 shots.

  In addition, the diameter of the produced through-hole 3 was 90 micrometers, and the pitch of the through-holes 3 was 200 micrometers. Thereafter, the double-sided copper-clad plate 15 subjected to carbon dioxide laser processing was treated with an 80 ° C. roughening solution composed of a potassium permanganate solution for 5 to 8 minutes. Thereafter, a through conductor is formed on the sealing conductor between the glass cloth and the resin and the wall surface of the through hole 3 by the electroless copper plating layer and the electrolytic copper plating layer. At that time, by changing the laser condition output and the number of shots, the shape of the divergence was changed, and a sample in which the length of the sealed conductor was as shown in Table 1 was obtained.

  Thereafter, the hole filling resin 27 is buried in the through hole 3, and after the hole filling resin 27 is cured, unnecessary portions of the hole filling resin 27 are removed by polishing, and a wiring pattern is formed by a conventionally known subtracting method to form a core substrate. The test piece was obtained.

Ten samples each having a different length of the sealing conductor were prepared, and 400 through-holes were formed in each sample. A temperature cycle test and an applied moisture resistance insulation reliability test were conducted after a heat resistance test assuming mounting on a semiconductor device and printed circuit board. After the heat resistance test and the temperature cycle test, the presence or absence of a disconnection was confirmed by an electrical continuity test, and the disconnection was observed for cracks in the vicinity of the through hole. Further, after the applied moisture resistance insulation reliability test, the insulation resistance was measured, and pass / fail was judged by the insulation resistance. A sample having an insulation resistance value of 10 ⁸ Ω or higher was accepted.

  The heat resistance test assuming semiconductor device mounting and mounting on a printed circuit board was performed three times under reflow conditions in which the peak temperature was 260 ° C. and the holding time was 200 ° C. or more and 60 seconds or more. The temperature cycle test was conducted at a temperature cycle of −55 ° C./125° C. under 1000 cycles. The applied moisture resistant insulation reliability test was called HAST, and the applied voltage was 5.5V and the moisture resistant environment condition was a temperature of 130 ° C. and a humidity of 85% for 168 hours.

Further, the shape of the divergence portion, that is, the shape of the sealing conductor was measured by observing a cross section of the sample subjected to the above test.

  Sample No. in which a sealed conductor which is outside the scope of the present invention is not formed. In No. 1, 3/10 disconnection failures occurred in the heat resistance test and the electrical continuity test after the temperature cycle, all of which were cracks in the vicinity of the through hole, and the cause was peeling between the glass cloth and the through conductor. It was confirmed that the reliability was inferior.

  On the other hand, Sample No. provided with the sealing conductor of the present invention. In Nos. 2 to 9, no disconnection failure occurred in the heat resistance test and the electrical continuity test after the temperature cycle, and no insulation failure after the insulation reliability test was confirmed.

  Further, among the samples provided with the sealing conductor of the present invention, the sample No. 2 having a sealing conductor length of 25 μm was used. 10, migration was partially confirmed in adjacent through conductors.

  In addition, when these samples were observed, the divergence part was opened so that a diameter might become large toward the penetration conductor side.

It is sectional drawing which shows one form of the wiring board of this invention. It is sectional drawing which shows the manufacturing method of the wiring board of this invention. It is sectional drawing which shows the manufacturing method of the wiring board of this invention. It is sectional drawing which shows the manufacturing method of the wiring board of this invention. It is sectional drawing which shows the manufacturing method of the wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fiber, glass cloth 3 ... Resin 5 ... Insulation base | substrate 7 ... Through-hole 9 ... Through-conductor 11 ... Sealing conductor 21 ... Wiring board A ... Deviation part

Claims (12)

In a wiring board comprising: an insulating base containing at least fibers and a resin; a through hole formed in the insulating base; and a through conductor made of a metal phase formed in the through hole. A wiring board comprising: a separation portion that is separated from a resin so as to open in the through hole; and a sealing conductor is formed in the separation portion. The wiring board according to claim 1, wherein the length of the separation portion increases toward the through hole side. The wiring substrate according to claim 1, wherein the through conductor and the sealing conductor are formed of the same metal phase. 4. The wiring board according to claim 1, wherein the length of the sealing conductor is 3 to 20 [mu] m. The wiring board according to claim 1, wherein the fiber has a wire diameter of 15 μm or less. 6. The wiring board according to claim 1, wherein the fiber is a glass fiber. A step of providing a through hole in an insulating base containing at least a fiber and a resin, a step of forming a gap between the fiber of the insulating base and the resin, and a step of forming a sealing conductor in the gap And a step of forming a through conductor in the through hole. The method for manufacturing a wiring board according to claim 7, wherein the through hole is formed by laser processing. The method for manufacturing a wiring board according to claim 7 or 8, wherein a gap between the fiber and the resin is formed by allowing the through hole of the insulating base to penetrate into the roughening solution. 10. The method of manufacturing a wiring board according to claim 7, wherein ultrasonic vibration is applied when the through hole of the insulating substrate is allowed to penetrate into the roughening liquid. The method for manufacturing a wiring board according to claim 7, wherein the sealing conductor is formed by a plating method. 12. The method for manufacturing a wiring board according to claim 7, wherein the through conductor is formed by a plating method.

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