JP2004027185A - Embedded resin composition and wiring board using the same - Google Patents

Abstract

An embedded resin composition is hardly crystallized while ensuring heat resistance, moisture resistance and embedding property.
An embedding resin composition of the present invention is for embedding an electronic component in a wiring board, and contains an inorganic filler, a thermal cation polymerization catalyst, and three or more resins. At least one of the three or more resins is an aliphatic cyclic epoxy resin or an oxetane resin as a thermosetting resin, and at least one is a bisphenol-type epoxy resin as a thermosetting resin. Those having a low viscosity of 20 Pa · s (25 ° C.) or less are used. As described above, by using a low-viscosity bisphenol-type epoxy resin as a crystallization inhibitor of the embedding resin composition 22, it is possible to make it difficult to crystallize without greatly reducing physical properties such as moisture resistance and heat resistance. it can.
[Selection diagram] Fig. 1

Description

そして、本発明者は、表１に示す各埋込樹脂組成物の特性を評価するための試験として、２４時間放置試験と、Ｔｇ（ガラス転移温度）調査と、ＰＣＴ評価とを行った。以下、それぞれについて具体的に説明する。
【００４９】
［２４時間放置試験］
混練直後の各埋込樹脂組成物を約１０ｇずつプラスチック製の容器に入れ、これを室温（約２５℃）で２４時間放置した。その後、各埋込樹脂組成物について、外観や物性を目視により観察すると共に、指による感触で樹脂成分の結晶化や凝固具合を確認した。そして更に、各埋込樹脂組成物を６０℃に３０分間加熱し、ワニス状になった場合には、硬化（結晶化）していないと判断した。
【００５０】
［Ｔｇ調査］
各埋込樹脂組成物について、ＤＭＡ（ｄｙｎａｍｉｃ　ｍｅｃｈａｎｉｃａｌａｎａｌｙｓｉｓ）によるｔａｎδの変曲点から、ガラス転移温度を調査し、１５０℃以上を合格とした。
【００５１】
［ＰＣＴ評価］
この試験では、各埋込樹脂組成物についてサンプルを２０枚ずつ作製して評価を行った。
ここで、本試験用のサンプルは、以下のように作製した。
【００５２】
まず、厚さ０．８ｍｍのＢＴ（ビスマレイミド−トリアジン）基板をコア基板とし、このコア基板に金型を用いて略長方形状の貫通孔を設ける。そして、このコア基板の一面に透明のバックテープを貼り付けて貫通孔の一方を塞ぎ、この塞いだ面を下側にしてコア基板を載置する。
【００５３】
次に、バックテープを貼り付けた面とは反対側の面から、貫通孔により形成された収納空間内におけるバックテープの粘着面上に、チップマウンタを用いてチップコンデンサを配置する。そして、このチップコンデンサとコア基板との隙間に、ディスペンサを用いて埋込樹脂組成物を流し込み、１２０℃×１５０分＋１７０℃×３００分の条件で脱泡及び熱硬化する。こうして硬化した埋込樹脂組成物の表面を、ベルトサンダーを用いて粗研磨した後、ラップ研磨にて仕上げ研磨する。そして、炭酸ガスレーザを照射してビアホールを形成し、チップコンデンサの電極を露出させる。
【００５４】
続いて、埋込樹脂組成物の露出面を、膨潤液とＫＭｎＯ_４溶液とを用いて粗化する。そして、この粗化面をＰｄ触媒活性化した後、無電界メッキ、電解メッキの順に銅メッキを施し、このメッキ面にレジストを形成して所定の配線パターンをパターニングし、更に、不要な銅をＮａ_２Ｓ_２Ｏ_８／濃硫酸を用いてエッチング除去した後レジストを剥離して、配線パターンを形成する。
【００５５】
更に、この配線層の上に、絶縁層となるフィルムをラミネートして熱硬化した後、レーザを照射してビアホールを形成し、絶縁層の表面を酸化剤を用いて粗化する。そして、前述した手法で配線パターンを形成する。
その後、配線基板の最表面にソルダーレジスト層となるドライフィルムをラミネートして半導体素子の実装パターンを露光、現像して形成し、ソルダーレジスト層を形成する。そして、半導体素子を実装する端子電極に、Ｎｉメッキ、Ａｕメッキの順番でメッキを施し、ハンダリフロー炉を通して半導体素子を実装する。更に、実装部にアンダーフィル材をディスペンサで充填した後、熱硬化させる。
【００５６】
こうして作製したサンプルを、ＰＣＴ（プレッシャークッカー試験）（１２１℃，２．１気圧，相対湿度１００％：３３６時間）にかけた後、表面及び切断面を観察し、埋込樹脂組成物の有効性を評価した。具体的には、クラックや埋込不良等が無ければ合格とした。尚、合格率が８５％以上（サンプル２０枚のうち、１７枚以上が合格）の埋込樹脂組成物を良好と判断した。
【００５７】
以上説明した各試験によって、表１から明らかなように、以下のような結果が得られた。
実施例１〜５の埋込樹脂組成物は、樹脂成分として、ナフタレン型エポキシ樹脂、脂肪族環状エポキシ樹脂及びビスフェノール型のエポキシ樹脂を含有し、硬化触媒として、熱カチオン重合触媒を含有したものであるが、何れも埋込樹脂組成物として満足のいく特性が得られた。
【００５８】
一方、比較例１及び比較例２の埋込樹脂組成物には、実施例１〜５の組成物に比べ、ビスフェノール型のエポキシ樹脂として粘度の高いものが用いられており、比較例１と比較例２とでは、その配合量が異なっている。そして、比較例１の埋込樹脂組成物は、２４時間放置試験の結果、結晶化してしまい、また、比較例２では、ＰＣＴ評価の結果、埋込不良となり、何れも埋込樹脂組成物として満足のいく特性が得られなかった。
【００５９】
一方また、比較例３の埋込樹脂組成物は、実施例１〜５の組成物と比較すると、樹脂成分としてビスフェノール型のエポキシ樹脂のみが用いられている点と、硬化触媒としてイミダゾール系触媒が用いられている点とで異なっている。そして、この比較例３の埋込樹脂組成物は、ＰＣＴ評価の結果、クラックや銅メッキとの剥離が発生してしまい、埋込樹脂組成物として満足のいく特性が得られなかった。
【００６０】
以上の結果から、樹脂成分として、ナフタレン型エポキシ樹脂、脂肪族環状エポキシ樹脂及び低粘度のビスフェノール型エポキシ樹脂を含有し、更に、硬化触媒として、熱カチオン重合触媒を含有した埋込樹脂組成物は、耐湿性、耐熱性、埋め込み性等に優れ、しかも結晶化し難いものとなることが分かる。したがって、このような埋込樹脂組成物を用いれば、電子部品が基板内部に確実に埋め込まれると共に、クラック、銅メッキとの密着等の不良が発生し難いといった信頼性の高い配線基板を実現することができる。
【図面の簡単な説明】
【図１】本発明の埋込樹脂組成物が用いられた配線基板の構成を表わす説明図である。
【図２】配線基板の製造方法を説明する説明図（その１）である。
【図３】配線基板の製造方法を説明する説明図（その２）である。
【符号の説明】
１…配線基板、３ａ，３ｂ…導体層、５…配線基板本体、７ａ，７ｂ…導体層、１１…スルーホール、１３…穴埋樹脂、１５…電子部品配置用貫通孔、１７…コンデンサ素子、２２…埋込樹脂組成物、２５ａ，２５ｂ…層間絶縁層、３１…フリップチップパッド、３３…フリップチップバンプ、３５ａ，３５ｂ…ソルダーレジスト層、３９ａ，３９ｂ…フィルドビア[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an embedding resin composition for embedding an electronic component in a substrate, and a wiring board in which an electronic component is embedded using the embedding resin composition.
[0002]
[Prior art]
In recent years, a multi-chip module (MCM) in which a number of semiconductor elements are mounted on a build-up wiring board has been studied. When mounting electronic components such as chip capacitors, chip inductors, chip resistors, and ICs on such a wiring board, it is common to mount the surface using solder on a mounting wiring layer formed on the surface of the wiring board. It is a target.
[0003]
However, in such a configuration in which electronic components are mounted on the substrate surface, there is a natural limit to miniaturization of the wiring board due to the necessity of securing a mounting area corresponding to each electronic component. In addition, the routing of the wiring at the time of surface mounting increases the parasitic inductance, which is not preferable in terms of characteristics, so that it is difficult to cope with a higher frequency of the electronic device.
[0004]
Therefore, a method of storing electronic components inside a substrate has been proposed, for example, disclosed in Patent Document 1 and Patent Document 2. By using this method, the electronic components can be mounted not only on the surface of the substrate but also inside the substrate, so that the size of the wiring substrate can be suitably reduced.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 11-126978 [Patent Document 2]
JP 2000-124352 A
[Problems to be solved by the invention]
By the way, in such a wiring board, it is preferable to fill the gap between the electronic component housed inside the board and the board with the embedding resin composition in order to enhance the reliability. Then, the inventor of the present invention combines such crystalline resin, solid resin or semi-solid resin with aliphatic cyclic epoxy resin or oxetane resin (thermosetting resin having oxetane ring) as such an embedded resin composition. Have been found to improve heat resistance, moisture resistance, embedding properties, and the like.
[0007]
Here, the crystalline resin is a resin crystallized at 0 ° C., and includes, for example, a high-purity naphthalene-type epoxy resin. The term “solid resin / semi-solid resin” means a resin in a solid state / semi-solid state at 0 ° C. For example, general-purpose products of naphthalene-type epoxy resin are exemplified as semi-solid resin, and phenol novolak-type epoxy resin Are exemplified as a solid resin or a semi-solid resin.
[0008]
However, an aliphatic cyclic epoxy resin or an oxetane resin, and a crystalline resin, a solid resin or a semi-solid resin, are combinations in which crystallization easily occurs, and are left for a long time after the embedding resin composition is prepared. Then, phase separation of the resin may occur due to crystallization. In this case, if the material is cured as it is, a local difference in the coefficient of thermal expansion occurs, which causes a crack or the like.
[0009]
The present invention has been made in view of such a problem, and an object of the present invention is to make the embedding resin composition difficult to crystallize while securing heat resistance, moisture resistance, and embedding property.
[0010]
Means for Solving the Problems and Effects of the Invention
The embedding resin composition of the present invention made to achieve the above object is for embedding an electronic component inside a wiring board, and contains an inorganic filler, a thermocation polymerization catalyst and three or more resins. I have. At least one of the three or more resins is an aliphatic cyclic epoxy resin or an oxetane resin as a thermosetting resin, and at least one is a bisphenol-type epoxy resin as a thermosetting resin. The viscosity is 20 Pa · s (25 ° C.) or less, and at least one type is a crystalline resin, a solid resin, or a semi-solid resin.
[0011]
In such an embedding resin composition of the present invention, the aliphatic cyclic epoxy resin or oxetane resin used as a viscosity reducing agent greatly reduces the physical properties originally required of the embedding resin composition such as heat resistance and moisture resistance. Low viscosity is realized without any problems. As a result, the gap between the electronic component housed in the substrate and the substrate can be satisfactorily filled. As the viscosity reducing agent, an acid anhydride-based curing agent and a flexibility-imparting agent are generally used. However, when an acid anhydride-based curing agent is used, ester bonds are increased in the resin structure and moisture resistance is increased. However, the use of a flexibility-imparting agent greatly reduces the heat resistance, and any of these is undesirable because it impairs the physical properties required for the embedded resin composition.
[0012]
Further, in the embedding resin composition of the present invention, a bisphenol-type epoxy resin is used as a crystallization inhibitor. Here, the bisphenol-type epoxy resin has a long molecular structure and thus has a high effect of inhibiting crystallization, and also has properties required for the embedded resin composition such as heat resistance and moisture resistance. Therefore, the embedded resin composition of the present invention hardly crystallizes while securing physical properties such as heat resistance and moisture resistance. In particular, the embedding resin composition of the present invention contains a crystalline resin, a solid resin or a semi-solid resin, and is a combination that easily crystallizes with an aliphatic cyclic epoxy resin or an oxetane resin. Crystallization can be effectively prevented by the epoxy resin.
[0013]
In addition, since the bisphenol-type epoxy resin used in the embedding resin composition of the present invention has a low viscosity of 20 Pa · s (25 ° C.) or less, a high embedding property can be realized by drastically lowering the viscosity. be able to. That is, when the viscosity of the bisphenol-type epoxy resin used in the embedding resin composition exceeds 20 Pa · s (25 ° C.), the embedding property is greatly reduced, and defects such as voids are easily generated. In the embedded resin composition, the occurrence of such a defect is prevented. In the description of the present specification, Pa · s (25 ° C.) means a viscosity at 25 ° C.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
As described above, a bisphenol-type epoxy resin is used as a crystallization inhibitor in the embedding resin composition of the present invention.
Here, as the bisphenol type epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin and the like can be used.
[0015]
Further, the blending amount of the bisphenol type epoxy resin is preferably 5% by weight or more in the resin component of the embedding resin composition. With such an amount, the effect of preventing crystallization can be further enhanced.
Examples of the crystalline resin include a high-purity naphthalene-type epoxy resin. Examples of the semi-solid resin include a general-purpose naphthalene epoxy resin, a phenol novolak epoxy resin, a phenol resin, and the like.
[0016]
On the other hand, in the embedding resin composition of the present invention, an aliphatic cyclic epoxy resin or an oxetane resin is used as a viscosity reducing agent.
Here, as the aliphatic cyclic epoxy resin, for example, YL-6663, YL-6753 manufactured by Japan Epoxy Resin Co., Ltd., Araldite CY-184, Araldite CY-192-1, Araldite CY manufactured by Ciba Specialty Chemicals Co., Ltd. -179, Araldite CY-177, Celloxide 2021, Celloxide 2081, Celloxide 2083, Celloxide 3000, Epolide GT301, Epolide GT302, Epolide GT302, Epolide GT401, Epolide GT403, etc. (all trade names) manufactured by Daicel Chemical Industries, Ltd. .
[0017]
In addition, as the oxetane resin, for example, OXT101, OXT121 (trade name) manufactured by Toagosei Co., Ltd. can be used.
Here, the compounding amount of the aliphatic cyclic epoxy resin or oxetane resin is preferably 1 to 49% by weight in the resin component of the embedding resin composition. This is because with such a compounding amount, the adhesion to the metal layer on the wiring board can be kept extremely good. Further, the embedding resin composition is desirably in a liquid or sheet form at room temperature. This is because a molding compound of a general sealing material requires a special tool such as a mold. In particular, in consideration of the positional accuracy after the installation of the electronic component, an embedded resin composition that is liquid at room temperature and can be operated without increasing the temperature is preferable.
[0018]
On the other hand, the embedded resin composition of the present invention contains an inorganic filler. With this inorganic filler, not only the effect of adjusting the thermal expansion coefficient of the embedding resin composition is obtained, but also the skeleton of the three-dimensional structure after curing, and the effect of the inorganic filler as an aggregate, the roughening treatment is performed. Of the embedded resin composition is prevented from being unnecessarily collapsed.
[0019]
As the inorganic filler, for example, it is preferable to use crystalline silica, fused silica, alumina, silicon nitride, talc, or the like. This is because the thermal expansion coefficient of the embedded resin composition can be effectively reduced. Here, the thermal expansion coefficient of the embedding resin composition is not particularly limited, but is preferably 30 ppm / ° C. or less, and more preferably 20 ppm / ° C. or less, from the viewpoint that reliability against heat can be improved.
[0020]
The filler diameter (particle diameter) of the inorganic filler is preferably 50 μm or less. This is because if the particle size is 50 μm or less, the embedded resin composition easily flows into a narrow gap such as between electrodes of an electronic component, and poor filling is prevented. In particular, if the shape of the inorganic filler is substantially spherical, the fluidity and the filling factor of the embedding resin composition can be further increased, and the silica-based inorganic filler is preferable because a spherical one can be easily obtained. . Further, the filling rate of the inorganic filler is preferably 30% by volume or more.
[0021]
Further, the surface of the inorganic filler may be subjected to a surface treatment with a coupling agent, if necessary. This is because the wettability of the inorganic filler with respect to the resin component is improved, and the fluidity of the embedded resin composition can be improved. Here, as the type of the coupling agent, for example, a silane type, a titanate type, an aluminate type, or the like can be used.
[0022]
On the other hand, in the embedding resin composition of the present invention, a thermal cationic polymerization catalyst is used as a curing catalyst. As a curing catalyst, for example, amines are also known. However, when an amine reacts with an alicyclic epoxy group, it is sterically hindered by a cyclohexane ring, so that the amine reacts with an aliphatic cyclic epoxy resin or an oxetane resin. Is not preferred in that it is slow.
[0023]
Examples of the thermal cationic polymerization catalyst include, for example, triflic acid salt, boron trifluoride etherate compound, metal fluoroboron complex salt, bis (perfluoroalkylsulfonyl) methane metal salt, aryldiazonium compound, aromatic onium salt, Dicarbonyl chelates of Group 3a-5a elements, thiopyrylium salts, 6b elements in the form of MF6-anions (where M is selected from phosphorus, antimony and arsenic), arylsulfonium complex salts, aromatic iodonium complex salts, aromatic Sulfonium complex salt, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluorometal salt (for example, phosphate, arsenate, antimonate and the like), arylsulfonium complex salt, halogen-containing complex ion aromatic sulfonium or Iodonium salt, hex Fluoro antimonate or hexafluorophosphate, ammonium salts, sulfonium salts, phosphonium salts or pyridinium salts or the like can be used.
[0024]
Among these thermal cationic polymerization catalysts, an aromatic onium salt is preferred in terms of excellent balance between handleability and latency and curability, and more preferred is hexafluoroantimonic acid or hexafluorophosphoric acid. , An ammonium salt, a sulfonium salt, a phosphonium salt or a pyridinium salt. By using these thermal cationic polymerization catalysts, the pot life of the embedded resin composition can be further extended.
[0025]
Furthermore, it is preferable that the weight of the thermocationic polymerization catalyst be 0.01 to 15 relative to the weight 100 of the thermosetting resin contained in the embedding resin composition. , 0.1 to 10 is more preferable. The reason for this is that if such a proportion is contained, the balance between the heat resistance and the moisture resistance can be kept very good.
[0026]
The wiring board used for embedding the electronic component with the embedding resin composition as described above ensures that the gap between the electronic component housed inside the substrate and the substrate is filled, and that a defect such as a crack occurs. Is less likely to occur, and has high reliability. Specifically, for example, it can be realized as a wiring board 1 as shown in FIG.
[0027]
That is, in the wiring board 1 shown in FIG. 1, the front and back of the wiring board main body 5 which is an insulating substrate made of a glass-epoxy resin composite material having a thickness of about 0.8 mm and having the conductor layers 3a and 3b formed therein. Conductive layers 7a and 7b having a thickness of about 25 μm are formed on both surfaces (first main surface 5a and second main surface 5b).
[0028]
In the wiring board main body 5, a through hole 11 having a diameter of about 250 μm is formed by plating an inner wall of a through hole through hole 9 penetrating from one of the two main surfaces 5a and 5b to the other. Through this through hole 11, conductor layer 7a on first main surface 5a and conductor layer 7b on second main surface 5b are mutually connected. The through-hole 11 is filled with a filling resin 13.
[0029]
The wiring board main body 5 is formed with an electronic component placement through hole 15 (about 12 mm × 12 mm in length and width) through which one of the two main surfaces 5 a and 5 b penetrates to the other. A plurality of capacitor elements 17 (about 3.2 mm × 1.6 mm × 0.7 mm) are provided inside. The capacitor element 17 includes a main body 19 made of a high dielectric ceramic mainly containing BaTiO ₃ and an electrode terminal 21 mainly containing Pd.
[0030]
Inside the through-hole 15 for disposing electronic components, the capacitor element 17 is fixed by the cured embedded resin composition 22 of the present invention. The capacitor element 17 is for suppressing switching noise generated in the IC chip 23 provided on the wiring board 1 and stabilizing an operation power supply voltage to be supplied to the IC chip 23. .
[0031]
On the conductor layers 7a and 7b, interlayer insulating layers 25a and 25b (about 30 μm in thickness) are laminated. Of these, a large number of flip chip pads 31 are formed on the interlayer insulating layer 25a on the first main surface 5a side to connect the IC chip 23 indicated by a broken line and the wiring of the wiring board 1, and each flip chip pad 31 is formed. A substantially hemispherical flip chip bump 33 made of a high-temperature solder is formed thereon.
[0032]
In addition, on the interlayer insulating layer 25a on the first main surface 5a side, around the flip chip pad 31, a solder resist for preventing the solder from flowing out around the flip chip pad 31 when the flip chip bump 33 is formed. A layer 35a (about 20 μm in thickness) is formed.
[0033]
On the other hand, on the interlayer insulating layer 25b on the second main surface 5b side, wiring of another wiring board such as a mother board and a large number of LGA pads 37 for connecting to wiring of the wiring board 1 are formed. Further, on the interlayer insulating layer 25b on the second main surface 5b side, a solder resist layer 35b is also formed around the LGA pad 37.
[0034]
The conductor layer 7a and the flip chip pad 31 on the first main surface 5a side are connected to each other by a filled via 39a formed in the interlayer insulating layer 25a. On the second main surface 5b side, the conductor layer 7b and the LGA pad 37 are connected to each other via a filled via 39b formed in the interlayer insulating layer 25b. By using the filled via for the interlayer connection in this manner, the electrode terminal 21 of the capacitor element and the flip chip pad 31 can be connected in a straight line (that is, a stacked via can be formed). Therefore, the IC chip 23 and the capacitor element 17 can be connected at a short distance, and the electrical characteristics can be improved.
[0035]
The wiring board 1 can be manufactured, for example, as follows.
That is, as shown in FIG. 2A, first, a through-hole 9 is formed in the wiring board main body 5 in which the conductor layers 3a and 3b are formed, and then the plating layer 40 is formed by performing panel plating. Further, a resin which is filled with the filling resin 13 in the through hole 9 and cured is prepared. The filling resin 13 is polished so as to form substantially the same surface as the plating layer 40 formed on both the main surfaces 5a and 5b of the wiring board main body 5.
[0036]
Then, as shown in FIG. 2B, an electronic component disposing through hole 15 for incorporating the electronic component is formed.
Subsequently, as shown in FIG. 2C, after the electronic component arranging through hole 15 is closed by the sheet material 41, the electronic component is adhered to the sheet material 41 via the adhesive 43 so that the capacitor component 17 is adhered to the sheet material 41. It is arranged inside the arrangement through hole 15. At this time, the capacitor element 17 adheres to the sheet material 41 at the electrode terminals 21, and a gap is formed between the main body 19 and the sheet material 41 so that the embedded resin composition 22 can flow therein. It is arranged so that. The electrode terminal 21 has ends 21a and 21b facing in opposite directions, and the ends 21a and 21b are directed toward the first main surface 5a and the second main surface 5b, respectively. Here, an end directed toward the first main surface 5a is referred to as an upper end 21a, and an end directed toward the second main surface 5b is referred to as a lower end 21b.
[0037]
Subsequently, as shown in FIG. 2D, among the openings of the through-holes 15 for arranging the electronic components, the openings not closed by the sheet material 41 (the first main surface 5 a side) are used. The embedded resin composition 22 of the present invention is injected into the through hole 15. Then, after removing bubbles from the embedded resin composition 22, the embedded resin composition 22 is cured. Thereby, the plurality of capacitor elements 17 are fixed in the through-holes 15 for disposing electronic components.
[0038]
Next, as shown in FIG. 2E, the front and back of the wiring board main body 5 (that is, the first main surface 5a and the second main surface 5b) are inverted, and further, as shown in FIG. The sheet material 41 is removed. Note that the wiring substrate body 5 may be inverted after the sheet material 41 is peeled off.
[0039]
Then, as shown in FIG. 3B, the embedded resin composition 22 is injected into the electronic component disposing through hole 15 from the second main surface 5b side, and after the defoaming from the embedded resin composition 22, Then, the embedded resin composition 22 is cured. If the electronic component placement through hole 15 is completely filled with resin only by injecting the resin from the first main surface 5a side, the second resin filling from the second main surface 5b side may be omitted. .
[0040]
After the embedded resin composition 22 is reliably filled in the through-holes 15 for disposing electronic components in this manner, the embedded resin composition 22 and the main surfaces 5a and 5b of the wiring board main body 5 are polished by a belt sander. As shown in FIG. 3C, the upper end 21a of the electrode terminal 21 is polished from the first main surface 5a side by polishing the embedding resin composition 22 on the first main surface 5a side. Exposed to the outside. In addition, by polishing the embedded resin composition 22 on the second main surface 5b side, the lower end 21b of the electrode terminal 21 is exposed to the outside of the embedded resin composition 22 from the second main surface 5b side. On the other hand, the main body 19 of the capacitor element 17 is buried in the buried resin composition 22.
[0041]
In addition, when the main surfaces 5a and 5b are polished, the embedded resin composition 22 formed around the capacitor element 17 is flattened, and the plating layer 40 and the surface of the embedded resin composition 22 are not polished. Height is aligned. That is, the plating layer 40 and the surface of the embedded resin composition 22 form the same plane. As a result, a flat conductor layer and an interlayer insulating layer can be formed on both main surfaces 5a and 5b by a known build-up method.
[0042]
After the main surfaces 5a and 5b are polished in this way, the conductor layers 7a and 7b are formed on the main surfaces 5a and 5b. That is, after performing electroless plating with Cu on the entire wiring board body 5 in which the capacitor element 17 is built in the through-hole 15 for disposing electronic components, and then further performing electrolytic plating with Cu, panel plating is performed. . By this panel plating, as shown in FIG. 3D, a plating layer 45 is laminated on the exposed surfaces of the plating layer 40, the embedded resin composition 22, the electrode terminals 21, the filling resin 13, and the like. .
[0043]
Then, as shown in FIG. 3E, unnecessary portions are removed by etching to form conductor layers 7a and 7b. After the formation of the conductor layers 7a and 7b, the following build-up process is performed. First, on the first main surface 5a side and the second main surface 5b side, an epoxy resin is a main component on the embedding resin composition 22, the conductor layers 7a and 7b, and the upper end 21a and the lower end 21b. A film-forming photosensitive resin is attached. Then, by exposing and developing this photosensitive resin, via holes are formed at positions where the upper end 21a and the lower end 21b are to be exposed, and the photosensitive resin is cured to form the interlayer insulating layers 25a, 25b. Form. The via holes may be formed by using a laser or the like after forming the interlayer insulating layers 25a and 25b with a non-photosensitive resin.
[0044]
Further, electroless plating and electrolytic plating are performed with Cu, a conductor is filled in the via holes formed in the interlayer insulating layers 25a and 25b, and panel plating is performed to form a plating layer. A dry film is stuck on the plating layer, exposed and developed to form an etching resist, and unnecessary portions in the plating layer are removed by etching. As a result, the wiring composed of the conductor layers 7a and 7b and the flip chip pad 31 are formed. The conductive layer may be formed by a well-known subtractive method, a full additive method, or a semi-additive method.
[0045]
After that, solder resist layers 35a and 35b are formed. Then, a Ni-Au plating layer is formed on the flip chip pads 31 exposed from the solder resist layer 35a, and a solder paste is applied and reflowed to form flip chip bumps 33.
[0046]
As described above, the wiring board 1 having the structure shown in FIG. 1 is completed.
In the wiring board 1, the capacitor element 17 is used as an electronic component. However, the present invention is not limited to this. A chip-shaped resistor, an inductor, a filter (SAW filter, LC filter, etc.), a transistor, a memory, a low noise amplifier (LNA) ), Various electronic components such as a semiconductor element, an FET, an antenna switch module, a coupler, and a diplexer. Further, among them, different kinds of electronic components may be incorporated in the same through hole.
[Example]
Hereinafter, the details of the experiments performed by the present inventors and the results thereof will be described.
[0047]
In this experiment, first, a plurality of types of embedding resin compositions (Examples 1 to 5 and Comparative Examples 1 to 3) shown in Table 1 were prepared by weighing and mixing the components, and kneading them with a three-roll mill. . Here, the details of the items described in Table 1 are as follows.
■ Epoxy resin “HP-4032D” (trade name): Naphthalene type epoxy resin (crystalline resin) manufactured by DIC (Dainippon Ink & Chemicals, Inc.)
“CELLOXIDE 3000” (trade name): an aliphatic cyclic epoxy resin manufactured by Daicel Chemical Industries, Ltd. (viscosity: 20 mPa · s (25 ° C.))
“E-828” (trade name): Bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. (viscosity 15 Pa · s (25 ° C.))
“E-828XA” (trade name): Bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. (viscosity: 23 Pa · s (25 ° C.))
“E-807” (trade name): Bisphenol F type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. (viscosity 4.5 Pa · s (25 ° C.))
■ Curing catalyst "San-Aid SI-100L" (trade name): a heat cationic polymerizable catalyst (sulfonium salt of hexafluoroantimonic acid) manufactured by Sanshin Chemical Industry Co., Ltd.
“2P4MHZ-PW” (trade name): imidazole catalyst manufactured by Shikoku Chemicals Co., Ltd. ■ Inorganic filler “TSS-6” (trade name): fused silica manufactured by Tatsumori Co., Ltd. (silane-coupled, particle size distribution) Maximum particle diameter 24 μm)
[0048]
[Table 1]

The present inventor conducted a 24-hour standing test, a Tg (glass transition temperature) investigation, and a PCT evaluation as tests for evaluating the characteristics of each of the embedded resin compositions shown in Table 1. Hereinafter, each will be described specifically.
[0049]
[24 hour standing test]
About 10 g of each embedding resin composition immediately after kneading was put into a plastic container, and this was left at room temperature (about 25 ° C.) for 24 hours. Thereafter, the appearance and physical properties of each embedded resin composition were visually observed, and the crystallization and solidification of the resin component were confirmed by touch with a finger. Further, each of the embedding resin compositions was heated to 60 ° C. for 30 minutes. When the resin composition became a varnish, it was determined that the resin had not been cured (crystallized).
[0050]
[Tg survey]
With respect to each embedding resin composition, the glass transition temperature was investigated from the inflection point of tan δ according to DMA (dynamic mechanical analysis), and 150 ° C. or higher was accepted.
[0051]
[PCT evaluation]
In this test, 20 samples of each embedding resin composition were prepared and evaluated.
Here, the sample for this test was produced as follows.
[0052]
First, a BT (bismaleimide-triazine) substrate having a thickness of 0.8 mm is used as a core substrate, and a substantially rectangular through hole is provided in the core substrate using a mold. Then, a transparent back tape is attached to one surface of the core substrate to close one of the through holes, and the core substrate is placed with the closed surface at the bottom.
[0053]
Next, a chip capacitor is arranged using a chip mounter on the adhesive surface of the back tape in the storage space formed by the through hole from the surface opposite to the surface to which the back tape is attached. Then, the embedded resin composition is poured into the gap between the chip capacitor and the core substrate using a dispenser, and defoamed and thermally cured under the conditions of 120 ° C. × 150 minutes + 170 ° C. × 300 minutes. The surface of the embedding resin composition thus hardened is roughly polished using a belt sander, and then finish-polished by lap polishing. Then, a via hole is formed by irradiating a carbon dioxide gas laser to expose the electrode of the chip capacitor.
[0054]
Subsequently, the exposed surface of the embedded resin composition is roughened using a swelling solution and a KMnO ₄ solution. After activating the roughened surface with a Pd catalyst, copper plating is performed in the order of electroless plating and electrolytic plating, a resist is formed on the plated surface, a predetermined wiring pattern is patterned, and unnecessary copper is further removed. After etching and removal using Na ₂ S ₂ O ₈ / concentrated sulfuric acid, the resist is peeled off to form a wiring pattern.
[0055]
Further, a film serving as an insulating layer is laminated on the wiring layer and thermally cured, and then a via hole is formed by irradiating a laser, and the surface of the insulating layer is roughened using an oxidizing agent. Then, a wiring pattern is formed by the method described above.
Thereafter, a dry film to be a solder resist layer is laminated on the outermost surface of the wiring substrate, and a mounting pattern of the semiconductor element is formed by exposing and developing, thereby forming a solder resist layer. Then, the terminal electrodes for mounting the semiconductor element are plated in the order of Ni plating and Au plating, and the semiconductor element is mounted through a solder reflow furnace. Further, after the mounting portion is filled with an underfill material by a dispenser, the material is thermally cured.
[0056]
After subjecting the thus prepared sample to PCT (pressure cooker test) (121 ° C., 2.1 atm, relative humidity 100%: 336 hours), the surface and cut surface were observed, and the effectiveness of the embedded resin composition was evaluated. evaluated. Specifically, if there were no cracks or poor embedding, etc., the test was passed. The embedding resin composition having a pass rate of 85% or more (17 or more out of 20 samples passed) was judged to be good.
[0057]
As is clear from Table 1, the following results were obtained by each test described above.
The embedding resin compositions of Examples 1 to 5 contain a naphthalene type epoxy resin, an aliphatic cyclic epoxy resin and a bisphenol type epoxy resin as a resin component, and contain a thermocation polymerization catalyst as a curing catalyst. However, in each case, satisfactory characteristics were obtained as the embedded resin composition.
[0058]
On the other hand, in the embedding resin compositions of Comparative Examples 1 and 2, compared to the compositions of Examples 1 to 5, a bisphenol-type epoxy resin having a higher viscosity was used. Example 2 differs from Example 2 in the amount thereof. The embedding resin composition of Comparative Example 1 was crystallized as a result of a 24-hour standing test, and in Comparative Example 2, the embedding was poor as a result of the PCT evaluation. Satisfactory properties were not obtained.
[0059]
On the other hand, the embedding resin composition of Comparative Example 3 is different from the compositions of Examples 1 to 5 in that only a bisphenol-type epoxy resin is used as a resin component, and an imidazole-based catalyst is used as a curing catalyst. The difference is that it is used. As a result of the PCT evaluation, the embedded resin composition of Comparative Example 3 was cracked and peeled off from the copper plating, and satisfactory characteristics as the embedded resin composition were not obtained.
[0060]
From the above results, as a resin component, containing a naphthalene-type epoxy resin, an aliphatic cyclic epoxy resin and a low-viscosity bisphenol-type epoxy resin, and further, as a curing catalyst, an embedding resin composition containing a thermal cation polymerization catalyst is It can be seen that they are excellent in moisture resistance, heat resistance, embedding property and the like and are hardly crystallized. Therefore, by using such an embedding resin composition, it is possible to realize a highly reliable wiring board in which electronic components are reliably embedded in the board, and cracks, defects such as adhesion with copper plating are unlikely to occur. be able to.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a wiring board using an embedding resin composition of the present invention.
FIG. 2 is an explanatory view (part 1) for explaining a method of manufacturing a wiring board;
FIG. 3 is an explanatory view (No. 2) for explaining the method of manufacturing the wiring board;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wiring board, 3a, 3b ... Conductor layer, 5 ... Wiring board main body, 7a, 7b ... Conductor layer, 11 ... Through hole, 13 ... Filled resin, 15 ... Through hole for electronic component arrangement, 17 ... Capacitor element, 22 embedded resin composition, 25a, 25b interlayer insulating layer, 31 flip chip pad, 33 flip chip bump, 35a, 35b solder resist layer, 39a, 39b filled via

Claims (4)

An embedding resin composition for embedding an electronic component inside a wiring board,
It contains an inorganic filler, a thermal cation polymerization catalyst and three or more types of resins, and among the three or more types of resins, at least one type is an aliphatic cyclic epoxy resin or an oxetane resin as a thermosetting resin; Is a bisphenol-type epoxy resin as a thermosetting resin and has a viscosity of 20 Pa · s (25 ° C.) or less, and at least one kind is a crystalline resin, a solid resin, or a semi-solid resin;
An embedding resin composition characterized by the following. In the embedding resin composition according to claim 1,
The thermal cationic polymerization catalyst, hexafluoroantimonic acid or hexafluorophosphoric acid, containing at least one of ammonium salt, sulfonium salt, phosphonium salt or pyridinium salt,
An embedding resin composition characterized by the following. In the embedding resin composition according to claim 1 or claim 2,
In the resin component of the embedding resin composition, the compounding amount of the bisphenol-type epoxy resin is 5% by weight or more,
An embedding resin composition characterized by the following. A wiring board in which electronic components are embedded,
An embedding resin composition for embedding the electronic component, wherein the embedding resin composition according to any one of claims 1 to 3 is used,
A wiring board characterized by the above-mentioned.

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