【０００１】
【発明の属する技術分野】
本発明は、高周波素子を収容する高周波装置に用いられる電波吸収蓋部材および高周波装置に関し、特にマイクロ波帯やミリ波帯の高周波（電磁波）の吸収特性に優れる電波吸収蓋部材および高周波装置に関する。
【０００２】
【従来の技術】
従来の電波吸収蓋部材の断面図を図４に、従来の高周波装置の断面図を図５に示す。これらの図に示すように、１１は電波吸収蓋部材、１２は金属蓋体、１３は電波吸収層、１４は高周波装置、１５は基体、１６は高周波素子、Ｓは接合材である。
【０００３】
近年、電子機器はますます高速化、高密度化、デジタル化が進み、小型、多機能化も加速傾向にある。電子機器の小型多機能化の要求から、特にマイクロ波帯やミリ波帯で使用される高周波素子１６は、配線基板への部品実装密度が非常に高まり、高周波素子１６のピン間、周辺回路、他の高周波素子等に電磁波障害が発生するといった問題がある。この原因は、高周波素子１６としての多数の半導体素子にあり、個々の半導体素子で発生する微弱な電磁波が他の半導体素子にとっては妨害波（放射ノイズ）となり、配線の線間結合やピン間の結合の増大、放射ノイズによる電磁干渉に起因する性能劣化や異常共振等が誘起され、電磁波障害が発生するためである。
【０００４】
従来、このようないわゆる電磁波障害に対しては、回路にノイズフィルタを挿入したり、高周波素子１６の周囲を金属板や金属メッキ層等の導電層をコーティングしたケースで囲んで成る電磁シールディングを施したり、または電波吸収シートから成る電波吸収層１３を回路基板表面、高周波装置１４表面に熱硬化性樹脂、低融点ガラスあるいは半田等の低融点ロウ材などの接合材Ｓで貼り付けて、電磁波障害を抑制してきた（下記の特許文献１参照）。
【０００５】
また、針状または扁平状であって表面に酸化被膜を有する軟磁性粉末と有機結合剤等とを含む複合磁性体で構成されているＥＭＩ（Ｅｌｅｃｔｒｏ Ｍａｇｎｅｔｉｃ Ｉｎｔｅｒｆｅｒｅｎｃｅ：電磁的障害）対策部品を、高周波装置の上面に配置して電磁波障害を抑制することが提案されている（下記の特許文献２参照）。
【０００６】
さらに、ガラスまたはセラミックスをマトリックスとし、Ｔｉ，Ｖ，Ｃｒ，Ｚｒ，Ｎｂ，Ｍｏ，Ｈｆ，Ｔａ，Ｗ，Ｆｅ，Ｎｉ，Ｃｏ，Ｃｕ，Ａｌ，Ｍｇ，Ｚｎおよびそれらの合金、ステンレス鋼、パーマロイおよび超耐熱性合金から選ばれる少なくとも一種である金属粒子を複合相とする複合材料から成る電波吸収材料が開示されている（下記の特許文献３参照）。
【０００７】
【特許文献１】
特開２００２−２８９７２０号公報
【０００８】
【特許文献２】
特開平１０−６４７１４号公報
【０００９】
【特許文献３】
特開平９−２５５４０８号公報
【００１０】
【発明が解決しようとする課題】
しかしながら、特許文献１に記載されている、電波吸収シートから成る電波吸収層１３を高周波装置１４表面に貼り付けるといった手段は、高周波装置１４全体の厚さが厚くなり、機器の小型化には不利である。また、電波吸収層１３がゴムやエポキシ樹脂等に磁性材料を混合させたものであり、また金属蓋体１２に電波吸収層１３を樹脂接着剤で貼り付けているため、電波吸収層１３や樹脂接着剤の耐熱性が非常に小さいことから、高周波素子１６の熱等によって電波吸収層１３に容易に反りが起こり、電波吸収層１３が金属蓋体１２から剥離するといった問題点があった。
【００１１】
また、特許文献２に記載されている、ＥＭＩ対策部品として用いられる扁平状、針状の軟磁性体粉末を用いた複合磁性体も有機結合材を含むため、耐熱性、寸法安定性に劣るといった問題があった。従って、この複合磁性体を高周波装置１４の構成部品として用いると、熱硬化性樹脂、低融点ろう材、低融点ガラス等による接合ができないといった問題点があった。
【００１２】
さらに、特許文献３に記載されている、ガラスまたはセラミックスをマトリックスとし、Ｔｉ等の金属粒子を複合相とする複合材料から成る電波吸収材料は、それ自体は耐熱性および機械的特性に優れたものである。しかしながら、特許文献３には、このような電波吸収材料を他の金属蓋体等に接合性良く被着させて、電波吸収蓋部材やパッケージ、電子装置、半導体装置等に好適に適用する点については一切開示されていない。
【００１３】
従って、本発明は上記従来の問題点を鑑みて完成されたものであり、その目的は、電波吸収蓋部材に電波吸収層を直接強固に被着できるようにして、電波吸収層が熱によって剥れることのない低背化された高周波装置を作製できる電波吸収蓋部材およびこれを用いた高周波装置を提供することにある。
【００１４】
【課題を解決するための手段】
本発明の電波吸収蓋部材は、金属蓋体の一主面に、Ｔｉ，ＺｒおよびＨｆのうちの１種以上を含有したＡｇ−Ｃｕ合金を主成分とする金属層と、該金属層の酸化層と、Ｎｉ−Ｆｅ合金を主成分とする磁性材を５１乃至９０質量％および軟化点が２５０乃至５００℃のガラスを１０乃至４９質量％含有するとともに、厚みが２００乃至５００μｍである電波吸収層とが順次積層されていることを特徴とする。
【００１５】
本発明の電波吸収蓋部材は、電波吸収層が、Ｎｉ−Ｆｅ合金を主成分とする磁性材を５１乃至９０質量％および軟化点が２５０乃至５００℃のガラスを１０乃至４９質量％含有していることから、耐熱性に優れたものとなり、高周波素子の熱や高周波装置を外部電気回路基板等に半田等で接合する際の熱によって電波吸収層が金属蓋体から剥離することがなくなる。また、電波吸収層の厚みが２００乃至５００μｍであることから、電波吸収蓋部材の大幅な薄型化が可能となり、高周波装置の大幅な低背化につながる。
【００１６】
また、電波吸収層は、Ｔｉ，ＺｒおよびＨｆのうちの１種以上を含有したＡｇ−Ｃｕ合金を主成分とする金属層と金属層の酸化層とを介して、金属蓋体の一主面に積層されていることから、金属層に含有されるＴｉ，Ｚｒ，Ｈｆの活性金属が金属蓋体の金属粒界に拡散して金属蓋体と金属層とを強固に接合するとともに、金属層の酸化層の酸化物が電波吸収層中のガラスの酸化物成分と反応して金属層と電波吸収層とを強固に接合する。その結果、金属蓋体を基体にシーム溶接やロウ付けする際に２３０〜２４０℃の熱履歴が加わったとしても、電波吸収層が熱によって剥離することがなくなる。
【００１７】
また、電波吸収層が電波吸収して電磁波のエネルギーを熱に変換した際に、その熱を互いに強固に接合された電波吸収層、金属層および金属蓋体を介して外部に効率良く放熱させることができる。
【００１８】
本発明の高周波装置は、上面に形成された凹部の底面に高周波素子が載置される載置部を有する基体と、前記載置部に載置固定された高周波素子と、前記基体の上面の前記凹部の周囲に前記一主面が前記高周波素子に対向するように取着された請求項１記載の電波吸収蓋部材とを具備していることを特徴とする。
【００１９】
本発明の高周波装置は、上記の構成により、電波吸収層が熱によって剥れることのない低背化されたものとなるとともに、内部で電磁波の共振が発生するのを抑えることができる。その結果、マイクロ波帯やミリ波帯の高周波帯域で良好にＥＭＩ対策の施された高周波装置を作製することができる。
【００２０】
【発明の実施の形態】
本発明の電波吸収蓋部材および高周波装置を以下に詳細に説明する。 図１は、本発明の電波吸収蓋部材の実施の形態の一例を示す断面図、図２はその要部拡大断面図である。これらの図において、１は電波吸収蓋部材、２は金属蓋体、３は電波吸収体、３ａは金属層、３ｂは電波吸収層、３ｃは酸化層であり、主にこれらで本発明の電波吸収蓋部材１が構成されている。
【００２１】
本発明の電波吸収蓋部材１は、金属蓋体２の一主面に、活性金属であるＴｉ，ＺｒおよびＨｆのうちの１種以上を含有したＡｇ−Ｃｕ合金を主成分とする金属層３ａと、金属層３ａの酸化層３ｃと、Ｎｉ−Ｆｅ合金を主成分とする磁性材を５１乃至９０質量％および軟化点が２５０乃至５００℃のガラスを１０乃至４９質量％含有するとともに、厚みが２００乃至５００μｍである電波吸収層３ｂとが順次積層されている。
【００２２】
本発明における金属蓋体２は、例えば４２アロイ（Ｆｅ−Ｎｉ合金）、Ｆｅ−Ｎｉ−Ｃｏ合金等の金属や合金から成るが好ましく、これらは電磁波シールド性や電波吸収層３ｂとの熱整合が良いという利点がある。そして、金属蓋体２は、Ｆｅ−Ｎｉ−Ｃｏ合金等の母材を打抜き金型で打抜くことによって、四角形状等の所定の形状に製作される。
【００２３】
なお、金属蓋体２の電波吸収層３ｂが被着されていない領域には、酸化腐食の防止とロウ付け性の向上のため、Ｎｉめっき層やＡｕめっき層等のめっき層が形成されている。
【００２４】
本発明の電波吸収層３ｂは、Ｎｉ−Ｆｅ合金を主成分とする磁性材を５１乃至９０質量％および軟化点が２５０乃至５００℃のガラスを１０乃至４９質量％含有するとともに、厚みが２００乃至５００μｍである。これにより、従来の２００℃程度の耐熱性しかないゴムや樹脂に磁性材を混入させたものと異なり耐熱性に優れ、接着剤を用いて貼り付けることもないので電波吸収層３ｂが金属蓋体２から剥離することもない。したがって、電波吸収層３ｂは、耐熱性に優れたものとなり、高周波素子の熱や高周波装置を外部電気回路基板等に半田等で接合する際の熱によって電波吸収層３ｂが金属蓋体２から剥離することがなくなる。また、電波吸収層３ｂの厚みが２００乃至５００μｍであることから、電波吸収蓋部材１の大幅な薄型化が可能となり、高周波装置の大幅な低背化につながる。
【００２５】
Ｎｉ−Ｆｅ合金を主成分とする磁性材としては、例えば３６−パーマロイ（Ｆｅを３６質量％含有するＦｅ−Ｎｉ合金）、４５−パーマロイ、７８−パーマロイ、スーパーマロイ（急冷熱処理Ｍｏ含有Ｆｅ−Ｎｉ合金）、Ｃｒ−パーマロイ（Ｃｒ含有Ｆｅ−Ｎｉ合金）、Ｍｏ−パーマロイ（Ｍｏ含有Ｆｅ−Ｎｉ合金）などが用いられる。
【００２６】
また、軟化点が２５０乃至５００℃のガラスとしては、高周波素子６（図３）への熱的影響を小さくすること、およびガラス内の残留応力を小さくする観点から、できる限り低温で溶融可能なものが好ましく、例えば、５０〜８０質量％の酸化鉛と１５〜２０質量％のフッ化鉛とを主成分として含むガラスが、軟化点が約３００℃であり耐熱性に優れたものであることから、好適に用いられる。
【００２７】
磁性材が９０質量％を超えると、粉体とされた磁性材のガラスへの分散性が悪くなり、電波吸収層３ｂの強度が著しく低下し、電波吸収層３ｂの剥離が発生し易くなる。一方、５１質量％未満だと、高周波装置と成した際に高周波装置内部で電磁波の共振を抑えることが不十分となり、また電波吸収層３ｂに反りが発生して剥離し易くなる。
【００２８】
ガラスが１０質量％未満だと、磁性材の分散性が悪くなり、電波吸収層３ｂの強度が著しく低下し、電波吸収層３ｂの剥離が発生し易くなる。一方、４９質量％を超えると、高周波装置と成した際に高周波装置内部で電磁波の共振を抑えることが不十分となり、また電波吸収層３ｂに反りが発生して剥離し易くなる。
【００２９】
ガラスの軟化点が２５０℃未満だと、電波吸収蓋部材１を高周波素子６を収容した基体にシーム溶接やロウ付けする際に、電波吸収層３ｂが溶融し易くなる。一方、ガラスの軟化点が５００℃を超えると、磁性材が凝集してしまい、その結果電波吸収層３ｂの強度が著しく低下して電波吸収層３ｂが剥離し易くなる。
【００３０】
電波吸収層３ｂの厚みが２００μｍ未満では、電波吸収特性が不十分となる傾向があり、厚みが５００μｍを超えると、電波吸収蓋部材１全体が厚くなり薄型化が困難になる。また、金属蓋体２と電波吸収層３ｂとの熱膨張差によって金属蓋体２に反りが発生して、電波吸収層３ｂが剥離し易くなる。
【００３１】
本発明の電波吸収蓋部材１は、電波吸収層３ｂは、活性金属であるＴｉ，ＺｒおよびＨｆのうちの１種以上を含有したＡｇ−Ｃｕ合金を主成分とする金属層３ａ、金属層３ａの酸化層３ｃを介して金属蓋体２の一主面に積層されていることから、金属層３ａに含有されるＴｉ，Ｚｒ，Ｈｆの活性金属が金属蓋体２の金属粒界に拡散して金属蓋体２と金属層３ａとを強固に接合するとともに、金属層３ａの酸化層３ｃの酸化物が電波吸収層３ｂ中のガラスの酸化物成分と反応して金属層３ａと電波吸収層３ｂとを強固に接合する。その結果、金属蓋体２を基体にシーム溶接やロウ付けする際に２３０〜２４０℃の熱履歴が加わったとしても、電波吸収層３ｂが熱によって剥離することがなくなる。
【００３２】
また、電波吸収層３ｂが電波吸収して電磁波のエネルギーを熱に変換した際に、その熱を互いに強固に接合された電波吸収層３ｂ、金属層３ａおよび金属蓋体２を介して外部に効率良く放熱させることができる。
【００３３】
このような電波吸収層３ｂ、金属層３ａは以下の方法により金属蓋体２に被着される。まず、Ａｇ−Ｃｕ合金粉末とＴｉ，ＺｒおよびＨｆのうちの１種以上の活性金属粉末、アクリル樹脂等の有機バインダ、トルエン，アセトン等の溶剤を混合して得た活性金属ペーストを、金属蓋体２に厚みが約７０μｍとなるようにスクリーン印刷し、還元雰囲気中、約８００℃の温度で熱処理して金属蓋体２に密着させる方法により金属層３ａを被着する。次に、Ｎｉ−Ｆｅ合金を主成分とする磁性材と軟化点が２５０乃至５００℃のガラスに有機溶剤、溶媒を添加混合して得た磁性材ペーストを、金属蓋体２に厚みが２００乃至５００μｍとなるようにスクリーン印刷して、電波吸収層３ｂとなる磁性材ペースト層を形成し、大気中、約３５０℃で焼成させることで、電波吸収層３ｂのガラス成分と金属層３ａの活性金属が酸化して形成された酸化層３ｃが同時に形成される。これにより、金属層３ａに電波吸収層３ｂが酸化層３ｃを介して強固に被着される。
【００３４】
金属層３ａの厚みは５０〜１００μｍが好ましい。５０μｍ未満では、活性金属が酸化して形成される酸化層３ｃが十分な厚さとならない傾向にある。１００μｍを超えると、還元雰囲気中で熱処理した際、金属層３ａ内で不均一な部分を生じることがある。
【００３５】
酸化層３ｃの厚みは１〜３μｍが好ましい。１μｍ未満では、金属層３ａと電波吸収層３ｂとの接合強度が弱くなり、熱により電波吸収層３ｂが金属層３ａから剥れ易くなる。３μｍを超えると、過剰酸化となり、酸化層３ｃと電波吸収層３ｂとの接合界面において気泡をまき込み易くなるため、接合面積が減少して電波吸収層３ｂが金属層３ａから剥れ易くなる。
【００３６】
次に、本発明の電波吸収蓋部材１を用いた高周波装置４について、図３に基づいて詳細に説明する。同図は、本発明の高周波装置４の実施の形態の一例を示し、（ａ）は金属から成る基体５ａを用いた高周波装置の断面図、（ｂ）は絶縁体から成る基体５ｂを用いた高周波装置の断面図である。これらの図に示すように、２は金属蓋体、３は電波吸収体、４は高周波装置、５ａ，５ｂは基体、６は高周波素子、７はメタライズ層、８は封止材である。
【００３７】
本発明の高周波装置は、上面に形成された凹部の底面に高周波素子６が載置される載置部を有する基体５ａ，５ｂと、載置部に載置固定された高周波素子６と、基体５ａ，５ｂの上面の凹部の周囲に一主面が高周波素子６に対向するように取着された本発明の電波吸収蓋部材１とを具備している。
【００３８】
本発明における基体５ａ，５ｂは、上面の中央部に高周波素子６を収容するための凹部が設けられており、この凹部の底面に高周波素子６が低融点ガラス、樹脂接着剤、ロウ材等の接着剤を介して接着固定される。また、基体５ａ，５ｂの凹部の側面や底面から外面にかけて、複数のメタライズ配線層や複数のリード端子（図示せず）が、基体５ａ，５ｂの表面をつたって、または基体５ａ，５ｂを貫通するとともにガラスで気密封止されて設けられている。このメタライズ配線層やリード端子の凹部の底面に位置する部位は、高周波素子６の各電極がボンディングワイヤ等（図示せず）を介して電気的に接続され、基体５ａ，５ｂの外面に導出された部位は、外部電気回路基板の配線導体（図示せず）にボンディングワイヤ等の導電性接続部材を介して電気的に接続される。
【００３９】
金属からなる基体５ａは、４２アロイやＦｅ−Ｎｉ−Ｃｏ合金等のから成るのが好ましく、それらの金属の母材を打抜き金型で打ち抜いたり、切削などの機械加工を施すことによって、凹部を有する所定の形状のものとして製作される。なお、基体５ａの表面に、耐食性に優れ、Ａｕ−Ｓｎロウ材や半田等のロウ材との濡れ性の良好な金等の金属をめっき法等により、０．１〜１μｍの厚さに被着させておくのが好ましい。
【００４０】
そして、基体５ａの上面の凹部の周囲と電波吸収蓋部材１の下面の外周部とを、シーム溶接などの抵抗溶接で接合する。または、電波吸収蓋部材１の下面の外周部に被着形成されたロウ材から成る封止材８を介して接合したり、さらにはシーム溶接とロウ付けとを組み合わせても構わない。
【００４１】
例えば、基体５ａと電波吸収蓋部材１とをシーム溶接する場合、基体５ａの上面の凹部の周囲に電波吸収蓋部材１を載置し、窒素雰囲気の下で、電波吸収蓋部材１の上面の外周部に通電されたローラー電極を当てて、電波吸収蓋部材１を基体５ａ側にローラー電極で一定圧力で押圧しつつローラー電極を周回させて、０．５〜１０分間圧着させることにより、気密に接合する。
【００４２】
一方、絶縁体からなる基体５ｂの場合、基体５ｂは、酸化アルミニウム質焼結体、ムライト質焼結体、窒化アルミニウム質焼結体、炭化珪素質焼結体、ガラスセラミックス等を主成分とする焼結体（セラミックス）等の無機材料、または樹脂から成る。例えば、基体５ｂが酸化アルミニウム質焼結体から成る場合、先ずアルミナ（Ａｌ２Ｏ３）やシリカ（ＳｉＯ２）、カルシア（ＣａＯ）、マグネシア（ＭｇＯ）等の原料粉末に適当な有機溶剤、溶媒を添加混合して泥漿状と成し、これを従来周知のドクターブレード法やカレンダーロール法等によりシート状に成形してセラミックグリーンシート（以下、グリーンシートともいう）を得る。その後、グリーンシートを所定形状に打ち抜き加工するとともに複数枚積層し、約１６００℃の温度で焼成することにより製作される。
【００４３】
そして、基体５ｂの場合、その上面の凹部の周囲には、電波吸収蓋部材１に接合するための枠状のメタライズ層７が被着される。このメタライズ層７や凹部の側面や底面に形成されたメタライズ配線層は、タングステンやモリブデン、マンガン等の高融点金属から成り、これらの粉末に有機溶剤、溶媒を添加混合した金属ペーストをそれぞれグリーンシートの所定位置に従来周知のスクリーン印刷法により所定パターンに被着形成させておき、グリーンシートと同時に焼成することにより形成される。なお、メタライズ層７の表面には、耐食性に優れ、Ａｕ−Ｓｎロウ材や半田等のロウ材との濡れ性の良好な金等の金属を、めっき法等により０．１〜１μｍの厚さに被着させておくのがよく、フラックスを用いることなく金属蓋体２と接合することが可能となる。
【００４４】
なお、半田等に含まれるフラックスは、高周波装置４内部に飛散すると、高周波素子６の電極を腐蝕し断線を発生させる原因となることから、メタライズ層７の表面には、金等の金属をめっき法等により被着させておき、メタライズ層７と電波吸収蓋部材１との接合をフラックスを用いずに行なうことが好ましい。そして、メタライズ層７に電波吸収蓋部材１が、その下面の外周部に被着形成された封止材８を介して接合される。
基体５ｂと電波吸収蓋部材１との接合は、基体５ｂ上面の凹部の周囲に形成されたメタライズ層７と電波吸収蓋部材１との間に封止材８が挟まるように電波吸収蓋部材１を基体５ｂ上面に載置し、電波吸収蓋部材１を基体５ｂ側に一定圧力で押圧しながらピーク温度が約２８０〜３００℃で窒素雰囲気のシール炉に０．５〜１０分間入れて、封止材８を溶融させることにより、封止材８が流れ出しフィレットを形成して気密に接合されることとなる。
【００４５】
かくして、本発明の電波吸収蓋部材１および高周波装置４は、基体５ａ，５ｂの凹部底面の載置部に半導体素子等の高周波素子６を樹脂接着剤等を介して載置固定し、高周波素子６の各電極をボンディングワイヤ等を介してリード端子やメタライズ配線層に接続し、しかる後、基体５ａの上面の凹部の周囲に電波吸収蓋部材１をシーム溶接で接合したり、あるいは電波吸収蓋部材１の下面の外周部に被着された封止材８を加熱溶融させ、メタライズ層７に接合することにより、基体５と電波吸収蓋部材１とを封止することによって、製品としての高周波装置４となる。
【００４６】
なお、本発明は上記実施の形態に限定されず、本発明の要旨を逸脱しない範囲内で種々の変更を施すことは何等差し支えない。例えば、上述の実施の形態では高周波素子６としてＩＣ，ＬＳＩ等の半導体素子を用いた例について説明したが、高周波素子６として圧電振動子や弾性表面波素子等の電子部品を用いることもできる。また、電波吸収蓋部材１を平板状とし、基体５ａ，５ｂを上面の中央部に凹部を有する形状としたが、基体５ａ，５ｂを平板状とし、基体５ａ，５ｂの上面の外周部に枠体をロウ材や樹脂接着剤で取着した高周波装置であってもよい。また、基体５ａ，５ｂを平板状とし、電波吸収蓋部材１を、基体５ａ，５ｂと対向する面に凹部を有する形状としてもよい。
【００４７】
【実施例】
本発明の電波吸収蓋部材の実施例を以下に説明する。
【００４８】
図１の電波吸収蓋部材１を以下のようにして製作した。まず、寸法が縦２１．１ｍｍ×横１９．６ｍｍ×厚み０．３ｍｍの四角形の板状で、Ｆｅ−Ｎｉ−Ｃｏ合金から成る金属蓋体２を準備し、その電波吸収層３ｂが形成される部位以外の部位の全面に厚さ２．０μｍのＮｉめっき層と厚さ０．５μｍのＡｕめっき層を被着た。
【００４９】
まず、金属蓋体２の一主面の電波吸収層３ｂが形成される部位に、活性金属としてＴｉを３質量％（Ａｇ−Ｃｕ合金を１００質量％とする）含有したＡｇ７２質量％−Ｃｕ２８質量％のＡｇ−Ｃｕ共晶からなる金属層３ａを、スクリーン印刷で厚さ７０μｍに形成し、還元雰囲気中、８００〜８５０℃の温度で熱処理して金属蓋体２に被着した。
【００５０】
電波吸収層３ｂは、パーマロイ（Ｆｅ４２質量％、Ｎｉ５８質量％のＦｅ−Ｎｉ合金）から成る磁性材と、酸化鉛−フッ化鉛系ガラス（ＰｂＯを５６質量％、ＰｂＦを１９質量％主成分として含有する軟化点２８０℃のガラス）を、種々の割合（下記表１参照）で混合し、これに多価アルコールエステル系有機溶剤（「ＣＫ−１７２」互応化学工業株式会社製）を少量添加し、スクリーン印刷法によって、縦１９．１ｍｍ×横１７．６ｍｍの大きさ、および焼成後に種々の厚み（下記表１参照）となるようにして、金属蓋体２の一主面の酸化層３ｃ上に塗布した。これを、炉中で温度３００℃〜３５０℃で焼成して、厚さ１．５μｍの酸化層３ｃを形成し、電波吸収層３ｂを金属蓋体２に被着形成した。
【００５１】
得られた各種試料について、電波吸収蓋部材１の反り、金属蓋体２と電波吸収層３ｂとの接着強度、電磁波減衰効果を測定した。
【００５２】
なお、電波吸収蓋部材１の反りについては、通炉前と通炉後を比較して、通炉後に反りが０．１５ｍｍ未満であったものを○、０．１５ｍｍ以上であったものを×とした。
【００５３】
接着強度の測定は、金属蓋体２の一主面に電波吸収層３ｂが被着されている状態で、４９Ｎ（ニュートン）の荷重で３点曲げ試験を行ない、プッシュプルゲージが１．０ｍｍまで下降した際に電波吸収層３ｂが剥がれなかったものを○、剥がれたのものを×とした。
【００５４】
電磁波減衰効果の測定は、図３（ａ）に示すように、基体５ａの凹部の底面に高周波素子６をＡｕ−Ｓｎロウ材で接合し、電波吸収蓋部材１を基体５ａにシーム溶接した高周波装置４の各試料を作製して、キャビティ共振抑制効果の評価を行った。すなわち、ネットワークアナライザー（アジレントテクノロジー社製「ＨＰ８５１０Ｃ」）を用いて、Ｓパラメータ（高周波入出力の比）の値からキャビティ共振抑制効果を測定した。
【００５５】
具体的には、高周波装置４内にマイクロストリップスルーラインが形成された配線基板を配置し、基体５ａの凹部の側面に取り付けられた高周波入出力端子とマイクロストリップスルーラインをＡｕ−Ｓｎ合金ロウ等のロウ材で電気的に接続して、高周波入出力端子とネットワークアナライザーを接続した。基体５ａの上面の凹部の周囲に電波吸収蓋部材１を配置することにより、高周波装置４内部は空洞共振器となり、試料サイズから決まる共振周波数とネットワークアナライザーから入射される高周波信号の周波数が一致したとき、マイクロストリップスルーラインからの放射を共振させてＳパラメータを測定した。このとき、電波吸収層３ｂがない状態を基準とし、キャビティ共振抑制効果はその基準に対して共振量が２０ｄＢ以下であれば○、２０ｄＢ以上であれば×とした。評価結果を表１に示す。
【００５６】
【表１】
表１より、パーマロイが９０質量％以上のもの（Ｎｏ．１）は、電波吸収層３ｂにおける磁性材の分散性が悪いために接着強度が弱くなり、電波吸収層３ｂが金属蓋体２から剥離して接着不良が発生した。また、パーマロイが５０質量％未満のもの（Ｎｏ．７，８）は、通炉後にキャビティ共振抑制効果が劣化した。これは、キャビティ共振抑制効果が電波吸収層３ｂにおける磁性材の粒子間距離に依存するためであり、磁性材の含有量が少ないと通炉後にガラス成分が固化して均一な粒子間距離が得られないからと考えられる。
【００５７】
これに対し、パーマロイの含有量が５１乃至９０質量％でガラスの含有量が１０乃至４９質量％である本発明のもの（Ｎｏ．２〜６）は、いずれも反りが小さく、接着強度、キャビティ共振抑制効果も優れていた。
【００５８】
また、ガラスの軟化点が２５０℃未満のもの（Ｎｏ．９）は、電波吸収蓋部材１を金属製の基体５ａにシーム溶接した際にガラスが溶融軟化したため、製品として使用できなくなった。また、ガラスの軟化点が５００℃を超えるもの（Ｎｏ．１４）は、５００℃を超える高温下で通炉するので電波吸収蓋部材１の反りが大きくなり、製品として使用できなくなった。
【００５９】
これに対して、ガラスの軟化点が２５０乃至５００℃である本発明のもの（Ｎｏ．１０〜１３）は、いずれも反りが小さく、接着強度、キャビティ共振抑制効果も優れていた。
【００６０】
次に、電波吸収層３ｂの厚みが２００μｍ未満のもの（Ｎｏ．１５）は、キャビティ共振抑制効果が悪く、製品として使用できなくなった。また、電波吸収層３ｂの厚みが５００μｍを超えるもの（Ｎｏ．１９）は、電波吸収蓋部材１全体が薄型化できず、またスクリーン印刷の作業性が悪いので実用的でなかった。
【００６１】
これに対し、電波吸収層３ｂの厚みが２００乃至５００μｍである本発明のもの（Ｎｏ．１６〜１８）は、いずれも反りが小さく、接着強度、キャビティ共振抑制効果も優れていた。
【００６２】
電波吸収層体３として、上記のＮｏ．１７の試料において金属層３ａを有していないものを比較例（Ｎｏ．１７Ａ）とし、Ｎｏ．１７の試料において金属層３ａの種類を変えた試料（Ｎｏ．２０〜２４）を作製した。これらについて、上記と同様に、電波吸収蓋部材１の反り、金属蓋体２と電波吸収層３ｂとの接着強度、キャビティ共振抑制効果を測定し、その結果を表２に示す。
【００６３】
【表２】
【００６４】
表２より、金属層３ａがＴｉ、ＺｒおよびＨｆのうちの１種以上の活性金属を含有したＡｇ−Ｃｕ合金を主成分とするものである試料（Ｎｏ．２０〜２４）は、電波吸収蓋部材１の反りがいずれも小さく、キャビティ共振抑制効果も優れていた。さらに接着強度についても、３点曲げ試験でプッシュプルゲージが１．０ｍｍまで下降した際に全く問題なく、さらに下降させ２．０ｍｍでも金属層３ａおよび電波吸収層３ｂが剥がず、非常に強固に被着されたものとなった。なお、表２で、２．０ｍｍまで下降しても剥がれないものを◎とした。
【００６５】
【発明の効果】
本発明の電波吸収蓋部材は、電波吸収層が、Ｎｉ−Ｆｅ合金を主成分とする磁性材を５１乃至９０質量％および軟化点が２５０乃至５００℃のガラスを１０乃至４９質量％含有していることから、耐熱性に優れたものとなり、高周波素子の熱や高周波装置を外部電気回路基板等に半田等で接合する際の熱によって電波吸収層が金属蓋体から剥離することがなくなる。また、電波吸収層の厚みが２００乃至５００μｍであることから、電波吸収蓋部材の大幅な薄型化が可能となり、高周波装置の大幅な低背化につながる。
【００６６】
また、電波吸収層は、Ｔｉ，ＺｒおよびＨｆのうちの１種以上を含有した金属層と金属層の酸化層とを介して、金属蓋体の一主面に積層されていることから、金属層に含有されるＴｉ，Ｚｒ，Ｈｆの活性金属が金属蓋体の金属粒界に拡散して金属蓋体と金属層とを強固に接合するとともに、金属層の酸化層の酸化物が電波吸収層中のガラスの酸化物成分と反応して金属層と電波吸収層とを強固に接合する。その結果、金属蓋体を基体にシーム溶接やロウ付けする際に２３０〜２４０℃の熱履歴が加わったとしても、電波吸収層が熱によって剥離することがなくなる。
【００６７】
また、電波吸収層が電波吸収して電磁波のエネルギーを熱に変換した際に、その熱を互いに強固に接合された電波吸収層、金属層および金属蓋体を介して外部に効率良く放熱させることができる。
【００６８】
本発明の高周波装置は、上面に形成された凹部の底面に高周波素子が載置される載置部を有する基体と、載置部に載置固定された高周波素子と、基体の上面の凹部の周囲に前記一主面が高周波素子に対向するように取着された本発明の電波吸収蓋部材とを具備していることにより、電波吸収層が熱によって剥れることのない低背化されたものとなるとともに、内部で電磁波の共振が発生するのを抑えることができる。その結果、マイクロ波帯やミリ波帯の高周波帯域で良好にＥＭＩ対策の施された高周波装置を作製することができる。
【図面の簡単な説明】
【図１】本発明の電波吸収蓋部材の実施の形態の一例を示す断面図である。
【図２】図１の電波吸収蓋部材の要部拡大断面図である。
【図３】（ａ），（ｂ）は本発明の高周波装置についてそれぞれ実施の形態の例を示す断面図である。
【図４】従来の電波吸収蓋部材の断面図である。
【図５】従来の高周波装置の断面図である。
【符号の説明】
１：電波吸収蓋部材
２：金属蓋体
３ａ：金属層
３ｂ：電波吸収層
３ｃ：酸化層
４：高周波装置
５ａ，５ｂ：基体
６：高周波素子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radio-wave absorbing cover member and a high-frequency device used for a high-frequency device containing a high-frequency element, and more particularly to a radio-wave absorbing cover member and a high-frequency device having excellent absorption characteristics of a high frequency (electromagnetic wave) in a microwave band or a millimeter band.
[0002]
[Prior art]
FIG. 4 is a cross-sectional view of a conventional radio wave absorbing cover member, and FIG. 5 is a cross-sectional view of a conventional high-frequency device. As shown in these figures, 11 is a radio wave absorbing lid member, 12 is a metal lid, 13 is a radio wave absorbing layer, 14 is a high frequency device, 15 is a base, 16 is a high frequency element, and S is a bonding material.
[0003]
2. Description of the Related Art In recent years, electronic devices have become increasingly faster, denser, and digital, and miniaturization and multifunctionality have been accelerating. Due to the demand for miniaturization and multi-functionality of electronic equipment, the high-frequency element 16 used particularly in the microwave band or the millimeter-wave band has a very high component mounting density on a wiring board, and has a large space between pins of the high-frequency element 16, peripheral circuits, There is a problem that electromagnetic wave interference occurs in other high-frequency elements and the like. This is due to a large number of semiconductor elements as the high-frequency element 16, and weak electromagnetic waves generated in each semiconductor element become interference waves (radiation noise) for other semiconductor elements, resulting in line-to-line coupling between wires and between pins. This is because an increase in coupling, performance degradation due to electromagnetic interference due to radiation noise, abnormal resonance, and the like are induced, and electromagnetic wave interference occurs.
[0004]
Conventionally, for such a so-called electromagnetic interference, an electromagnetic shielding in which a noise filter is inserted into a circuit or a high-frequency element 16 is surrounded by a case coated with a conductive layer such as a metal plate or a metal plating layer is used. Or a radio wave absorbing layer 13 made of a radio wave absorbing sheet is adhered to the surface of the circuit board and the surface of the high-frequency device 14 with a bonding material S such as a thermosetting resin, a low melting point glass or a low melting point brazing material such as solder. Obstacles have been suppressed (see Patent Document 1 below).
[0005]
Further, an EMI (Electro Magnetic Interference) countermeasure component made of a composite magnetic material containing a needle-shaped or flat soft magnetic powder having an oxide film on the surface and an organic binder is used. It has been proposed to arrange on the upper surface of the device to suppress electromagnetic wave interference (see Patent Document 2 below).
[0006]
Further, glass or ceramics are used as a matrix, and Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Fe, Ni, Co, Cu, Al, Mg, Zn and alloys thereof, stainless steel, permalloy and A radio wave absorbing material composed of a composite material having a composite phase containing at least one metal particle selected from a super heat-resistant alloy is disclosed (see Patent Document 3 below).
[0007]
[Patent Document 1]
JP 2002-289720 A
[0008]
[Patent Document 2]
JP-A-10-64714
[0009]
[Patent Document 3]
JP-A-9-255408
[0010]
[Problems to be solved by the invention]
However, the means described in Patent Document 1 for attaching the radio wave absorbing layer 13 made of a radio wave absorbing sheet to the surface of the high frequency device 14 increases the thickness of the high frequency device 14 as a whole, and is disadvantageous for miniaturization of equipment. It is. Further, since the electromagnetic wave absorbing layer 13 is formed by mixing a magnetic material with rubber, epoxy resin, or the like, and since the electromagnetic wave absorbing layer 13 is attached to the metal cover 12 with a resin adhesive, the electromagnetic wave absorbing layer 13 or the resin Since the heat resistance of the adhesive is very low, there is a problem that the radio wave absorbing layer 13 easily warps due to heat of the high frequency element 16 or the like, and the radio wave absorbing layer 13 is separated from the metal lid 12.
[0011]
Further, the composite magnetic material using a flat or acicular soft magnetic material powder used as an EMI countermeasure component described in Patent Literature 2 includes an organic binder, and thus is inferior in heat resistance and dimensional stability. There was a problem. Therefore, when this composite magnetic body is used as a component of the high-frequency device 14, there has been a problem that bonding with a thermosetting resin, a low-melting brazing material, low-melting glass, or the like cannot be performed.
[0012]
Further, the radio wave absorbing material described in Patent Document 3 which is composed of a composite material in which glass or ceramic is used as a matrix and metal particles such as Ti are used as a composite phase is itself excellent in heat resistance and mechanical properties. It is. However, Patent Document 3 discloses that such a radio wave absorbing material is adhered to another metal lid or the like with good bonding properties, and is suitably applied to a radio wave absorbing lid member, a package, an electronic device, a semiconductor device, or the like. Is not disclosed at all.
[0013]
Therefore, the present invention has been completed in view of the above-mentioned conventional problems, and an object of the present invention is to make it possible to directly and firmly attach a radio wave absorbing layer to a radio wave absorbing cover member, and to peel off the radio wave absorbing layer by heat. It is an object of the present invention to provide a radio wave absorbing lid member capable of manufacturing a low-frequency high-frequency device which is not reduced and a high-frequency device using the same.
[0014]
[Means for Solving the Problems]
The radio wave absorbing lid member according to the present invention includes, on one main surface of a metal lid body, a metal layer mainly composed of an Ag-Cu alloy containing at least one of Ti, Zr and Hf, and oxidation of the metal layer. A radio wave absorbing layer containing 51 to 90% by mass of a magnetic material mainly composed of a Ni-Fe alloy, 10 to 49% by mass of glass having a softening point of 250 to 500 ° C, and a thickness of 200 to 500 µm. Are sequentially laminated.
[0015]
In the radio wave absorbing cover member of the present invention, the radio wave absorbing layer contains 51 to 90% by mass of a magnetic material mainly composed of a Ni—Fe alloy and 10 to 49% by mass of glass having a softening point of 250 to 500 ° C. Therefore, the radio wave absorbing layer is excellent in heat resistance, and the radio wave absorbing layer does not peel off from the metal lid due to heat of the high-frequency element or heat at the time of bonding the high-frequency device to an external electric circuit board or the like by soldering or the like. In addition, since the thickness of the radio wave absorbing layer is 200 to 500 μm, the thickness of the radio wave absorbing lid member can be significantly reduced, and the height of the high frequency device can be significantly reduced.
[0016]
Further, the radio wave absorption layer is formed on one main surface of the metal cover via a metal layer mainly composed of an Ag—Cu alloy containing at least one of Ti, Zr and Hf and an oxide layer of the metal layer. Since the active metal of Ti, Zr, Hf contained in the metal layer diffuses into the metal grain boundaries of the metal lid, the metal lid and the metal layer are firmly joined, and The oxide of the oxide layer reacts with the oxide component of the glass in the radio wave absorption layer to firmly join the metal layer and the radio wave absorption layer. As a result, even if a heat history of 230 to 240 ° C. is applied when the metal lid is seam-welded or brazed to the base, the radio wave absorbing layer does not peel off due to heat.
[0017]
In addition, when the radio wave absorption layer absorbs radio waves and converts the energy of electromagnetic waves into heat, the heat is efficiently radiated to the outside through the radio wave absorption layer, metal layer, and metal lid that are firmly joined to each other. Can be.
[0018]
The high-frequency device of the present invention includes a base having a mounting portion on which the high-frequency element is mounted on the bottom surface of the concave portion formed on the upper surface, a high-frequency element mounted and fixed on the mounting portion, and an upper surface of the base. 2. The radio wave absorbing lid member according to claim 1, wherein the one main surface is attached around the concave portion so as to face the high frequency element.
[0019]
According to the high frequency device of the present invention, with the above configuration, the radio wave absorbing layer has a low profile that does not peel off due to heat, and can suppress the occurrence of electromagnetic wave resonance inside. As a result, it is possible to manufacture a high-frequency device in which EMI countermeasures are favorably performed in a high-frequency band such as a microwave band or a millimeter wave band.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
The radio wave absorbing lid member and the high frequency device of the present invention will be described in detail below. FIG. 1 is a sectional view showing an example of an embodiment of a radio wave absorbing cover member of the present invention, and FIG. 2 is an enlarged sectional view of a main part thereof. In these figures, 1 is a radio wave absorbing cover member, 2 is a metal cover, 3 is a radio wave absorber, 3a is a metal layer, 3b is a radio wave absorbing layer, and 3c is an oxide layer. An absorption lid member 1 is configured.
[0021]
In the radio wave absorbing cover member 1 of the present invention, a metal layer 3a mainly composed of an Ag-Cu alloy containing at least one of active metals Ti, Zr and Hf is formed on one main surface of a metal cover 2. The oxide layer 3c of the metal layer 3a, the magnetic material containing a Ni-Fe alloy as a main component in a content of 51 to 90% by mass, and a glass having a softening point of 250 to 500 ° C in a content of 10 to 49% by mass and a thickness of A radio wave absorbing layer 3b of 200 to 500 μm is sequentially laminated.
[0022]
The metal cover 2 in the present invention is preferably made of a metal or alloy such as a 42 alloy (Fe-Ni alloy) or an Fe-Ni-Co alloy, and these have good electromagnetic wave shielding properties and thermal matching with the radio wave absorbing layer 3b. It has the advantage of being good. The metal cover 2 is manufactured in a predetermined shape such as a square shape by punching a base material such as an Fe-Ni-Co alloy with a punching die.
[0023]
Note that a plating layer such as a Ni plating layer or an Au plating layer is formed in a region of the metal cover 2 where the radio wave absorbing layer 3b is not attached, in order to prevent oxidative corrosion and improve brazing properties. .
[0024]
The radio wave absorbing layer 3b of the present invention contains 51 to 90% by mass of a magnetic material mainly composed of a Ni-Fe alloy, 10 to 49% by mass of glass having a softening point of 250 to 500 ° C, and has a thickness of 200 to 49%. It is 500 μm. As a result, unlike the conventional rubber or resin having a heat resistance of only about 200 ° C. mixed with a magnetic material, it has excellent heat resistance and does not need to be attached using an adhesive. No peeling from 2 Therefore, the radio wave absorbing layer 3b has excellent heat resistance, and the radio wave absorbing layer 3b is separated from the metal lid 2 by heat of the high-frequency element or heat when the high-frequency device is bonded to an external electric circuit board or the like by soldering or the like. Will not be done. In addition, since the thickness of the radio wave absorbing layer 3b is 200 to 500 μm, the thickness of the radio wave absorbing cover member 1 can be significantly reduced, and the height of the high frequency device can be significantly reduced.
[0025]
Examples of the magnetic material mainly containing a Ni-Fe alloy include 36-permalloy (Fe-Ni alloy containing 36% by mass of Fe), 45-permalloy, 78-permalloy, and supermalloy (Fe-Ni containing quenching heat treatment Mo). Alloy), Cr-permalloy (Cr-containing Fe-Ni alloy), Mo-permalloy (Mo-containing Fe-Ni alloy), or the like is used.
[0026]
Further, the glass having a softening point of 250 to 500 ° C. can be melted at as low a temperature as possible from the viewpoint of reducing the thermal effect on the high-frequency element 6 (FIG. 3) and reducing the residual stress in the glass. Preferably, for example, glass containing 50 to 80% by mass of lead oxide and 15 to 20% by mass of lead fluoride as a main component has a softening point of about 300 ° C. and is excellent in heat resistance. From, it is preferably used.
[0027]
If the magnetic material exceeds 90% by mass, the dispersibility of the powdered magnetic material in the glass is deteriorated, the strength of the radio wave absorbing layer 3b is remarkably reduced, and the radio wave absorbing layer 3b is easily peeled. On the other hand, when the content is less than 51% by mass, it is insufficient to suppress the resonance of the electromagnetic wave inside the high-frequency device when the device is formed as a high-frequency device, and the radio wave absorbing layer 3b is easily warped and peeled.
[0028]
When the glass content is less than 10% by mass, the dispersibility of the magnetic material is deteriorated, the strength of the radio wave absorbing layer 3b is remarkably reduced, and the radio wave absorbing layer 3b is easily peeled. On the other hand, if the content exceeds 49% by mass, it becomes insufficient to suppress the resonance of electromagnetic waves inside the high-frequency device when the device is formed as a high-frequency device, and the radio wave absorbing layer 3b is easily warped and peeled.
[0029]
If the softening point of the glass is less than 250 ° C., the radio wave absorbing layer 3b is easily melted when the radio wave absorbing lid member 1 is seam welded or brazed to the base housing the high frequency element 6. On the other hand, when the softening point of the glass exceeds 500 ° C., the magnetic material aggregates, and as a result, the strength of the radio wave absorbing layer 3b is significantly reduced, and the radio wave absorbing layer 3b is easily peeled.
[0030]
If the thickness of the radio wave absorbing layer 3b is less than 200 μm, the radio wave absorbing characteristics tend to be insufficient. If the thickness exceeds 500 μm, the entire radio wave absorbing cover member 1 becomes thick and it is difficult to make it thin. Also, the metal cover 2 is warped due to a difference in thermal expansion between the metal cover 2 and the radio wave absorbing layer 3b, and the radio wave absorbing layer 3b is easily peeled off.
[0031]
In the radio wave absorbing cover member 1 of the present invention, the radio wave absorbing layer 3b has a metal layer 3a and a metal layer 3a mainly composed of an Ag-Cu alloy containing at least one of Ti, Zr and Hf as active metals. The active metal of Ti, Zr, and Hf contained in the metal layer 3a diffuses into the metal grain boundaries of the metal lid 2 because the active metal is laminated on one main surface of the metal lid 2 via the oxide layer 3c. The metal cover 2 and the metal layer 3a are firmly joined to each other, and the oxide of the oxide layer 3c of the metal layer 3a reacts with the oxide component of the glass in the radio wave absorption layer 3b to form the metal layer 3a and the radio wave absorption layer. 3b. As a result, even when a heat history of 230 to 240 ° C. is applied when the metal lid 2 is seam-welded or brazed to the base, the radio wave absorbing layer 3b does not peel off due to heat.
[0032]
Further, when the radio wave absorbing layer 3b absorbs radio waves and converts the energy of the electromagnetic wave into heat, the heat is efficiently transmitted to the outside through the radio wave absorbing layer 3b, the metal layer 3a, and the metal lid 2, which are firmly joined to each other. The heat can be radiated well.
[0033]
The radio wave absorbing layer 3b and the metal layer 3a are attached to the metal lid 2 by the following method. First, an active metal paste obtained by mixing an Ag-Cu alloy powder, one or more active metal powders of Ti, Zr, and Hf, an organic binder such as an acrylic resin, and a solvent such as toluene and acetone is mixed with a metal cover. The body 2 is screen-printed to a thickness of about 70 μm, heat-treated at a temperature of about 800 ° C. in a reducing atmosphere, and adhered to the metal lid 2 to adhere the metal layer 3 a. Next, a magnetic material paste obtained by adding and mixing an organic solvent and a solvent to glass having a softening point of 250 to 500 ° C. and a magnetic material having a Ni—Fe alloy as a main component, A magnetic material paste layer to be a radio wave absorbing layer 3b is formed by screen printing so as to have a thickness of 500 μm, and baked at about 350 ° C. in the air, so that a glass component of the radio wave absorbing layer 3b and an active metal of the metal layer 3a are formed. An oxide layer 3c formed by oxidizing is formed at the same time. As a result, the radio wave absorbing layer 3b is firmly attached to the metal layer 3a via the oxide layer 3c.
[0034]
The thickness of the metal layer 3a is preferably 50 to 100 μm. If it is less than 50 μm, the oxide layer 3c formed by oxidizing the active metal tends not to have a sufficient thickness. If it exceeds 100 μm, when heat treatment is performed in a reducing atmosphere, an uneven portion may be formed in the metal layer 3a.
[0035]
The thickness of the oxide layer 3c is preferably 1 to 3 μm. If it is less than 1 μm, the bonding strength between the metal layer 3a and the radio wave absorbing layer 3b becomes weak, and the radio wave absorbing layer 3b is easily peeled off from the metal layer 3a by heat. If the thickness exceeds 3 μm, excessive oxidation occurs, and bubbles are easily introduced at the bonding interface between the oxide layer 3c and the radio wave absorbing layer 3b. Therefore, the bonding area is reduced and the radio wave absorbing layer 3b is easily peeled from the metal layer 3a.
[0036]
Next, a high-frequency device 4 using the radio wave absorbing cover member 1 of the present invention will be described in detail with reference to FIG. FIG. 2 shows an example of an embodiment of the high-frequency device 4 of the present invention, in which (a) is a cross-sectional view of a high-frequency device using a metal base 5a, and (b) is a substrate using an insulator base 5b. It is sectional drawing of a high frequency device. As shown in these figures, 2 is a metal lid, 3 is a radio wave absorber, 4 is a high frequency device, 5a and 5b are bases, 6 is a high frequency element, 7 is a metallized layer, and 8 is a sealing material.
[0037]
The high-frequency device according to the present invention includes bases 5a and 5b each having a mounting portion on which a high-frequency element 6 is mounted on a bottom surface of a concave portion formed on an upper surface; a high-frequency element 6 mounted and fixed on the mounting portion; The radio wave absorbing lid member 1 of the present invention is provided around the concave portions on the upper surfaces of 5a and 5b so that one main surface is opposed to the high frequency element 6.
[0038]
The bases 5a and 5b according to the present invention are provided with a concave portion for accommodating the high-frequency element 6 at the center of the upper surface, and the high-frequency element 6 is formed on the bottom surface of the concave portion with low melting point glass, resin adhesive, brazing material or the like. It is bonded and fixed via an adhesive. A plurality of metallized wiring layers and a plurality of lead terminals (not shown) extend over the surfaces of the bases 5a and 5b or penetrate through the bases 5a and 5b from the side surfaces or the bottom surfaces of the concave portions of the bases 5a and 5b to the outer surface. And hermetically sealed with glass. The electrodes located on the bottom surface of the metallized wiring layer and the recess of the lead terminal are electrically connected to the respective electrodes of the high-frequency element 6 via bonding wires or the like (not shown) and led out to the outer surfaces of the bases 5a and 5b. The connected portion is electrically connected to a wiring conductor (not shown) of the external electric circuit board via a conductive connection member such as a bonding wire.
[0039]
The base 5a made of a metal is preferably made of a 42 alloy, an Fe-Ni-Co alloy, or the like, and the concave portion is formed by punching a base material of the metal with a punching die or performing machining such as cutting. It is manufactured as having a predetermined shape. The surface of the substrate 5a is coated with a metal such as gold having excellent corrosion resistance and good wettability with a brazing material such as an Au-Sn brazing material or solder by a plating method or the like to a thickness of 0.1 to 1 μm. It is preferable to keep it on.
[0040]
Then, the periphery of the concave portion on the upper surface of the base 5a and the outer peripheral portion on the lower surface of the radio wave absorbing lid member 1 are joined by resistance welding such as seam welding. Alternatively, bonding may be performed via a sealing material 8 formed of a brazing material adhered to the outer peripheral portion of the lower surface of the radio wave absorbing lid member 1, or a combination of seam welding and brazing may be used.
[0041]
For example, when the base member 5a and the radio wave absorbing lid member 1 are seam-welded, the radio wave absorbing lid member 1 is placed around a concave portion on the upper surface of the base member 5a, and the upper surface of the radio wave absorbing lid member 1 is placed under a nitrogen atmosphere. By applying an energized roller electrode to the outer peripheral portion and pressing the radio wave absorbing lid member 1 against the base 5a side at a constant pressure with the roller electrode, the roller electrode is rotated and pressed for 0.5 to 10 minutes to be airtight. To join.
[0042]
On the other hand, in the case of the base 5b made of an insulator, the base 5b is mainly composed of an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body, a silicon carbide sintered body, a glass ceramic, or the like. It is made of an inorganic material such as a sintered body (ceramic) or a resin. For example, when the substrate 5b is made of an aluminum oxide sintered body, first, alumina (Al 2 O 3 ) And silica (SiO 2 ), Calcia (CaO), magnesia (MgO), etc., to an appropriate organic solvent and solvent, and mixed to form a slurry, which is formed into a sheet by a well-known doctor blade method or calender roll method. By molding, a ceramic green sheet (hereinafter, also referred to as a green sheet) is obtained. Thereafter, the green sheet is manufactured by punching into a predetermined shape, laminating a plurality of green sheets, and firing at a temperature of about 1600 ° C.
[0043]
In the case of the base 5b, a frame-shaped metallized layer 7 for bonding to the radio wave absorbing lid member 1 is attached around the concave portion on the upper surface. The metallized layer 7 and the metallized wiring layer formed on the side and bottom surfaces of the recesses are made of a high melting point metal such as tungsten, molybdenum, or manganese. Is formed in a predetermined pattern at a predetermined position by a conventionally known screen printing method, and is formed by firing simultaneously with the green sheet. A metal such as gold having excellent corrosion resistance and good wettability with a brazing material such as an Au-Sn brazing material or a solder having a thickness of 0.1 to 1 μm is formed on the surface of the metallized layer 7 by a plating method or the like. It is preferable to adhere to the metal cover 2 without using a flux.
[0044]
Since the flux contained in the solder and the like scatters inside the high-frequency device 4, it causes corrosion of the electrodes of the high-frequency device 6 to cause disconnection. Therefore, a metal such as gold is plated on the surface of the metallized layer 7. It is preferable that the metallized layer 7 and the radio wave absorbing lid member 1 are bonded without using a flux. Then, the radio wave absorbing lid member 1 is bonded to the metallized layer 7 via a sealing material 8 formed on the outer peripheral portion of the lower surface thereof.
The base member 5b and the radio wave absorbing cover member 1 are joined together such that the sealing member 8 is sandwiched between the metallized layer 7 formed around the recess on the upper surface of the base member 5b and the radio wave absorbing cover member 1. Is placed on the upper surface of the base 5b, and the electromagnetic wave absorbing lid member 1 is pressed against the base 5b side at a constant pressure while being placed in a sealing furnace in a nitrogen atmosphere at a peak temperature of about 280 to 300 ° C. for 0.5 to 10 minutes to seal. By melting the stopper 8, the sealing member 8 flows out to form a fillet and is joined airtightly.
[0045]
Thus, the radio wave absorbing lid member 1 and the high-frequency device 4 of the present invention mount and fix the high-frequency element 6 such as a semiconductor element on the mounting portion on the bottom surface of the concave portion of the bases 5a and 5b via the resin adhesive or the like. 6 is connected to a lead terminal or a metallized wiring layer via a bonding wire or the like, and thereafter, the radio wave absorbing lid member 1 is joined to the periphery of the concave portion on the upper surface of the base 5a by seam welding, or The sealing material 8 attached to the outer peripheral portion of the lower surface of the member 1 is heated and melted, and is bonded to the metallized layer 7, thereby sealing the base 5 and the radio wave absorbing lid member 1, thereby providing a high-frequency product as a product. The device 4 is obtained.
[0046]
It should be noted that the present invention is not limited to the above-described embodiment, and various changes may be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example has been described in which a semiconductor element such as an IC or an LSI is used as the high-frequency element 6, but an electronic component such as a piezoelectric vibrator or a surface acoustic wave element can be used as the high-frequency element 6. Further, the radio wave absorbing lid member 1 has a flat plate shape, and the bases 5a and 5b have a concave shape at the center of the upper surface. A high-frequency device in which the body is attached with a brazing material or a resin adhesive may be used. Further, the bases 5a and 5b may be formed in a flat plate shape, and the radio wave absorbing lid member 1 may have a shape having a concave portion on a surface facing the bases 5a and 5b.
[0047]
【Example】
An embodiment of the radio wave absorbing lid member of the present invention will be described below.
[0048]
The radio wave absorbing lid member 1 of FIG. 1 was manufactured as follows. First, a metal lid 2 made of an Fe-Ni-Co alloy and having a rectangular plate shape of 21.1 mm long × 19.6 mm wide × 0.3 mm thick is prepared, and its radio wave absorbing layer 3 b is formed. A Ni plating layer having a thickness of 2.0 μm and an Au plating layer having a thickness of 0.5 μm were applied to the entire surface of the part other than the part.
[0049]
First, at a portion where the radio wave absorbing layer 3b is formed on one main surface of the metal cover 2, Ag 72 mass% -Cu 28 mass containing 3 mass% of Ti as an active metal (100 mass% of Ag-Cu alloy). % Of a Ag-Cu eutectic was formed to a thickness of 70 μm by screen printing, and was heat-treated at a temperature of 800 to 850 ° C. in a reducing atmosphere to be adhered to the metal lid 2.
[0050]
The electromagnetic wave absorbing layer 3b is composed of a magnetic material composed of permalloy (Fe-Ni alloy of 42% by mass of Fe and 58% by mass of Ni) and a lead oxide-lead fluoride glass (56% by mass of PbO and 19% by mass of PbF as main components). The glass having a softening point of 280 ° C.) contained therein was mixed at various ratios (see Table 1 below), and a small amount of a polyhydric alcohol ester-based organic solvent (“CK-172” manufactured by Ryo Kagaku Kogyo Co., Ltd.) was added thereto. By the screen printing method, the size of 19.1 mm long × 17.6 mm wide and various thicknesses after baking (see Table 1 below) are set on the oxide layer 3 c on one main surface of the metal lid 2. Was applied. This was fired in a furnace at a temperature of 300 ° C. to 350 ° C. to form an oxide layer 3 c having a thickness of 1.5 μm, and a radio wave absorbing layer 3 b was formed on the metal lid 2.
[0051]
With respect to the obtained various samples, the warpage of the radio wave absorbing cover member 1, the adhesive strength between the metal cover 2 and the radio wave absorbing layer 3b, and the electromagnetic wave attenuation effect were measured.
[0052]
In addition, regarding the warpage of the radio wave absorbing cover member 1, when the warpage was less than 0.15 mm after the furnace was compared before and after the furnace was passed, the case where the warp was less than 0.15 mm and the case where the warp was 0.15 mm or more were ×. And
[0053]
The bond strength was measured by performing a three-point bending test under a load of 49 N (Newton) with the radio wave absorbing layer 3 b adhered to one main surface of the metal lid 2, and the push-pull gauge was increased to 1.0 mm. When the radio wave absorbing layer 3b did not peel off when descending, it was evaluated as ○, and when it did, it was evaluated as ×.
[0054]
As shown in FIG. 3 (a), the measurement of the electromagnetic wave attenuation effect is performed by joining a high frequency element 6 to the bottom surface of the concave portion of the base 5a with an Au-Sn brazing material and seam welding the radio wave absorbing lid member 1 to the base 5a. Each sample of the device 4 was manufactured, and the cavity resonance suppressing effect was evaluated. That is, using a network analyzer (“HP8510C” manufactured by Agilent Technologies), the cavity resonance suppression effect was measured from the value of the S parameter (ratio of high frequency input / output).
[0055]
Specifically, a wiring board on which a microstrip through line is formed is arranged in the high frequency device 4, and the high frequency input / output terminal and the microstrip through line attached to the side surface of the concave portion of the base 5 a are connected to the Au—Sn alloy brazing or the like. The high frequency input / output terminal and the network analyzer were connected electrically. By arranging the radio wave absorbing cover member 1 around the concave portion on the upper surface of the base 5a, the inside of the high-frequency device 4 becomes a cavity resonator, and the resonance frequency determined by the sample size and the frequency of the high-frequency signal incident from the network analyzer match. At that time, the S-parameter was measured by resonating the radiation from the microstrip through line. At this time, the state in which the radio wave absorbing layer 3b was not provided was used as a reference, and the cavity resonance suppression effect was evaluated as ○ when the resonance amount was 20 dB or less, and × when the resonance amount was 20 dB or more. Table 1 shows the evaluation results.
[0056]
[Table 1]
From Table 1, it can be seen that, when the permalloy is 90% by mass or more (No. 1), the adhesive strength is weak due to poor dispersibility of the magnetic material in the radio wave absorbing layer 3b, and the radio wave absorbing layer 3b is separated from the metal lid 2. And adhesion failure occurred. Further, those having less than 50% by mass of permalloy (Nos. 7 and 8) had a reduced cavity resonance suppression effect after passing the furnace. This is because the effect of suppressing the cavity resonance depends on the distance between the particles of the magnetic material in the radio wave absorbing layer 3b. If the content of the magnetic material is small, the glass component is solidified after the furnace is passed and a uniform distance between the particles is obtained. It is thought that it is not possible.
[0057]
On the other hand, in the case of the present invention (Nos. 2 to 6) in which the content of permalloy is 51 to 90% by mass and the content of glass is 10 to 49% by mass, the warpage is small, the adhesive strength and the cavity are all small. The resonance suppression effect was also excellent.
[0058]
In the case where the softening point of the glass was less than 250 ° C. (No. 9), the glass was melt-softened when the radio wave absorbing lid member 1 was seam-welded to the metal base 5a, and thus could not be used as a product. In the case of glass having a softening point exceeding 500 ° C. (No. 14), the electric wave absorbing lid member 1 was warped at a high temperature exceeding 500 ° C., and thus became unusable as a product.
[0059]
On the other hand, those of the present invention (Nos. 10 to 13) in which the softening point of the glass is 250 to 500 ° C. were all small in warpage, and were excellent in the adhesive strength and the cavity resonance suppressing effect.
[0060]
Next, when the thickness of the radio wave absorbing layer 3b was less than 200 μm (No. 15), the effect of suppressing the cavity resonance was poor, and it could not be used as a product. When the thickness of the radio wave absorbing layer 3b exceeds 500 μm (No. 19), the entire radio wave absorbing cover member 1 cannot be reduced in thickness, and the workability of screen printing is poor.
[0061]
On the other hand, in the case of the present invention (Nos. 16 to 18) in which the thickness of the radio wave absorbing layer 3b is 200 to 500 μm, the warpage was small, and the adhesive strength and the cavity resonance suppressing effect were all excellent.
[0062]
As the radio wave absorbing layer body 3, Sample No. 17 having no metal layer 3a was designated as Comparative Example (No. 17A). Samples (Nos. 20 to 24) were prepared by changing the type of the metal layer 3a in the 17 samples. With respect to these, similarly to the above, the warpage of the radio wave absorbing cover member 1, the adhesive strength between the metal cover 2 and the radio wave absorbing layer 3b, and the effect of suppressing cavity resonance were measured, and the results are shown in Table 2.
[0063]
[Table 2]
[0064]
Table 2 shows that the samples (Nos. 20 to 24) in which the metal layer 3a is mainly composed of an Ag-Cu alloy containing at least one active metal of Ti, Zr, and Hf are radio wave absorbing lids. The warpage of the member 1 was small and the cavity resonance suppressing effect was excellent. Further, regarding the adhesive strength, there was no problem when the push-pull gauge was lowered to 1.0 mm in the three-point bending test, and even when the push-pull gauge was lowered to 2.0 mm, the metal layer 3a and the radio wave absorbing layer 3b did not peel off, and were very strong. It was attached. In Table 2, those that did not come off even when lowered to 2.0 mm were marked as ◎.
[0065]
【The invention's effect】
In the radio wave absorbing cover member of the present invention, the radio wave absorbing layer contains 51 to 90% by mass of a magnetic material mainly composed of a Ni—Fe alloy and 10 to 49% by mass of glass having a softening point of 250 to 500 ° C. Therefore, the radio wave absorbing layer is excellent in heat resistance, and the radio wave absorbing layer does not peel off from the metal lid due to heat of the high-frequency element or heat at the time of bonding the high-frequency device to an external electric circuit board or the like by soldering or the like. In addition, since the thickness of the radio wave absorbing layer is 200 to 500 μm, the thickness of the radio wave absorbing lid member can be significantly reduced, and the height of the high frequency device can be significantly reduced.
[0066]
Further, since the radio wave absorption layer is laminated on one main surface of the metal cover via a metal layer containing at least one of Ti, Zr and Hf and an oxide layer of the metal layer, The active metal of Ti, Zr, Hf contained in the layer diffuses into the metal grain boundaries of the metal lid to firmly join the metal lid and the metal layer, and the oxide of the oxide layer of the metal layer absorbs radio waves. It reacts with the oxide component of the glass in the layer to firmly join the metal layer and the radio wave absorption layer. As a result, even if a heat history of 230 to 240 ° C. is applied when the metal lid is seam-welded or brazed to the base, the radio wave absorbing layer does not peel off due to heat.
[0067]
In addition, when the radio wave absorption layer absorbs radio waves and converts the energy of electromagnetic waves into heat, the heat is efficiently radiated to the outside through the radio wave absorption layer, metal layer, and metal lid that are firmly joined to each other. Can be.
[0068]
The high-frequency device of the present invention includes a base having a mounting portion on which a high-frequency element is mounted on a bottom surface of a concave portion formed on an upper surface, a high-frequency element mounted and fixed on the mounting portion, and a concave portion on the upper surface of the base. By having the radio wave absorbing lid member of the present invention attached so that the one main surface is opposed to the high-frequency element, the radio wave absorbing layer has a low profile that does not peel off due to heat. And the occurrence of electromagnetic wave resonance inside can be suppressed. As a result, it is possible to manufacture a high-frequency device in which EMI countermeasures are favorably performed in a high-frequency band such as a microwave band or a millimeter wave band.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of a radio wave absorbing lid member of the present invention.
FIG. 2 is an enlarged sectional view of a main part of the radio wave absorbing lid member of FIG.
FIGS. 3A and 3B are cross-sectional views showing examples of embodiments of the high-frequency device of the present invention.
FIG. 4 is a cross-sectional view of a conventional radio wave absorbing lid member.
FIG. 5 is a cross-sectional view of a conventional high-frequency device.
[Explanation of symbols]
1: Radio wave absorbing lid member
2: Metal cover
3a: metal layer
3b: radio wave absorption layer
3c: oxide layer
4: High frequency device
5a, 5b: substrate
6: High frequency device
