JP4863559B2 - Printed wiring board and printed wiring board manufacturing method - Google Patents

Description

【０１０３】
Steam試験は、蒸気に当て湿度１００％に保った。また、ＨＡＳＴ試験では、相対湿度１００％、印加電圧１．３Ｖ、温度１２１℃で１００時間放置した。ＴＳ試験では、−１２５℃で３０分、５５℃で３０分放置する試験を１０００回線り返した。
【０１０４】
上記信頼性試験において、チップコンデンサを内蔵するプリント配線板においても、既存のコンデンサ表面実装形と同等の信頼性が達成できていることが分かった。また、上述したように、ＴＳ試験において、セラミックから成るコンデンサ２０と、樹脂からなるコア基板３０及び接着層４０との熱膨張率の違いから、内部応力が発生しても、チップコンデンサ２０と接着層４０との間で剥離、コア基板３０及び接着層４０にクラックが発生せず、長期に渡り高い信頼性を達成できることが判明した。
【０１０５】
【発明の効果】
本願発明の構造により、インダクタンスを起因とする電気特性の低下することはない。
また、コンデンサのメタライズからなる電極の表面に導電性ペーストが塗布されてるため、メタライズからなり表面の抵抗の高い電極の電気接続性を改善することができる。また、メタライズからなる電極は、表面に凹凸があり、導電性接着剤で直接接続を取っても、完全に密着することができないが、導電性ペーストにより凹凸を無くすことができ、密着性を高め、接続抵抗を下げることができる。また、メタライズからなる電極が、周囲の樹脂層と導電性ペーストを介して接触するため、電極と樹脂層との熱膨張差による応力の発生を抑え、樹脂層のクラックや剥離が無くなる。
また、コンデンサを銅によって被覆されている場合にも、マイグレーションの発生を防止することができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係るプリント配線板の製造工程図である。
【図２】本発明の第１実施形態に係るプリント配線板の製造工程図である。
【図３】本発明の第１実施形態に係るプリント配線板の製造工程図である。
【図４】本発明の第１実施形態に係るプリント配線板の製造工程図である。
【図５】本発明の第１実施形態に係るプリント配線板の製造工程図である。
【図６】本発明の第１実施形態に係るプリント配線板の製造工程図である。
【図７】第１実施形態に係るプリント配線板の断面図である。
【図８】第１実施形態に係るプリント配線板の断面図である。
【図９】第１実施形態の第１改変例に係るプリント配線板の断面図である。
【図１０】第１実施形態の第２改変例に係るプリント配線板の断面図である。
【図１１】第１実施形態の第３改変例に係るプリント配線板の断面図である。
【図１２】（Ａ）は、第１実施形態のチップコンデンサの断面図であり、（Ｂ）は、第１実施形態の第１改変例のチップコンデンサの断面図である。
【図１３】ＩＣチップへの供給電圧と時間との変化を示すグラフである。
【図１４】（Ａ）、（Ｂ）、（Ｃ）、（Ｄ）は、第２実施形態のプリント配線板のチップコンデンサの平面図である。
【図１５】第２実施形態に係るプリント配線板のチップコンデンサの平面図である。
【図１６】第２実施形態の改変例に係るプリント配線板のチップコンデンサの平面図である。
【図１７】（Ａ）及び（Ｂ）は、従来技術に係るプリント配線板のループインダクタンスの説明図である。
【符号の説明】
１０ プリント配線板
２０ チップコンデンサ
２１ 第１電極
２２ 第２電極
２３ 誘電体
２３ａ 粗化面
２３ｂ ポイリミド膜
２６ 導電性ペースト
２８ａ 無電解銅めっき膜
２８ｂ 電解銅めっき膜
２８ 複合金属膜
２５ 収容層
３０ コア基板
３１ 収容層
３１ａ キャビティ
３４ 導電性接着剤
３６ スルーホール
４０ 接続層
４２ 回路パターン
４３ 非貫通孔
４６ バイアホール
６０ 層間樹脂絶縁層
６６ バイアホール
６８ 導体回路
８４ 導電性ピン
９０ ＩＣチップ
９４ ドータボード[0001]
BACKGROUND OF THE INVENTION
The present invention also relates to a printed wiring board on which an electronic component such as an IC chip is placed, and particularly relates to a printed wiring board with a built-in capacitor.
[0002]
[Prior art]
Usually, in the computer, the wiring distance between the power source and the IC chip is long, and the loop inductance of this wiring portion is very large. For this reason, the fluctuation of the IC drive voltage at the time of high-speed operation becomes large, which may cause an IC malfunction. It is also difficult to stabilize the power supply voltage. For this reason, a capacitor is mounted on the surface of the printed wiring board as an auxiliary to power supply.
[0003]
That is, the loop inductance that causes voltage fluctuation is the wiring length from the power source shown in FIG. 17A to the power source terminal 272P of the IC chip 270 via the power source line in the printed wiring board 300, and the ground terminal of the IC chip 270. It depends on the wiring length from 272E to the power supply through the ground wire in the printed wiring board 300 from the power supply. In addition, the loop inductance can be reduced by narrowing the distance between the power lines and the ground lines, for example, between the wirings through which currents flow in opposite directions.
For this reason, as shown in FIG. 17B, by mounting a chip capacitor 298 on the printed wiring board 300, the inside of the printed wiring board 300 connecting the IC chip 270 and the chip capacitor 292 serving as a power supply source. The loop inductance is reduced by shortening the wiring length between the power line and the grounding wire and reducing the wiring interval.
[0004]
[Problems to be solved by the invention]
However, the magnitude of the voltage drop causing the IC drive voltage fluctuation depends on the frequency. For this reason, as the driving frequency of the IC chip increases, the loop inductance cannot be reduced even if the chip capacitor is mounted on the surface as described above with reference to FIG. It became difficult to keep it down.
[0005]
For this reason, this inventor had the idea of accommodating a chip capacitor in a printed wiring board. As a technique for embedding a capacitor in a substrate, JP-A-6-326472, JP-A-7-263619, JP-A-10-256429, JP-A-11-45955, JP-A-11-126978, and JP-A-11-31868 are disclosed. Etc.
[0006]
Japanese Patent Application Laid-Open No. 6-326472 discloses a technique of embedding a capacitor in a resin substrate made of glass epoxy. With this configuration, it is possible to reduce power supply noise, eliminate the need for a space for mounting a chip capacitor, and reduce the size of the insulating substrate. Japanese Patent Application Laid-Open No. 7-263619 discloses a technique for embedding a capacitor in a substrate such as ceramic or alumina. With this configuration, by connecting between the power supply layer and the ground layer, the wiring length is shortened and the wiring inductance is reduced.
[0007]
However, the above-described technology cannot reduce the distance from the IC chip to the capacitor so much, and in the further high frequency region of the IC chip, the inductance cannot be reduced as currently required. In particular, in the resin-made multilayer build-up wiring board, due to the difference in thermal expansion coefficient between the ceramic capacitor and the resin core substrate and the interlayer resin insulation layer, the disconnection between the terminal of the chip capacitor and the via hole, Peeling occurred between the chip capacitor and the interlayer resin insulation layer, and cracks occurred in the interlayer resin insulation layer, and high reliability could not be achieved over a long period of time.
[0008]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a printed wiring board that can reduce loop inductance and has high reliability, and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, in claim 1, a printed wiring board formed by laminating a resin insulating layer and a conductor circuit on a core substrate,
The core substrate is composed of a connection layer formed of an insulating resin layer that is at least one layer and a containing layer containing a capacitor in a counterbore part,
On the surface of the electrode made of metallization of the capacitor , a conductive paste is applied with a thickness of 1 to 30 μm so as to eliminate the unevenness of the electrode made of metallization ,
A metal layer is provided on the conductive paste of the capacitor electrode;
The connection layer and the electrode of the capacitor are technically characterized by being connected via a conductive adhesive.
[0010]
It means a circuit formed by a build-up method in which an interlayer resin insulation layer is provided on a core substrate, and via holes or through holes are provided in the interlayer resin insulation layer to form a conductor circuit as a conductive layer. For them, either a semi-additive method or a full additive method can be used.
[0011]
According to the first aspect, since the capacitor is arranged in the printed wiring board, the distance between the IC chip and the capacitor is shortened, and the loop inductance can be reduced. In addition, the core substrate includes at least one connection layer and a storage layer that stores the capacitor. Since the capacitor is stored in the thick storage layer, the core substrate does not become thick, and an interlayer resin is formed on the core substrate. Even if the insulating layer and the conductor circuit are laminated, the printed wiring board is not thickened.
[0012]
Further, since the conductive paste is applied to the surface of the electrode made of the metallization of the capacitor, the electrical connectivity of the electrode made of metallization and having a high surface resistance can be improved. In addition, electrodes made of metallized have irregularities on the surface, and even if they are directly connected with a conductive adhesive, they cannot be adhered completely, but the conductive paste can eliminate irregularities and improve adhesion. The connection resistance can be lowered. In addition, since the electrode made of metallized is in contact with the surrounding resin layer via the conductive paste, the generation of stress due to the difference in thermal expansion between the electrode and the resin layer is suppressed, and the resin layer is not cracked or peeled off.
[0013]
According to the first aspect , since the metal layer is provided on the conductive paste of the electrode of the capacitor, it is possible to prevent migration at the electrode and to further reduce the connection resistance. The electrode made of metallized has irregularities on the surface, and even if it is directly connected with a conductive adhesive, it cannot be completely adhered, but by applying a conductive paste and further providing a metal layer, the irregularities can be obtained. It can be completely eliminated, adhesion can be increased, and connection resistance can be reduced.
[0014]
According to a second aspect of the present invention , a roughening process is performed on the surface of the capacitor. As a result, the adhesiveness between the ceramic chip capacitor and the adhesive layer made of resin and the interlayer resin insulating layer is increased, and the adhesive layer and the interlayer resin insulating layer peel off at the interface even when the heat cycle test is performed. There is nothing.
[0015]
According to a third aspect of the present invention , wettability improving processes such as a sealing coupling and a resin coating are applied to the surface of the capacitor. As a result, the adhesiveness between the ceramic chip capacitor and the adhesive layer made of resin and the interlayer resin insulating layer is increased, and the adhesive layer and the interlayer resin insulating layer peel off at the interface even when the heat cycle test is performed. There is nothing.
[0016]
It is desirable to fill the recess with resin. By eliminating the gap between the capacitor and the core substrate, the built-in capacitor is less likely to behave, and even if stress originating from the capacitor is generated, it can be relaxed by the filled resin. The resin also has an effect of reducing adhesion and migration between the capacitor and the core substrate.
[0017]
According to the fourth aspect of the present invention , the containing layer is made of a resin substrate in which a core material is impregnated with a resin.
[0018]
According to the first aspect of the present invention , the connection layer and the capacitor housed in the housing layer are connected via a conductive adhesive. This ensures electrical connection with the capacitor and adhesion between the capacitor and the connection layer. Conductive adhesives have conductivity and adhesive properties such as solder (Sn / Pb, Sn / Ag, Sn / Sb, Sn / Ag / Cu), conductive paste, or resin impregnated with metal particles. What is combined can be used.
[0019]
It is desirable to fill the gap between the conductive adhesive and the capacitor with resin. This is because the behavior caused by the capacitor can be relaxed and migration of the conductive adhesive can be prevented.
[0020]
According to the fifth aspect , since a circuit connected to the conductive adhesive is provided between the connection layer and the containing layer, the capacitor can be reliably connected through the circuit. Further, by disposing a circuit made of a metal layer between the connection layer and the containing layer, warping of the core substrate can be prevented.
[0021]
According to the sixth aspect of the present invention , the external board (daughter board, motherboard) connected to the back side of the printed wiring board and the capacitor terminal are connected via via holes provided in the connection layer and through holes formed in the core board. Is done. That is, since the through hole is formed in the containing layer that is provided with the core material and is difficult to process and the capacitor terminal and the external substrate are not directly connected, the connection reliability can be improved.
[0022]
According to the seventh aspect of the present invention , the wiring for connecting the IC chip and the external substrate is disposed between the capacitors, and the signal line does not pass through the capacitor. Therefore, reflection due to impedance discontinuity due to the high dielectric and propagation due to passage through the high dielectric There is no delay. By providing a capacitor for power supply, it is possible to easily supply large power to the IC chip. Further, it is possible to reduce noise of signal propagation on the printed wiring board.
[0023]
Further, by providing the connection wiring, it is possible to provide the wiring also under the capacitor. Therefore, the degree of freedom of wiring is increased, and the density and size can be reduced.
[0024]
According to the eighth aspect , in addition to the capacitor accommodated in the substrate, the capacitor is disposed on the surface. Since the capacitor is accommodated in the printed wiring board, the distance between the IC chip and the capacitor is shortened, the loop inductance can be reduced, and the power can be supplied instantaneously. Since the capacitor is disposed, a large-capacity capacitor can be attached, and a large amount of power can be easily supplied to the IC chip.
[0025]
According to the ninth aspect of the present invention , the capacitance of the capacitor on the surface is equal to or greater than the capacitance of the capacitor on the inner layer, so that there is no shortage of power supply in the high frequency region, and a desired IC chip operation is ensured.
[0026]
According to the tenth aspect of the present invention , since the inductance of the capacitor on the surface is equal to or larger than the inductance of the capacitor on the inner layer, there is no shortage of power supply in the high frequency region, and the desired operation of the IC chip is ensured.
[0027]
According to the eleventh aspect , the resin is filled between the counterbore part of the core substrate and the capacitor, and the thermal expansion coefficient of the resin is set smaller than that of the core substrate, that is, close to the capacitor made of ceramic. For this reason, in the heat cycle test, even if an internal stress occurs due to a difference in thermal expansion coefficient between the core substrate and the capacitor, cracks, peeling, and the like hardly occur in the core substrate, and high reliability can be achieved. In addition, migration can be prevented.
[0028]
According to the twelfth aspect , since the chip capacitor in which the electrode is formed on the inner side of the outer edge is used, the external electrode can be made large even if conduction is made through the via hole, and the allowable range of alignment is widened.
[0029]
According to the thirteenth aspect , since a capacitor having electrodes formed in a matrix is used, a large chip capacitor can be easily accommodated in the core substrate. As a result, the capacitance can be increased, and the electrical problem can be solved. Further, even after various thermal histories, the printed wiring board is hardly warped.
[0030]
In the fourteenth aspect , a plurality of chip capacitors may be connected to the capacitor. Thereby, the capacitance can be adjusted as appropriate, and the IC chip can be operated appropriately.
[0031]
The method for producing a printed wiring board according to claim 15 has at least the following steps (a) to (c) as technical features:
(A) A conductive paste having a thickness of 1 to 30 μm on a resin plate having a circuit pattern formed on one side or both sides, on the metallized electrode on the circuit pattern via an adhesive material so as to eliminate the unevenness of the electrode made of metallized. And connecting a capacitor provided with a metal layer on the conductive paste;
(B) a step of attaching a resin substrate on which a cavity for accommodating the capacitor is formed to the resin plate to form a core substrate;
(C) A step of forming a via hole by providing an opening reaching the circuit pattern in the resin plate.
According to the printed wiring board manufacturing method of the fifteenth aspect , the chip capacitor can be accommodated in the core substrate, and a printed wiring board with reduced loop inductance can be provided.
[0033]
Further, since the conductive paste is applied to the surface of the electrode made of the metallization of the capacitor, the electrical connectivity of the electrode made of metallization and having a high surface resistance can be improved. In addition, electrodes made of metallized have irregularities on the surface, and even if they are directly connected with a conductive adhesive, they cannot be adhered completely, but the conductive paste can eliminate irregularities and improve adhesion. The connection resistance can be lowered. In addition, since the electrode made of metallized is in contact with the surrounding resin layer via the conductive paste, the generation of stress due to the difference in thermal expansion between the electrode and the resin layer is suppressed, and the resin layer is not cracked or peeled off.
[0034]
In the method for manufacturing a printed wiring board according to claim 16, since a core substrate is formed by applying a pressure to both surfaces of a resin substrate containing a capacitor and a resin plate to form a core substrate, the interlayer is provided with high reliability. A resin insulating layer and a conductor circuit can be laminated.
[0035]
In the printed wiring board manufacturing method according to claim 17 , since the through-hole between the IC chip and the external substrate is disposed between the capacitors and the signal line does not pass through the capacitor, reflection due to impedance discontinuity due to a high dielectric, and Propagation delay due to passing through the high dielectric does not occur. By providing a capacitor for power supply, it is possible to easily supply large power to the IC chip.
[0036]
In the present invention, the thermosetting resin sheet used as an interlayer resin insulation layer and a connection layer is a resin in which particles soluble in an acid or an oxidant (hereinafter referred to as soluble particles) are poorly soluble in an acid or an oxidant (hereinafter, poorly soluble). Resin).
As used herein, the terms “poorly soluble” and “soluble” refer to those having a relatively fast dissolution rate as “soluble” for convenience when immersed in a solution of the same acid or oxidizing agent for the same time. A relatively slow dissolution rate is referred to as “slightly soluble” for convenience.
[0037]
Examples of the soluble particles include resin particles soluble in an acid or an oxidizing agent (hereinafter, soluble resin particles), inorganic particles soluble in an acid or an oxidizing agent (hereinafter, soluble inorganic particles), and a metal soluble in an acid or an oxidizing agent. Examples thereof include particles (hereinafter, soluble metal particles). These soluble particles may be used alone or in combination of two or more.
[0038]
The shape of the soluble particles is not particularly limited, and examples thereof include spherical shapes and crushed shapes. Moreover, it is desirable that the soluble particles have a uniform shape. This is because a roughened surface having unevenness with uniform roughness can be formed.
[0039]
The average particle size of the soluble particles is preferably 0.1 to 10 μm. If it is the range of this particle size, you may contain the thing of a 2 or more types of different particle size. That is, it contains soluble particles having an average particle diameter of 0.1 to 0.5 μm and soluble particles having an average particle diameter of 1 to 3 μm. Thereby, a more complicated roughened surface can be formed and it is excellent also in adhesiveness with a conductor circuit. In the present invention, the particle size of the soluble particles is the length of the longest part of the soluble particles.
[0040]
Examples of the soluble resin particles include those made of a thermosetting resin, a thermoplastic resin, and the like, as long as the dissolution rate is higher than that of the hardly soluble resin when immersed in a solution made of an acid or an oxidizing agent. There is no particular limitation.
Specific examples of the soluble resin particles include, for example, an epoxy resin, a phenol resin, a polyimide resin, a polyphenylene resin, a polyolefin resin, a fluorine resin, and the like, and may be composed of one of these resins. And it may consist of a mixture of two or more resins.
[0041]
Moreover, as the soluble resin particles, resin particles made of rubber can be used. Examples of the rubber include polybutadiene rubber, epoxy-modified, urethane-modified, (meth) acrylonitrile-modified various modified polybutadiene rubber, carboxyl group-containing (meth) acrylonitrile-butadiene rubber, and the like. By using these rubbers, the soluble resin particles are easily dissolved in an acid or an oxidizing agent. That is, when soluble resin particles are dissolved using an acid, acids other than strong acids can be dissolved. When soluble resin particles are dissolved using an oxidizing agent, permanganese having a relatively low oxidizing power is used. Even acid salts can be dissolved. Even when chromic acid is used, it can be dissolved at a low concentration. Therefore, no acid or oxidant remains on the resin surface, and as described later, when a catalyst such as palladium chloride is applied after the roughened surface is formed, the catalyst is not applied or the catalyst is oxidized. There is nothing to do.
[0042]
Examples of the soluble inorganic particles include particles composed of at least one selected from the group consisting of aluminum compounds, calcium compounds, potassium compounds, magnesium compounds, and silicon compounds.
[0043]
Examples of the aluminum compound include alumina and aluminum hydroxide. Examples of the calcium compound include calcium carbonate and calcium hydroxide. Examples of the potassium compound include potassium carbonate. Examples of the magnesium compound include magnesia, dolomite, basic magnesium carbonate and the like, and examples of the silicon compound include silica and zeolite. These may be used alone or in combination of two or more.
[0044]
Examples of the soluble metal particles include particles composed of at least one selected from the group consisting of copper, nickel, iron, zinc, lead, gold, silver, aluminum, magnesium, calcium, and silicon. Further, the surface layer of these soluble metal particles may be coated with a resin or the like in order to ensure insulation.
[0045]
When two or more kinds of the soluble particles are used in combination, the combination of the two kinds of soluble particles to be mixed is preferably a combination of resin particles and inorganic particles. Both of them have low electrical conductivity, so that the insulation of the resin film can be ensured, and the thermal expansion can be easily adjusted between the poorly soluble resin, and no crack occurs in the interlayer resin insulation layer made of the resin film. This is because no peeling occurs between the interlayer resin insulation layer and the conductor circuit.
[0046]
The poorly soluble resin is not particularly limited as long as it can maintain the shape of the roughened surface when the roughened surface is formed using an acid or an oxidizing agent in the interlayer resin insulation layer. For example, thermosetting Examples thereof include resins, thermoplastic resins, and composites thereof. Moreover, the photosensitive resin which provided photosensitivity to these resin may be sufficient. By using a photosensitive resin, a via opening can be formed in the interlayer resin insulation layer using exposure and development processes.
Among these, those containing a thermosetting resin are desirable. This is because the shape of the roughened surface can be maintained by the plating solution or various heat treatments.
[0047]
Specific examples of the hardly soluble resin include, for example, epoxy resins, phenol resins, phenoxy resins, polyimide resins, polyphenylene resins, polyolefin resins, fluororesins and the like. These resins may be used alone or in combination of two or more.
Furthermore, an epoxy resin having two or more epoxy groups in one molecule is more desirable. Not only can the aforementioned roughened surface be formed, but also has excellent heat resistance, etc., so that stress concentration does not occur in the metal layer even under heat cycle conditions, and peeling of the metal layer is unlikely to occur. Because.
[0048]
Examples of the epoxy resin include cresol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol F type epoxy resin, naphthalene type epoxy resin, Examples thereof include cyclopentadiene type epoxy resins, epoxidized products of condensates of phenols and aromatic aldehydes having a phenolic hydroxyl group, triglycidyl isocyanurate, and alicyclic epoxy resins. These may be used alone or in combination of two or more. Thereby, it will be excellent in heat resistance.
[0049]
In the resin film used in the present invention, it is desirable that the soluble particles are dispersed almost uniformly in the hardly soluble resin. A roughened surface having unevenness of uniform roughness can be formed, and even if a via or a through hole is formed in a resin film, adhesion of a metal layer of a conductor circuit formed thereon can be secured. Because. Moreover, you may use the resin film containing a soluble particle only in the surface layer part which forms a roughening surface. As a result, since the portion other than the surface layer portion of the resin film is not exposed to the acid or the oxidizing agent, the insulation between the conductor circuits via the interlayer resin insulation layer is reliably maintained.
[0050]
In the resin film, the blending amount of the soluble particles dispersed in the hardly soluble resin is preferably 3 to 40% by weight with respect to the resin film. When the blending amount of the soluble particles is less than 3% by weight, a roughened surface having desired irregularities may not be formed. When the blending amount exceeds 40% by weight, the soluble particles are dissolved using an acid or an oxidizing agent. In addition, the resin film is melted to the deep part of the resin film, and the insulation between the conductor circuits through the interlayer resin insulating layer made of the resin film cannot be maintained, which may cause a short circuit.
[0051]
The resin film preferably contains a curing agent, other components and the like in addition to the soluble particles and the hardly soluble resin.
Examples of the curing agent include imidazole curing agents, amine curing agents, guanidine curing agents, epoxy adducts of these curing agents, microcapsules of these curing agents, triphenylphosphine, and tetraphenylphosphorus. And organic phosphine compounds such as nium tetraphenylborate.
[0052]
The content of the curing agent is desirably 0.05 to 10% by weight with respect to the resin film. If it is less than 0.05% by weight, since the resin film is not sufficiently cured, the degree of penetration of the acid and the oxidant into the resin film increases, and the insulating properties of the resin film may be impaired. On the other hand, if it exceeds 10% by weight, an excessive curing agent component may denature the composition of the resin, which may lead to a decrease in reliability.
[0053]
Examples of the other components include fillers such as inorganic compounds or resins that do not affect the formation of the roughened surface. Examples of the inorganic compounds, for example, silica, alumina, dolomite and the like. Examples of the resin include polyimide resin, polyacrylic resin, polyamideimide resin, polyphenylene resin, Mera Mi down resin, olefin resin or the like can be mentioned It is done. By containing these fillers, it is possible to improve the performance of the printed wiring board by matching the thermal expansion coefficient, improving heat resistance, and chemical resistance.
[0054]
Moreover, the said resin film may contain the solvent. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and aromatic hydrocarbons such as ethyl acetate, butyl acetate, cellosolve acetate, toluene, and xylene. These may be used alone or in combination of two or more.
[0055]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
First, the configuration of the printed wiring board according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 7 shows a cross section of the printed wiring board 10, and FIG. 8 shows a state in which the IC chip 90 is mounted on the printed wiring board 10 shown in FIG.
[0056]
As shown in FIG. 7, the printed wiring board 10 includes a chip capacitor 20, a core substrate 30 that houses the chip capacitor 20, and an interlayer resin insulating layer 60 that constitutes the build-up layers 80A and 80B. The core substrate 30 includes an accommodation layer 31 that accommodates the capacitor 20 and a connection layer 40. A via hole 46 and a conductor circuit 48 are formed in the connection layer 40, and a via hole 66 and a conductor circuit 68 are formed in the interlayer resin insulation layer 60. In the present embodiment, the buildup layer is composed of one interlayer resin insulation layer 60, but the buildup layer can be composed of a plurality of interlayer resin insulation layers.
[0057]
As shown in FIG. 8, bumps 76 for connecting to pads 92S1, 92S2, 92P1, and 92P2 of the IC chip 90 are formed in the via holes 66 of the upper buildup layer 80A. On the other hand, in the via hole 66 of the lower buildup layer 80B, bumps 76 for connecting to the pads 96S1, 96S2, 96P1, and 96P2 of the daughter board 94 are disposed. A through hole 36 is formed in the core substrate 30.
[0058]
As shown in FIG. 12, the chip capacitor 20 includes a first electrode 21, a second electrode 22, and a dielectric 23 sandwiched between the first and second electrodes. The dielectric 23 includes a first electrode. A plurality of first conductive films 24 connected to the 21 side and second conductive films 25 connected to the second electrode 22 side are arranged to face each other. The surface of the first electrode 21 and the second electrode 22 is covered with a conductive paste 26.
[0059]
Here, the first electrode 21 and the second electrode 22 are made of Ni, Pb, or Ag metallization. The conductive paste 26 is made of a paste containing metal particles such as Cu, Ni, or Ag. Here, the particle diameter of the metal particles is preferably 0.1 to 10 μm, and particularly preferably 1 to 5 μm. As the conductive paste, an organic conductive paste in which a thermosetting resin such as an epoxy resin or a polyphenylene sulfide (PPS) resin is added to metal particles is desirable. The thickness of the conductive paste 26 is desirably 1 to 30 μm. If the thickness is less than 1 μm, the unevenness of the electrode surface cannot be eliminated. On the other hand, if the thickness exceeds 30 μm, the effect is not particularly improved. Here, a thickness of 5 to 20 μm is most desirable. It is also possible to use a paste in which two or more types of particles having different diameters are blended, and to coat two or more types of different metal pastes.
[0060]
In the first embodiment, since the conductive paste 26 is applied to the surfaces of the electrodes 21 and 22 made of metallization of the capacitor 20, the electrical connectivity of the electrodes 21 and 22 made of metallization and having high surface resistance can be improved. it can. Further, the electrodes 21 and 22 made of metallized have irregularities on the surface, and even if they are directly connected with the conductive adhesive 34, they cannot be completely adhered, but the conductive paste 26 can eliminate the irregularities. Adhesion can be increased and connection resistance can be lowered. In addition, since the electrodes 21 and 22 made of metallized are in contact with the resin filler 32 and the core substrate 30 via the conductive paste 26, due to the difference in thermal expansion between the electrodes 21 and 22 and the resin filler 32 and the core substrate 30. Generation of stress is suppressed, and peeling of the resin filler 32 and generation of cracks in the core substrate 30 are eliminated.
[0061]
The signal pad 92S2 of the IC chip 90 shown in FIG. 8 is connected to the signal pad 96S2 of the daughter board 94 via the bump 76-conductor circuit 68-via hole 66-through hole 36-via hole 66-bump 76. It is connected. On the other hand, the signal pad 92S1 of the IC chip 90 is connected to the signal pad 96S1 of the daughter board 94 via the bump 76-via hole 66-through hole 36-via hole 66-bump 76.
[0062]
The power supply pad 92P1 of the IC chip 90 is connected to the first electrode 21 of the chip capacitor 20 via the bump 76-via hole 66-conductor circuit 48-via hole 46. On the other hand, the power supply pad 96P1 of the daughter board 94 is connected to the first electrode 21 of the chip capacitor 20 via the bump 76-via hole 66-through hole 36-conductor circuit 48-via hole 46.
[0063]
The power supply pad 92P2 of the IC chip 90 is connected to the second electrode 22 of the chip capacitor 20 via the bump 76, the via hole 66, the conductor circuit 48, and the via hole 46. On the other hand, the power supply pad 96P2 of the daughter board 94 is connected to the second electrode 22 of the chip capacitor 20 via the bump 76-via hole 66-through hole 36-conductor circuit 48-via hole 46.
[0064]
In the printed wiring board 10 of the present embodiment, the chip capacitor 20 is disposed immediately below the IC chip 90, so the distance between the IC chip and the capacitor is shortened, and power can be instantaneously supplied to the IC chip side. Become. That is, the loop length that determines the loop inductance can be shortened.
[0065]
Further, a through hole 36 is provided between the chip capacitor 20 and the chip capacitor 20 so that the signal line does not pass through the chip capacitor 20. For this reason, it is possible to prevent reflection due to impedance discontinuity due to the high dielectric material generated when the capacitor is passed and propagation delay due to passage through the high dielectric material.
[0066]
Further, an external board (daughter board) 94 connected to the back side of the printed wiring board and the first terminal 21 and the second terminal 22 of the capacitor 20 include a via hole 46 and a core provided in the connection layer 40 on the IC chip side. Connection is made through a through hole 36 formed in the substrate 30. That is, since the through hole is formed in the containing layer 31 that is provided with the core material and is difficult to process and the capacitor terminal and the external substrate are not directly connected, the connection reliability can be improved.
[0067]
In the present embodiment, as shown in FIG. 12, a roughened layer 23a is provided on the surface of the dielectric 23 made of ceramic of the chip capacitor 20. For this reason, the adhesiveness between the ceramic chip capacitor 20 and the adhesive layer 40 made of resin is high, and even if a heat cycle test is performed, the adhesive layer 40 does not peel off at the interface. The roughened layer 23a can be formed by polishing the surface of the chip capacitor 20 after firing, or by performing a roughening treatment before firing.
[0068]
In the present embodiment, as shown in FIG. 7, a resin filler 32 is interposed between the side surface of the cavity 31 a of the core substrate 30 and the chip capacitor 20. Here, the thermal expansion coefficient of the resin filler 32 is set to be smaller than that of the core substrate 30 and the adhesive layer 40, that is, close to the chip capacitor 20 made of ceramic. For this reason, in the heat cycle test, even if an internal stress is generated between the core substrate and the adhesive layer 40 and the chip capacitor 20 due to a difference in thermal expansion coefficient, cracks, peeling, and the like hardly occur in the core substrate 30 and the adhesive layer 40. High reliability can be achieved. In addition, migration can be prevented.
[0069]
Next, a method for manufacturing the printed wiring board described above with reference to FIG. 7 will be described with reference to FIGS.
A connection layer, which is a resin layer that forms the core substrate, is formed, and a circuit pattern made of a metal layer is formed on one surface thereof. Therefore, a resin film 40α having a metal film 41 laminated on one side is prepared (FIG. 1A). As the resin film 40α, a thermosetting resin such as epoxy, BT, polyimide, or olefin, or a mixture of a thermosetting resin and a thermoplastic resin can be used. Here, a film that does not include a core material is desirable so that the through-holes can be easily formed. The metal film 41 is pattern-etched to form a predetermined circuit pattern 42 (FIG. 1B). Next, the chip capacitor 20 is bonded to the circuit pattern 42 on the lower surface of the resin film 40α via the conductive adhesive 34 (FIG. 1C). Thereby, the electrical connection with the capacitor 20 and the adhesion between the capacitor 20 and the circuit pattern 42 are ensured. The conductive adhesive 34 has conductivity and adhesive properties such as solder (Sn / Pb, Sn / Sb, Sn / Ag, Sn / Ag / Cu), conductive paste, or resin impregnated with metal particles. What is combined can be used. The gap generated between the conductive adhesive and the capacitor should be filled with resin.
[0070]
On the other hand, an accommodation layer laminate 31α having a cavity 31a for accommodating a chip capacitor is prepared (FIG. 1C).
The cavity 31a is formed by counterbore. In addition to the counterbore, a laminate having a cavity can be formed by joining a prepreg having a through hole and a prepreg having no through hole, or by injection molding. As the accommodation layer laminate 31α, a laminate obtained by laminating a prepreg obtained by impregnating a core material such as glass cloth with an epoxy resin can be used. In addition to epoxies, those generally used in printed wiring boards such as those containing reinforcing materials such as BT, phenolic resin or glass cloth can be used. It is also possible to use a resin substrate that does not have a core material such as glass cloth. However, it was not possible to use a ceramic substrate on the core substrate. This is because the substrate has poor external formability and cannot accommodate a capacitor, and even if it is filled with resin, voids are generated. Since the resin substrate has a melting point of 300 ° C. or lower, if a temperature exceeding 350 ° C. is applied, dissolution, softening or carbonization occurs.
[0071]
Then, the resin film 40α to which the chip capacitor 20 is attached, the core substrate resin laminate 30α having the capacitor accommodating portion, and another resin film 40α are laminated and pressed from both sides to flatten the surface ( FIG. 1D). In the present embodiment, the housing layer 31 housing the capacitor 20 and the connection layer 40 are bonded together to form the core substrate 30 by applying pressure to both surfaces, so that the surface is flattened. Thereby, the interlayer resin insulation layer 60 and the conductor circuit 68 can be laminated so as to have high reliability in a process described later. At this time, the gap between the capacitor 20 and the resin film 40α is filled with the resin that oozes from the resin film 40α. Here, when the gap cannot be sufficiently filled, a filler 32α having a smaller thermal expansion coefficient than that of the core substrate is arranged between the circuit patterns 42 on the resin film 40α side as shown in FIG. 2D and filling as shown in FIG. 2D. Alternatively, as shown in FIG. 2C, a filler 32α is disposed on the capacitor 20 side, and filling is performed as shown in FIG. 2D. It is also possible to do.
[0072]
Thereafter, by heating and curing, the core substrate 30 including the accommodation layer 31 that accommodates the chip capacitor 20 and the connection layer 40 is formed (FIG. 3A). In addition, it is preferable to fill the cavity 31a of the core substrate with a resin filler 32 having a smaller coefficient of thermal expansion than that of the core substrate to improve the airtightness. Further, here, the resin film 40α is laminated using a film having no metal layer, but a resin film (RCC) having a metal layer disposed on one side may be used. That is, a double-sided plate, a single-sided plate, a resin plate without a metal film, or a resin film can be used.
[0073]
In the present embodiment, since the circuit pattern 42 connected to the conductive adhesive 34 is provided between the connection layer 40 forming the core substrate 30 and the containing layer 31, the capacitor 20 is connected via the circuit pattern 42. Can be securely connected to. Further, by arranging the circuit pattern 42 made of a metal layer between the connection layer 40 and the containing layer 31, it is possible to prevent the core substrate 30 from warping.
[0074]
Next, a non-through hole 43 serving as a via hole is formed in the connection layer 40 on the upper surface side by a CO2 laser, a YAG laser, an excimer laser, or a UV laser (FIG. 3B). Depending on the case, an area mask with through holes formed corresponding to the positions of the non-through holes may be placed and area processing may be performed with a laser. Furthermore, when forming the thing from which the magnitude | size and diameter of a via hole differ, you may form by the laser of mixing.
[0075]
If necessary, smear in the via hole may be performed by a gas plasma treatment using oxygen, nitrogen or the like, a dry treatment such as a corona treatment, or a treatment by immersion using an oxidizing agent such as permanganic acid. Subsequently, through-holes 33 for through-holes are drilled with a diameter of 50 to 500 μm in the core substrate 30 including the connection layer 40, the containing layer 31 and the connection layer 40 with a drill or a laser (FIG. 3C). .
[0076]
A metal film is formed in the surface layer of the connection layer 40 of the core substrate 30, the via hole non-through hole 43, and the through hole through hole 33. For this purpose, a palladium catalyst is applied to the surface of the connection layer 40, and then the core substrate 30 is immersed in the electroless plating solution to uniformly deposit the electroless copper plating film 44 (FIG. 4A). Although electroless plating is used here, a metal layer such as copper or nickel can be formed by sputtering. Sputtering is disadvantageous in terms of cost, but has an advantage that adhesion with the resin layer can be improved. In some cases, the electroless plating film may be formed after the sputtering. This is because, depending on the resin, it is effective for the case where the application of the catalyst is not stable, and the deposition with electroless plating is more stable when formed with an electroless plating film. The metal film 44 is desirably formed in a range of 0.1 to 3 mm.
[0077]
Thereafter, a photosensitive dry film is attached to the surface of the metal film 44, a mask is placed, and exposure / development processing is performed to form a resist 51 having a predetermined pattern. Then, the core substrate 30 is immersed in the electrolytic plating solution, and an electric current is passed through the electroless plating film 44 to deposit the electrolytic copper plating film 45 (FIG. 4B). After peeling off the resist 50 and the resist 51 with 5% KOH, the electroless plating film 44 under the resist 51 is removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide, and the via hole 46 and the conductor circuit 48 are formed in the connection layer 40. On the other hand, a through hole 36 is formed in the through hole 33 of the core substrate 30 (FIG. 4C).
[0078]
A roughening layer is provided on the surface of the conductor layer of the conductor circuit 48, the via hole 46 and the through hole 36. The roughening layer is applied by an oxidation (blackening) -reduction treatment, an electroless plating film such as an alloy made of Cu-Ni-P, or an etching treatment such as an etching solution made of a cupric complex and an organic acid salt. The roughened layer has Ra (average roughness height) = 0.01 to 5 μm. Particularly desirable is a range of 0.5 to 3 μm. Although the roughened layer is formed here, it is also possible to directly fill the resin and attach the resin film as described later without forming the roughened layer.
[0079]
Subsequently, the resin layer 38 is filled into the through hole 36. The resin layer may be either a non-conductive resin containing a resin such as an epoxy resin as a main component or a conductive resin containing a metal paste such as copper. In this case, what is contained in the thermosetting epoxy resin to match the coefficient of thermal expansion such as silica is filled as a resin filler. After filling the through hole 36 with the resin 38, the resin film 60α is pasted (FIG. 5A). In addition, it is also possible to apply | coat resin instead of sticking a resin film. After the resin film 60α is attached, a via hole 63 having an opening diameter of 20 to 250 μm is formed in the insulating layer 60α by photo and laser and then thermally cured (FIG. 5B). Thereafter, a catalyst is applied to the core substrate and immersed in electroless plating to deposit a 0.9 μm-thick electroless plating film 64 uniformly on the surface of the interlayer resin insulation layer 60, and then a predetermined pattern is resisted 70 (FIG. 5C).
[0080]
It is immersed in an electrolytic plating solution, and an electric current is passed through the electroless plating film 64 to form an electrolytic copper plating film 65 in a portion where the resist 70 is not formed (FIG. 6A). After the resist 70 is peeled and removed, the electroless plating film 64 under the plating resist is dissolved and removed to obtain a conductor circuit 68 and a via hole 66 composed of the electroless plating film 64 and the electrolytic copper plating film 65 (FIG. 6B )).
[0081]
A roughened surface (not shown) was formed on the surfaces of the conductor circuit 68 and the via hole 66 by an etching solution containing a second copper complex and an organic acid. Furthermore, Sn substitution may be performed on the surface.
[0082]
Solder bumps are formed on the printed wiring board described above. After applying a solder resist composition on both sides of the substrate and performing a drying process, a photomask film (not shown) on which a circular pattern (mask pattern) is drawn is placed in close contact, and exposed to ultraviolet rays. Develop. Further, heat treatment is performed to form a solder resist layer (thickness 20 μm) 72 having an opening 72a of a solder pad portion (including a via hole and its land portion) (FIG. 6C).
[0083]
Then, a solder paste is filled in the opening 72a of the solder resist layer 72 (not shown). Thereafter, the solder filled in the opening 72a is reflowed at 200 ° C. to form solder bumps (solder bodies) 76 (see FIG. 7). In order to improve the corrosion resistance, a metal layer such as Ni, Au, Ag, or Pd can be formed on the opening 72a by plating or sputtering.
[0084]
Next, placement of the IC chip on the printed wiring board and attachment to the daughter board will be described with reference to FIG. The IC chip 90 is mounted so that the solder pads 92S1, 92S2, 92P1, and 92P2 of the IC chip 90 correspond to the solder bumps 76 of the completed printed wiring board 10, and the IC chip 90 is attached by performing reflow. Do. Similarly, the printed wiring board 10 is attached to the daughter board 94 by reflowing the pads 96S1, 96S2, 96P1, and 96P2 of the daughter board 94 to the solder bumps 76 of the printed wiring board 10.
[0085]
Next, a printed wiring board according to a first modification of the first embodiment of the present invention will be described with reference to FIG. The printed wiring board of the first modification is almost the same as that of the first embodiment described above. However, in the printed wiring board of the first modified example, the conductive pins 84 are disposed and formed so as to be connected to the daughter board via the conductive pins 84. In the embodiment described above with reference to FIG. 1A, the resin film 40α having the metal film 41 laminated on one side is used. However, in the first modified example, a resin film having a metal film laminated on both sides is used. An interlayer resin insulating layer 60 on the IC chip 90 side is manufactured. That is, the circuit pattern 42 is formed by pattern etching the metal film on the upper surface. Further, the opening 42a of the circuit pattern 42 is used as a conformal mask, and a non-through hole 43 is formed by a laser to form a via hole 46.
[0086]
FIG. 12B shows a cross section of the chip capacitor 20 according to the first modification. In the first embodiment, the surface of the capacitor is roughened to improve the adhesion with the resin. However, in the modified example, the surface wettability is improved by forming the polyimide film 23b instead. It is. Instead of the polyimide film, a silane coupling process can be applied to the surface of the capacitor.
[0087]
In the first modified example, a composite metal film 28 composed of an electroless copper plating film 28 a and an electrolytic copper plating film 28 b is formed on the conductive paste 26. The thickness of the composite metal film 28 is desirably 0.1 to 10 μm, and optimally 1 to 5 μm. Instead of the composite metal film, it is also possible to form a single-layer metal film.
[0088]
In the first modified example, since the metal layer 28 is provided on the conductive paste 26 of the electrodes 21 and 22 of the capacitor 20, the occurrence of migration at the electrodes 21 and 22 can be prevented, and the connection resistance is reduced. Further reduction can be achieved. The electrodes 21 and 22 made of metallized have irregularities on the surface, and even if they are directly connected with the conductive adhesive 34, they cannot be completely adhered, but the conductive paste 26 is applied and the metal layer 28 is further applied. As a result, the unevenness can be completely eliminated, adhesion can be improved, and connection resistance can be lowered.
[0089]
In the first embodiment described above, only the chip capacitor 20 accommodated in the core substrate 30 is provided. However, in the first modified example, large-capacity chip capacitors 86 are mounted on the front surface and the back surface.
[0090]
An IC chip consumes a large amount of power instantaneously and performs complicated arithmetic processing. Here, in order to supply large power to the IC chip side, in this embodiment, the printed circuit board is provided with a chip capacitor 20 for power supply and a chip capacitor 86. The effect of this chip capacitor will be described with reference to FIG.
[0091]
In FIG. 13, the vertical axis indicates the voltage supplied to the IC chip, and the horizontal axis indicates time. Here, an alternate long and two short dashes line C indicates a voltage fluctuation of a printed wiring board not provided with a power supply capacitor. When the power supply capacitor is not provided, the voltage is greatly attenuated. A broken line A indicates voltage fluctuation of a printed wiring board having a chip capacitor mounted on the surface. The voltage does not drop much as compared with the two-dot chain line C, but the loop length becomes long, so the rate-determining power supply cannot be sufficiently performed. That is, the voltage drops at the start of power supply. A two-dot chain line B indicates a voltage drop of the printed wiring board containing the chip capacitor described above with reference to FIG. Although the loop length can be shortened, the voltage fluctuates because a large-capacity chip capacitor cannot be accommodated in the core substrate 30. Here, the solid line E shows the voltage fluctuation of the printed wiring board of the first modified example in which the chip capacitor 20 in the core substrate described above with reference to FIG. 9 and the large-capacity chip capacitor 86 are mounted on the surface. Yes. By providing the chip capacitor 20 in the vicinity of the IC chip and the chip capacitor 86 having a large capacity (and relatively large inductance), voltage fluctuation is minimized.
[0092]
Next, a printed wiring board according to a second modification of the first embodiment of the present invention will be described with reference to FIG. The printed wiring board of the second modification is almost the same as that of the first embodiment described above. However, in the printed wiring board of the second modified example, the first electrode 21 and the second electrode 22 of the chip capacitor 20 are directly connected to the power supply pads 92P1 and 92P2 of the IC chip 90 via the bumps 76. . In the second modification, the distance between the IC chip and the chip capacitor can be further shortened.
[0093]
Next, a printed wiring board according to a third modification of the first embodiment of the present invention will be described with reference to FIG. The printed wiring board of the third modified example is substantially the same as that of the first embodiment described above. However, in the printed wiring board of the third modified example, the first electrode 21 and the second electrode 22 of the capacitor 20 and the through hole 36 are formed by the circuit pattern 42 provided between the housing layer 31 and the connection layer 40. Connected directly. In the third modification, the wiring length between the first electrode 21 and the second electrode 22 of the capacitor 20 and the daughter board can be shortened.
[0094]
Next, the configuration of the printed wiring board according to the second embodiment of the present invention will be described with reference to FIG.
The configuration of the printed wiring board of the second embodiment is substantially the same as that of the first embodiment described above. However, the chip capacitor 20 accommodated in the core substrate 30 is different. FIG. 14 is a plan view of the chip capacitor. FIG. 14A shows a chip capacitor before cutting for multi-piece cutting, and a one-dot chain line in the drawing indicates a cutting line. In the printed wiring board of the first embodiment described above, the first electrode 21 and the second electrode 22 are disposed on the side edge of the chip capacitor as shown in the plan view of FIG. FIG. 14C shows the chip capacitor before cutting for multi-piece fabrication according to the second embodiment, and the alternate long and short dash line in the drawing indicates the cutting line. In the printed wiring board of the second embodiment, the first electrode 21 and the second electrode 22 are disposed inside the side edge of the chip capacitor as shown in the plan view of FIG. The electrode is formed with a conductive paste as in the first embodiment, or a conductive paste and a composite metal layer as in the first modification of the first embodiment.
[0095]
In the printed wiring board according to the second embodiment, since the chip capacitor 20 in which the electrode is formed inside the outer edge is used, a chip capacitor having a large capacity can be used.
[0096]
Next, a printed wiring board according to a first modification of the second embodiment will be described with reference to FIG.
FIG. 15 is a plan view of the chip capacitor 20 accommodated in the core substrate of the printed wiring board according to the first modification. In the first embodiment described above, a plurality of small-capacity chip capacitors are accommodated in the core substrate. However, in the first modification, a large-capacity large-sized chip capacitor 20 is accommodated in the core substrate. Here, the chip capacitor 20 includes a first electrode 21, a second electrode 22, a dielectric 23, a first conductive film 24 connected to the first electrode 21, and a second electrode connected to the second electrode 22 side. The conductive film 25 and the connection electrodes 27 on the upper and lower surfaces of the chip capacitor not connected to the first conductive film 24 and the second conductive film 25 are formed. The IC chip side and the daughter board side are connected via this electrode 27.
[0097]
Since the large-sized chip capacitor 20 is used in the printed wiring board of the first modified example, a chip capacitor having a large capacity can be used. Further, since the large chip capacitor 20 is used, the printed wiring board is not warped even when the heat cycle is repeated. The electrode is formed with a conductive paste as in the first embodiment, or a conductive paste and a composite metal layer as in the first modification of the first embodiment.
[0098]
A printed wiring board according to a second modification will be described with reference to FIG. FIG. 16A shows a chip capacitor before cutting for multi-piece production. In the drawing, a one-dot chain line shows a normal cutting line, and FIG. 16B shows a plan view of the chip capacitor. . As shown in FIG. 16B, in this second modified example, a plurality of chip capacitors (three in the example in the figure) are connected and used in a large format.
[0099]
In the second modified example, since a large chip capacitor 20 is used, a chip capacitor having a large capacity can be used. Further, since the large chip capacitor 20 is used, the printed wiring board is not warped even when the heat cycle is repeated. The electrode is formed with a conductive paste as in the first embodiment, or a conductive paste and a composite metal layer as in the first modification of the first embodiment.
[0100]
In the second embodiment described above, the chip capacitor is built in the printed wiring board. However, instead of the chip capacitor, it is also possible to use a plate-like capacitor in which a conductive film is provided on a ceramic plate.
[0101]
Here, with respect to the printed wiring board of the first embodiment, values obtained by measuring the inductance of the chip capacitor 20 embedded in the core substrate and the inductance of the chip capacitor mounted on the back surface (surface on the daughter board side) of the printed wiring board are as follows. Show.
In the case of a single capacitor, embedded type 137pH
Back mounting type 287pH
Embedded type 60pH when 8 capacitors are connected in parallel
Back mounting type 72pH
As described above, even when the capacitor is used alone, the inductance can be reduced by incorporating the chip capacitor even when they are connected in parallel to increase the capacitance.
[0102]
Next, the results of the reliability test will be described. Here, in the printed wiring board of the first embodiment, the change rate of the capacitance of one chip capacitor was measured.

[0103]
The steam test was kept at 100% humidity by exposure to steam. In the HAST test, the sample was left for 100 hours at a relative humidity of 100%, an applied voltage of 1.3 V, and a temperature of 121 ° C. In the TS test, a test that was allowed to stand at -125 ° C for 30 minutes and at 55 ° C for 30 minutes was repeated 1000 lines.
[0104]
In the above reliability test, it was found that a printed wiring board with a built-in chip capacitor can achieve the same reliability as the existing capacitor surface mount type. Further, as described above, in the TS test, even if an internal stress is generated due to the difference in thermal expansion coefficient between the ceramic capacitor 20 and the resin core substrate 30 and the adhesive layer 40, the chip capacitor 20 is bonded. It has been found that separation from the layer 40 and cracks in the core substrate 30 and the adhesive layer 40 do not occur, and high reliability can be achieved over a long period of time.
[0105]
【Effect of the invention】
With the structure of the present invention, the electrical characteristics due to inductance are not deteriorated.
Further, since the conductive paste is applied to the surface of the electrode made of the metallization of the capacitor, the electrical connectivity of the electrode made of metallization and having a high surface resistance can be improved. In addition, electrodes made of metallized have irregularities on the surface, and even if they are directly connected with a conductive adhesive, they cannot be adhered completely, but the conductive paste can eliminate irregularities and improve adhesion. The connection resistance can be lowered. In addition, since the electrode made of metallized is in contact with the surrounding resin layer via the conductive paste, the generation of stress due to the difference in thermal expansion between the electrode and the resin layer is suppressed, and the resin layer is not cracked or peeled off.
Also, migration can be prevented when the capacitor is covered with copper.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram of a printed wiring board according to a first embodiment of the present invention.
FIG. 2 is a manufacturing process diagram of the printed wiring board according to the first embodiment of the present invention.
FIG. 3 is a manufacturing process diagram of the printed wiring board according to the first embodiment of the present invention.
FIG. 4 is a manufacturing process diagram of the printed wiring board according to the first embodiment of the present invention.
FIG. 5 is a manufacturing process diagram of the printed wiring board according to the first embodiment of the present invention.
FIG. 6 is a manufacturing process diagram of the printed wiring board according to the first embodiment of the present invention.
FIG. 7 is a cross-sectional view of the printed wiring board according to the first embodiment.
FIG. 8 is a cross-sectional view of the printed wiring board according to the first embodiment.
FIG. 9 is a cross-sectional view of a printed wiring board according to a first modification of the first embodiment.
FIG. 10 is a cross-sectional view of a printed wiring board according to a second modification of the first embodiment.
FIG. 11 is a cross-sectional view of a printed wiring board according to a third modification of the first embodiment.
12A is a cross-sectional view of the chip capacitor of the first embodiment, and FIG. 12B is a cross-sectional view of the chip capacitor of the first modified example of the first embodiment.
FIG. 13 is a graph showing changes in supply voltage to IC chip and time.
14A, 14B, 14C, and 14D are plan views of chip capacitors of a printed wiring board according to the second embodiment.
FIG. 15 is a plan view of a chip capacitor of the printed wiring board according to the second embodiment.
FIG. 16 is a plan view of a chip capacitor of a printed wiring board according to a modification of the second embodiment.
FIGS. 17A and 17B are explanatory diagrams of loop inductance of a printed wiring board according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Printed wiring board 20 Chip capacitor 21 1st electrode 22 2nd electrode 23 Dielectric 23a Roughened surface 23b Polyimide film 26 Conductive paste 28a Electroless copper plating film 28b Electrolytic copper plating film 28 Composite metal film 25 Housing layer 30 Core substrate 31 Containment layer 31a Cavity 34 Conductive adhesive 36 Through hole 40 Connection layer 42 Circuit pattern 43 Non-through hole 46 Via hole 60 Interlayer resin insulation layer 66 Via hole 68 Conductor circuit 84 Conductive pin 90 IC chip 94 Daughter board

Claims (17)

A printed wiring board formed by laminating a resin insulating layer and a conductor circuit on a core substrate,
The core substrate is composed of a connection layer formed of an insulating resin layer that is at least one layer and a containing layer containing a capacitor in a counterbore part,
On the surface of the electrode made of metallization of the capacitor , a conductive paste is applied with a thickness of 1 to 30 μm so as to eliminate the unevenness of the electrode made of metallization ,
A metal layer is provided on the conductive paste of the capacitor electrode;
The printed wiring board, wherein the connection layer and the capacitor electrode are connected via a conductive adhesive.   The printed wiring board according to claim 1, wherein a surface of the capacitor is roughened.   3. The printed wiring board according to claim 1, wherein a surface wettability improving process is performed on the surface of the capacitor.   The printed wiring board according to any one of claims 1 to 3, wherein the housing layer is made of a resin substrate in which a core material is impregnated with a resin, and the connection layer is made of a resin substrate having no core material.   The printed wiring board according to claim 1, wherein a circuit connected to the conductive adhesive is provided between the connection layer and the containing layer in the core substrate. The IC chip disposed on the surface side of the printed wiring board and the terminal of the capacitor are connected via a via hole provided in the connection layer,
The external board disposed on the back side of the printed wiring board and the terminal of the capacitor are connected to each other through the via hole and a through hole formed in the core board. Printed wiring board.   The printed wiring board according to claim 1, wherein a plurality of the capacitors are accommodated, and a wiring for connecting the IC chip and the external substrate is disposed between the capacitors.   The printed wiring board according to claim 1, wherein a chip capacitor is mounted on a surface of the printed wiring board.   9. The printed wiring board according to claim 8, wherein the capacitance of the chip capacitor on the surface is equal to or greater than the capacitance of the inner layer capacitor.   9. The printed wiring board according to claim 8, wherein an inductance of the surface chip capacitor is equal to or greater than an inductance of the inner layer capacitor.   The printed wiring board according to claim 1, wherein a resin having a smaller coefficient of thermal expansion than that of the core substrate is filled between the counterbore portion of the core substrate and the capacitor.   The printed wiring board according to claim 1, wherein a chip capacitor having an electrode formed inside an outer edge is used as the capacitor.   13. The printed wiring board according to claim 1, wherein a chip capacitor having electrodes formed in a matrix is used as the capacitor.   14. The printed wiring board according to claim 1, wherein a plurality of chip capacitors for connecting multiple capacitors are used as the capacitor. A method for producing a printed wiring board comprising at least the following steps (a) to (c):
(A) A conductive paste having a thickness of 1 to 30 μm on a resin plate having a circuit pattern formed on one side or both sides, on the metallized electrode on the circuit pattern via an adhesive material so as to eliminate the unevenness of the electrode made of metallized. And connecting a capacitor provided with a metal layer on the conductive paste;
(B) a step of attaching a resin substrate on which a cavity for accommodating the capacitor is formed to the resin plate to form a core substrate;
(C) A step of forming a via hole by providing an opening reaching the circuit pattern in the resin plate.   The method for manufacturing a printed wiring board according to claim 15, wherein pressure is applied from both sides of the substrate at the time of attaching in the step (c).   16. The method according to claim 15, wherein a through hole is formed in the core substrate formed by attaching the resin substrate to the resin plate before and after the step (c). Item 17. A method for producing a printed wiring board according to Item 16.

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