JP3891554B2 - Epoxy resin composition for optical semiconductor encapsulation and optical semiconductor device - Google Patents
Epoxy resin composition for optical semiconductor encapsulation and optical semiconductor device Download PDFInfo
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Description
【0001】
【発明の属する技術分野】
本発明は、透明性、耐半田性及び離型性に優れた光半導体封止用エポキシ樹脂組成物及びその製法、その硬化物で封止された光半導体装置に関するのものである。
【0002】
【従来の技術】
近年、通信情報機器の小型化、集積密度の向上及び製造プロセスの簡略化をねらい、半導体産業において従来の実装方法にかわり、表面実装方法の要求が急速に高まっている。さらにオプトエレクトロニクスの分野に着目すると、従来の半導体封止樹脂の機能に加えて、透明性が非常に重要な要因となっている。すなわち、フォトセンサー、LED、発光素子等のオプトデバイスにおいては、表面実装におけるIRリフロー等の実装方式を行っても、透明性が損なわれることなく、その上、熱衝撃によるパッケージクラックの発生や、チップやリードフレームと樹脂間に剥離を生じず、高い信頼性のある封止用樹脂が求められている。
【0003】
また、このような光半導体素子の生産効率を高めるべく、従来用いられてきたような液状封止材による封止は次第にマルチ成形機によるトランスファー成形へと移りつつある。この場合、樹脂組成物は必然的に常温で固体である必要があり、流動時のムラや速硬化による着色の問題などの新たな問題を解決しなくてはならない。特に着色は、低波長な光線の発光を妨げ、特に青色や、白色の発光素子の発光効率や色合いに悪影響を及ぼすことがある。
【0004】
トランスファー成形に用いる、常温で固体のエポキシ樹脂組成物の製法としては、一般的に常温で固体のエポキシ樹脂と、常温で固体の硬化剤を、加熱ニーダー等の装置を用いて溶融混練して得る手法が一般的に知られているが、溶融混練という操作において、加熱が不十分である場合、材料のムラが原因となり特性が低下することが問題であった。
【0005】
この問題に対し、特許第2970214号公報では、特定の分子量範囲に含まれるビスフェノールA型エポキシ樹脂に対し、一定割合で脂環式エポキシ樹脂もしくは含複素環エポキシ樹脂を組み合わせることで耐熱性と透明性が得られ、かつムラの発生を抑えることができると示されている。しかし、この場合硬化剤としては、主に固体の硬化剤を使用することが条件となる。固体の酸無水物硬化剤は、不飽和結合などの、光透過性を低下させる要因を含むものが多く、硬化物の透過率が低波長領域において低下する傾向にあった。
【0006】
また、ムラを無くす技術として、特許2656336号広報には、溶剤にエポキシ樹脂組成物を溶解し、均一に混合した後に、溶剤を除去してムラの無い組成物を得る技術が述べられているが、この場合も同様に、トランスファー成形に供するためには、硬化剤の種類は常温で固体のものを主としなくてはならないという制約がある。
【0007】
一方、硬化物の表面実装信頼性として、吸水率を低くすることが求められており、吸水率を低減するために充填剤を添加することが代表的な手法であることは当業者間では公知のことである。これは、シリカなどの無機質充填材を、樹脂組成物中に高い比率で充填することで、封止樹脂組成物の吸水率、線膨張係数を低下させ、高温時の変形やクラックなどを抑止できるものであるが、このようにして得た樹脂組成物は、シリカ粒子と樹脂の界面で起こる光の反射や屈折の影響により、樹脂硬化物の光透過性は極端に低いものとなる。樹脂組成物の硬化物中を光線が透過する際、樹脂と充填材との界面において反射・屈折される光線の量は、界面前後での屈折率の差に比例する事が知られており、一般的なシリカ粒子の屈折率は、1.4前後であるのに対し、エポキシ樹脂の硬化体は、1.5前後であり、充填材種を変えない限り、この点を解消することは難しい。
【0008】
これを解消するために、特開平6−65473号公報では、シリカ以外の充填材として、SiO2、CaOおよびAl2O3を主成分とするガラス粒子を、光半導体封止用樹脂組成物の充填材として用いる技術が述べられている。この技術によれば、各成分の組成を変化させることや、金属元素類を添加することで、充填材の屈折率を容易に変化させることができる。しかし、本発明者らが光半導体封止用樹脂組成物の充填材として、該技術によるガラス充填材を用いたところ、確かに透明性は高くなり、吸水率および線膨張係数も低減されるが、不十分であり、透明性と表面実装の能力を両立することは難しい。これより、本発明者らは、表面実装能力と透明性を両立するには、充填剤の添加のみだけではなく樹脂そのものの特性も高める必要があるとの結論に至った。
【0009】
更に、光半導体封止用材料は、可視光を透過することが必須であるが、同時に金型からの離型性も重要な項目である。従来は離型性を良くするために、定期的に離型剤成分を含んだ材料を成形したり、フッ素系やシリコーン系などの離型剤を金型に直接噴霧する手法がとられているが、その場合連続成形の生産効率を下げるのみでなく、金型に離型剤が残り汚染される問題がある。そこで、これまでに封止材料中に離型剤を予め添加混合する検討が行われている。従来公知の離型剤を添加した場合、離型剤の種類によっては、その添加量を増やすと離型性は向上するが、樹脂硬化物に曇りが生じ、光透過率が低下する。添加量を減らすと離型性が悪くなり、金型からパッケージが離型する際に、パッケージにクラックが生じたり、リードフレームの曲がりが光半導体装置の変形が発生する。すなわち、透明性と離型性の面で両方の特性を満たす樹脂組成物は、未だ開発がなされていない。
【0010】
特許2781279号公報には、ポリエーテル構造と長鎖アルキル基からなる構造の界面活性剤を離型剤として、光半導体封止用の材料に予め添加することが記載されているが、本発明者らが光半導体封止用の材料に添加したところ、金型からの離型性は優れるが、高温での硬化時に樹脂硬化物に曇りが生じ、光半導体封止用樹脂組成物としては、未だ不十分な透明性である。
【0011】
【発明が解決しようとする課題】
本発明は、透明性、耐半田性及び離型性に優れた光半導体封止用エポキシ樹脂組成物、及びその硬化物で封止された光半導体装置を提供することにある。
【0012】
【課題を解決するための手段】
本発明らは、樹脂組成物の硬化時に発生する曇りが、樹脂硬化後に溶解度が変化し、樹脂硬化物中で非相溶となった離型剤が大きな領域を形成することに起因すると考え、鋭意検討の結果、特定構造の離型剤の、樹脂に対する相溶性が異なる部分どうしの結合部に、中間的な相溶性の部分を導入することで、光損失の大きな領域の発生を低減できることを見出すとともに、特定の組み合わせのエポキシ樹脂及び凝固点が50℃以下の酸無水物硬化剤の、中間反応物を用いた、吸水率及び透明性に適した特性を発現する組成物に、さらに特定の無機充填剤及び離型剤を用いることで、より吸水率を低減し、かつ高い光透過率を維持し、耐半田性及び離型性にも優れた特性を発現する光半導体封止用組成物を得るに至った。
【0013】
即ち、本発明は、(1)〜(8)項に記載の光半導体封止用エポキシ樹脂組成物である。
(1)エポキシ樹脂と硬化剤の中間反応物(A)、硬化促進剤(B)、無機充填剤(C)、離型剤(D)を必須成分とする光半導体封止用エポキシ樹脂組成物において、中間反応物(A)が下記成分(a)、及び成分(b)を含んでなり、且つ無溶媒下、80℃以上150℃以下の温度で、溶融混合して得られたものであることを特徴とする光半導体封止用エポキシ樹脂組成物である。
(a)トリグリシジルイソシアヌレート、及びビスフェノール型エポキシ樹脂からなり、成分(a)全体の平均エポキシ当量が200以上400以下のエポキシ樹脂。
(b)凝固点50℃以下の酸無水物硬化剤。
【0014】
(2)ビスフェノール型エポキシ樹脂が、210以上1100以下の平均エポキシ当量を有し、トリグリシジルイソシアヌレートが、(a)成分中に5%以上45%以下で含まれることを特徴とする前記(1)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0015】
(3)ビスフェノール型エポキシ樹脂が、更に好ましくは、一般式(1)で表されるエポキシ樹脂であることを特徴とする前記(2)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0016】
【化3】
(但し、式(1)中、nの値が1〜7であり、RはC(CH3)2及びCH2を示し、1分子中それぞれ少なくとも1個以上有する。)
【0017】
(4)凝固点50℃以下の酸無水物硬化剤(b)が、好ましくは、ヘキサヒドロ無水フタル酸及び4−メチルヘキサヒドロ無水フタル酸からなる群より選ばれる少なくとも1つであることを特徴とする前記(1)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0018】
(5)硬化促進剤(B)が、イミダゾール類、イミダゾール塩類、双環式アミジン類、双環式アミジンのカルボン酸類、及びホスホニウム塩類からなる群より少なくとも1つ選ばれることを特徴とする前記(1)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0019】
(6)無機充填材(C)の屈折率と、無機充填材(C)以外の成分の硬化物の屈折率との差が、0.01以下である前記(1)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0020】
(7)無機充填剤(C)が、SiO2、CaO、およびAl2O3からなる、平均粒径5μm以上100μm以下の球状ガラス粒子であり、光半導体封止用エポキシ樹脂組成物中に5重量%以上、70重量%以下の割合で配合されてなることを特徴とする前記(1)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0021】
(8)離型剤(D)が、一般式(2)で表される化合物であり、光半導体封止用エポキシ樹脂組成物中に0.01重量%以上、5重量%以下の割合で配合されてなることを特徴とする前記(1)項に記載の光半導体封止用エポキシ樹脂組成物である。
【0022】
【化4】
(但し、式(2)中、kの値が40〜60であり、mの値は1〜5であり、nの値は15〜45である。R1、R2は水素原子もしくは一価のアルキル基であり、少なくとも一方が一価のアルキル基である。)
【0023】
更に本発明は、前記(1)〜(8)項のいずれかに記載の光半導体封止用エポキシ樹脂組成物の硬化物で封止された光半導体装置である。
【0024】
【発明の実施の形態】
本発明に用いる、エポキシ樹脂と硬化剤の中間反応物(A)は、成分(a)のトリグリシジルイソシアヌレート、及びビスフェノール型エポキシ樹脂からなり、成分(a)全体の平均エポキシ当量が200以上400以下のエポキシ樹脂成分と、成分(b)の凝固点50℃以下の酸無水物硬化剤成分を含み、80℃以上150℃以下の温度で、且つ無溶媒で、溶融混合して得られる化合物であり、従来の加熱ニーダーやロール混練機を用い、他添加剤も加えた上で一括して溶融混合する手法に比べ、軟化点もしくは凝固点の低い原料が多量に含まれていても、Bステージ化反応をより促進できるため、反応後には常温で固体の中間反応物とすることができることを特徴とする。
【0025】
本発明で、中間反応物(A)を得る工程としては、加熱反応釜などの一般的な加熱反応装置を用いることができる。具体的な方法としては、成分(a)、及び成分(b)を、反応釜で、無溶剤で、上記温度で、60〜240分間加熱混合し、使用に好ましい軟化点、具体的には常温での取り扱いに問題を生じない50℃以上、が得られた時点で、反応物を取り出し、冷却粉砕して中間反応物を得る方法が挙げられる。
【0026】
中間反応物(A)に用いる、トリグリシジルイソシアヌレート及びビスフェノール型エポキシ樹脂からなる、全体の平均エポキシ当量が200以上400以下のエポキシ樹脂(a)において、平均エポキシ当量が200より下回る場合で、トリグリシジルイソシアヌレートの配合比率が高い場合は、エポキシ樹脂の反応性が著しく高まり、前述の中間反応時に、増粘や材料のゲル化を生じ易くなるのに加え、得られる硬化物が、非常にもろくなるために本発明の目的には適さず、また、ビスフェノール型エポキシ樹脂のエポキシ当量が小さい場合、ビスフェノール型エポキシ樹脂が液状であったり、軟化点が低いために、中間反応を行っても、常温で固体の中間反応物とするのが難しい。
平均エポキシ当量が400を越える場合で、トリグリシジルイソシアヌレートの比率が低い場合、多官能な成分が減少することにより、期待した耐熱性が得られず、また、ビスフェノール型エポキシ樹脂のエポキシ当量が大きい場合、エポキシ樹脂の粘度が非常に高いものとなり、金型未充填などの成形不良を発生するため不適である。
【0027】
本発明に用いるエポキシ樹脂(a)において、前記平均エポキシ当量を得るにあたり、ビスフェノール型エポキシ樹脂の平均エポキシ当量が210以上1100以下であり、エポキシ樹脂(a)中に含まれるトリグリシジルイソシアヌレートの配合比率が、5重量%以上45重量%以下であることが好ましい。
【0028】
本発明に用いるビスフェノール型エポキシ樹脂としては、ビスフェノール骨格を有するものであれば、何ら制限されるものではないが、透明性の観点から着色の少ないエポキシ樹脂を用いることがより好ましい。具体的には、ビスフェノールA型エポキシ樹脂、ビスフェノールF型エポキシ樹脂などが挙げられるが、一般式(1)で表される構造のビスフェノール型エポキシ樹脂はビスフェノールA型エポキシ樹脂の色調安定性とビスフェノールF型エポキシ樹脂の低粘度の性質を兼ね備えるため、特性上より好ましい。
【0029】
本発明に用いる、凝固点が50℃以下の酸無水物硬化剤(b)としては、従来公知のものが使用できる。具体的には、ヘキサヒドロ無水フタル酸、4−メチル−ヘキサヒドロ無水フタル酸、3−メチル−ヘキサヒドロ無水フタル酸と4−メチル−ヘキサヒドロ無水フタル酸との混合物、及びエンドメチレンテトラヒドロ無水フタル酸などが例示されるが、特にこれらに限定されるものではなく、これらの単独もしくは2種以上用いることができる。これらの酸無水物のうち、ヘキサヒドロ無水フタル酸および4−メチルヘキサヒドロ無水フタル酸が透明性およびBステージ化中間反応物の溶融粘度が低い点に加え、透明性に優れる硬化物を得られるという点で非常に優れ、より好ましい。
【0030】
これらの凝固点が50℃以下の酸無水物硬化剤(b)は、エポキシ樹脂(a)との中間反応の際に、その反応物の溶融粘度を低減し、反応が均一に進行させることを可能とし、低い温度でも容易に液化するため、反応温度を低く保つことが可能であり、結果として中間反応時のゲル化による反応の暴走を抑えることができる。
【0031】
本発明の中間反応物(A)において、エポキシ樹脂(a)と硬化剤(b)の配合比は、酸無水物硬化剤の酸無水物基に対する、エポキシ樹脂のエポキシ基のモル比が、0.8〜1.4が好ましく、より好ましくは1.0〜1.2である。
【0032】
本発明に用いる硬化促進剤(B)としては、通常、エポキシ樹脂のアニオン硬化に用いられるものは、すべて使用可能であり、具体的にはイミダゾール類、4級アンモニウム塩類、アミン類、ホスフィン類、ホスホニウム塩類、双環式アミジン類およびそれらの塩類などがあげられる。これらは、単独でも2種以上用いても差し支えない。これらのうち、2−メチルイミダゾール、2−フェニル−4−イミダゾールなどのイミダゾール類、2−フェニルイミダゾール イソシアヌル酸付加物などのイミダゾール塩類、1,8−ジアザビシクロ(5,4,0)ウンデセン−7などの双環式アミジン類、1,8−ジアザビシクロ(5,4,0)ウンデセン−7のオクチル酸塩などの双環式アミジンのカルボン酸塩類、およびテトラフェニルホスホニウムブロマイドなどのホスホニウム塩類を用いると、硬化性がよく、着色がなくより好ましい。
硬化促進剤の添加量は、中間反応物(A)100重量部に対して、0.5〜2重量部が好ましい。
【0033】
本発明に用いる無機充填材(C)は、透明性を損なわないために、エポキシ樹脂組成物において、無機充填材の屈折率と無機充填材以外の成分の屈折率とを整合する必要がある。具体的には、無機充填材とそれ以外の樹脂成分の硬化物の屈折率の差が、適用する製品の透過すべき光波長において計測した屈折率の差が0.01以下であることが、特に好ましい。屈折率を測定する波長としては、適用する光半導体用製品の発光ピーク、もしくは受光する光線の波長ピークを用いればよい。このような条件を満たす充填材であれば、従来公知のものが使用できる。
具体的には、シリカ粉末、タルク、カオリンクレー、マイカ等の天然化合物、ガラス等の合成化合物が使用できるが、天然化合物は屈折率が一義的に決定されているものが多く、樹脂成分に整合するものは、おのずと限られてくる。そのため、本発明に用いる無機充填材としては、SiO2、CaO、およびAl2O3からなる、球状ガラス粒子が、任意の屈折率のものが容易に得られるという点でより好ましい。
本発明の樹脂組成物における(C)成分以外の成分の硬化物に、前述組成のガラス粒子の屈折率を整合するためには、SiO2を40〜70重量%、CaOを1〜40重量%、Al2O3を5〜30重量%、合計で100重量%となるような組成が好ましい。ただし、必要に応じて、他成分として金属元素類、金属酸化物類などを添加することは差し支えない。
【0034】
また、前述ガラス粒子は、球状であり、平均粒径が5μm以上、100μm以下であると良い。形状を球状とすることにより、光の散乱損失を小さく抑えることができる。また平均粒径が5μm未満の場合、ガラス粒子が凝集して透明性を低下させる。一方、平均粒径が100μmを越える場合、樹脂組成物成形時に金型のゲート部で樹脂詰まりがおこり、未充填となる場合がある。
【0035】
無機充填剤の配合量としては、エポキシ樹脂組成物中に5重量パーセント以上、70重量パーセント以下であることがより好ましい。配合量が、5重量パーセント未満の場合、吸水率の低減効果が僅かであり、耐半田性が向上しない場合がある。一方、70重量パーセントを超える場合、成形時に前述の未充填のような成形不良が生じる場合がある。
【0036】
本発明で用いる離型剤(D)は、一般式(2)で表される化合物である。
一般式(2)で表される化合物は、1分子内にエポキシ樹脂に相溶する性質と相溶しない性質の両者の性質を有しているため、従来の離型剤とは異なり、透明性と離型性を両立することができる。
【0037】
離型剤(D)の配合量としては、全エポキシ樹脂組成物中に0.01重量%以上、5重量%以下が好ましい。0.01重量%を下まわるとパッケージの離型性が悪くなる恐れがあり、また、5重量%を越えると樹脂硬化物に曇りが生じ、透明性が低下する恐れがある。
【0038】
本発明の光半導体封止用エポキシ樹脂組成物には、上記成分以外に、必要に応じて、従来公知の酸化防止剤、離型剤、カップリング剤、充填剤、着色剤、紫外線吸収剤等の当業者にて公知の添加剤、副資材を組み合わせることは何らさしつかえない。
【0039】
本発明の樹脂組成物は、(A)〜(D)成分、及びその他の添加剤を、ミキサー等を用いて混合後、加熱ニーダや加熱ロール、押し出し機等を用いて加熱混練し、続いて冷却、粉砕することで得られる。
【0040】
このようにして得られた光半導体封止用エポキシ樹脂組成物を用いての封止は、一般的な方法でできるが、例えば、トランスファー成形法等により、光半導体素子を封止して、エポキシ樹脂組成物の硬化物で封止された光半導体装置を得ることができる。
【0041】
【実施例】
以下に、本発明について更に詳細に説明するため実施例を示すが、これらに本発明が限定されるものではない。
【0042】
(実施例1〜7)
成分(a)、及び成分(b)に相当する成分を、表1に示した配合割合で、100℃の反応釜で130〜220分加熱反応させて得た中間反応物に、成分(B)〜(D)に相当する成分、及び各種添加剤等を表1に示した配合割合で混合し、2本ロールを用いて、50〜90℃で5分間混練し、得られた混練物シートを、冷却後粉砕して、樹脂組成物を得た。評価方法は以下の通り。結果は表1にまとめて示す。
【0043】
(比較例1)
成分(a)に該当するエポキシ樹脂、成分(b)に相当する酸無水物に、本発明の中間反応を経ずに、成分(B)〜(D)に相当する成分、及び各種添加剤等を表2に示した配合割合で混合し、加熱ニーダーを用いて、90℃で20分間混練し、得られた混練物シートを冷却したが、混練物の軟化点が十分に得られず、成形可能な材料を得ることができなかった。
【0044】
(比較例2)
特許2656336号公報に開示されている技術に基づき、成分(a)に該当するエポキシ樹脂、成分(b)に相当する酸無水物、及び成分(B)〜(D)に相当する成分の合計量100重量部を、500重量部のジクロルメタンに加温しながら完全に溶解した後、還流させながら温度39〜41℃の状態で50時間混合を継続し、150℃のゲル化時間が60秒の溶液を作成した。この溶液を45℃に加温しながら減圧し、その後加温して、トランスファー成形に供することができる軟化点が得られるまで反応を進行させたが、軟化点が十分に得られずにゲル化が進行して、成形可能な材料を得ることができなかった。
【0045】
(比較例3)
特許2970214号公報に開示されている技術に基づき、成分(a)に該当するエポキシ樹脂、成分(b)に相当する酸無水物に、本発明の中間反応を経ずに、成分(B)〜(D)に相当する成分、及び各種添加剤等を表2に示した配合割合で混合し、90℃の熱ロールで15分間混練し、得られた混練物シートを冷却粉砕し、樹脂組成物を得た。評価方法は以下の通り。結果は表2にまとめて示す。
【0046】
(比較例4〜8)
成分(a)、成分(b)に相当する成分を、表2に示した配合割合で、100℃の反応釜で110〜200分加熱反応させて得た中間反応物に、成分(B)〜(D)に相当する成分、及び各種添加剤等を表2に示した配合割合で混合し、2本ロールを用いて、50〜90℃で5分間混練し、得られた混練物シートを、冷却後粉砕して、樹脂組成物を得た。評価方法は以下の通り。結果は表2にまとめて示す。
【0047】
[軟化点の測定]
合成した成分(A)の、中間反応物の軟化点は、室温から250℃の温度傾斜を持たせた銅棒上に、粉砕した成分(A)を散布し、10秒後に刷毛を用いて、はきとることの可否の境界温度をもって軟化点とした。この際、50℃未満で測定不可能な軟化点のものを×と表記した。
【0048】
[光透過率の測定]
上記の樹脂組成物タブレットを、金型温度150℃、注入圧力6.86MPa、硬化時間90秒の条件でトランスファー成形し、30×10×1mmの成形品を得た。この成形品を、積分球を搭載した分光光度計(島津製作所製自記分光光度計UV−3100)を用いて、波長400nm、厚み1mmの光透過率を測定した。
【0049】
[流動性の評価]
成形前の樹脂組成物を、EMMI−I−66に準じたスパイラルフロー測定用の金型を用い、成形温度175℃、注入圧力6.86MPa、硬化時間5分の条件で成形し、充填した長さを測定し、この長さが60cm以上得られたものを流動性○、そうでないものを×とした。
【0050】
[ガラス転移温度の測定]
上記の樹脂組成物タブレットを、金型温度150℃、注入圧力6.86MPa、硬化時間90秒の条件でトランスファー成形し、この成形品を、温度150℃の熱風オーブンで2時間ポストキュアした後、熱膨張計(セイコー電子社製TMA120)を用い、5℃/分の昇温速度で昇温して、前記成形品の伸び率が急激に変化する温度をガラス転移点として測定した。
【0051】
[離型性の評価]
上記の樹脂組成物タブレットを、メラミン樹脂クリーニング材によりクリーニング済みの表面実装用パッケージ(12ピンSOP、4×5mm、厚み1.2mm、チップサイズは1.5mm×2.0mm、リードフレームは42アロイ製)金型を用いて、金型温度150℃、注入圧力6.86MPa、硬化時間90秒でトランスファー成形した。評価はパッケージがイジェクトピンによって金型から離型する場合を○、パッケージの変形やクラックが発生する場合を×とした。
【0052】
[耐半田性の評価]
上記の樹脂組成物タブレットを、メラミン樹脂クリーニング材によりクリーニング済みの表面実装用パッケージ(12ピンSOP、4×5mm、厚み1.2mm、チップサイズは1.5mm×2.0mm、リードフレームは42アロイ製)金型を用いて、金型温度150℃、注入圧力6.86MPa、硬化時間90秒でトランスファー成形し、温度150℃の熱風オーブンで、2時間後硬化させた。得られた光半導体パッケージを、温度85℃、相対湿度60%の環境下で、168時間放置し、その後240℃のIRリフロー処理を行った。処理したパッケージを顕微鏡及び超音波探傷装置で観察し、クラック、チップと樹脂との剥離の有無を確認した。
【0053】
【表1】
【0054】
表1中、注1:油化シェルエポキシ製ビスフェノールA型エポキシ樹脂(エポキシ当量475)、 注2:三井化学製ビスフェノール型エポキシ樹脂(エポキシ当量500、 一般式(2)で表されるエポキシ樹脂で、C(CH3)2が70%、CH2が30%含み、n=2)、 注3:三井化学製ビスフェノール型エポキシ樹脂(エポキシ当量980、 一般式(2)で表されるエポキシ樹脂で、C(CH3)2が70%、CH2が30%含み、n=4)、 注4:日産化学製 トリグリシジルイソシアヌレート(エポキシ当量100)、 注5:新日本理化製ヘキサヒドロ無水フタル酸とメチルヘキサヒドロ無水フタル酸との混合物(凝固点−15℃)、 注6:新日本理化製ヘキサヒドロ無水フタル酸(凝固点37℃)、 注7:サンアプロ製ジアザビシクロウンデセンとオクチル酸との塩、 注8:四国化成製イミダゾール、 注9:北興化学製テトラフェニルホスホニウムブロマイド、 注10:北興化学製トリフェニルホスフィン、 注11:SiO2、CaO、およびAl2O3からなり、平均粒径25μmで、表1の屈折率差に調整した球状ガラス、 注12:SiO2、CaO、およびAl2O3からなり、平均粒径40μmで、表1の屈折率差に調整した球状ガラス、 注13:SiO2、CaO、およびAl2O3からなり、平均粒径25μmで、表1の屈折率差に調整した球状ガラス、 注14:平均粒径20μmの平板状タルク、 注15:一般式(1)で表される離型剤である化合物A(式中k=48、m=2、n=21、R1=H、R2=CH3)、 注16:一般式(1)で表される離型剤である化合物B(式中k=54、m=4、n=18、R1=H、R2=CH3CH2CH2)、 注17:住友化学製リン系酸化防止剤、 注18:住友化学製フェノール系酸化防止剤。
【0055】
【表2】
【0056】
表1中、注1:油化シェルエポキシ製ビスフェノールA型エポキシ樹脂(エポキシ当量475)、 注2:三井化学製ビスフェノールF型エポキシ樹脂(エポキシ当量950)、 注3:三井化学製ビスフェノール型エポキシ樹脂(エポキシ当量500、 一般式(2)で表されるエポキシ樹脂で、C(CH3)2が70%、CH2が30%含み、n=2)、 注4:三井化学製ビスフェノール型エポキシ樹脂(エポキシ当量980、 一般式(2)で表されるエポキシ樹脂で、C(CH3)2が70%、CH2が30%含み、n=4)、 注5:日産化学製 トリグリシジルイソシアヌレート(エポキシ当量100)、 注6:三井化学製3官能エポキシ樹脂(エポキシ当量210)、 注7:新日本理化製ヘキサヒドロ無水フタル酸とメチルヘキサヒドロ無水フタル酸との混合物(凝固点−15℃)、注8:新日本理化製ヘキサヒドロ無水フタル酸(凝固点37℃)、 注9:新日本理化製テトラヒドロ無水フタル酸(凝固点100℃)、 注10:サンアプロ製ジアザビシクロウンデセンとオクチル酸との塩、 注11:四国化成製イミダゾール類、 注12:北興化学製テトラフェニルホスホニウムブロマイド、 13:SiO2、CaO、およびAl2O3からなり、平均粒径25μmで、表2の屈折率差に調整した球状ガラス、 注14:SiO2、CaO、およびAl2O3からなり、平均粒径40μmで、表2の屈折率差に調整した球状ガラス、 注15:平均粒径15μmの、屈折率を調整した球状ガラス、 注16:SiO2、CaO、およびAl2O3からなり、平均粒径5μmで、表2の屈折率差に調整した球状ガラス、 注17:一般式(1)で表される離型剤である化合物A(式中k=48、m=2、n=21、R1=H、R2=CH3)、 注18:一般式(1)で表される離型剤である化合物B(式中k=54、m=4、n=18、R1=H、R2=CH3CH2CH2)、 注19:クラリアントジャパン製離型剤、 注20:住友化学製フェノール系酸化防止剤、 注21:住友化学製リン系酸化防止剤、 注22:中間反応の溶融混合において、ゲル化が進行した。
【0057】
表の結果から明らかなように、本発明の樹脂組成物は耐半田性、離型性に優れるとともに、80%以上の良好な光透過率を両立していることがわかる。
【0058】
【発明の効果】
本発明、透明性、耐半田性及び離型性に優れた光半導体封止用エポキシ樹脂組成物が得られ、これを用いて、高い信頼性を有したオプトデバイスを提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin composition for encapsulating an optical semiconductor excellent in transparency, solder resistance and releasability, a method for producing the same, and an optical semiconductor device encapsulated with a cured product thereof.
[0002]
[Prior art]
In recent years, with the aim of downsizing communication information devices, improving integration density, and simplifying manufacturing processes, the demand for surface mounting methods in the semiconductor industry has rapidly increased in place of conventional mounting methods. Further, in the field of optoelectronics, transparency is a very important factor in addition to the function of the conventional semiconductor sealing resin. That is, in opto devices such as photosensors, LEDs, and light emitting elements, even if a mounting method such as IR reflow in surface mounting is performed, transparency is not impaired, and further, generation of package cracks due to thermal shock, There is a need for a highly reliable sealing resin that does not cause separation between the chip or lead frame and the resin.
[0003]
Further, in order to increase the production efficiency of such an optical semiconductor element, sealing with a liquid sealing material as conventionally used is gradually shifting to transfer molding with a multi-molding machine. In this case, the resin composition inevitably needs to be solid at room temperature, and new problems such as unevenness during flow and coloring due to rapid curing must be solved. In particular, the coloring hinders the emission of light having a low wavelength, and may adversely affect the light emission efficiency and color tone of the blue and white light emitting elements.
[0004]
As a method for producing an epoxy resin composition that is solid at room temperature and used for transfer molding, it is generally obtained by melt-kneading an epoxy resin that is solid at room temperature and a solid curing agent at room temperature using an apparatus such as a heating kneader. Although the technique is generally known, in the operation of melt kneading, if the heating is insufficient, there is a problem that the characteristics deteriorate due to unevenness of the material.
[0005]
With respect to this problem, in Japanese Patent No. 2970214, heat resistance and transparency are obtained by combining an alicyclic epoxy resin or a heterocyclic epoxy resin at a certain ratio with respect to a bisphenol A type epoxy resin included in a specific molecular weight range. Is obtained, and it is shown that the occurrence of unevenness can be suppressed. However, in this case, it is a condition that a solid curing agent is mainly used as the curing agent. Many solid acid anhydride curing agents include factors that reduce light transmission, such as unsaturated bonds, and the transmittance of the cured product tends to decrease in a low wavelength region.
[0006]
In addition, as a technology for eliminating unevenness, Japanese Patent No. 2656336 discloses a technology in which an epoxy resin composition is dissolved in a solvent and mixed uniformly, and then the solvent is removed to obtain a uniform composition. In this case as well, in order to be used for transfer molding, there is a restriction that the type of curing agent must be mainly solid at room temperature.
[0007]
On the other hand, as surface mounting reliability of the cured product, it is required to lower the water absorption rate, and it is known among those skilled in the art that a typical method is to add a filler to reduce the water absorption rate. That's it. This is because by filling the resin composition with an inorganic filler such as silica at a high ratio, the water absorption rate and the linear expansion coefficient of the sealing resin composition can be reduced, and deformation and cracking at high temperatures can be suppressed. However, the resin composition thus obtained has extremely low light transmittance of the cured resin due to the influence of light reflection and refraction occurring at the interface between the silica particles and the resin. When light rays pass through the cured resin composition, the amount of light reflected and refracted at the interface between the resin and the filler is known to be proportional to the difference in refractive index before and after the interface, The refractive index of general silica particles is around 1.4, whereas the cured epoxy resin is around 1.5, and it is difficult to eliminate this point unless the type of filler is changed. .
[0008]
In order to solve this problem, Japanese Patent Application Laid-Open No. 6-65473 discloses SiO 2 as a filler other than silica. 2 , CaO and Al 2 O Three A technique is described in which glass particles containing as a main component are used as a filler for a resin composition for sealing an optical semiconductor. According to this technique, the refractive index of the filler can be easily changed by changing the composition of each component or adding metal elements. However, when the present inventors used a glass filler according to this technique as a filler for a resin composition for encapsulating an optical semiconductor, the transparency is certainly increased, and the water absorption rate and the linear expansion coefficient are also reduced. It is inadequate and it is difficult to achieve both transparency and surface mounting capability. From this, the present inventors have come to the conclusion that it is necessary to enhance not only the addition of the filler but also the characteristics of the resin itself in order to achieve both surface mounting ability and transparency.
[0009]
Furthermore, the optical semiconductor sealing material is required to transmit visible light, but at the same time, releasability from the mold is an important item. Conventionally, in order to improve releasability, a method of regularly molding a material containing a release agent component or spraying a release agent such as a fluorine type or a silicone type directly onto a mold is used. However, in this case, there is a problem that not only the production efficiency of the continuous molding is lowered but also the mold release agent remains in the mold and is contaminated. Thus, studies have been made so far in which a release agent is added and mixed in advance into the sealing material. When a conventionally known release agent is added, depending on the type of the release agent, increasing the addition amount improves the release property, but the cured resin is clouded and the light transmittance is reduced. When the addition amount is reduced, the releasability is deteriorated, and when the package is released from the mold, the package is cracked or the lead frame is bent, and the optical semiconductor device is deformed. That is, a resin composition that satisfies both characteristics in terms of transparency and releasability has not been developed yet.
[0010]
Japanese Patent No. 2781279 describes that a surfactant having a polyether structure and a long-chain alkyl group is added in advance to a material for optical semiconductor encapsulation as a release agent. Added to the material for sealing an optical semiconductor, the release property from the mold is excellent, but the cured resin is clouded when cured at a high temperature, and as a resin composition for sealing an optical semiconductor, Insufficient transparency.
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide an epoxy resin composition for sealing an optical semiconductor excellent in transparency, solder resistance, and releasability, and an optical semiconductor device sealed with a cured product thereof.
[0012]
[Means for Solving the Problems]
The present inventors believe that the haze that occurs when the resin composition is cured is caused by the change in solubility after the resin is cured and the release agent that has become incompatible in the resin cured product forms a large region, As a result of intensive studies, it has been found that the introduction of an intermediate compatible part into the bonding part between the parts of the release agent with a specific structure that have different compatibility with the resin can reduce the occurrence of a region with a large light loss. In addition to a specific combination of an epoxy resin and an acid anhydride curing agent having a freezing point of 50 ° C. or lower, a composition that exhibits characteristics suitable for water absorption and transparency, and a specific inorganic By using a filler and a release agent, a composition for encapsulating an optical semiconductor that further reduces water absorption, maintains high light transmittance, and exhibits excellent solder resistance and release properties. I came to get.
[0013]
That is, this invention is an epoxy resin composition for optical semiconductor sealing as described in (1)-(8) term.
(1) Epoxy resin composition for encapsulating an optical semiconductor comprising an intermediate reaction product (A) of an epoxy resin and a curing agent, a curing accelerator (B), an inorganic filler (C), and a release agent (D) as essential components. The intermediate reaction product (A) comprises the following component (a) and component (b), and is obtained by melt mixing at a temperature of 80 ° C. or higher and 150 ° C. or lower in the absence of a solvent. The epoxy resin composition for optical semiconductor sealing characterized by the above-mentioned.
(A) An epoxy resin comprising triglycidyl isocyanurate and a bisphenol-type epoxy resin, wherein the average epoxy equivalent of the whole component (a) is 200 or more and 400 or less.
(B) An acid anhydride curing agent having a freezing point of 50 ° C or lower.
[0014]
(2) The bisphenol-type epoxy resin has an average epoxy equivalent of 210 or more and 1100 or less, and triglycidyl isocyanurate is contained in the component (a) at 5% or more and 45% or less (1) The epoxy resin composition for optical semiconductor encapsulation according to the item).
[0015]
(3) The epoxy resin composition for encapsulating an optical semiconductor according to (2) above, wherein the bisphenol-type epoxy resin is more preferably an epoxy resin represented by the general formula (1). .
[0016]
[Chemical 3]
(However, in Formula (1), the value of n is 1-7, R is C (CH Three ) 2 And CH 2 Each having at least one per molecule. )
[0017]
(4) The acid anhydride curing agent (b) having a freezing point of 50 ° C. or lower is preferably at least one selected from the group consisting of hexahydrophthalic anhydride and 4-methylhexahydrophthalic anhydride. It is the epoxy resin composition for optical semiconductor sealing as described in said (1) term.
[0018]
(5) The curing accelerator (B) is selected from the group consisting of imidazoles, imidazole salts, bicyclic amidines, carboxylic acids of bicyclic amidines, and phosphonium salts, An epoxy resin composition for optical semiconductor encapsulation according to item 1).
[0019]
(6) The optical semiconductor according to (1), wherein the difference between the refractive index of the inorganic filler (C) and the refractive index of the cured product of components other than the inorganic filler (C) is 0.01 or less. It is an epoxy resin composition for sealing.
[0020]
(7) Inorganic filler (C) is SiO 2 , CaO, and Al 2 O Three Spherical glass particles having an average particle size of 5 μm or more and 100 μm or less, and is blended in the epoxy resin composition for sealing an optical semiconductor at a ratio of 5 wt% or more and 70 wt% or less. The epoxy resin composition for optical semiconductor encapsulation according to item (1).
[0021]
(8) The mold release agent (D) is a compound represented by the general formula (2), and is blended in the epoxy resin composition for sealing an optical semiconductor at a ratio of 0.01% by weight or more and 5% by weight or less. The epoxy resin composition for optical semiconductor encapsulation according to item (1), wherein the composition is an epoxy resin composition for optical semiconductor encapsulation.
[0022]
[Formula 4]
(However, in Formula (2), the value of k is 40-60, the value of m is 1-5, and the value of n is 15-45.) 1 , R 2 Is a hydrogen atom or a monovalent alkyl group, at least one of which is a monovalent alkyl group. )
[0023]
Furthermore, this invention is the optical semiconductor device sealed with the hardened | cured material of the epoxy resin composition for optical semiconductor sealing in any one of said (1)-(8) term.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
The intermediate reaction product (A) of the epoxy resin and the curing agent used in the present invention comprises the component (a) triglycidyl isocyanurate and a bisphenol type epoxy resin, and the average epoxy equivalent of the whole component (a) is 200 or more and 400. A compound obtained by melt-mixing the following epoxy resin component and an acid anhydride curing agent component having a freezing point of 50 ° C. or lower of the component (b) at a temperature of 80 ° C. or higher and 150 ° C. or lower and without a solvent. Compared to conventional melt kneading methods using a heat kneader or roll kneader and adding other additives, B-stage reaction Since the reaction can be further promoted, the reaction product is characterized by being an intermediate reaction product that is solid at room temperature after the reaction.
[0025]
In the present invention, for the step of obtaining the intermediate reactant (A), a general heating reaction apparatus such as a heating reaction kettle can be used. As a specific method, the component (a) and the component (b) are heated and mixed in a reaction kettle with no solvent at the above temperature for 60 to 240 minutes, and a softening point preferable for use, specifically room temperature. When a temperature of 50 ° C. or higher that does not cause a problem in handling is obtained, the reaction product is taken out and cooled and ground to obtain an intermediate reaction product.
[0026]
In the epoxy resin (a) composed of triglycidyl isocyanurate and bisphenol type epoxy resin used for the intermediate reactant (A) and having an average epoxy equivalent of 200 to 400, the average epoxy equivalent is less than 200. When the blending ratio of glycidyl isocyanurate is high, the reactivity of the epoxy resin is remarkably increased, and in addition to the above-mentioned intermediate reaction, it is easy to cause thickening and gelation of the material, and the resulting cured product is very brittle. Therefore, when the epoxy equivalent of the bisphenol-type epoxy resin is small, the bisphenol-type epoxy resin is liquid or has a low softening point. It is difficult to obtain a solid intermediate reactant.
When the average epoxy equivalent exceeds 400 and the ratio of triglycidyl isocyanurate is low, the expected heat resistance cannot be obtained due to the decrease in polyfunctional components, and the epoxy equivalent of the bisphenol type epoxy resin is large. In such a case, the viscosity of the epoxy resin becomes very high, and molding defects such as unfilling of the mold occur, which is not suitable.
[0027]
In the epoxy resin (a) used in the present invention, in obtaining the average epoxy equivalent, the average epoxy equivalent of the bisphenol-type epoxy resin is 210 or more and 1100 or less, and the blend of triglycidyl isocyanurate contained in the epoxy resin (a) The ratio is preferably 5% by weight or more and 45% by weight or less.
[0028]
The bisphenol-type epoxy resin used in the present invention is not limited as long as it has a bisphenol skeleton, but it is more preferable to use an epoxy resin with little coloring from the viewpoint of transparency. Specific examples include bisphenol A type epoxy resins and bisphenol F type epoxy resins. The bisphenol type epoxy resin having the structure represented by the general formula (1) is the color stability of bisphenol A type epoxy resin and bisphenol F type. In view of the low-viscosity properties of the type epoxy resin, it is more preferable in terms of properties.
[0029]
As the acid anhydride curing agent (b) having a freezing point of 50 ° C. or lower used in the present invention, conventionally known ones can be used. Specific examples include hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, a mixture of 3-methyl-hexahydrophthalic anhydride and 4-methyl-hexahydrophthalic anhydride, and endomethylenetetrahydrophthalic anhydride. However, it is not particularly limited to these, and these can be used alone or in combination of two or more. Among these acid anhydrides, hexahydrophthalic anhydride and 4-methylhexahydrophthalic anhydride are said to provide transparency and a cured product with excellent transparency in addition to the low melt viscosity of the B-staged intermediate reactant. Very excellent in terms and more preferable.
[0030]
These acid anhydride curing agents (b) having a freezing point of 50 ° C. or lower can reduce the melt viscosity of the reaction product during the intermediate reaction with the epoxy resin (a) and allow the reaction to proceed uniformly. The reaction temperature can be kept low because the liquid is easily liquefied even at a low temperature, and as a result, the runaway reaction due to gelation during the intermediate reaction can be suppressed.
[0031]
In the intermediate reactant (A) of the present invention, the molar ratio of the epoxy resin (a) and the curing agent (b) is such that the molar ratio of the epoxy group of the epoxy resin to the acid anhydride group of the acid anhydride curing agent is 0. .8 to 1.4 is preferable, and 1.0 to 1.2 is more preferable.
[0032]
As the curing accelerator (B) used in the present invention, all those usually used for anionic curing of epoxy resins can be used. Specifically, imidazoles, quaternary ammonium salts, amines, phosphines, Examples thereof include phosphonium salts, bicyclic amidines and salts thereof. These may be used alone or in combination of two or more. Among these, imidazoles such as 2-methylimidazole and 2-phenyl-4-imidazole, imidazole salts such as 2-phenylimidazole isocyanuric acid adduct, 1,8-diazabicyclo (5,4,0) undecene-7 and the like And bicyclic amidine carboxylates such as 1,8-diazabicyclo (5,4,0) undecene-7 octylate, and phosphonium salts such as tetraphenylphosphonium bromide, It is more preferable because it has good curability and is not colored.
As for the addition amount of a hardening accelerator, 0.5-2 weight part is preferable with respect to 100 weight part of intermediate reaction materials (A).
[0033]
In order that the inorganic filler (C) used in the present invention does not impair transparency, it is necessary to match the refractive index of the inorganic filler and the refractive index of components other than the inorganic filler in the epoxy resin composition. Specifically, the difference in refractive index between the inorganic filler and the cured product of the other resin component is such that the difference in refractive index measured at the light wavelength to be transmitted by the product to be applied is 0.01 or less. Particularly preferred. As the wavelength for measuring the refractive index, the emission peak of the optical semiconductor product to be applied or the wavelength peak of the received light beam may be used. Conventionally known fillers can be used as long as they satisfy such conditions.
Specifically, natural compounds such as silica powder, talc, kaolin clay, and mica, and synthetic compounds such as glass can be used, but many natural compounds have a refractive index that is uniquely determined and match the resin components. What you do is naturally limited. Therefore, the inorganic filler used in the present invention is SiO 2 , CaO, and Al 2 O Three Spherical glass particles consisting of the above are more preferred in that they can be easily obtained with any refractive index.
In order to match the refractive index of the glass particles having the above-mentioned composition to the cured product other than the component (C) in the resin composition of the present invention, SiO 2 2 40 to 70 wt%, CaO 1 to 40 wt%, Al 2 O Three Is preferably 5 to 30% by weight, and a total of 100% by weight. However, if necessary, it is possible to add metal elements, metal oxides, etc. as other components.
[0034]
The glass particles are spherical and have an average particle size of 5 μm or more and 100 μm or less. By making the shape spherical, light scattering loss can be reduced. On the other hand, when the average particle size is less than 5 μm, the glass particles aggregate to reduce transparency. On the other hand, when the average particle size exceeds 100 μm, resin clogging may occur at the gate portion of the mold when the resin composition is molded, and it may become unfilled.
[0035]
As a compounding quantity of an inorganic filler, it is more preferable that it is 5 to 70 weight% in an epoxy resin composition. When the blending amount is less than 5 weight percent, the effect of reducing the water absorption rate is slight and the solder resistance may not be improved. On the other hand, when it exceeds 70 weight percent, the above-mentioned unfilled molding may occur during molding.
[0036]
The release agent (D) used in the present invention is a compound represented by the general formula (2).
The compound represented by the general formula (2) has both a property compatible with an epoxy resin and a property not compatible with each other in one molecule. And releasability can be achieved.
[0037]
As a compounding quantity of a mold release agent (D), 0.01 to 5 weight% is preferable in all the epoxy resin compositions. If it is less than 0.01% by weight, the release property of the package may be deteriorated, and if it exceeds 5% by weight, the resin cured product may be clouded and the transparency may be lowered.
[0038]
In the epoxy resin composition for optical semiconductor encapsulation of the present invention, in addition to the above components, conventionally known antioxidants, mold release agents, coupling agents, fillers, colorants, ultraviolet absorbers, etc., if necessary Any combination of additives and sub-materials known to those skilled in the art can be combined.
[0039]
In the resin composition of the present invention, the components (A) to (D) and other additives are mixed using a mixer or the like, then heated and kneaded using a heating kneader, a heating roll, an extruder, or the like, and then Obtained by cooling and grinding.
[0040]
Sealing using the epoxy resin composition for optical semiconductor sealing thus obtained can be performed by a general method. For example, the optical semiconductor element is sealed by a transfer molding method or the like, An optical semiconductor device sealed with a cured product of the resin composition can be obtained.
[0041]
【Example】
EXAMPLES Examples will be shown below to describe the present invention in more detail, but the present invention is not limited to these examples.
[0042]
(Examples 1-7)
The component (a) and the component corresponding to the component (b) are mixed at the blending ratio shown in Table 1, and the intermediate reaction product obtained by heating and reacting in a reaction vessel at 100 ° C. for 130 to 220 minutes is added to the component (B). The components corresponding to ~ (D), various additives, and the like are mixed in the blending ratio shown in Table 1, and are kneaded at 50 to 90 ° C for 5 minutes using the two rolls. After cooling, the mixture was pulverized to obtain a resin composition. The evaluation method is as follows. The results are summarized in Table 1.
[0043]
(Comparative Example 1)
The epoxy resin corresponding to the component (a), the acid anhydride corresponding to the component (b), the components corresponding to the components (B) to (D) without undergoing the intermediate reaction of the present invention, various additives, etc. Were mixed at a blending ratio shown in Table 2, and kneaded at 90 ° C. for 20 minutes using a heating kneader, and the resulting kneaded material sheet was cooled, but the softening point of the kneaded material was not sufficiently obtained, and molding was performed. A possible material could not be obtained.
[0044]
(Comparative Example 2)
Based on the technology disclosed in Japanese Patent No. 2656336, the total amount of epoxy resin corresponding to component (a), acid anhydride corresponding to component (b), and components corresponding to components (B) to (D) 100 parts by weight is completely dissolved in 500 parts by weight of dichloromethane, and then mixed for 50 hours at a temperature of 39 to 41 ° C. while refluxing, and a gelation time of 150 ° C. for 60 seconds. It was created. The solution was depressurized while being heated to 45 ° C., then heated, and the reaction was allowed to proceed until a softening point that could be used for transfer molding was obtained. However, the gelation occurred without sufficiently obtaining the softening point. As a result, the moldable material could not be obtained.
[0045]
(Comparative Example 3)
Based on the technique disclosed in Japanese Patent No. 2970214, the epoxy resin corresponding to the component (a) and the acid anhydride corresponding to the component (b) are subjected to the components (B) to (B) without undergoing the intermediate reaction of the present invention. The components corresponding to (D), various additives, and the like are mixed at the blending ratio shown in Table 2, kneaded with a hot roll at 90 ° C. for 15 minutes, and the resulting kneaded material sheet is cooled and pulverized to obtain a resin composition. Got. The evaluation method is as follows. The results are summarized in Table 2.
[0046]
(Comparative Examples 4 to 8)
The components corresponding to the components (a) and (b) at the blending ratios shown in Table 2 were heated to react in a reaction kettle at 100 ° C. for 110 to 200 minutes. The components corresponding to (D), various additives and the like are mixed at the blending ratio shown in Table 2, and are kneaded at 50 to 90 ° C. for 5 minutes using a two-roll, and the obtained kneaded sheet is obtained as follows: After cooling, the mixture was pulverized to obtain a resin composition. The evaluation method is as follows. The results are summarized in Table 2.
[0047]
[Measurement of softening point]
The softening point of the intermediate reaction product of the synthesized component (A) is determined by spraying the pulverized component (A) on a copper rod having a temperature gradient from room temperature to 250 ° C., and using a brush after 10 seconds. The softening point was defined as the boundary temperature at which peeling was possible. At this time, those having a softening point that was not measurable at less than 50 ° C. were indicated as x.
[0048]
[Measurement of light transmittance]
The resin composition tablet was transfer molded under the conditions of a mold temperature of 150 ° C., an injection pressure of 6.86 MPa, and a curing time of 90 seconds to obtain a molded product of 30 × 10 × 1 mm. The molded product was measured for light transmittance at a wavelength of 400 nm and a thickness of 1 mm using a spectrophotometer equipped with an integrating sphere (Self-recorded spectrophotometer UV-3100 manufactured by Shimadzu Corporation).
[0049]
[Evaluation of fluidity]
The resin composition before molding was molded and filled using a mold for spiral flow measurement in accordance with EMMI-I-66 at a molding temperature of 175 ° C., an injection pressure of 6.86 MPa, and a curing time of 5 minutes. When the length was 60 cm or more, the fluidity ◯ was obtained.
[0050]
[Measurement of glass transition temperature]
The above resin composition tablet was transfer molded under the conditions of a mold temperature of 150 ° C., an injection pressure of 6.86 MPa and a curing time of 90 seconds, and this molded product was post-cured in a hot air oven at a temperature of 150 ° C. for 2 hours. Using a thermal dilatometer (TMA120 manufactured by Seiko Electronics Co., Ltd.), the temperature was increased at a rate of temperature increase of 5 ° C./min, and the temperature at which the elongation rate of the molded product changed rapidly was measured as the glass transition point.
[0051]
[Evaluation of releasability]
The above resin composition tablet is cleaned with a melamine resin cleaning material for a surface mounting package (12-pin SOP, 4 × 5 mm, thickness 1.2 mm, chip size 1.5 mm × 2.0 mm, lead frame 42 alloy) (Manufactured) Using a mold, transfer molding was performed at a mold temperature of 150 ° C., an injection pressure of 6.86 MPa, and a curing time of 90 seconds. In the evaluation, the case where the package was released from the mold by the eject pin was indicated as “◯”, and the case where the package was deformed or cracked was indicated as “X”.
[0052]
[Evaluation of solder resistance]
The above resin composition tablet is cleaned with a melamine resin cleaning material for a surface mounting package (12-pin SOP, 4 × 5 mm, thickness 1.2 mm, chip size 1.5 mm × 2.0 mm, lead frame 42 alloy) (Manufactured) Using a mold, transfer molding was performed at a mold temperature of 150 ° C., an injection pressure of 6.86 MPa, a curing time of 90 seconds, and post-cured in a hot air oven at a temperature of 150 ° C. for 2 hours. The obtained optical semiconductor package was allowed to stand for 168 hours in an environment of a temperature of 85 ° C. and a relative humidity of 60%, and then an IR reflow treatment at 240 ° C. was performed. The treated package was observed with a microscope and an ultrasonic flaw detector to confirm the presence or absence of cracks and separation between the chip and the resin.
[0053]
[Table 1]
[0054]
In Table 1, Note 1: Oily Shell Epoxy Bisphenol A type epoxy resin (epoxy equivalent 475), Note 2: Mitsui Chemicals Bisphenol type epoxy resin (epoxy equivalent 500, epoxy resin represented by the general formula (2) , C (CH Three ) 2 Is 70%, CH 2 30%, n = 2), Note 3: Mitsui Chemicals bisphenol type epoxy resin (epoxy equivalent 980, epoxy resin represented by general formula (2), C (CH Three ) 2 Is 70%, CH 2 30%, n = 4), Note 4: Triglycidyl isocyanurate manufactured by Nissan Chemical Co., Ltd. (epoxy equivalent 100), Note 5: Mixture of hexahydrophthalic anhydride and methylhexahydrophthalic anhydride manufactured by Shin Nippon Rika Co., Ltd. Note 6: Nippon Hydro Chemical's hexahydrophthalic anhydride (freezing point 37 ° C), Note 7: San Apro diazabicycloundecene and octyl acid salt, Note 8: Shikoku Kasei Imidazole, Note 9: Hokuko Chemical tetraphenylphosphonium bromide, Note 10: Hokuko Chemical Triphenylphosphine, Note 11: SiO 2 , CaO, and Al 2 O Three Spherical glass having an average particle size of 25 μm and adjusted to the refractive index difference shown in Table 1 Note 12: SiO 2 , CaO, and Al 2 O Three Spherical glass having an average particle size of 40 μm and adjusted to the refractive index difference shown in Table 1 Note 13: SiO 2 , CaO, and Al 2 O Three Spherical glass having an average particle size of 25 μm and adjusted to the refractive index difference of Table 1. Note 14: Flat talc with an average particle size of 20 μm Note 15: A release agent represented by the general formula (1) Compound A (wherein k = 48, m = 2, n = 21, R 1 = H, R 2 = CH Three Note 16: Compound B which is a release agent represented by the general formula (1) (wherein k = 54, m = 4, n = 18, R 1 = H, R 2 = CH Three CH 2 CH 2 Note 17: Phosphorous antioxidant manufactured by Sumitomo Chemical, Note 18: Phenolic antioxidant manufactured by Sumitomo Chemical.
[0055]
[Table 2]
[0056]
In Table 1, Note 1: Oily Shell Epoxy Bisphenol A Type Epoxy Resin (Epoxy Equivalent 475), Note 2: Mitsui Chemicals Bisphenol F Type Epoxy Resin (Epoxy Equivalent 950), Note 3: Mitsui Chemicals Bisphenol Type Epoxy Resin (Epoxy equivalent 500, epoxy resin represented by general formula (2), C (CH Three ) 2 Is 70%, CH 2 Is 30%, n = 2), Note 4: Mitsui Chemicals bisphenol type epoxy resin (epoxy equivalent 980, epoxy resin represented by the general formula (2), C (CH Three ) 2 Is 70%, CH 2 30%, n = 4), Note 5: Triglycidyl isocyanurate (Epoxy equivalent 100) manufactured by Nissan Chemical, Note 6: Trifunctional epoxy resin (Epoxy equivalent 210) manufactured by Mitsui Chemicals, Note 7: Hexahydro manufactured by Shin Nippon Rika Mixture of phthalic anhydride and methylhexahydrophthalic anhydride (freezing point −15 ° C.), Note 8: Hexahydrophthalic anhydride (freezing point 37 ° C.) manufactured by Nippon Nippon Chemical Co., Ltd. Note 10: salt of diazabicycloundecene and octylic acid manufactured by San Apro, Note 11: imidazoles manufactured by Shikoku Chemicals, Note 12: tetraphenylphosphonium bromide manufactured by Hokuko Chemical, 13: SiO 2 , CaO, and Al 2 O Three Spherical glass having an average particle size of 25 μm and adjusted to the refractive index difference of Table 2, Note 14: SiO 2 , CaO, and Al 2 O Three Spherical glass having an average particle size of 40 μm and adjusted to the difference in refractive index shown in Table 2. Note 15: Spherical glass having an average particle size of 15 μm and an adjusted refractive index Note 16: SiO 2 , CaO, and Al 2 O Three Spherical glass having an average particle size of 5 μm and adjusted to the refractive index difference of Table 2. Note 17: Compound A which is a release agent represented by the general formula (1) (wherein k = 48, m = 2 , N = 21, R 1 = H, R 2 = CH Three Note 18: Compound B which is a release agent represented by the general formula (1) (wherein k = 54, m = 4, n = 18, R 1 = H, R 2 = CH Three CH 2 CH 2 ), Note 19: Release agent manufactured by Clariant Japan, Note 20: Phenolic antioxidant manufactured by Sumitomo Chemical, Note 21: Phosphorous antioxidant manufactured by Sumitomo Chemical, Note 22: Gelation progresses in melt mixing of intermediate reaction did.
[0057]
As is apparent from the results in the table, it can be seen that the resin composition of the present invention is excellent in solder resistance and releasability and also has a good light transmittance of 80% or more.
[0058]
【The invention's effect】
The epoxy resin composition for optical semiconductor sealing excellent in the present invention, transparency, solder resistance and releasability can be obtained, and an optical device having high reliability can be provided using this.
Claims (9)
(a)トリグリシジルイソシアヌレート、及びビスフェノール型エポキシ樹脂からなり、成分(a)全体の平均エポキシ当量が200以上400以下のエポキシ樹脂。
(b)凝固点50℃以下の酸無水物硬化剤。In an epoxy resin composition for encapsulating an optical semiconductor comprising an intermediate reaction product (A) of an epoxy resin and a curing agent, a curing accelerator (B), an inorganic filler (C), and a release agent (D) as essential components. The reaction product (A) comprises the following component (a) and component (b), and is obtained by melt mixing at a temperature of 80 ° C. or higher and 150 ° C. or lower in the absence of a solvent. An epoxy resin composition for optical semiconductor encapsulation.
(A) An epoxy resin comprising triglycidyl isocyanurate and a bisphenol-type epoxy resin, wherein the average epoxy equivalent of the whole component (a) is 200 or more and 400 or less.
(B) An acid anhydride curing agent having a freezing point of 50 ° C or lower.
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CN112592460A (en) * | 2019-10-02 | 2021-04-02 | 日东电工株式会社 | Resin molded article for sealing optical semiconductor and method for producing same |
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