JP2004015668A - Film for surface acoustic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film for a surface acoustic wave (SAW) device which improves reliability and balance in forming workability during adhesion, reduces contamination in a space between a SAW element and a packaging substrate and imparts characteristics in the substrate such as heat resistance and chemicals resistance of the film after forming. <P>SOLUTION: In a polyimide film which is used for the film for the SAW device and mainly composed of a polyimide resin composed of a diamine component containing a tetracarboxylic acid anhydride component and a diamino siloxane component in 10-35 mol%, a volatilization quantity of silicone contained in the polyimide film is made into ≤ 700ppm. <P>COPYRIGHT: (C)2004,JPO

Description

【化２】

（一般式（１）及び（２）において、Ａｒ_１は４価の芳香族基を示し、Ａｒ_２は２価の芳香族基を示し、Ｒ_１及びＲ_２は２価の炭化水素基を示し、Ｒ_３〜Ｒ_６は炭素数１〜６の炭化水素基を示し、ｎは１〜２０の数を示す）
【００１０】
上記一般式（１）及び一般式（２）で表される繰り返し単位を有するポリイミド樹脂は、テトラカルボン酸二無水物成分と芳香族ジアミンとジアミノシロキサンからなるジアミン成分とを反応させることにより得られる。
【００１１】
テトラカルボン酸二無水物の好ましい具体例としては、３，３’，４，４’−ジフェニルエーテルテトラカルボン酸二無水物、３，３’，４，４’　−ジフェニルスルホンテトラカルボン酸二無水物、３，３’　，４，４’　−ベンゾフェノンテトラカルボン酸二無水物、２，２’，３，３’−ベンゾフェノンテトラカルボン酸二無水物等が挙げられる。これらの他にその一部として３，３’　，４，４’−ビフェニルテトラカルボン酸二無水物、２，３’　，３，４’−ビフェニルテトラカルボン酸二無水物、１，４，５，８，−ナフタレンテトラカルボン酸二無水物、１，２，５，６−ナフタレンテトラカルボン酸二無水物等を併用することも好ましい。
【００１２】
前記、芳香族ジアミンとしては、１）ビフェニル系ジアミン化合物、ジフェニルエーテル系ジアミン化合物、ベンゾフェノン系ジアミン化合物、ジフェニルスルホン系ジアミン化合物、ジフェニルメタン系ジアミン化合物、２，２−ヒ゛ス（フェニル）プロパンなどのジフェニルアルカン系ジアミノ化合物、２）ジ（フェノキシ）ベンゼン系ジアミン化合物、ジ（フェニル）ベンゼン系ジアミン化合物、３）ジ（フェノキシフェニル）ヘキサフルオロプロパン系ジアミン系化合物、ビス（フェノキシフェニル）スルホン系ジアミン化合物等の芳香族環（ベンゼン環など）を２個以上、特に２〜５個有する芳香族ジアミン化合物を主として含有する芳香族ジアミンを挙げることができ、それらを単独あるいは混合して使用できることができる。
【００１３】
芳香族ジアミンは、特に２，２−ビス（３−アミノフェノキシフェニル）プロパン、２，２−ビス（４−アミノフェノキシフェニル）プロパン、３，３−ビス（３−アミノフェノキシフェニル）スルホン、４，４−ビス（３−アミノフェノキシフェニル）スルホン、３，３−ビス（４−アミノフェノキシフェニル）スルホン、３，３−ビス（４−アミノフェノキシフェニル）スルホン、３，３−ビス（４−アミノフェノキシフェニル）スルホン」、４，４−ビス（４−アミノフェノキシフェニル）スルホン、４，４−ビス（４−アミノフェノキシフェニル）スルホン、２，２−ビス（３−アミノフェノキシフェニル）ヘキサフルオロプロパン、２−２―ビス（４−アミノフェノキシフェニル）ヘキサフルオロプロパン、１，４−ビス（４−アミノフェノキシ）ベンゼン、１，３−ビス（４−アミノフェノキシ）ベンゼン、４，４−（ｐ−フェニレンジイソプロピリデン）ビスアニリン、４，４−（ｍ−フェニレンジイソプロピリデン）ビスアニリン等の３つ以上の芳香環を有するジアミンを用いることが望ましい。
【００１４】
更に、上記芳香族ジアミンの１部にエポキシ樹脂と反応性を有する官能基を有する下記一般式（３）で表されるジアミンを配合することも好ましい。
【化３】

（但し、Ａｒ_３は３価又は４価の芳香族基を示し、Ｘは水酸基、アミノ基又はカルボキシル基を示し、ｍは１又は２を示す）
【００１５】
このようなエポキシ樹脂に対して反応性官能基を有する芳香族ジアミンとしては、２，５−ジアミノフェノール、３，５−ジアミノフェノール、４，４’−（３，３’−ジヒドロキシ）ジアミノビフェニル、４，４’−（２，２’−ジヒドロキシ）ジアミノビフェニル、２，２’−ビス（３アミノ−４−ヒドロキシフェニル）ヘキサフルオロプロパン、３，３’、４，４’−ビフェニルテトラアミン、３，３’、４，４’−テトラアミノジフェニルエーテル、４，４’−（３，３’−ジカルボキシ）ジフェニルアミン、３，３’−ジカルボキシ−４，４’−ジアミノジフェニルエーテル等が挙げられ、４，４’−（３，３’−ジヒドロキシ）ジフェニルアミンは好ましいものの１つである。これらの芳香族ジアミンを用いることにより加熱圧着時にエポキシ樹脂と反応し架橋機構を形成するため、本発明の封止樹脂フィルムの接着強度、耐薬品性をさらに向上させることができる。上記エポキシ樹脂に対して反応性官能基を有する芳香族ジアミンは、全芳香族ジアミンの少なくとも１モル％以上用いることができるが、好ましくは１〜１０モル％の範囲である。
【００１６】
ジアミノシロキサンとしては、下記一般式（４）で表されるものが挙げられる。
【化４】

（但し、Ｒ_１及びＲ_２は２価の炭化水素基を示し、Ｒ_３〜Ｒ_６は炭素数１〜６の炭化水素基を示し、ｎは１〜２０の数を示す）
上記式中ジアミノシロキサンの平均ｎ数は、好ましくは１〜１０の範囲であり、より好ましくは５〜８の範囲である。ｎの値がこの値より小さいと封止樹脂フィルムとしたときの充填性が低下し、また、この値より大きいと接着性が低下するので好ましくない。本発明においては、更に、原材料であるジアミノシロキサンに含まれる環状シロキサン（不純物）の量が２．５％以下であることが好ましい。これらのジアミノシロキサンを用いてポリイミド樹脂中にシリコンユニットを導入することにより、封止樹脂フィルム中のシリコーン揮発分量をコントロールし、更に加熱圧着に流動性を与え、加工時の応力緩和効果を持たせながら、封止性を向上させることができる。
【００１７】
本発明で用いるポリイミド樹脂（Ａ）は、上記テトラカルボン酸二無水物とジアミノシロキサンを溶媒中で反応後イミド化を行い、その後、芳香族ジアミンを更に添加し加熱して、前記一般式（１）及び（２）で表される繰り返し単位を有するシリコーンユニットを有するポリイミド樹脂が製造できる。このとき一般式（１）及び（２）で表される繰り返し単位の構成比が、（１）／（２）＝１０／９０〜３５／６５の範囲であることが必要である。この範囲を外れると、本発明の用途に適さないものとなる。すなわち、一般式（１）で表される構成単位の割合が３５を超えると可とう性が良くなる反面、耐熱性及び揮発分量の増加により、樹脂フィルムから発生するガス中に含有される不純物により、電極の汚染が生じ信頼性等が低下する傾向にあり好ましくなく、また、その割合が１０に満たないと製品化する際の加工温度が高温となるほか、加工時の応力が高くなり弾性表面波素子にダメージを与えるため好ましくない。
【００１８】
本発明で用いるエポキシ樹脂（Ｂ）は、特に制限されないが、好ましいエポキシ樹脂として、多官能固形エポキシ樹脂が挙げられる。ここで、多官能固形エポキシ樹脂という場合には３以上のエポキシ基を有するものをいう。多官能固形エポキシ樹脂の中でも、ノボラック型エポキシ樹脂が好ましいものとして例示される。なお、固形とは、常温で液状でないものをいい、粉末状のものも当然含まれる。また、使用するエポキシ樹脂はＢｒ含有率をエポキシ当量あたり３０〜４０％の範囲とすることが好ましい。
【００１９】
エポキシ樹脂（Ｂ）はポリイミド樹脂（Ａ）１００重量部に対して、１０〜４５重量部、好ましくは１５〜３５重量部用いることが好ましい。エポキシ樹脂の使用量が少ないと本発明で特徴とする比較的低温での加熱圧着が困難となり好ましくなく、また、多すぎるとフィルム化した場合の耐熱性が低下する傾向あり好ましくない。
【００２０】
本発明では、上記ポリイミド樹脂とエポキシ樹脂と併用して、シランカップリング剤（Ｃ）を用いることが好ましい。用いられるシランカップリング剤を例示すると、アミノシランカップリング剤、グリシドキシシランカップリング剤、ビニルシランカップリング剤、メルカプトンカップリング剤、メタクリロキシシランカップリング剤等が挙げられる。これらの中でもポリイミド樹脂やエポキシ樹脂との相溶性の良いものが望ましい。具体的には、メルカプト変性されたものが特に望ましく、３−メルカプトプロピルトリメトキシシラン（ＴＳＬ−８３８０：東芝シリコーン社製）、ＳＨ６０６２（東レダウコーニング社製）等が挙げられる。
【００２１】
また、シランカップリング剤（Ｃ）の使用量は、ポリイミド樹脂（Ａ）１００重量部に対して０．１〜２０重量部、好ましくは、０．１〜５重量部の範囲である。シランカップリング剤の使用量が０．１重量部以下では、被着材との密着性を向上させる効果が小さく、また、２０重量部を超えると樹脂フィルムから発生する不純物ガスが増加するため好ましくない。
【００２２】
本発明においては、必要により硬化促進の目的でエポキシ樹脂硬化剤（Ｄ）を使用することもできる。エポキシ樹脂硬化剤の具体例としては、フェノールノボラック、ｏ−クレゾールノボラック等のフェノール類、無水ピロメリット酸、無水フタル酸等の酸無水物類などが挙げられる。エポキシ樹脂硬化剤を使用する場合には、多官能エポキシ樹脂（Ｂ）１００重量部に対して、２０〜１２０重量部の範囲であることが望ましいが、本発明においては使用しないことが望ましい。
【００２３】
本発明の封止樹脂フィルムは、上記各成分を適当な有機溶媒に溶解したものを公知の方法でフィルム化することが可能である。好適なフィルム化方法の具体例としては、ポリイミド樹脂、エポキシ樹脂及び必要によりその他の成分よりなる樹脂を溶媒に溶解し、得られた樹脂溶液を適当な基材上に公知の方法でコーティングした後、乾燥し基材から剥離する方法が挙げられる。
【００２４】
樹脂溶液が塗布される基材（支持基材）は、特に限定されるものではないが、その表面が剥離しやすくするために離型処理されている金属箔又はＰＥＴフィルムがよい。好ましい基材の厚さは１００μｍ以下、更に好ましくは２０〜８０μｍの範囲である。基材上の接着フィルムの好ましい厚さは、封止樹脂フィルムとして使用される状態で、６０μｍ以下であることがよく、特に４０〜５０μｍの範囲であることが好ましい。この状態においては、数％の溶媒を含んでいてもよい。また、基材上に封止樹脂フィルムが設けられた積層体は、この２層から形成されることが好ましく合計で９０〜１１０μｍの範囲の厚さが弾性表面波装置の製造工程に適する。
【００２５】
上記フィルム化の際に用いられる溶媒として代表的なものは、Ｎ，Ｎ’−ジメチルホルムアミド（ＤＭＦ）、Ｎ，Ｎ’−ジメチルアセトアミド（ＤＭＡｃ）、Ｎ−メチル−２−ピロリドン（ＮＭＰ）、テトラヒドロフラン（ＴＨＦ）、ジグライム、シクロヘキサノン、１，４−ジオキサン（１，４−ＤＯ）などである。また、フィルム成形時の溶媒として、ポリイミド樹脂製造時に用いた溶媒をそのまま使用してもなんら差し支えない。
【００２６】
本発明の封止樹脂フィルムの好適な使用方法としては、例えば、封止樹脂フィルムを弾性表面素子のカバーに使用することが挙げられる。加工条件としては、温度１６０〜１８０℃下で真空引きを行い、好ましくはさらに所定時間保持し、エポキシ樹脂を硬化させることにより、被接着物の間に接着層を形成させる方法が挙げられる。
【００２７】
本発明で用いられるポリイミド樹脂（Ａ）は溶剤可溶性であるためエポキシ樹脂との複合化が可能であるとともに、シリコーンユニットとエポキシ樹脂を有するため熱圧着時に良好な流動性を示し、被接着物に対して優れた充填性及び密着性を有する。また、エポキシ樹脂と反応性を有する芳香族ジアミンを用いることによりエポキシ樹脂と架橋し、強度、耐熱性にも優れた接着層を形成できるという特徴を有する。また、ガラス転移点が高すぎないため比較的低温で接着できる。
【００２８】
本発明の樹脂フィルムは、シリコーン揮発分量が一定値以下であることを特徴とする。この値を制御するには、原料に使用するジアミノシロキサンに環状シロキサンの含有量が少ないものを使用し、全ジアミンに対するシロキサンジアミンの使用量を調整すること、また、併用して使用される添加剤成分にも環状シロキサンが含まれる場合にはその添加量を制限することで可能となる。更に、樹脂フィルムがポリイミド樹脂とエポキシ樹脂から構成される場合には、その配合組成を好ましい範囲とすることにより、弾性表面波装置用途により適したものとすることができる。樹脂フィルム中のシリコーン揮発分量は７００ｐｐｍ以下であることが必要であり、５００ｐｐｍ以下とすることが好ましい。
【００２９】
【実施例】
以下、本発明を実施例に基づき説明するが、本発明はこれら実施例に限定されるものではない。なお、実施例中の各種物性値等は下記測定方法によるものである。
【００３０】
［ガラス転移温度］
封止樹脂フィルムを、アルミキャリアから引き剥がした後、１９０℃雰囲気下の熱風オーブンで６０分硬化させた。この硬化した封止樹脂フィルムを、粘弾性測定装置（レオメトリック社製）で昇温させながら弾性率挙動を調べた。このときの条件は、１Ｈｚにおける２０℃〜３５０℃までの動的損失正接（ｔａｎδ）のヒ゜ークをガラス転移温度とした。
【００３１】
［シリコーン揮発分量］
封止樹脂フィルムをアルミキャリアから引き剥がした後、２０〜３０　ｍｇ切り取り試験片とした。次に分析装置（熱分析部：キューリポイントバイロライザー；日本分析工業社製、ＧＣ・ＭＳ部：ガスクロマトグラフ、質量分析装置；横河電気社製）を使用しシリコーン不純物の測定を行った。測定条件は、試験片を１７０℃、１０ｓｅｃ加熱した後、発生したガスをＤＢ‐５（Ｊ＆Ｗ社製）のカラムにて環状シロキサン量を検出した。これを、シリコーン揮発分とした。
【００３２】
［弾性率］
封止樹脂フィルムを、アルミキャリアから引き剥がし１８０℃雰囲気下の熱風オーブンで６０分硬化させた後、この硬化フィルムを用いて、粘弾性測定装置で１Ｈｚにおける２０〜３５０℃までの損失弾性率と貯蔵弾性率の測定を行った。このときの測定値は２５℃における貯蔵弾性率の値とした。
【００３３】
実施例１
乾燥窒素ガス導入管、温度計、攪拌機を備えた、５００ｍｌのセパラブルフラスコに３，３’，４，４’−ジフェニルスルホンテトラカルボン酸二無水物（ＤＳＤＡ）０．１１０モル、Ｎ−メチル−２−ピロリドン（ＮＭＰ）２００ｇ及びキシレン１０ｇを入れ、窒素ガスを流し、系中を室温で良く混合した。次に、ＰＳＸ−Ｘ（平均分子量７４０のジアミノシロキサン：東レダウコーニング社製　ＢＹ１６−８５３Ｘ）０．０１５モルを滴下し、この反応溶液を攪拌下で氷冷し、２，２’−ビス（４−アミノフェノキシフェニル）プロパン（ＢＡＰＰ）０．０９０モル及び、４，４’−ジアミノ−３，３’−ヒドロキシ−ビフェニル（ＨＡＢ）０．００４モルを添加し、室温にて２時間攪拌し、ポリアミック酸を得た。このポリアミック酸を１９０℃に昇温、１４ｈｒ加熱、攪拌を続け、加熱時に発生する水を系外に除いた。１４ｈｒの加熱したところで、系を冷却することにより対数粘度０．６０ｄｌ／ｇのポリイミド溶液を得た。
【００３４】
次に、得られたポリイミド溶液の固形分１００重量部に対し、ノボラック型エポキシ樹脂（Ｂ−ＣＮＢ：ブロモクレゾールノボラック型エポキシ樹脂、軟化点８４℃、エポキシ当量２８３）２５重量部及びシランカップリング剤として３−メルカプトプロピルトリメトキシシラン０．５重量部を混合し、３時間攪拌させて、封止樹脂フィルム用樹脂溶液を調製した。この樹脂溶液を離型処理された金属箔に乾燥後５０μｍになるように塗布し、その後９０℃、５分−１７０℃、５分熱風乾燥機中で乾燥後、封止樹脂フィルムとした。
前記した各測定条件により、ガラス転移温度、弾性率、シロキサン不純物量を測定した。結果を表３に示す。
【００３５】
実施例２
ジアミノシロキサンの不純物量の異なるモノマーを表１に示す組成で実施例１と同様にしてポリイミド樹脂を得、表２に示す配合割合によりフィルムを調製し、その諸特性を測定した。なお、実施例１〜２、比較例１には実施例１で用いたシランカップリング剤が同量使用されている。結果を表３に示す。
【００３６】
表中、ＰＳＸ−Ｘ及びＰＳＸ−Ｃの略号は下記のものを示す。
ＰＳＸ−Ｘ：ジアミノシロキサン中の環状シロキサン量２．５ｗｔ％以下である。
ＰＳＸ−Ｃ：ジアミノシロキサン中の環状シロキサン量５．０ｗｔ％以下である。
【００３７】
比較例１
実施例１と同様にして表１、表２に示す組成で封止樹脂フィルムを調製し、その諸特性を測定した。結果表３に示す。
【００３８】
【表１】

【００３９】
【表２】

【００４０】
【表３】

【００４１】
図１に示すように、セラミック基板１をベースとして、これに弾性表面波素子２を搭載し、これを被覆するように樹脂フィルム３熱圧着させて、封止したところ、樹脂フィルム３と弾性表面波素子（ＳＡＷチップ）２との密着性が高く、弾性表面波素子２と基板の空間における汚染性についても問題ない封止樹脂フィルムであることが確認された。
【００４２】
【発明の効果】
本発明の弾性表面波装置用フィルムは、低温加工性と接着性、加工時のシリコーン揮発分量等のバランスに優れるばかりでなく、実用的な接着強度、半導体周辺における信頼性等も良好である。
【図面の簡単な説明】
【図１】弾性表面波装置の断面図
【符号の説明】
１　　セラミック基板
２　　弾性表面波素子
３　　樹脂フィルム[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a film for a surface acoustic wave device, and more particularly to a film for a surface acoustic wave device formed of a polyimide resin having a silicone unit.
[0002]
[Prior art]
One of the electronic materials is a surface acoustic wave device. This surface acoustic wave device is a filter component used for noise reduction of electric equipment. As a conventional manufacturing method, a surface acoustic wave element is connected to a base substrate such as a ceramic substrate, and then the entire surface acoustic wave element is connected. Is generally known. However, it has been pointed out that it is difficult to seal the element without deforming and contaminating the comb-shaped electrode formed on the surface acoustic wave element by the metal sealing method. On the other hand, since the surface acoustic wave device is used as a noise prevention filter for small mobile communication devices, its workability is regarded as important when miniaturizing components and sealing them. Further, since the surface acoustic wave device is mounted on a substrate, the same reliability as that of the substrate is required, and it is necessary to ensure the same characteristics as the material of the substrate.
[0003]
When manufacturing the surface acoustic wave device, a surface acoustic wave element used therein is fixed to a base substrate in a face-down manner, and when the element is sealed, a resin material having flexibility in terms of processability. The use of is considered. See, for example, JP-A-2002-16475 and JP-A-2000-196407 as related technologies. As a flexible material, a polyimide resin film containing a silicone unit is known in JP-A-6-200216 and the like, and has been widely used as a substrate material for coverlays, bonding sheets and the like. However, in parts requiring high contamination resistance and reliability other than the substrate use, sufficient characteristics were not obtained, so that the use was limited.
[0004]
Conventionally, reduction of the volatile component of the polyimide resin has been studied, but since most of the uses are for the above-mentioned wiring board, development of a material suitable for manufacturing a surface acoustic wave device has been desired.
[0005]
[Problems to be solved by the invention]
The present invention satisfies the processability by providing a flexible film material suitable for manufacturing a surface acoustic wave device in a small size, and has an adverse effect on electrodes and the like of the product during and after manufacturing. It is an object of the present invention to provide a film for a surface acoustic wave device that has a small amount of a volatile component to be provided and has both heat resistance and chemical resistance necessary for maintaining the reliability of a molded product.
[0006]
[Means for Solving the Problems]
As a result of repeated studies on the above problems, the present inventors have found that by controlling the components and the amount of gas generated from the material, the electrodes and the like are not contaminated and have good workability, heat resistance, chemical resistance, etc. It has been found that a film for a surface acoustic wave device, which also has the following, can be provided, and the present invention has been completed.
[0007]
That is, the present invention relates to a polyimide film containing, as a main component, a polyimide resin comprising a tetracarboxylic dianhydride component and a diamine component containing 10 to 35 mol% of a diaminosiloxane component. A film for a surface acoustic wave device having a content of 700 ppm or less.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. In the following description, the surface acoustic wave device film of the present invention may be simply referred to as a sealing resin film.
The polyimide resin (A) used in the present invention is a polyimide resin comprising a diamine component containing a tetracarboxylic dianhydride component and a diaminosiloxane component in an amount of 10 to 35 mol%. Examples of such a polyimide resin include those having repeating units represented by the following general formulas (1) and (2).
[0009]
Embedded image

Embedded image

(In the general formulas (1) and (2), Ar ₁ represents a tetravalent aromatic group, Ar ₂ represents a divalent aromatic group, and R ₁ and R ₂ represent a divalent hydrocarbon group. , R _{3 to} R ₆ represent a hydrocarbon group having 1 to ₆ carbon atoms, and n represents a number of 1 to 20)
[0010]
The polyimide resin having the repeating units represented by the general formulas (1) and (2) is obtained by reacting a tetracarboxylic dianhydride component with a diamine component composed of an aromatic diamine and diaminosiloxane. .
[0011]
Preferred specific examples of the tetracarboxylic dianhydride include 3,3 ′, 4,4′-diphenylethertetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride and the like can be mentioned. In addition to these, as a part thereof, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, 1,4,5, It is also preferable to use a combination of 8, -naphthalenetetracarboxylic dianhydride and 1,2,5,6-naphthalenetetracarboxylic dianhydride.
[0012]
Examples of the aromatic diamine include: 1) diphenylalkane compounds such as biphenyl diamine compound, diphenyl ether diamine compound, benzophenone diamine compound, diphenylsulfone diamine compound, diphenylmethane diamine compound, and 2,2-bis (phenyl) propane. Aroma such as diamino compound, 2) di (phenoxy) benzene diamine compound, di (phenyl) benzene diamine compound, 3) di (phenoxyphenyl) hexafluoropropane diamine compound, bis (phenoxyphenyl) sulfone diamine compound, etc. Aromatic diamines mainly containing an aromatic diamine compound having two or more, particularly 2 to 5, aromatic rings (such as benzene rings) can be mentioned, and these can be used alone or as a mixture.
[0013]
Aromatic diamines are, in particular, 2,2-bis (3-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) propane, 3,3-bis (3-aminophenoxyphenyl) sulfone, 4-bis (3-aminophenoxyphenyl) sulfone, 3,3-bis (4-aminophenoxyphenyl) sulfone, 3,3-bis (4-aminophenoxyphenyl) sulfone, 3,3-bis (4-aminophenoxy) Phenyl) sulfone ", 4,4-bis (4-aminophenoxyphenyl) sulfone, 4,4-bis (4-aminophenoxyphenyl) sulfone, 2,2-bis (3-aminophenoxyphenyl) hexafluoropropane, 2-bis (4-aminophenoxyphenyl) hexafluoropropane, 1,4-bis (4-a Three or more such as nophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4- (p-phenylenediisopropylidene) bisaniline, and 4,4- (m-phenylenediisopropylidene) bisaniline It is desirable to use a diamine having an aromatic ring.
[0014]
Furthermore, it is also preferable to mix a diamine represented by the following general formula (3) having a functional group reactive with an epoxy resin in one part of the aromatic diamine.
Embedded image

(However, Ar ₃ represents a trivalent or tetravalent aromatic group, X represents a hydroxyl group, an amino group or a carboxyl group, and m represents 1 or 2.)
[0015]
Examples of the aromatic diamine having a reactive functional group with respect to such an epoxy resin include 2,5-diaminophenol, 3,5-diaminophenol, 4,4 ′-(3,3′-dihydroxy) diaminobiphenyl, 4,4 ′-(2,2′-dihydroxy) diaminobiphenyl, 2,2′-bis (3 amino-4-hydroxyphenyl) hexafluoropropane, 3,3 ′, 4,4′-biphenyltetraamine, , 3 ', 4,4'-tetraaminodiphenyl ether, 4,4'-(3,3'-dicarboxy) diphenylamine, 3,3'-dicarboxy-4,4'-diaminodiphenyl ether, and the like. , 4 '-(3,3'-Dihydroxy) diphenylamine is one of the preferred ones. By using these aromatic diamines, they react with the epoxy resin at the time of heating and pressing to form a crosslinking mechanism, so that the adhesive strength and chemical resistance of the sealing resin film of the present invention can be further improved. The aromatic diamine having a reactive functional group with respect to the epoxy resin can be used in an amount of at least 1 mol% of the total aromatic diamine, but is preferably in a range of 1 to 10 mol%.
[0016]
Examples of the diaminosiloxane include those represented by the following general formula (4).
Embedded image

(However, R ₁ and R ₂ represent a divalent hydrocarbon group, R _{3 to} R ₆ represent a hydrocarbon group having 1 to ₆ carbon atoms, and n represents a number of 1 to 20)
In the above formula, the average n of the diaminosiloxane is preferably in the range of 1 to 10, more preferably 5 to 8. If the value of n is smaller than this value, the filling property of the sealing resin film decreases, and if it is larger than this value, the adhesiveness decreases, which is not preferable. In the present invention, the amount of the cyclic siloxane (impurities) contained in the diaminosiloxane as the raw material is preferably 2.5% or less. By introducing silicone units into the polyimide resin using these diaminosiloxanes, the amount of silicone volatiles in the sealing resin film is controlled, and further, fluidity is imparted to the heat-compression bonding to provide a stress relaxation effect during processing. Meanwhile, the sealing property can be improved.
[0017]
The polyimide resin (A) used in the present invention is obtained by reacting the above tetracarboxylic dianhydride and diaminosiloxane in a solvent, followed by imidization, then further adding an aromatic diamine and heating to obtain the above-mentioned general formula (1) ) And a polyimide resin having a silicone unit having a repeating unit represented by (2). At this time, the composition ratio of the repeating units represented by the general formulas (1) and (2) needs to be in the range of (1) / (2) = 10/90 to 35/65. Outside this range, it is not suitable for the use of the present invention. That is, when the proportion of the structural unit represented by the general formula (1) exceeds 35, the flexibility is improved, but the heat resistance and the amount of volatile components are increased, so that the impurities contained in the gas generated from the resin film cause If the ratio is less than 10, undesirably, the electrode will be contaminated and the reliability tends to decrease. If the ratio is less than 10, the processing temperature will increase when commercializing the product, and the stress during processing will increase, resulting in an increase in the elastic surface. It is not preferable because the wave element is damaged.
[0018]
The epoxy resin (B) used in the present invention is not particularly limited, but preferred epoxy resins include polyfunctional solid epoxy resins. Here, a multifunctional solid epoxy resin refers to a resin having three or more epoxy groups. Among polyfunctional solid epoxy resins, a novolak type epoxy resin is exemplified as a preferable one. In addition, solids are those that are not liquid at normal temperature, and naturally include powdery ones. The epoxy resin used preferably has a Br content in the range of 30 to 40% per epoxy equivalent.
[0019]
The epoxy resin (B) is used in an amount of 10 to 45 parts by weight, preferably 15 to 35 parts by weight, based on 100 parts by weight of the polyimide resin (A). If the amount of the epoxy resin is small, it is difficult to heat and press at a relatively low temperature, which is a feature of the present invention, which is not preferable. On the other hand, if the amount is too large, the heat resistance when formed into a film tends to decrease, which is not preferable.
[0020]
In the present invention, it is preferable to use a silane coupling agent (C) in combination with the above polyimide resin and epoxy resin. Examples of the silane coupling agent to be used include an amino silane coupling agent, a glycidoxy silane coupling agent, a vinyl silane coupling agent, a mercapton coupling agent, and a methacryloxy silane coupling agent. Among them, those having good compatibility with the polyimide resin and the epoxy resin are desirable. Specifically, those modified with mercapto are particularly desirable, and examples thereof include 3-mercaptopropyltrimethoxysilane (TSL-8380: manufactured by Toshiba Silicone Co., Ltd.) and SH6062 (manufactured by Toray Dow Corning).
[0021]
The amount of the silane coupling agent (C) used is in the range of 0.1 to 20 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polyimide resin (A). When the amount of the silane coupling agent is 0.1 parts by weight or less, the effect of improving the adhesion to the adherend is small, and when the amount exceeds 20 parts by weight, impurity gas generated from the resin film increases, which is preferable. Absent.
[0022]
In the present invention, an epoxy resin curing agent (D) may be used for the purpose of accelerating curing, if necessary. Specific examples of the epoxy resin curing agent include phenols such as phenol novolak and o-cresol novolak, and acid anhydrides such as pyromellitic anhydride and phthalic anhydride. When an epoxy resin curing agent is used, the amount is preferably in the range of 20 to 120 parts by weight with respect to 100 parts by weight of the polyfunctional epoxy resin (B), but is preferably not used in the present invention.
[0023]
The sealing resin film of the present invention can be formed into a film by dissolving each of the above components in an appropriate organic solvent by a known method. As a specific example of a preferred film forming method, a resin comprising a polyimide resin, an epoxy resin and other components as necessary is dissolved in a solvent, and the obtained resin solution is coated on a suitable substrate by a known method. , Drying and peeling from the substrate.
[0024]
The substrate (supporting substrate) to which the resin solution is applied is not particularly limited, but is preferably a metal foil or a PET film which has been subjected to a release treatment so that the surface thereof is easily peeled. The preferred thickness of the substrate is 100 μm or less, more preferably in the range of 20 to 80 μm. The preferred thickness of the adhesive film on the base material is preferably 60 μm or less, particularly preferably in the range of 40 to 50 μm when used as a sealing resin film. In this state, it may contain several percent of the solvent. Further, the laminate in which the sealing resin film is provided on the base material is preferably formed of these two layers, and the total thickness in the range of 90 to 110 μm is suitable for the manufacturing process of the surface acoustic wave device.
[0025]
Typical solvents used for forming the film include N, N'-dimethylformamide (DMF), N, N'-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and tetrahydrofuran. (THF), diglyme, cyclohexanone, 1,4-dioxane (1,4-DO) and the like. Further, as the solvent for forming the film, the solvent used for producing the polyimide resin may be used as it is.
[0026]
As a preferred method of using the sealing resin film of the present invention, for example, use of the sealing resin film for a cover of an elastic surface element can be mentioned. As a processing condition, there is a method in which an evacuation is performed at a temperature of 160 to 180 ° C., and preferably further maintained for a predetermined time, and the epoxy resin is cured to form an adhesive layer between the adherends.
[0027]
Since the polyimide resin (A) used in the present invention is solvent-soluble, it can be compounded with an epoxy resin. In addition, since it has a silicone unit and an epoxy resin, it exhibits good fluidity during thermocompression bonding. It has excellent filling properties and adhesion. Further, by using an aromatic diamine reactive with the epoxy resin, the aromatic diamine is crosslinked with the epoxy resin to form an adhesive layer having excellent strength and heat resistance. Further, since the glass transition point is not too high, bonding can be performed at a relatively low temperature.
[0028]
The resin film of the present invention is characterized in that the amount of volatile silicone is not more than a certain value. In order to control this value, diaminosiloxane used as a raw material should have a low content of cyclic siloxane, and the amount of siloxane diamine used relative to all diamines should be adjusted. When a cyclic siloxane is also contained in the component, it becomes possible by limiting the amount of the cyclic siloxane added. Further, when the resin film is composed of a polyimide resin and an epoxy resin, by setting the compounding composition within a preferable range, it is possible to make the resin film more suitable for a surface acoustic wave device. The volatile content of silicone in the resin film needs to be 700 ppm or less, and preferably 500 ppm or less.
[0029]
【Example】
Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples. The various physical properties and the like in the examples are based on the following measurement methods.
[0030]
[Glass-transition temperature]
After peeling off the sealing resin film from the aluminum carrier, it was cured in a hot air oven at 190 ° C. for 60 minutes. The elastic modulus behavior of the cured sealing resin film was examined while raising the temperature with a viscoelasticity measuring device (manufactured by Rheometrics). The condition at this time was a glass transition temperature at a peak of dynamic loss tangent (tan δ) from 20 ° C. to 350 ° C. at 1 Hz.
[0031]
[Silicone volatile content]
After peeling off the sealing resin film from the aluminum carrier, a test piece was cut out from 20 to 30 mg. Next, silicone impurities were measured using an analyzer (thermal analyzer: Curie point virolyzer; manufactured by Nippon Kagaku Kogyo Co., Ltd .; GC / MS unit: gas chromatograph, mass spectrometer; manufactured by Yokogawa Electric Corporation). The measurement conditions were as follows: After heating the test piece at 170 ° C. for 10 seconds, the amount of cyclic siloxane in the generated gas was detected using a DB-5 (manufactured by J & W) column. This was taken as silicone volatile matter.
[0032]
[Elastic modulus]
After peeling off the sealing resin film from the aluminum carrier and curing it in a hot air oven at 180 ° C. for 60 minutes, using this cured film, a viscoelasticity measuring device was used to measure the loss elastic modulus from 20 to 350 ° C. at 1 Hz. The storage modulus was measured. The measured value at this time was the value of the storage modulus at 25 ° C.
[0033]
Example 1
0.110 mol of 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA) in a 500 ml separable flask equipped with a dry nitrogen gas inlet tube, a thermometer and a stirrer, and N-methyl- 200 g of 2-pyrrolidone (NMP) and 10 g of xylene were added, nitrogen gas was flown, and the system was mixed well at room temperature. Next, 0.015 mol of PSX-X (diaminosiloxane having an average molecular weight of 740: BY16-853X manufactured by Toray Dow Corning Co., Ltd.) was added dropwise, and the reaction solution was ice-cooled with stirring, and 2,2′-bis (4 -Aminophenoxyphenyl) propane (BAPP) (0.090 mol) and 4,4'-diamino-3,3'-hydroxy-biphenyl (HAB) (0.004 mol) were added, and the mixture was stirred at room temperature for 2 hours. The acid was obtained. The temperature of this polyamic acid was raised to 190 ° C., and heating and stirring were continued for 14 hours, and water generated during heating was removed from the system. After heating for 14 hours, the system was cooled to obtain a polyimide solution having an logarithmic viscosity of 0.60 dl / g.
[0034]
Next, 25 parts by weight of a novolak-type epoxy resin (B-CNB: bromocresol novolak-type epoxy resin, softening point 84 ° C., epoxy equivalent 283) and 100 parts by weight of a solid content of the obtained polyimide solution and a silane coupling agent Was mixed with 0.5 part by weight of 3-mercaptopropyltrimethoxysilane and stirred for 3 hours to prepare a resin solution for a sealing resin film. This resin solution was applied to a release-treated metal foil so as to have a thickness of 50 μm after drying, and then dried at 90 ° C. for 5 minutes to 170 ° C. for 5 minutes in a hot air drier to obtain a sealing resin film.
The glass transition temperature, the elastic modulus, and the amount of siloxane impurities were measured under the above-described measurement conditions. Table 3 shows the results.
[0035]
Example 2
Polyimide resins were obtained in the same manner as in Example 1 by using monomers having different amounts of impurities of diaminosiloxane in the composition shown in Table 1, films were prepared according to the mixing ratio shown in Table 2, and various characteristics were measured. In Examples 1 and 2 and Comparative Example 1, the same amount of the silane coupling agent used in Example 1 was used. Table 3 shows the results.
[0036]
In the table, the abbreviations of PSX-X and PSX-C indicate the following.
PSX-X: The amount of cyclic siloxane in diaminosiloxane is 2.5 wt% or less.
PSX-C: The amount of cyclic siloxane in diaminosiloxane is 5.0% by weight or less.
[0037]
Comparative Example 1
In the same manner as in Example 1, sealing resin films having the compositions shown in Tables 1 and 2 were prepared, and their properties were measured. The results are shown in Table 3.
[0038]
[Table 1]

[0039]
[Table 2]

[0040]
[Table 3]

[0041]
As shown in FIG. 1, a ceramic substrate 1 is used as a base, a surface acoustic wave element 2 is mounted thereon, and a resin film 3 is thermocompression-bonded so as to cover the ceramic surface element 1 and sealed. It was confirmed that the sealing resin film had high adhesion to the wave element (SAW chip) 2 and had no problem with respect to contamination in the space between the surface acoustic wave element 2 and the substrate.
[0042]
【The invention's effect】
The film for a surface acoustic wave device of the present invention not only has excellent balance between low-temperature processability and adhesiveness, the amount of silicone volatile components during processing, etc., but also has good practical adhesive strength, reliability around semiconductors, and the like.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a surface acoustic wave device.
DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Surface acoustic wave element 3 Resin film

Claims (3)

A polyimide film mainly composed of a polyimide resin composed of a diamine component containing 10 to 35 mol% of a tetracarboxylic dianhydride component and a diaminosiloxane component, wherein the amount of volatile silicone contained in the polyimide film is 700 ppm or less. A film for a surface acoustic wave device for sealing a surface acoustic wave element. The surface acoustic wave device film according to claim 1, wherein the polyimide film is a polyimide resin composition obtained by mixing 10 to 45 parts by weight of an epoxy resin with 100 parts by weight of the polyimide resin. A laminate in which the film for a surface acoustic wave device according to claim 1 is laminated on a peelable support film.

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