JP2004165274A - Manufacturing method of low-temperature calcination ceramic circuit substrate - Google Patents

Manufacturing method of low-temperature calcination ceramic circuit substrate Download PDF

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Publication number
JP2004165274A
JP2004165274A JP2002326959A JP2002326959A JP2004165274A JP 2004165274 A JP2004165274 A JP 2004165274A JP 2002326959 A JP2002326959 A JP 2002326959A JP 2002326959 A JP2002326959 A JP 2002326959A JP 2004165274 A JP2004165274 A JP 2004165274A
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JP
Japan
Prior art keywords
green sheet
low
shrinkage
temperature
conductor
Prior art date
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Pending
Application number
JP2002326959A
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Japanese (ja)
Inventor
Sadahiro Nakamura
禎宏 中村
Satoshi Adachi
聡 足立
Shigekazu Onozumi
重和 小野住
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tanaka Kikinzoku Kogyo KK
Sumitomo Metal SMI Electronics Device Inc
Original Assignee
Tanaka Kikinzoku Kogyo KK
Sumitomo Metal SMI Electronics Device Inc
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Publication date
Application filed by Tanaka Kikinzoku Kogyo KK, Sumitomo Metal SMI Electronics Device Inc filed Critical Tanaka Kikinzoku Kogyo KK
Priority to JP2002326959A priority Critical patent/JP2004165274A/en
Priority to GB0315957A priority patent/GB2391116B/en
Priority to GB0327735A priority patent/GB2393332B/en
Priority to DE2003131811 priority patent/DE10331811A1/en
Publication of JP2004165274A publication Critical patent/JP2004165274A/en
Pending legal-status Critical Current

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Abstract

<P>PROBLEM TO BE SOLVED: To improve the dimensional accuracy of a substrate by reducing the warpage of a calcination substrate and improve the connecting strength of a conductor pattern and a low-temperature calcination ceramic which are calcined simultaneously. <P>SOLUTION: When the shrinkage factor of a green sheet from the calcination shrinkage starting temperature of the green sheet of a low-temperature calcination ceramic to 900°C is shown by a(%) and the shrinkage factor of a wiring pattern 16 from the calcination shrinkage starting temperature of the green sheet to 900°C is shown by b(%), the relation of 0.26≤b/a≤0.73 is set. Further, the difference between the shrinkage factor from the calcination starting temperature of the green sheet to 480°C and the shrinkage factor of the conductor pattern from the starting temperature of calcination to 480°C is set so as not to be higher than 3.5%. On the other hand, a conductor paste employed for the printing of the wiring pattern is an Ag base conductor paste, in which 0.005-0.050 wt.% of Rh is added to the 100 wt.% of Ag base conductor powder. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
本発明は、低温焼成セラミックのグリーンシートと、該グリーンシートに印刷された導体パターンとを同時焼成して低温焼成セラミック回路基板を製造する方法に関するものである。
【0002】
【従来の技術】
従来より、セラミック基板として最も多く用いられているアルミナ基板は、誘電率が高く、しかも、1500℃以上の高温で焼成する必要があるため、同時焼成する配線導体としてMo,W等の抵抗値の高い高融点金属を使用せざるを得ない。このため、近年の信号処理の高速化・高周波化の要求に対して、アルミナ基板ではパッケージ設計が困難になってきている。
【0003】
このような事情から、近年、800〜1000℃で焼成可能な低温焼成セラミック基板の需要が急速に拡大している。この低温焼成セラミック基板は、グリーンシートと同時焼成する配線導体として、Ag、Ag−Pd、Au、Cu等の低抵抗導体の使用が可能で、且つ、セラミックの誘電率が低く、信号処理の高速化・高周波化に対応できるという特長がある。
【0004】
【発明が解決しようとする課題】
一般に、図3に示すように、低温焼成セラミックのグリーンシートは、焼成収縮開始温度が650〜820℃の範囲であるのに対して、従来のAg系導体ペーストは、400〜600℃の範囲で大きく収縮して焼結がほぼ完了するため、600〜900℃の間のAg系導体ペーストの収縮量は小さい。このため、600〜900℃の温度領域では、Ag系の導体と低温焼成セラミックの収縮率の差が温度上昇に伴って拡大し、それによって、両者の接合部に大きな熱応力が発生して焼成基板が反ってしまい、焼成基板の寸法精度を確保できなかったり、或は、導体と低温焼成セラミックとの接合部の接合強度が低下して、接合部が剥がれやすくなり、品質低下、信頼性低下の問題が発生する。
【0005】
本発明はこのような事情を考慮してなされたものであり、従ってその目的は、焼成基板の反りを小さくして基板寸法精度を向上させると共に、同時焼成する導体パターンと低温焼成セラミックとの接合強度を向上させて、低温焼成セラミック回路基板の製品品質・信頼性を向上させることができる低温焼成セラミック回路基板の製造方法を提供することにある。
【0006】
【課題を解決するための手段】
上記目的を達成するために、請求項1に記載の低温焼成セラミック回路基板の製造方法は、低温焼成セラミックのグリーンシートの焼成収縮開始温度から900℃までのグリーンシートの収縮率をa(%)とし、グリーンシートの焼成収縮開始温度から900℃までの導体パターンの収縮率をb(%)とした場合に、
0.26≦b/a≦0.73
の関係を満たすようにしたものである。
【0007】
後述する本発明者らの試験結果によれば、0.26≦b/a≦0.73の範囲であれば、グリーンシートの焼成収縮開始温度(一般に650〜820℃)から900℃までのグリーンシートと導体パターンとの収縮挙動の相違が従来よりも小さくなるため、焼成基板の反りを小さくできて基板寸法精度を向上させることができると共に、同時焼成する導体パターンと低温焼成セラミックとの接合強度を確保することができ、低温焼成セラミック回路基板の製品品質・信頼性を向上させることができる。
【0008】
更に、請求項2のように、グリーンシートの焼成開始から480℃までの収縮率(%)と、導体パターンの焼成開始から480℃までの収縮率(%)との差(%)が3.5(%)以下となるようにすると良い。グリーンシートや導体パターンの温度が焼成開始から480℃に上昇するまでに、グリーンシートや導体パターンに含まれる有機物(有機ビヒクル)がほとんど熱分解して蒸発し、その過程で、グリーンシートや導体パターンが収縮する。このように、有機物の熱分解によって生じるグリーンシートと導体パターンの収縮率の差が大きいと、焼成基板の反りを大きくしたり、導体パターンと低温焼成セラミックとの接合強度を低下させる原因となる。後述する本発明者らの試験結果によれば、焼成開始から480℃までのグリーンシートと導体パターンの収縮率の差が3.5(%)以下であれば、焼成基板の反りを小さくして基板寸法精度を向上させることができると共に、同時焼成する導体パターンと低温焼成セラミックとの接合強度を向上させることができる。
【0009】
また、請求項3のように、導体パターンの印刷に用いる導体ペーストは、導体粉末としてAg粉末又はAg系合金粉末(以下これらを「Ag系粉末」と総称する)を主として含有し、且つ、導体粉末:100重量%に対して、Rh(ロジウム)を0.005〜0.050重量%添加したAg系導体ペーストを使用すると良い。
【0010】
この場合、RhはAg系導体パターンの焼結を抑制する効果があるため、このRhを適量添加することで、導体パターンの焼結を緩やかに進行させることができる。これにより、導体パターンの焼成収縮開始後の収縮率を従来よりも小さくすることができ、焼成時の導体パターンの収縮挙動をグリーンシートの収縮挙動に近付けることができて、焼成基板の反りを少なくできる。しかも、焼結抑制剤としてのRhの添加量が微量であるため、Rhの添加による導体パターンの電気抵抗値の増加も極めて少なく、導体パターンの電気的特性を良好に維持することができる。
【0011】
また、グリーンシートと導体パターンとを同時焼成する際に、グリーンシートの焼成収縮開始温度から900℃までの温度領域で、グリーンシートに含まれるガラス成分が軟化流動するが、Rhの焼結抑制効果により導体パターンの焼結が抑制され、導体パターンの緻密化が遅らされるため、グリーンシートのガラス成分が導体パターンの内部に効率良く浸透拡散して、導体パターンと焼成基板との接合強度を高める効果も期待できる。
【0012】
尚、グリーンシートを成形する材料は、1000℃以下で焼成する低温焼成セラミックであれば、その組成を問わず、本発明を適用できるが、例えば、請求項4のように、CaO−SiO−Al−B系ガラスとアルミナとの混合物からなる低温焼成セラミックのグリーンシートを用いると良い。この組成の低温焼成セラミックは、焼成収縮開始温度が730℃という比較的低い温度であり、収縮挙動を上記適正範囲内に調整しやすいという特長があると共に、Rhの添加によって顕著な焼結抑制効果が得られるという特長がある。
【0013】
【発明の実施の形態】
以下、本発明の一実施形態を図面に基づいて説明する。ここで、図1は本実施形態の製造工程で製造する低温焼成セラミック多層回路基板の一例を模式的に示す縦断面図、図2は本実施形態の製造工程の流れを示す工程フローチャートである。
【0014】
本実施形態の製造工程では、まず、低温焼成セラミックのグリーンシート11を低温焼成セラミックのスラリーを用いてドクターブレード法等によりテープ成形する。この際、低温焼成セラミックとしては、CaO−SiO−Al−B系ガラス:50〜65重量%(好ましくは60重量%)とアルミナ:50〜35重量%(好ましくは40重量%)との混合物を用いる。この他、例えばMgO−SiO−Al−B系ガラスとアルミナとの混合物、SiO−B系ガラスとアルミナとの混合物、PbO−SiO−B系ガラスとアルミナとの混合物、コージェライト系結晶化ガラス等、800〜1000℃で焼成できる種々の低温焼成セラミック材料の中から適宜選択すれば良い。
【0015】
この後、テープ成形した低温焼成セラミックのグリーンシート11を所定寸法に切断した後、そのグリーンシート11の所定位置にビアホール12,13をパンチング加工する。図1の構成例では、径の大きい方のビアホール13は、搭載部品14の熱を放熱させるためのサーマルビア15を形成するビアホールであり、径の小さい方のビアホール12は、層間の導体パターン16を接続するビア導体18を形成するビアホールである。この場合、ビアホール12,13の穴径とグリーンシート11の厚みとの比(穴径/シート厚み)を、0.1〜5、より好ましくは0.2〜3に設定している。
【0016】
ビアホール12,13のパンチング加工後、同時印刷工程に進み、各グリーンシート11のビアホール12,13の穴埋め印刷と導体パターン16の印刷とを下記の組成のAg系導体ペーストを用いて同時に行う。
【0017】
尚、本発明は、ビアホール12,13の穴埋め印刷と導体パターン16の印刷とを同時に行う場合に限定されず、ビアホール12,13の穴埋め印刷を行った後に、導体パターン16の印刷を行うようにしても良い。この場合は、ビアホール12,13の穴埋め印刷と導体パターン16の印刷とで異なる組成の導体ペーストを用いるようにしても良い。
【0018】
この印刷工程で使用するAg系導体ペーストは、導体粉末としてAg粉末を主として含有し、必要に応じて他の貴金属粉末(例えばPd、Pt、Au等の粉末)を添加するようにしても良い。この際、Agと他の貴金属との合金粉末を用いても良い。
【0019】
Ag粉末にPd粉末やPt粉末を添加(又は合金化)したAg−Pd、Ag−Pt、Ag−Pd−Ptの導体は、Agのみの導体と比較して耐半田性等が向上する特長があり、また、Pd粉末やPt粉末の添加によって焼結抑制効果も期待できる。従って、耐半田性等の要求特性に応じてAgに対する他の貴金属の添加量を決定すれば良い。
【0020】
この場合、Ag系粉末(Ag粉末又はAg系の合金粉末)の粒径は、電子顕微鏡観察法で測定した一次粒子の平均粒径が1.5〜4.5μm、より好ましくは1.7〜4.1μmで、且つ、遠心沈降法で測定した凝集粒子の平均粒径(累積50%径)が5.0〜12μmとなるように調製している。ここで、一次粒子とは、粒子の最小単位であって、それ以上分割されない粒子のことであり、凝集粒子とは複数の一次粒子が凝集して一塊となった一次粒子の集合体のことである。
【0021】
電子顕微鏡観察法は、例えば走査型電子顕微鏡(SEM)を用いてAg系粉末を撮影し、その撮影写真の所定範囲内に粒子全体が見える一次粒子の最も長い箇所の径を測定して、その平均値を一次粒子の平均粒径として求める。
【0022】
また、遠心沈降法は、遠心沈降光透過法とも呼ばれ、遠心式自動粒径分布測定装置を用いて、遠心力下で粒子が沈降することによる透過光量の増加から凝集粒子の粒径分布を測定し、その測定結果から凝集粒子の平均粒径(累積50%径)を求める。
【0023】
この場合、Ag系粉末は、比表面積が0.1〜0.4m/g、より好ましくは0.13〜0.33m/gとなるものを用いると良い。この比表面積は、一次粒子の凝集の程度や粒子形状(例えば表面の粗さや空孔の多さ)を評価する指標となり、BET法等で測定すれば良い。
【0024】
また、このAg系導体ペーストには、導体粉末:100重量%に対して焼結抑制剤としてRhを、0.005〜0.050重量%、より好ましくは0.005〜0.040重量%、最も好ましくは0.0075〜0.030重量%添加している。Rhの添加形態は、Rh単体、Rh化合物のいずれを用いても良い。Rh単体としては、BET法等で測定した比表面積が50〜150m/g、より好ましくは80〜140m/gとなるRh粉末を用いると良く、また、Rh化合物としては、例えば環式テルペン含硫黄Rh化合物等のいわゆるRhレジネートを用いれば良いが、これらに限定されるものではない。Rh化合物を用いる場合は、Rh化合物中のRh含有量が上記の範囲内となるようにRh化合物の添加量を決定すれば良い。
【0025】
また、このAg系導体ペーストに含まれる無機物は、上述した導体粉末(Ag粉末、他の貴金属粉末)、Rhの他に、密着性向上、焼結抑制等のためにガラスフリットや金属酸化物(例えば、TiO、SiO等)を添加しても良い。ガラスフリットは、導体パターンと同時焼成する低温焼成セラミックグリーンシート11に含まれるガラス成分と同種のガラス(例えばCaO−SiO−Al−B系ガラス)を用いれば良いが、これに限定されるものではない。
【0026】
このAg系導体ペーストの無機物中のAg含有率を85重量%以上に設定すると良い。このようにすれば、無機物中のAg以外の添加物(例えばガラスフリットや金属酸化物)が15重量%未満となって、導体パターンの電気抵抗値の増加を防ぐことができ、導体パターンの電気的特性を安定させることができる。
【0027】
また、このAg系導体ペーストに含まれる有機物は、バインダ樹脂(例えばエチルセルロース系樹脂、アクリル系樹脂等)と、有機溶剤(例えばテルピネオール[TPO]、ブチルカルビトールアセテート[BCA]、エステルアルコール等)と可塑剤からなり、可塑剤を添加した有機溶剤にバインダ樹脂を溶解して作製した有機ビヒクルと呼ばれる状態で上記無機物と混合して、Ag系導体ペーストが作製される。
【0028】
このAg系導体ペーストの有機物の配合量を8〜27重量%とし、無機物の配合量を73〜92重量%とすると良い。この範囲の有機物、無機物の配合量とすれば、導体ペーストの有機物と無機物との配合比が適正となり、導体ペーストの粘度がビアホール穴埋め充填性と導体パターン印刷性とを両立できる適度な粘度となると共に、焼成開始から有機物の熱分解温度である400℃付近に昇温するまでの有機物の熱分解による導体パターンの減量も少なくなり、導体パターンの電気的特性を安定させることができる。尚、このAg系導体ペーストの粘度を調整するために、増粘剤(例えば金属石鹸)等を添加するようにしても良い。
【0029】
この場合、図4に示すように、グリーンシート11の焼成収縮開始温度から900℃までのグリーンシート11の収縮率をa(%)とし、グリーンシート11の焼成収縮開始温度から900℃までの導体パターン16の収縮率をb(%)としたときに、下記の関係を満たすように、グリーンシート11及び/又は導体パターン16の収縮率を例えばRhの添加量によって調整する。
0.26≦b/a≦0.73
【0030】
グリーンシート11がCaO−SiO−Al−B系ガラスとアルミナからなる低温焼成セラミックで成形されている場合は、焼成収縮開始温度が730℃である。一般に、850〜900℃で焼成する低温焼成セラミックグリーンシートは、焼成収縮開始温度が650〜820℃程度である。
【0031】
更に、本実施形態では、グリーンシート11の焼成開始から480℃までの収縮率(%)と、乾燥状態の導体パターン16の焼成開始から480℃までの収縮率(%)との差c(%)が3.5(%)以下となるように、グリーンシート11及び/又は導体パターン16の収縮率を例えば有機物の配合量等によって調整する。
尚、導体パターン16やグリーンシート11の収縮率の測定は、熱機械分析(TMA:Thermo Mechanical Analysis )装置を用いて行えば良い。
【0032】
同時印刷工程では、ビアホール12,13と導体パターン16を印刷するための印刷パターン(図示せず)が形成されたスクリーンマスク(図示せず)をグリーンシート11上にセットして、そのスクリーンマスク上に上記組成のAg系導体ペーストを供給し、そのスクリーンマスク上面に沿ってスキージ(図示せず)を摺動させることで、ビアホール12,13の穴埋め印刷と導体パターン16の印刷とを同時に行う。
【0033】
尚、最下層のグリーンシート11は、その上面に印刷する内層導体パターン16をビアホール12,13と同時に印刷し、その後、該最下層のグリーンシート11の下面に裏面パターン19を印刷する。この裏面パターン19の印刷は、後述するグリーンシート11の積層後又は焼成後に行っても良い。
【0034】
一方、最上層のグリーンシート11の上面に、表層導体パターン16をビアホール12,13と同時に印刷する際に、部品搭載ランド20等の導体パターン以外の導体パターンも同時に印刷する。尚、表層導体パターン16や部品搭載ランド20等の印刷は、後述するグリーンシート11の積層後又は焼成後に行っても良い。
【0035】
同時印刷工程終了後、積層・圧着工程に進み、各層のグリーンシート11を積層し、この積層体を例えば60〜150℃、0.1〜30MPa(好ましくは1〜10MPa)の条件で加熱圧着して一体化する。
【0036】
この後、焼成工程に進み、グリーンシート11の積層体を、昇温速度:10℃/分、焼成ピーク温度:800〜1000℃(好ましくは900℃前後)、20分ホールドの条件で空気雰囲気中で焼成し、グリーンシート11の積層体を内層・表層導体パターン16、ビア導体15,18と同時に焼成して低温焼成セラミック多層回路基板を製造する。
【0037】
【実施例】
本発明者らは、上記製造方法で製造した低温焼成セラミック多層回路基板の収縮率パラメータb/a、c及びRh添加量に関して、その適正範囲を考察する試験を行ったので、その試験結果を次の表1及び図7、図8に示す。
【0038】
【表1】

Figure 2004165274
【0039】
ここで、収縮率パラメータb/aは、グリーンシートの焼成収縮開始温度から900℃までのグリーンシートの収縮率a(%)に対する導体パターン16の収縮率b(%)の比率であり、収縮率パラメータcは、グリーンシートの焼成開始から480℃までの収縮率(%)と、乾燥状態の導体パターンの焼成開始から480℃までの収縮率(%)との差である。
【0040】
実施例1〜9と比較例1〜3は、厚さ300μmのグリーンシートを4層に積層し、このグリーンシート上に、表1の組成の導体ペーストを用いて、図5に示すように、線幅400μの配線パターン(導体パターン)を蛇行状に印刷すると共に、縦横2mm×2mmの測定強度測定用パッド(導体パターン)を4個印刷した。グリーンシートは、CaO−SiO−Al−B系ガラス:60重量%とアルミナ:40重量%との混合物からなる低温焼成セラミックにより成形したものを用いた。
【0041】
このグリーンシートの焼成収縮開始温度は730℃であり、コンベア炉中で、各実施例と各比較例のサンプル基板を890℃にて焼成し、焼成後の配線パターンと測定強度測定用パッドの膜厚を測定したところ、膜厚が10〜14μmであった。尚、各実施例と各比較例で使用した導体ペーストに含まれる導体は、Agが100重量%、又は、Agに微量のPt又はPdを添加したAg系導体であり、このAg系導体粉末:100重量%に対して、有機ビヒクルを23重量%配合したAg系導体ペーストを使用した。また、実施例6のみ、導体ペーストに2重量%のガラスフリットを添加した。
【0042】
図5に示すように、配線パターンの膜厚の測定は、配線パターンの両端で行い、焼成基板の反り量の測定は、配線パターン印刷領域の中央位置▲1▼とその両側位置▲2▼、▲3▼でそれぞれ高さを測定し、中央位置▲1▼の高さからその両側位置▲2▼、▲3▼の高さの平均値を差し引いた値を反り量とした(図6参照)。
【0043】
表1に示す実施例1〜9は、収縮率パラメータb/aが0.26〜0.73の範囲であり、収縮率パラメータcが0.7〜3.5%の範囲である。また、Rh添加量が0.005〜0.050重量%の範囲である。実施例7のみ、Rhの添加をRhレジネートにて行い、他の実施例と比較例は、Rh粉末を使用した。
【0044】
実施例1〜9は、電気抵抗値が2.3〜5.3μΩ・cmの範囲であり、焼成基板の反り量が23〜87μmの範囲である。また、パッドと基板の接合強度が16〜21Nの範囲である。
【0045】
これに対し、比較例1〜3は、いずれも焼成基板の反り量が110μm以上という大きな値となる。特に、比較例1は、導体ペーストにRhが添加されていないため、導体ペーストの焼結抑制効果が全く得られず、グリーンシートと配線パターンの収縮率の差が大きくなりすぎる。その結果、比較例1は、収縮率パラメータb/aが0.08という非常に小さい値となると共に、収縮率パラメータcが11.1という非常に大きい値となるため、焼成基板の反り量が125μmという非常に大きい値となり、焼成基板の寸法精度を確保できなくなると共に、パッドと基板の接合強度が10Nという非常に小さい値となってしまい、パッドの剥がれが発生しやすくなる。
【0046】
また、比較例2は、導体ペーストにRhを添加しているものの、Rh添加量が0.001重量%という非常に少ない量であるため、Rh添加による導体ペーストの焼結抑制効果が不足して、グリーンシートと配線パターンの収縮率の差を十分に小さくすることができない。その結果、比較例2は、収縮率パラメータb/aが0.14という小さい値となると共に、収縮率パラメータcが8.1という大きい値となり、その結果、焼成基板の反り量が110μmという大きい値となり、焼成基板の寸法精度を十分に確保できなくなると共に、パッドと基板の接合強度が14Nという小さい値となってしまい、パッドの剥がれが発生する可能性があり、品質低下、信頼性低下の問題が発生する。
【0047】
また、比較例3は、Rh添加量が0.075重量%で、Rh添加による導体ペーストの焼結抑制効果が期待できるが、収縮率パラメータb/aが0.11という小さい値となるため、焼成基板の反り量が110μmという大きい値となり、焼成基板の寸法精度を十分に確保できない。しかも、比較例3は、Rh添加による不具合(抵抗増加現象)が顕著に現れて、電気抵抗値が9.0μΩ・cmという大きな値となってしまい、電気的特性が悪化する欠点がある。
【0048】
これに対し、実施例1〜9は、収縮率パラメータb/aが0.26〜0.73、収縮率パラメータcが0.7〜3.5%、Rh添加量が0.005〜0.050重量%である。収縮率パラメータb/aが0.26〜0.73の範囲であれば、グリーンシートの焼成収縮開始温度(730℃)から900℃までのグリーンシートと配線パターンとの収縮挙動の相違を小さくすることができる。しかも、収縮率パラメータcが0.7〜3.5%であれば、グリーンシートの焼成収縮開始前の温度領域でも、グリーンシートと配線パターンとの収縮挙動の相違を小さくすることができる。
【0049】
更に、実施例1〜9のように、Rh添加量が0.005〜0.050重量%であれば、適度な導体ペーストの焼結抑制効果を得ることができ、上述した収縮率パラメータb/a、cの適正化と相俟って、図7に示すように、焼成基板の反り量を84μm以下に抑えることができ、良好な基板寸法精度を確保できる。しかも、Rh添加量が0.005〜0.050重量%という微量であれば、Rhの添加による配線パターンの電気抵抗値の増加も少なく、図8に示すように、電気抵抗値を5.3μΩ・cm以下に抑えることができ、良好な電気的特性を確保できる。その上、パッドと基板の接合強度が16N以上となり、パッドの剥がれを防止できて、良好な接続信頼性を確保できる。
【0050】
尚、図1の構成例では、サーマルビア15を形成するようにしたが、サーマルビア15を形成しない構成としても良いことは言うまでもない。
その他、本発明は、セラミック多層回路基板の構造や低温焼成セラミックグリーンシートの積層枚数等を変更したり、低温焼成セラミックグリーンシートに厚膜抵抗体ペースト等を印刷する印刷工程を追加するようにしても良い等、種々変更して実施することができる。
【0051】
【発明の効果】
以上の説明から明らかなように、本発明によれば、焼成基板の反りを小さくして基板寸法精度を向上させることができると共に、同時焼成する導体パターンと低温焼成セラミックとの接合強度を向上させることができ、低温焼成セラミック回路基板の製品品質・信頼性を向上させることができる。
【図面の簡単な説明】
【図1】本発明の一実施形態の製造方法で製造する低温焼成セラミック多層回路基板の構成例を模式的に示す図
【図2】製造工程の流れを示す工程フローチャート
【図3】従来のAg系導体ペーストと低温焼成セラミックグリーンシートの焼成時の収縮挙動を測定したグラフ
【図4】本発明の実施例のAg系導体ペーストと低温焼成セラミックグリーンシートの焼成時の収縮挙動を測定したグラフ
【図5】実施例1〜9及び比較例1〜3のサンプル基板の平面図
【図6】焼成基板の反り量の測定方法を説明するサンプル基板の側面図
【図7】導体ペーストのRh添加量と反り量との関係を示すグラフ
【図8】導体ペーストのRh添加量と電気抵抗値との関係を示すグラフ
【符号の説明】
11…低温焼成セラミックグリーンシート、12,13…ビアホール、15…サーマルビア、16…導体パターン、18…ビア導体。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a low-temperature fired ceramic circuit board by simultaneously firing a green sheet of a low-temperature fired ceramic and a conductor pattern printed on the green sheet.
[0002]
[Prior art]
Conventionally, an alumina substrate, which has been most frequently used as a ceramic substrate, has a high dielectric constant and needs to be fired at a high temperature of 1500 ° C. or more. High refractory metals must be used. For this reason, it has become difficult to design a package for an alumina substrate in response to recent demands for higher speed and higher frequency of signal processing.
[0003]
Under these circumstances, in recent years, the demand for low-temperature fired ceramic substrates that can be fired at 800 to 1000 ° C. has been rapidly expanding. This low-temperature fired ceramic substrate can use a low-resistance conductor such as Ag, Ag-Pd, Au, or Cu as a wiring conductor that is fired simultaneously with the green sheet, has a low dielectric constant of ceramic, and has a high signal processing speed. It has the feature that it can respond to high frequency and high frequency.
[0004]
[Problems to be solved by the invention]
Generally, as shown in FIG. 3, a green sheet of a low-temperature fired ceramic has a firing shrinkage onset temperature of 650 to 820 ° C., whereas a conventional Ag-based conductor paste has a temperature of 400 to 600 ° C. Since the sintering is substantially completed due to large shrinkage, the shrinkage of the Ag-based conductor paste between 600 and 900 ° C. is small. For this reason, in the temperature range of 600 to 900 ° C., the difference in the shrinkage ratio between the Ag-based conductor and the low-temperature fired ceramic increases as the temperature rises. The substrate warps and the dimensional accuracy of the fired substrate cannot be ensured, or the bonding strength of the joint between the conductor and the low-temperature fired ceramic decreases, and the joint tends to peel off, resulting in lower quality and lower reliability. Problems occur.
[0005]
The present invention has been made in view of such circumstances, and therefore has as its object to reduce the warpage of a fired substrate, improve the dimensional accuracy of the substrate, and join a conductor pattern to be fired simultaneously with a low-temperature fired ceramic. An object of the present invention is to provide a method for manufacturing a low-temperature fired ceramic circuit board capable of improving strength and improving the product quality and reliability of the low-temperature fired ceramic circuit board.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a low-temperature fired ceramic circuit board according to claim 1 is characterized in that the shrinkage rate of a green sheet of a low-temperature fired ceramic green sheet from a firing shrinkage starting temperature to 900 ° C. is a (%). When the shrinkage ratio of the conductor pattern from the firing shrinkage start temperature of the green sheet to 900 ° C. is b (%),
0.26 ≦ b / a ≦ 0.73
This is to satisfy the relationship.
[0007]
According to the test results of the present inventors described below, when the range of 0.26 ≦ b / a ≦ 0.73 is satisfied, the green sheet starts firing at the time of firing shrinkage (generally 650 to 820 ° C.) to 900 ° C. Since the difference in the shrinkage behavior between the sheet and the conductor pattern is smaller than before, the warpage of the fired substrate can be reduced and the dimensional accuracy of the substrate can be improved. , And the product quality and reliability of the low-temperature fired ceramic circuit board can be improved.
[0008]
Further, the difference (%) between the shrinkage rate (%) from the start of firing of the green sheet to 480 ° C. and the shrinkage rate (%) from the start of firing of the conductor pattern to 480 ° C. is 3. It is good to be 5 (%) or less. By the time the temperature of the green sheet or the conductor pattern rises to 480 ° C from the start of firing, most of the organic substances (organic vehicles) contained in the green sheet and the conductor pattern are thermally decomposed and evaporated. Contracts. As described above, a large difference in shrinkage between the green sheet and the conductor pattern caused by the thermal decomposition of the organic substance causes an increase in the warpage of the fired substrate and a decrease in the bonding strength between the conductor pattern and the low-temperature fired ceramic. According to the test results of the present inventors described below, if the difference in shrinkage ratio between the green sheet and the conductor pattern from the start of firing to 480 ° C. is 3.5 (%) or less, the warpage of the fired substrate is reduced. The dimensional accuracy of the substrate can be improved, and the bonding strength between the simultaneously fired conductor pattern and the low-temperature fired ceramic can be improved.
[0009]
Further, as in claim 3, the conductor paste used for printing the conductor pattern mainly contains Ag powder or Ag-based alloy powder (hereinafter, these are collectively referred to as “Ag-based powder”) as the conductor powder. It is preferable to use an Ag-based conductor paste in which 0.005 to 0.050% by weight of Rh (rhodium) is added to 100% by weight of powder.
[0010]
In this case, since Rh has an effect of suppressing sintering of the Ag-based conductor pattern, by adding an appropriate amount of Rh, sintering of the conductor pattern can be slowly advanced. As a result, the contraction rate of the conductor pattern after the start of firing shrinkage can be made smaller than before, and the shrinkage behavior of the conductor pattern at the time of firing can be made closer to the shrinkage behavior of the green sheet, thereby reducing the warpage of the fired substrate. it can. In addition, since the amount of Rh added as a sintering inhibitor is very small, the increase in the electrical resistance of the conductor pattern due to the addition of Rh is extremely small, and the electrical characteristics of the conductor pattern can be maintained well.
[0011]
Further, when the green sheet and the conductor pattern are simultaneously fired, the glass component contained in the green sheet softens and flows in a temperature region from the firing shrinkage starting temperature of the green sheet to 900 ° C., but the effect of suppressing sintering of Rh. As a result, the sintering of the conductor pattern is suppressed, and the densification of the conductor pattern is delayed, so that the glass component of the green sheet efficiently diffuses into the inside of the conductor pattern and increases the bonding strength between the conductor pattern and the fired substrate. It can also be expected to increase the effect.
[0012]
In addition, as long as the material for forming the green sheet is a low-temperature fired ceramic fired at 1000 ° C. or lower, the present invention can be applied irrespective of its composition. For example, as described in claim 4, CaO—SiO 2 — al 2 O 3 -B 2 O 3 system is preferably used a low-temperature fired ceramic green sheet made of a mixture of glass and alumina. The low-temperature fired ceramic having this composition has a relatively low firing shrinkage starting temperature of 730 ° C., and has a feature that the shrinkage behavior can be easily adjusted within the above-mentioned appropriate range, and a remarkable sintering suppressing effect by the addition of Rh. Is obtained.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, FIG. 1 is a longitudinal sectional view schematically showing an example of a low-temperature fired ceramic multilayer circuit board manufactured in the manufacturing process of the present embodiment, and FIG. 2 is a process flowchart showing a flow of the manufacturing process of the present embodiment.
[0014]
In the manufacturing process of the present embodiment, first, a green sheet 11 of a low-temperature fired ceramic is tape-formed using a slurry of the low-temperature fired ceramic by a doctor blade method or the like. In this case, as the low temperature co-fired ceramic, CaO-SiO 2 -Al 2 O 3 -B 2 O 3 based glass: 50-65% by weight (preferably 60 wt%) alumina: 50 to 35 wt% (preferably 40 % By weight). In addition, for example, MgO-SiO 2 -Al 2 O 3 -B 2 mixture of O 3 based glass and alumina, a mixture of SiO 2 -B 2 O 3 based glass and alumina, PbO-SiO 2 -B 2 O 3 It may be appropriately selected from various low-temperature fired ceramic materials that can be fired at 800 to 1000 ° C., such as a mixture of a system glass and alumina, a cordierite crystallized glass, and the like.
[0015]
Thereafter, the green sheet 11 of the tape-formed low-temperature fired ceramic is cut into a predetermined size, and the via holes 12 and 13 are punched at predetermined positions of the green sheet 11. In the configuration example of FIG. 1, the via hole 13 having a larger diameter is a via hole for forming a thermal via 15 for radiating heat of the mounted component 14, and the via hole 12 having a smaller diameter is a conductor pattern 16 between the layers. Are via holes that form via conductors 18 for connecting via holes. In this case, the ratio of the hole diameter of the via holes 12 and 13 to the thickness of the green sheet 11 (hole diameter / sheet thickness) is set to 0.1 to 5, more preferably 0.2 to 3.
[0016]
After the punching of the via holes 12 and 13, the process proceeds to a simultaneous printing step, and the filling printing of the via holes 12 and 13 of each green sheet 11 and the printing of the conductor pattern 16 are simultaneously performed using an Ag-based conductor paste having the following composition.
[0017]
Note that the present invention is not limited to the case where the filling printing of the via holes 12 and 13 and the printing of the conductor pattern 16 are simultaneously performed, and the printing of the conductor pattern 16 is performed after the filling printing of the via holes 12 and 13 is performed. May be. In this case, a conductor paste having a different composition may be used between the filling of the via holes 12 and 13 and the printing of the conductor pattern 16.
[0018]
The Ag-based conductor paste used in this printing step mainly contains Ag powder as the conductor powder, and other precious metal powders (for example, powders of Pd, Pt, Au, etc.) may be added as necessary. At this time, an alloy powder of Ag and another noble metal may be used.
[0019]
Ag-Pd, Ag-Pt, and Ag-Pd-Pt conductors obtained by adding (or alloying) Pd powder or Pt powder to Ag powder have the advantage of improving solder resistance, etc., as compared to Ag-only conductors. In addition, an effect of suppressing sintering can be expected by adding Pd powder or Pt powder. Therefore, the amount of other noble metal added to Ag may be determined according to the required characteristics such as solder resistance.
[0020]
In this case, the average particle size of the primary particles measured by an electron microscope observation method is 1.5 to 4.5 μm, more preferably 1.7 to 500 μm, as the particle size of the Ag-based powder (Ag powder or Ag-based alloy powder). It is prepared so that the average particle diameter (cumulative 50% diameter) of the aggregated particles measured by the centrifugal sedimentation method is 4.1 μm and 5.0 to 12 μm. Here, the primary particles are the smallest units of the particles and are particles that are not further divided, and the aggregated particles are an aggregate of the primary particles in which a plurality of primary particles are aggregated into one lump. is there.
[0021]
Electron microscopy is, for example, using a scanning electron microscope (SEM) to take an image of an Ag-based powder and measuring the diameter of the longest point of the primary particle in which the entire particle is visible within a predetermined range of the photographed photograph. The average value is determined as the average particle size of the primary particles.
[0022]
In addition, the centrifugal sedimentation method is also referred to as a centrifugal sedimentation light transmission method, and uses a centrifugal automatic particle size distribution measuring device to increase the amount of transmitted light due to the sedimentation of particles under centrifugal force to determine the particle size distribution of aggregated particles. The average particle diameter (cumulative 50% diameter) of the aggregated particles is determined from the measurement results.
[0023]
In this case, the Ag-based powder having a specific surface area of 0.1 to 0.4 m 2 / g, more preferably 0.13 to 0.33 m 2 / g may be used. The specific surface area serves as an index for evaluating the degree of aggregation of the primary particles and the particle shape (for example, surface roughness and large number of pores), and may be measured by a BET method or the like.
[0024]
In addition, this Ag-based conductor paste contains 0.005 to 0.050 wt%, more preferably 0.005 to 0.040 wt%, of Rh as a sintering inhibitor with respect to 100 wt% of conductor powder. Most preferably, 0.0075 to 0.030% by weight is added. Regarding the addition form of Rh, either Rh alone or Rh compound may be used. The Rh alone, BET method measured specific surface area of 50 to 150 m 2 / g, the more preferably better With Rh powder becomes 80~140m 2 / g, also, as the Rh compound, for example, cyclic terpene A so-called Rh resinate such as a sulfur-containing Rh compound may be used, but is not limited thereto. When an Rh compound is used, the amount of the Rh compound added may be determined so that the Rh content in the Rh compound falls within the above range.
[0025]
In addition to the above-mentioned conductor powder (Ag powder and other noble metal powder) and Rh, the inorganic substance contained in the Ag-based conductor paste may be glass frit or metal oxide (for improving adhesion and suppressing sintering). For example, TiO 2 , SiO 2 or the like may be added. Glass frit, may be used a glass of the glass component and the same type contained in the low-temperature co-fired ceramic green sheet 11 which co-fired with a conductor pattern (e.g., CaO-SiO 2 -Al 2 O 3 -B 2 O 3 based glass), It is not limited to this.
[0026]
The Ag content in the inorganic substance of the Ag-based conductor paste is preferably set to 85% by weight or more. By doing so, the amount of additives (eg, glass frit and metal oxide) other than Ag in the inorganic substance is less than 15% by weight, and it is possible to prevent an increase in the electric resistance of the conductor pattern, and to reduce the electric resistance of the conductor pattern. Characteristic can be stabilized.
[0027]
Organic substances contained in the Ag-based conductor paste include a binder resin (for example, ethyl cellulose-based resin, acrylic resin, etc.) and an organic solvent (for example, terpineol [TPO], butyl carbitol acetate [BCA], ester alcohol, etc.). An Ag-based conductor paste is produced by mixing with the above-mentioned inorganic substance in a state called an organic vehicle produced by dissolving a binder resin in an organic solvent to which a plasticizer is added.
[0028]
It is preferable that the amount of the organic substance in the Ag-based conductor paste is 8 to 27% by weight, and the amount of the inorganic substance is 73 to 92% by weight. If the compounding amount of the organic substance and the inorganic substance is within this range, the compounding ratio of the organic substance and the inorganic substance of the conductor paste becomes appropriate, and the viscosity of the conductor paste becomes an appropriate viscosity capable of satisfying both via hole filling and fillability and conductor pattern printability. At the same time, the loss of the conductor pattern due to the thermal decomposition of the organic substance from the start of baking until the temperature rises to around 400 ° C., which is the thermal decomposition temperature of the organic substance, is reduced, and the electrical characteristics of the conductive pattern can be stabilized. In order to adjust the viscosity of the Ag-based conductor paste, a thickener (for example, metal soap) or the like may be added.
[0029]
In this case, as shown in FIG. 4, the contraction rate of the green sheet 11 from the firing shrinkage start temperature of the green sheet 11 to 900 ° C. is a (%), and the conductor from the firing shrinkage start temperature of the green sheet 11 to 900 ° C. When the contraction rate of the pattern 16 is b (%), the contraction rate of the green sheet 11 and / or the conductor pattern 16 is adjusted by, for example, the amount of Rh added so as to satisfy the following relationship.
0.26 ≦ b / a ≦ 0.73
[0030]
If the green sheet 11 is formed by low-temperature fired ceramic made of CaO-SiO 2 -Al 2 O 3 -B 2 O 3 based glass and alumina, the firing shrinkage initiation temperature of 730 ° C.. In general, low-temperature fired ceramic green sheets fired at 850 to 900 ° C have firing shrinkage onset temperatures of about 650 to 820 ° C.
[0031]
Furthermore, in this embodiment, the difference c (%) between the shrinkage rate (%) from the start of firing of the green sheet 11 to 480 ° C. and the shrinkage rate (%) from the start of firing of the conductor pattern 16 in the dry state to 480 ° C. ) Is 3.5 (%) or less, the shrinkage ratio of the green sheet 11 and / or the conductor pattern 16 is adjusted by, for example, the blending amount of the organic substance.
The measurement of the shrinkage of the conductor pattern 16 and the green sheet 11 may be performed by using a thermomechanical analysis (TMA) device.
[0032]
In the simultaneous printing step, a screen mask (not shown) on which a print pattern (not shown) for printing the via holes 12 and 13 and the conductor pattern 16 is set on the green sheet 11, and the screen mask is formed. Is supplied, and a squeegee (not shown) is slid along the upper surface of the screen mask, so that the filling of the via holes 12 and 13 and the printing of the conductive pattern 16 are simultaneously performed.
[0033]
In the lowermost green sheet 11, an inner conductor pattern 16 to be printed on the upper surface thereof is printed simultaneously with the via holes 12 and 13, and thereafter, a lower surface pattern 19 is printed on the lower surface of the lowermost green sheet 11. The printing of the back surface pattern 19 may be performed after lamination or firing of the green sheet 11 described later.
[0034]
On the other hand, when the surface layer conductor pattern 16 is printed on the upper surface of the uppermost green sheet 11 at the same time as the via holes 12 and 13, the conductor pattern other than the conductor pattern such as the component mounting land 20 is also printed. The printing of the surface conductor patterns 16 and the component mounting lands 20 may be performed after laminating or firing the green sheets 11 described later.
[0035]
After completion of the simultaneous printing process, the process proceeds to a laminating / compressing process, in which the green sheets 11 of each layer are laminated, and the laminate is heated and press-bonded at, for example, 60 to 150 ° C. and 0.1 to 30 MPa (preferably 1 to 10 MPa). And unite.
[0036]
Thereafter, the process proceeds to a firing step, and the laminate of the green sheets 11 is heated in an air atmosphere under the conditions of a heating rate of 10 ° C./min, a firing peak temperature of 800 to 1000 ° C. (preferably around 900 ° C.), and a hold of 20 minutes. Then, the laminated body of the green sheet 11 is fired simultaneously with the inner / surface conductor pattern 16 and the via conductors 15 and 18 to manufacture a low-temperature fired ceramic multilayer circuit board.
[0037]
【Example】
The present inventors conducted a test to consider the appropriate ranges for the shrinkage ratio parameters b / a, c and the amount of Rh added to the low-temperature fired ceramic multilayer circuit board manufactured by the above manufacturing method. Table 1 and FIGS. 7 and 8.
[0038]
[Table 1]
Figure 2004165274
[0039]
Here, the shrinkage ratio parameter b / a is a ratio of the shrinkage ratio b (%) of the conductor pattern 16 to the shrinkage ratio a (%) of the green sheet from the firing start temperature of the green sheet to 900 ° C. Parameter c is the difference between the shrinkage (%) from the start of firing of the green sheet to 480 ° C. and the shrinkage (%) from the start of firing of the dry conductor pattern to 480 ° C.
[0040]
In Examples 1 to 9 and Comparative Examples 1 to 3, a green sheet having a thickness of 300 μm was laminated in four layers, and a conductive paste having the composition shown in Table 1 was used on the green sheet as shown in FIG. A wiring pattern (conductor pattern) having a line width of 400 μm was printed in a meandering shape, and four measurement strength measurement pads (conductor pattern) measuring 2 mm × 2 mm were printed. Green sheets, CaO-SiO 2 -Al 2 O 3 -B 2 O 3 based glass: used was molded by low-temperature fired ceramic comprising a mixture of 40 wt%: 60 wt% alumina.
[0041]
The firing shrinkage temperature of this green sheet is 730 ° C., and the sample substrates of Examples and Comparative Examples are fired at 890 ° C. in a conveyor furnace, and the wiring pattern after firing and the film of the measurement strength measuring pad are fired. When the thickness was measured, the thickness was 10 to 14 μm. The conductor contained in the conductor paste used in each of the examples and the comparative examples is an Ag-based conductor obtained by adding 100% by weight of Ag or a small amount of Pt or Pd to Ag. An Ag-based conductor paste containing 23% by weight of an organic vehicle with respect to 100% by weight was used. In addition, only in Example 6, 2% by weight of glass frit was added to the conductor paste.
[0042]
As shown in FIG. 5, the measurement of the film thickness of the wiring pattern is performed at both ends of the wiring pattern, and the measurement of the amount of warpage of the fired substrate is performed at the center position (1) of the wiring pattern printing area and the positions (2) on both sides thereof. The height was measured in (3), and the value obtained by subtracting the average of the heights in both sides (2) and (3) from the height in the center (1) was defined as the amount of warpage (see FIG. 6). .
[0043]
In Examples 1 to 9 shown in Table 1, the shrinkage ratio parameter b / a is in the range of 0.26 to 0.73, and the shrinkage ratio parameter c is in the range of 0.7 to 3.5%. The amount of Rh added is in the range of 0.005 to 0.050% by weight. Only in Example 7, Rh was added using Rh resinate, and in other Examples and Comparative Examples, Rh powder was used.
[0044]
In Examples 1 to 9, the electric resistance value is in the range of 2.3 to 5.3 μΩ · cm, and the warped amount of the fired substrate is in the range of 23 to 87 μm. The bonding strength between the pad and the substrate is in the range of 16 to 21N.
[0045]
On the other hand, in Comparative Examples 1 to 3, the amount of warpage of the fired substrate is as large as 110 μm or more. In particular, in Comparative Example 1, since Rh was not added to the conductor paste, no effect of suppressing the sintering of the conductor paste was obtained at all, and the difference in shrinkage between the green sheet and the wiring pattern became too large. As a result, in Comparative Example 1, the shrinkage ratio parameter b / a has a very small value of 0.08, and the shrinkage ratio parameter c has a very large value of 11.1. This is a very large value of 125 μm, which makes it impossible to secure the dimensional accuracy of the fired substrate, and the bonding strength between the pad and the substrate is a very small value of 10 N, so that peeling of the pad is likely to occur.
[0046]
Further, in Comparative Example 2, although Rh was added to the conductor paste, the amount of Rh added was as small as 0.001% by weight, so that the effect of suppressing the sintering of the conductor paste by Rh addition was insufficient. In addition, the difference in shrinkage between the green sheet and the wiring pattern cannot be sufficiently reduced. As a result, in Comparative Example 2, the shrinkage ratio parameter b / a has a small value of 0.14, and the shrinkage ratio parameter c has a large value of 8.1. As a result, the amount of warpage of the fired substrate is as large as 110 μm. Value, the dimensional accuracy of the fired substrate cannot be sufficiently ensured, and the bonding strength between the pad and the substrate becomes a small value of 14 N, which may cause the peeling of the pad, resulting in a decrease in quality and a decrease in reliability. Problems arise.
[0047]
In Comparative Example 3, the effect of suppressing the sintering of the conductor paste by the addition of Rh can be expected when the amount of Rh added is 0.075% by weight, but the shrinkage ratio parameter b / a is as small as 0.11. The warpage of the fired substrate is as large as 110 μm, and the dimensional accuracy of the fired substrate cannot be sufficiently ensured. In addition, Comparative Example 3 has a drawback that a defect (resistance increase phenomenon) due to the addition of Rh appears remarkably, and the electric resistance value becomes as large as 9.0 μΩ · cm, and the electric characteristics are deteriorated.
[0048]
On the other hand, in Examples 1 to 9, the shrinkage ratio parameter b / a was 0.26 to 0.73, the shrinkage ratio parameter c was 0.7 to 3.5%, and the Rh addition amount was 0.005 to 0.5. 050% by weight. When the shrinkage ratio parameter b / a is in the range of 0.26 to 0.73, the difference in shrinkage behavior between the green sheet and the wiring pattern from the firing shrinkage start temperature (730 ° C.) of the green sheet to 900 ° C. is reduced. be able to. Moreover, if the shrinkage ratio parameter c is 0.7 to 3.5%, the difference in shrinkage behavior between the green sheet and the wiring pattern can be reduced even in the temperature region before the start of firing and shrinking of the green sheet.
[0049]
Furthermore, as in Examples 1 to 9, when the amount of Rh added is 0.005 to 0.050% by weight, an appropriate effect of suppressing sintering of the conductor paste can be obtained, and the above-described shrinkage rate parameter b / Along with the optimization of a and c, as shown in FIG. 7, the amount of warpage of the fired substrate can be suppressed to 84 μm or less, and good substrate dimensional accuracy can be ensured. Moreover, when the amount of Rh added is as small as 0.005 to 0.050 wt%, the increase in the electrical resistance of the wiring pattern due to the addition of Rh is small, and as shown in FIG. 8, the electrical resistance is reduced to 5.3 μΩ. Cm or less, and good electrical characteristics can be secured. In addition, the bonding strength between the pad and the substrate is 16 N or more, the peeling of the pad can be prevented, and good connection reliability can be secured.
[0050]
Although the thermal via 15 is formed in the configuration example of FIG. 1, it goes without saying that the thermal via 15 may not be formed.
In addition, the present invention changes the structure of the ceramic multilayer circuit board, the number of laminated low-temperature fired ceramic green sheets, and the like, and adds a printing step of printing a thick film resistor paste or the like on the low-temperature fired ceramic green sheets. And various other modifications.
[0051]
【The invention's effect】
As is clear from the above description, according to the present invention, the warpage of the fired substrate can be reduced to improve the dimensional accuracy of the substrate, and the bonding strength between the simultaneously fired conductor pattern and the low-temperature fired ceramic can be improved. Therefore, the product quality and reliability of the low-temperature fired ceramic circuit board can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration example of a low-temperature fired ceramic multilayer circuit board manufactured by a manufacturing method according to an embodiment of the present invention; FIG. 2 is a process flowchart showing a flow of a manufacturing process; FIG. FIG. 4 is a graph showing the measurement of shrinkage behavior during firing of a system-based conductor paste and a low-temperature fired ceramic green sheet. FIG. 5 is a plan view of the sample substrates of Examples 1 to 9 and Comparative Examples 1 to 3. FIG. 6 is a side view of the sample substrate for explaining a method of measuring the amount of warpage of the fired substrate. FIG. FIG. 8 is a graph showing the relationship between the amount of warpage and the amount of warpage. FIG. 8 is a graph showing the relationship between the amount of Rh added to the conductive paste and the electrical resistance value.
11: low temperature fired ceramic green sheet, 12, 13: via hole, 15: thermal via, 16: conductor pattern, 18: via conductor.

Claims (4)

1000℃以下で焼成する低温焼成セラミックのグリーンシートと、該グリーンシートに導体ペーストで印刷された導体パターンとを同時焼成して低温焼成セラミック回路基板を製造する方法において、
前記グリーンシートの焼成収縮開始温度から900℃までの前記グリーンシートの収縮率をa(%)とし、前記グリーンシートの焼成収縮開始温度から900℃までの前記導体パターンの収縮率をb(%)とした場合に、
0.26≦b/a≦0.73
の関係を満たすことを特徴とする低温焼成セラミック回路基板の製造方法。
A method for manufacturing a low-temperature fired ceramic circuit board by simultaneously firing a green sheet of a low-temperature fired ceramic fired at 1000 ° C. or lower and a conductor pattern printed with a conductive paste on the green sheet,
The shrinkage rate of the green sheet from the firing shrinkage start temperature of the green sheet to 900 ° C is a (%), and the shrinkage rate of the conductor pattern from the firing shrinkage start temperature of the green sheet to 900 ° C is b (%). And if
0.26 ≦ b / a ≦ 0.73
Characterized by satisfying the following relationship:
前記グリーンシートの焼成開始から480℃までの収縮率(%)と、前記導体パターンの焼成開始から480℃までの収縮率(%)との差(%)が3.5(%)以下となるようにしたことを特徴とする請求項1に記載の低温焼成セラミック回路基板の製造方法。The difference (%) between the shrinkage (%) from the start of firing of the green sheet to 480 ° C. and the shrinkage (%) from the start of firing of the conductor pattern to 480 ° C. is 3.5 (%) or less. The method for manufacturing a low-temperature fired ceramic circuit board according to claim 1, wherein: 前記導体パターンの印刷に用いる導体ペーストは、導体粉末としてAg粉末又はAg系合金粉末(以下これらを「Ag系粉末」と総称する)を主として含有するAg系導体ペーストであり、前記導体粉末:100重量%に対してRhが0.005〜0.050重量%添加されていることを特徴とする請求項1又は2に記載の低温焼成セラミック回路基板の製造方法。The conductor paste used for printing the conductor pattern is an Ag-based conductor paste mainly containing Ag powder or Ag-based alloy powder (hereinafter collectively referred to as “Ag-based powder”) as the conductor powder. The method for producing a low-temperature fired ceramic circuit board according to claim 1, wherein 0.005 to 0.050 wt% of Rh is added to the wt%. 前記グリーンシートを、CaO−SiO−Al− B系ガラスとアルミナとの混合物からなる低温焼成セラミックにより成形することを特徴とする請求項1乃至3のいずれかに記載の低温焼成セラミック回路基板の製造方法。According to any one of claims 1 to 3, characterized in that molded by low-temperature fired ceramic comprising a mixture of B 2 O 3 based glass and alumina - the green sheet, CaO-SiO 2 -Al 2 O 3 A method for manufacturing a low-temperature fired ceramic circuit board.
JP2002326959A 2002-07-15 2002-11-11 Manufacturing method of low-temperature calcination ceramic circuit substrate Pending JP2004165274A (en)

Priority Applications (4)

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JP2002326959A JP2004165274A (en) 2002-11-11 2002-11-11 Manufacturing method of low-temperature calcination ceramic circuit substrate
GB0315957A GB2391116B (en) 2002-07-15 2003-07-08 Conductor paste,method of printing the conductor paste and method of fabricating ceramic circuit board
GB0327735A GB2393332B (en) 2002-07-15 2003-07-08 Conductor paste, method of printing the conductor paste and method of fabricating ceramic circuit board
DE2003131811 DE10331811A1 (en) 2002-07-15 2003-07-14 Conductive paste, method for printing the conductive paste and method for producing a ceramic printed circuit board

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008043763A1 (en) 2007-11-16 2009-08-13 DENSO CORPORATION, Kariya-shi Connecting material and method for producing a ceramic joint body
JP2011238907A (en) * 2010-04-12 2011-11-24 Asahi Glass Co Ltd Ceramic substrate and manufacturing method therefor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008043763A1 (en) 2007-11-16 2009-08-13 DENSO CORPORATION, Kariya-shi Connecting material and method for producing a ceramic joint body
US8696841B2 (en) 2007-11-16 2014-04-15 Denso Corporation Bonding material with increased reliability and method of manufacturing ceramic bonded body
JP2011238907A (en) * 2010-04-12 2011-11-24 Asahi Glass Co Ltd Ceramic substrate and manufacturing method therefor

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