JP2005079474A - Multilayer wiring board, base therefor, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To relieve a phenomenon caused by difference in the material characteristics between the conductive substance used for interlayer continuity and an insulating layer, and to suppress the occurrence of ion migration at a boundary section in the insulating layer. <P>SOLUTION: In a base (1) for multilayer wiring boards, a through hole (4) is formed in an insulating layer (2) whose one side has a conductive layer (3) for composing a wiring pattern, and a protection insulating layer (5) is formed on the circumferential face of the through hole (4). Then, a conductive substance (6) for obtaining interlayer continuity in the conductive layer (3) is arranged in the through hole (4) inside the protection insulating layer (5). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer wiring board, a substrate for a multilayer wiring board, and a manufacturing method thereof, and more particularly to a flexible multilayer wiring board, a substrate for a flexible multilayer wiring board, and a manufacturing method thereof.

  In recent years, electronic devices have become smaller and lighter in addition to high-frequency signals, digitization, etc. Along with this, printed wiring boards to be mounted are also required to be compact and high-density mounting, and prints that meet these requirements Many multilayer wiring boards have been announced as wiring boards.

  In general, the means for interlayer connection in a multilayer wiring board is roughly divided into two types, a through hole and a via hole.

  The through hole is used to form an interlayer conductive portion by punching the substrate after multilayer lamination in a lump, and filling this hole (substrate through hole) by plating or filling a conductive composition. The number of man-hours can be reduced because the holes are made in a lump after stacking, but the interlayer conduction part must be straight in the depth direction of the substrate, so the degree of freedom of wiring is small and suitable for high-density wiring I can't say that.

On the other hand, a via hole is one in which an interlayer conductive portion is formed for each layer. In particular, an IVH (Interstitial Via Hole) type multilayer wiring board has a higher wiring density and a higher degree of freedom in wiring. Therefore, it is widely used for small electric products such as mobile phones. Typical examples of the construction method include the ALIVH construction method (see Non-Patent Document 1) manufactured by Matsushita Electronic Parts Co., Ltd. and the B ² it construction method (see Non-Patent Document 2) manufactured by DT Circuit Technology.

  Common to these methods is the build-up method. In the case of the build-up method, the build-up layer is sequentially laminated from the core layer one by one, and is built up. Since the alignment between the layers is easy, it is used for most IVH multilayer wiring boards. For these reasons, IVH multilayer wiring boards are often referred to as build-up boards.

  However, in the case of the build-up method, since the layers are sequentially laminated one by one, the circuit forming process is required for the number of layers. This causes problems such as delay in trial delivery and cost increase due to an increase in the number of manufacturing processes.

Therefore, recently, development of an IVH multilayer wiring board by a collective laminating method in which a plurality of substrates on which circuits have been formed is superposed and laminated together is becoming active. As an example thereof, there is a trade name PALAP (see Non-Patent Document 3) by Denso Corporation. In the case of this construction method, not only the manufacturing process can be greatly simplified, but also the defective layer can be replaced and removed in advance and only the good layer can be laminated, which greatly contributes to the yield improvement.
“Electronic Materials” October 1995 issue, p52-58, Seiichi Nakatani et al. “Resin multilayer substrate with all-layer IVH structure“ ALIVH ”” “Journal of Japan Institute of Electronics Packaging” Vol. 3, no. 7 (2000), p563-568, Yoshitaka Fukuoka “Thick film / thin film hybrid high-density build-up wiring board technology” “Proceedings of the 16th Electronics Packaging Conference” p67-68, Rikiya Uemura, etc. “Examination of printed circuit board recycling system using PALAP substrate”

  However, since such a multilayer wiring board is a composite of various materials, it is necessary to ensure reliability by matching the thermal characteristics and mechanical characteristics of each material to some extent. In particular, it is important to match the characteristics of the material of the insulating layer and the material of the interlayer conductive portion, but in reality, it is difficult to completely match them.

  For example, due to the difference in the coefficient of linear expansion between the material of the insulating layer constituting the via hole or the through hole and the interlayer conductive material in the via hole or the through hole, the interlayer conductive portion is cracked during the thermal shock test, or There arises a problem that the electrical resistance is greatly increased.

  In the case of a multilayer wiring board, a structure in which a large number of insulating layers are stacked is adopted. Therefore, the boundary portion of the insulating layer has a problem that the mechanical strength is weaker than that inside the insulating layer other than the boundary, and ion migration easily proceeds from there.

  The object of the present invention is to eliminate the problems of the above-mentioned conventional ones, to alleviate the phenomenon caused by the difference in material characteristics between the conductive material used for interlayer conduction and the insulating layer, and to reduce the ions at the boundary portion of the insulating layer. An object of the present invention is to provide a multilayer wiring board capable of suppressing the occurrence of migration, a substrate for multilayer wiring board, and a method for manufacturing the same.

  The present invention solves the above-mentioned problem, and the invention according to claim 1 forms a through hole in an insulating layer provided on one side with a conductive layer forming a wiring pattern, and the conductive layer is formed in the through hole. In the multilayer wiring board base material on which a conductive material for obtaining interlayer conduction is disposed, the protective wiring layer is formed on the peripheral surface of the through hole.

  According to this multilayer wiring board substrate, since the protective insulating layer is formed between the conductive substance and the insulating layer, the phenomenon caused by the difference in material characteristics between the conductive substance and the insulating layer is prevented. Can be relaxed.

  The invention according to claim 2 is the invention according to claim 1, wherein the insulating layer includes an insulating base material on which the conductive layer is provided on one side surface and an interlayer provided on the other side surface of the insulating base material. It is a base material for multilayer wiring boards composed of an adhesive layer.

  According to this multilayer wiring board substrate, a plurality of multilayer wiring board substrates can be easily joined using the interlayer adhesive layer.

  A third aspect of the present invention is the multilayer wiring board substrate according to the second aspect, wherein the protective insulating layer is formed so as to cover a boundary between the insulating substrate and the interlayer adhesive layer.

  According to this multilayer wiring board substrate, the boundary between the insulating substrate and the interlayer adhesive layer is covered with the protective insulating layer so that it does not come into direct contact with the conductive material. Therefore, the occurrence of ion migration can be suppressed.

  A fourth aspect of the present invention is the multilayer wiring according to any one of the first to third aspects, wherein the protective insulating layer is made of a material having a Young's modulus smaller than that of the insulating layer or the insulating base material. It is a base material for board.

  According to this multilayer wiring board base material, the protective insulating layer made of a material having a lower Young's modulus than the insulating layer or the insulating base material has a linear expansion between the conductive substance and the insulating layer or the insulating base material. The stress generated by the difference in coefficient can be relaxed and the resistance in the thermal shock test can be improved.

  Moreover, according to this multilayer wiring board substrate, the protective insulating layer made of a material having a lower Young's modulus than the insulating substrate is formed so as to cover the boundary between the insulating substrate and the interlayer adhesive layer. By doing so, it is possible to achieve both suppression of the occurrence of ion migration and relaxation of stress generated due to the difference in the coefficient of linear expansion between the conductive material and the insulating base material.

  A fifth aspect of the present invention is the multilayer wiring according to any one of the first to fourth aspects, wherein the protective insulating layer is made of a material having a lower dielectric constant than the insulating layer or the insulating substrate. It is a base material for board.

  According to this multilayer wiring board substrate, the protective insulating layer made of a material having a lower dielectric constant than that of the insulating layer or the insulating substrate can avoid a delay in transmission speed.

  Further, according to this multilayer wiring board substrate, the protective insulating layer is made of a material having a lower Young's modulus and a lower dielectric constant than the insulating layer or the insulating substrate. It is possible to achieve both relaxation of stress generated due to a difference in coefficient of linear expansion from the insulating layer or the insulating base material and avoidance of transmission speed delay.

  Further, according to the multilayer wiring board substrate, the protective insulating layer made of a material having a lower dielectric constant than the insulating layer or the insulating substrate is formed between the insulating layer or the insulating substrate and the interlayer adhesive layer. By being formed so as to cover the boundary, it is possible to achieve both suppression of ion migration and avoidance of transmission speed delay.

  Furthermore, according to this multilayer wiring board substrate, the protective insulating layer made of a material having a lower Young's modulus and a lower dielectric constant than the insulating layer or the insulating substrate is provided with the insulating layer or the insulating substrate. Is formed so as to cover the boundary between the conductive layer and the interlayer adhesive layer, thereby suppressing the occurrence of ion migration and mitigating the stress generated by the difference in linear expansion coefficient between the conductive material and the insulating layer or insulating base material. Both avoidance of transmission rate delay can be realized.

  The invention according to claim 6 is the substrate according to any one of claims 1 to 5, wherein the insulating layer or the insulating substrate is a substrate for a multilayer wiring board composed of a flexible resin such as polyimide. is there.

  According to this multilayer wiring board substrate, the insulating layer or the insulating substrate made of a flexible resin such as polyimide can be easily bent. In particular, the protective insulating layer is made of a material having a lower Young's modulus than that of the insulating layer or the insulating base material, so that the conductive material is peeled off from the insulating layer or the insulating base material when bent, and the conductive material. Can be prevented from breaking.

  The invention according to claim 7 provides a plurality of the multilayer wiring board substrates according to any one of claims 1 to 6, wherein the conductive substance of any multilayer wiring board substrate is the multilayer wiring board. The multilayer wiring board is positioned and joined to each other so as to establish interlayer conduction between the conductive layer of the substrate for use and the conductive layer of the other substrate for multilayer wiring board in contact with the conductive substance.

  According to this multilayer wiring board, it is possible to suppress the occurrence of ion migration by forming the protective insulating layer on the peripheral surface of the through hole.

  According to an eighth aspect of the present invention, a through hole is formed in an insulating layer provided with a conductive layer forming a wiring pattern on one side, and a conductive substance for obtaining interlayer conduction of the conductive layer is disposed in the through hole. And a manufacturing method of a substrate for a multilayer wiring board in which a protective insulating layer is formed on a peripheral surface of the through hole, the step of forming the through hole in the insulating layer, and the peripheral surface of the through hole A method for manufacturing a substrate for a multilayer wiring board, comprising: forming a protective insulating layer; and filling the through hole with the conductive substance inside the protective insulating layer.

  According to this method for manufacturing a multilayer wiring board substrate, after forming a through hole in the insulating layer, a protective insulating layer is formed on the peripheral surface of the through hole, and then conductive inside the through hole inside the protective insulating layer. The base material for multilayer wiring boards can be manufactured by filling the functional material.

  The invention according to claim 9 is the invention according to claim 8, wherein in the step of forming the protective insulating layer, the through-hole is filled with a protective insulating layer forming material having a property of being hardened by volume shrinkage by heating. And a step of coating the protective insulating layer on the peripheral surface of the through hole by heating and shrinking the volume of the protective insulating layer forming material to form a substrate for a multilayer wiring board.

  According to this multilayer wiring board substrate manufacturing method, a multilayer wiring board substrate can be easily manufactured using a printing method.

  As described above, according to the present invention, a through hole is formed in an insulating layer having a conductive layer forming a wiring pattern on one side, and a conductive substance for obtaining interlayer conduction of the conductive layer is disposed in the through hole. Since the protective insulating layer is formed on the peripheral surface of the through hole, the phenomenon caused by the difference in material characteristics between the conductive material used for interlayer conduction and the insulating layer can be alleviated, and the boundary portion of the insulating layer This has the effect of suppressing the occurrence of ion migration.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an embodiment of a multilayer wiring board substrate according to the present invention, and this multilayer wiring board substrate 1 will be described together with its manufacturing method.

  First, as shown to Fig.1 (a), the polyimide base material 11 with the single-sided copper foil in which the copper foil 31 was adhere | attached on the single side | surface of the polyimide base material 21 is prepared as a starting material.

  Next, by etching the copper foil 31 using a subtractive method on the polyimide substrate 11 with a single-sided copper foil, the conductive layer 3 forming the wiring pattern is formed on one side as shown in FIG. The circuit-formed wiring board 12 provided is prepared.

  Instead of this method, for example, it is also possible to use a polyimide base material having no copper foil on both sides as a starting material, and to form a circuit using this additive base material using an additive method or a semi-additive method.

  Next, as shown in FIG.1 (c), the interlayer contact bonding layer 22 is formed in the surface on the opposite side to the conductive layer 3 which makes the wiring pattern of the polyimide base material 21 in the wiring board 12 by which the circuit was formed. As the interlayer adhesive layer 22, a thermoplastic polyimide provided with a thermosetting function can be used. In addition to this, for example, a thermosetting resin typified by epoxy or the like, or a thermoplastic resin such as thermoplastic polyimide may be used as the interlayer adhesive layer.

  And what combined the polyimide base material 21 and the interlayer adhesion layer 22 comprises the insulating layer 2 of this base material 1 for multilayer wiring boards. That is, FIG. 1C shows the insulating layer 2 having the conductive layer 3 forming the wiring pattern on one side.

  Next, as shown in FIG. 1 (d), a through hole 4 penetrating the interlayer adhesive layer 22 and the polyimide base material 21 is formed at a position corresponding to the conductive layer 3 of the insulating layer 2. The through hole 4 is a via hole, and can be formed by performing desmearing by performing soft etching by plasma irradiation after drilling with a UV-YAG laser.

  Instead of the UV-YAG laser, for example, a carbon dioxide laser, an excimer laser, or the like can be used to process at higher speed. Further, as a desmear method, wet desmear using a permanganate is very common and can be used.

  From FIG. 1D, the via hole 4 is formed by the polyimide base material 21 and the interlayer adhesive layer 22, and a boundary 23 between different materials (the polyimide base material 21 and the interlayer adhesive layer 22) is present in the via hole 4. You can see that it exists.

  Next, as shown in FIG. 1E, a protective insulating layer 5 is formed on the peripheral surface of the via hole 4. That is, first, necessary masking is performed, and the via hole 4 is filled by squeezing a THF (tetrahydrofuran) solution of thermoplastic polyimide by a printing method.

  Since the THF (tetrahydrofuran) solution of thermoplastic polyimide has the property that the THF (tetrahydrofuran) solution is removed by heating and shrinks in volume, the volume shrinks by filling the via hole 4 and heating. The cured thermoplastic polyimide is coated on the peripheral surface of the via hole 4.

  As the resin constituting the protective insulating layer 5, in addition to thermoplastic polyimide, any suitable resin can be used as long as it is a liquid resin such as an epoxy resin or a mixture of epoxy resins.

  However, the protective insulating layer 5 is preferably made of a material having a lower Young's modulus than the polyimide base material 21 and made of a material having a lower Young's modulus than the interlayer adhesive layer 22 after bonding. Is preferred.

  The protective insulating layer 5 is preferably made of a material having a lower dielectric constant than that of the polyimide base material 21 and is made of a material having a lower dielectric constant than that of the interlayer adhesive layer 22 after bonding. Is preferred.

  Next, as shown in FIG. 1 (f), the inner hole of the protective insulating layer 5 is filled with silver or a silver paste as the conductive material 6, and is cured by heating. As the conductive material 6 used for filling the hole, various conductive compositions can be used. For example, various metal pastes such as copper paste, carbon paste, and nickel paste can be used.

  The substrate 1 for the multilayer wiring board is thus completed. As shown in FIG. 1 (f), the multilayer wiring board substrate 1 has a protective insulating layer 5 formed between the conductive material 6 and the insulating layer 2 (polyimide substrate 21 and interlayer adhesive layer 22). Therefore, the phenomenon caused by the difference in material characteristics between the conductive substance 6 and the insulating layer 2 can be mitigated by the protective insulating layer 5.

  In addition, the multilayer wiring board substrate 1 is not in direct contact with the conductive material 6 because the boundary 23 between the polyimide substrate 21 and the interlayer adhesive layer 22 is covered with the protective insulating layer 5. Therefore, the occurrence of ion migration can be suppressed.

  Further, the substrate 1 for multilayer wiring board has a difference in linear expansion coefficient between the conductive material 6 and the polyimide base material 21 because the protective insulating layer 5 made of a material having a lower Young's modulus than the polyimide base material 21 is used. Can relieve the stress generated by the heat resistance and improve the resistance in the thermal shock test.

  Similarly, the protective insulating layer 5 made of a material having a lower Young's modulus than the bonded interlayer adhesive layer 22 is generated due to a difference in linear expansion coefficient between the conductive material 6 and the bonded interlayer adhesive layer 22. The stress can be relaxed and the resistance in the thermal shock test can be improved.

  Further, in this multilayer wiring board substrate 1, the protective insulating layer 5 made of a material having a lower dielectric constant than the polyimide substrate 21 can avoid a delay in transmission speed.

  Similarly, the protective insulating layer 5 made of a material having a lower dielectric constant than the interlayer adhesive layer 22 after bonding can avoid a delay in transmission speed.

  FIG. 2 shows a multilayer wiring board constructed by laminating a plurality of (two in the figure) substrate 1 for multilayer wiring board produced as shown in FIG. 1 and a circuit-formed wiring board 12 in the lowermost layer. It is explanatory drawing shown.

  In this multilayer wiring board 8, the conductive materials 6a and 6b of the two multilayer wiring board substrates 1a and 1b establish interlayer conduction between the conductive layers 3a and 3b, and the circuit-formed wiring board 12 After being aligned so as to obtain interlayer conduction with the conductive layer 3, they are superposed and joined and formed by heating and pressurizing under a vacuum degree of 1 kPa or less by a vacuum hot press.

  For this alignment, it is possible to adopt a pin alignment method. However, in this case, a space for opening a pin hole is required, which is not preferable. For this reason, it is preferable to employ alignment by image recognition.

  When the multilayer wiring board 8 thus manufactured was subjected to a migration test under the conditions of 85 ° C., 85 RH%, and 30 V, the insulation resistance was maintained at 1 GΩ or more after 1000 hours or more when the via pitch was 500 μm. did.

  On the other hand, when a similar migration test was performed on a multilayer wiring board manufactured using a conventional multilayer wiring board base material in which a protective insulating layer was not formed on the peripheral surface of the via hole, a via pitch was 500 μm. In this case, the insulation resistance decreased to 1 GΩ or less in about 500 hours.

  Also, a multilayer wiring board 8 made of a multilayer wiring board substrate 1 having a protective insulating layer 5 made of a material having a Young's modulus smaller than that of the insulating layer 2 on the peripheral surface of the via hole 4, and such a protective insulating layer For a multilayer wiring board made of a conventional multilayer wiring board substrate that is not formed, the stress generated on the peripheral surface of the via hole is compared by a finite element method. Superiority was recognized in the multilayer wiring board 8 made of the substrate 1.

  3-5 is explanatory drawing which shows other embodiment of the multilayer wiring board by this invention, This multilayer wiring board 100 is demonstrated with the manufacturing method.

  First, as shown in FIG. 3 (a), a glass epoxy base material 111 having a double-sided copper foil with a single-sided circuit formed thereon is used as a starting material, two of them are prepared, aligned, and then an interlayer adhesive 122 is sandwiched between them. By overlapping and heating and pressurizing, the multilayer wiring board substrate 101 is formed by bonding as shown in FIG.

  As the interlayer adhesive 122, an epoxy-based sheet adhesive can be used. In addition to this, it is possible to use an arbitrary adhesive such as olefin or silicon.

  Next, as shown in FIG.3 (c), the through-hole 104 is formed with a drill in the predetermined position of the base material 101 for multilayer wiring boards. The through hole 104 is a through hole.

  Next, as shown in FIG. 4D, an epoxy resin is applied to the peripheral surface of the through-hole 104 and cured by heating to form a protective insulating layer 105.

  As the resin used for the protective insulating layer 105, any other liquid resin composition such as thermoplastic polyimide dispersed in an organic solvent, polyamic acid that is a precursor of polyimide, or a mixture of epoxies may be used. Can be used.

  Next, as shown in FIG. 4E, a silver paste as a conductive composition 106 is filled in the hole inside the protective insulating layer 105 by a printing method, and is cured by heating. As the conductive composition 106 used for filling the holes, for example, various metal pastes such as a copper paste, a carbon paste, and a nickel paste can be used.

  When the conductive composition 106 protrudes to the surface of the multilayer wiring board substrate 101, the protruding conductive composition 106 is buffed, as shown in FIG. 4F, for the multilayer wiring board. The surface of the substrate 101 is flattened.

  Next, as shown in FIG. 5G, a copper plating layer 107 is deposited on the surface of the multilayer wiring board substrate 101 by electrolytic plating. Thereby, the adhesion between the copper foil 131 and the conductive composition 106 becomes stronger.

  Finally, as shown in FIG. 5 (h), the multilayer wiring board 100 is manufactured by performing circuit formation by etching the copper foil 131 on the surface.

  Also for the multilayer wiring board 100, an insulating layer (two polyimide base materials 121 and an interlayer adhesive sandwiched between them) is formed on the peripheral surface of the through-hole 104 by a finite element method, similarly to the multilayer wiring board 8 shown in FIG. When the stress generated on the peripheral surface of the through hole 104 was compared with and without the protective insulating layer 105 having a Young's modulus smaller than that of 122), superiority was recognized when the protective insulating layer 105 was present.

It is explanatory drawing which shows one Embodiment of the base material for multilayer wiring boards by this invention. It is explanatory drawing which shows one Embodiment of the multilayer wiring board by this invention. It is explanatory drawing which shows other embodiment of the multilayer wiring board by this invention. It is explanatory drawing which shows other embodiment of the multilayer wiring board by this invention. It is explanatory drawing which shows other embodiment of the multilayer wiring board by this invention.

Explanation of symbols

1,101 Substrate for multilayer wiring board 2,122 Insulating layer 3,103 Conductive layer 4 Through hole (via hole)
5,105 Protective insulating layer 6 Conductive material 8,100 Multilayer wiring board 104 Through hole (through hole)
106 conductive composition

Claims (9)

In a multilayer wiring board substrate in which a through hole is formed in an insulating layer provided on one side with a conductive layer forming a wiring pattern, and a conductive material for obtaining interlayer conduction of the conductive layer is disposed in the through hole.
A base material for a multilayer wiring board, wherein a protective insulating layer is formed on a peripheral surface of the through hole.   The said insulating layer is comprised with the insulating base material in which the said conductive layer was provided in one side surface, and the interlayer contact bonding layer provided in the other side surface of this insulating base material. Base material for multilayer wiring boards.   3. The multilayer wiring board substrate according to claim 2, wherein the protective insulating layer is formed so as to cover a boundary between the insulating substrate and the interlayer adhesive layer.   The base material for a multilayer wiring board according to any one of claims 1 to 3, wherein the protective insulating layer is made of a material having a Young's modulus smaller than that of the insulating layer or the insulating base material.   The base material for a multilayer wiring board according to any one of claims 1 to 4, wherein the protective insulating layer is made of a material having a dielectric constant lower than that of the insulating layer or the insulating base material.   6. The multilayer wiring board substrate according to claim 1, wherein the insulating layer or the insulating substrate is made of a flexible resin such as polyimide.   A plurality of multilayer wiring board substrates according to any one of claims 1 to 6, wherein the conductive substance of any multilayer wiring board substrate is the conductive layer of the multilayer wiring board substrate. A multilayer wiring board characterized in that it is positioned and joined to each other so as to establish interlayer conduction with a conductive layer of another multilayer wiring board substrate that is in contact with the conductive substance. A through hole is formed in an insulating layer having a conductive layer forming a wiring pattern on one side, and a conductive material for obtaining interlayer conduction of the conductive layer is disposed in the through hole, and the peripheral surface of the through hole A method for producing a multilayer wiring board substrate on which a protective insulating layer is formed,
Forming the through hole in the insulating layer;
Forming the protective insulating layer on the peripheral surface of the through hole;
Filling the through hole with the conductive material inside the protective insulating layer;
The manufacturing method of the base material for multilayer wiring boards characterized by including this. The step of forming the protective insulating layer includes:
Filling the through-hole with a protective insulating layer forming material having a property of shrinking and curing by heating; and
Coating the protective insulating layer on the peripheral surface of the through hole by heating the protective insulating layer forming material and volume shrinkage hardening; and
The manufacturing method of the base material for multilayer wiring boards of Claim 8 characterized by the above-mentioned.

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