JPH0585850A

JPH0585850A - Solder paste for joining aluminum nitride substrate to copper plate

Info

Publication number: JPH0585850A
Application number: JP28061291A
Authority: JP
Inventors: Masahiro Saito; 政浩斉藤; Yutaka Takeshima; 裕竹島; Yasunobu Yoneda; 康信米田; Yukio Sakabe; 行雄坂部
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 1991-09-30
Filing date: 1991-09-30
Publication date: 1993-04-06

Abstract

PURPOSE:To prevent deterioration of joining strength of a solder paste for joining by adding aluminum nitride powder and organic vehicle having prescribed ratio to metal powder. CONSTITUTION:The subject solder paste for joining is formed by adding 0.5-10 pts.wt. aluminum nitride powder and a residual amount of organic vehicle to 100 pts.wt. metallic powder. The metallic powder includes silver, copper and titanium. When a copper plate to which the solder paste was applied is put on an aluminum nitride substrate and these components are heat-treated to join these components, thermal coefficient of expansion of the solder material layer becomes small owing to aluminum nitride powder. Consequently, crack on aluminum nitride substrate side caused by thermal shock is not generated and deterioration of joining strength after heat cycle is prevented.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は窒化アルミニウム基板と
銅板の接合用ロウペーストに関する。具体的にいうと、
例えばＩＣパッケージやパワーダイオードなどの基板と
して用いられる窒化アルミニウム−銅接合基板を作製す
る際に用いられる接合用ロウペーストに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing paste for joining an aluminum nitride substrate and a copper plate. Specifically,
For example, the present invention relates to a brazing paste for joining used in producing an aluminum nitride-copper joined substrate used as a substrate for IC packages, power diodes, and the like.

【０００２】[0002]

【従来の技術】半導体デバイスの高密度化、高速化及び
高出力化に伴う発熱量の増大に対応するため、基板材料
としては放熱性に優れたものが要求されてきている。放
熱性に優れた基板材料としては、従来よりアルミナ基板
が用いられてきたが、最近では熱伝導率の高い窒化アル
ミニウム（以下、ＡｌＮと記す。）基板が注目されてい
る。しかし、実装基板としての放熱性を良好にするため
には、ＡｌＮ基板にヒートシンクとして厚さ数1００μ
ｍの銅板等の金属板を接合させる必要がある。このた
め、従来にあってはＴｉ（チタン）等の活性金属を添加
したロウ材を用いてＡｌＮ基板に金属板を接合させてい
る。2. Description of the Related Art In order to cope with an increase in the amount of heat generated by higher density, higher speed and higher output of semiconductor devices, a substrate material having excellent heat dissipation has been required. An alumina substrate has been conventionally used as a substrate material having excellent heat dissipation, but recently, an aluminum nitride (hereinafter referred to as AlN) substrate having a high thermal conductivity has been attracting attention. However, in order to improve the heat dissipation as a mounting board, a thickness of several hundred μm is used as a heat sink on the AlN board.
It is necessary to join a metal plate such as a copper plate of m. For this reason, conventionally, a metal plate is bonded to an AlN substrate using a brazing material to which an active metal such as Ti (titanium) is added.

【０００３】図１（ａ）（ｂ）はＡｌＮ基板と銅板の接
合方法を示す断面図である。この接合体４は、図１
（ａ）に示すように表面が平坦な銅板１にＴｉ−Ｃｕ−
Ａｇ系ロウペースト３を塗布した後、銅板１のペースト
印刷面をＡｌＮ基板２に仮接着し、その上から荷重をか
けた状態で真空中において熱処理を施してロウペースト
３を溶融させ、その後固化したＴｉ−Ｃｕ−Ａｇ系ロウ
材層を介して図１（ｂ）のようにＡｌＮ基板２の表面に
銅板１を強固に接合させたものである。こうしてＡｌＮ
基板２と接合された銅板１はヒートシンクとして働き、
実装基板としての放熱性を良好にする。また、銅板１は
配線パターンとしても使用できる。1A and 1B are sectional views showing a method of joining an AlN substrate and a copper plate. This joined body 4 is shown in FIG.
As shown in (a), Ti-Cu-
After applying the Ag-based wax paste 3, the paste-printed surface of the copper plate 1 is temporarily adhered to the AlN substrate 2, and a heat treatment is applied in a vacuum from above to melt the wax paste 3 and then solidify. As shown in FIG. 1B, the copper plate 1 is firmly bonded to the surface of the AlN substrate 2 via the Ti-Cu-Ag brazing material layer. Thus AlN
The copper plate 1 joined to the substrate 2 functions as a heat sink,
Improves heat dissipation as a mounting board. The copper plate 1 can also be used as a wiring pattern.

【０００４】[0004]

【発明が解決しようとする課題】しかしながら、上記の
ような方法で製造された接合体にあっては、ＡｌＮ基板
と銅板との接合強度に大きなばらつきを生じたり、ヒー
トサイクルテスト後に接合強度が大きく劣化したりする
ため、接合体の信頼性及び耐久性に大きな問題があっ
た。However, in the bonded body manufactured by the above method, the bonding strength between the AlN substrate and the copper plate varies greatly, and the bonding strength becomes large after the heat cycle test. Since it deteriorates, there is a big problem in reliability and durability of the bonded body.

【０００５】本発明は叙上の従来例の問題点に鑑みてな
されたものであり、その目的とするところは、ＡｌＮ基
板と銅板の接合体の接合強度のばらつきを小さくし、ま
たヒートサイクルテスト後の接合体の接合強度の劣化を
小さくすることにより、接合体の信頼性及び耐久性を向
上させることにある。The present invention has been made in view of the problems of the above conventional examples, and an object of the present invention is to reduce variations in the bonding strength of a bonded body of an AlN substrate and a copper plate and to perform a heat cycle test. It is to improve the reliability and durability of the bonded body by reducing the deterioration of the bonding strength of the bonded body that follows.

【０００６】[0006]

【課題を解決するための手段】本発明による窒化アルミ
ニウム基板と銅板の接合用ロウペーストは、窒化アルミ
ニウム基板と銅板を接合するためのロウペーストであっ
て、金属粉末と、金属粉末合計１００重量部に対してほ
ぼ０.５重量部以上１０重量部以下添加された窒化アル
ミニウム粉末と、有機ビヒクルとからなることを特徴と
している。A brazing paste for joining an aluminum nitride substrate and a copper plate according to the present invention is a brazing paste for joining an aluminum nitride substrate and a copper plate, and contains 100 parts by weight of metal powder and metal powder in total. On the other hand, it is characterized in that it is composed of aluminum nitride powder added in an amount of 0.5 to 10 parts by weight and an organic vehicle.

【０００７】また、典型的には、前記金属粉末として
は、銅、銀及びチタン元素を含むものを用いることがで
きる。Further, typically, as the metal powder, one containing copper, silver and titanium elements can be used.

【０００８】[0008]

【作用】本発明の接合用ロウペーストにあっては、Ｔｉ
−Ｃｕ−Ａｇ系等の金属粉末からなるロウ材中にＡｌＮ
粉末が分散しているので、熱処理後のロウ材層の熱膨張
率が小さくなり、ＡｌＮ粉末を添加していないロウ材層
に比較して当該ロウ材層の熱膨張率がＡｌＮ基板に近く
なる。このため、熱処理後にＡｌＮ基板にかかる残留応
力が小さくなる。この結果、熱処理時の冷却及びヒート
サイクル時の熱衝撃に起因するＡｌＮ基板側のクラック
が発生しなくなり、ＡｌＮ基板と銅板の接合体の接合強
度のばらつきや、ヒートサイクル後の接合強度の劣化を
小さくすることができる。In the joining wax paste of the present invention, Ti
-AlN in a brazing material made of metal powder such as Cu-Ag
Since the powder is dispersed, the thermal expansion coefficient of the brazing material layer after the heat treatment becomes small, and the thermal expansion coefficient of the brazing material layer becomes closer to that of the AlN substrate as compared with the brazing material layer to which the AlN powder is not added. .. Therefore, the residual stress applied to the AlN substrate after the heat treatment becomes small. As a result, cracks on the AlN substrate side due to cooling during heat treatment and thermal shock during heat cycles do not occur, and variations in the bonding strength of the bonded body of the AlN substrate and the copper plate and deterioration of the bonding strength after the heat cycle are prevented. Can be made smaller.

【０００９】なお、ＴｉＮ粉末の添加量が、金属粉末１
００重量部に対してほぼ０.５重量部以下であると、接
合の初期強度のばらつきが大きく、ヒートサイクル後の
接合強度の劣化も著しくなる。また、ほぼ１０重量部以
上であると、初期接合強度が小さく、十分な接合強度を
得られない。The addition amount of the TiN powder is equal to that of the metal powder 1.
When the amount is about 0.5 parts by weight or less with respect to 00 parts by weight, the initial strength of the bonding varies widely, and the bonding strength after heat cycle is significantly deteriorated. On the other hand, when the amount is approximately 10 parts by weight or more, the initial bonding strength is small and sufficient bonding strength cannot be obtained.

【００１０】[0010]

【実施例】本発明の典型的な実施例による接合用ロウペ
ーストは、Ｔｉ、Ｃｕ及びＡｇからなる金属粉末にＡｌ
Ｎ粉末が添加され、さらに残部が有機ビヒクル（有機
物）からなるものである。EXAMPLE A bonding wax paste according to a typical example of the present invention is a metal powder composed of Ti, Cu and Ag and Al.
N powder is added, and the balance consists of an organic vehicle (organic material).

【００１１】このようなＡｌＮ粉末が添加されたロウペ
ーストを塗布した銅板等の金属板をＡｌＮ基板に重ね、
荷重をかけながら熱処理して接合させると、ロウ材中に
分散しているＡｌＮ粉末のためにロウ材層の熱膨張率が
小さくなり、ロウ材層の熱膨張率がＡｌＮ基板に近くな
る。この結果、熱処理後にＡｌＮ基板にかかる残留応力
が小さくなって、熱処理時の冷却及びヒートサイクル時
の熱衝撃に起因するＡｌＮ基板側のクラックが発生しな
くなり、ＡｌＮ基板と銅板の接合体の接合強度のばらつ
きや、ヒートサイクル後の接合強度の劣化を小さくする
ことができる。A metal plate such as a copper plate coated with a wax paste to which such an AlN powder is added is stacked on the AlN substrate,
When heat treatment and bonding are performed while applying a load, the thermal expansion coefficient of the brazing material layer becomes small due to the AlN powder dispersed in the brazing material, and the thermal expansion coefficient of the brazing material layer becomes close to that of the AlN substrate. As a result, the residual stress applied to the AlN substrate after heat treatment is reduced, cracks on the AlN substrate side due to thermal shock during cooling and heat cycle during heat treatment do not occur, and the joint strength between the joined body of the AlN substrate and the copper plate is reduced. And the deterioration of the bonding strength after the heat cycle can be reduced.

【００１２】このロウペーストにおけるＡｌＮの最適な
添加量を求めるため、以下のような数種のサンプルを作
製し、その接合強度を評価した。この結果を以下に説明
する。In order to determine the optimum amount of AlN added to this wax paste, the following several types of samples were prepared and their bonding strengths were evaluated. The results will be described below.

【００１３】まず、ＴｉとＡｇとＣｕを一般的に用いら
れている重量比で混合して金属粉末を調製し、表１の
「ＡｌＮ添加量」の欄に示すように当該金属粉末の合計
１００重量部に対してＡｌＮ粉末をそれぞれ０重量部、
０.１重量部、０.５重量部、１重量部、３重量部、５重
量部、１０重量部、２０重量部の割合で添加し、さらに
残部に有機物を加えてサンプルNo.１〜８のロウぺース
トを準備した。なお、表１のサンプルNo.において記号
＊の付されているものは、本発明の範囲外のサンプルで
ある。First, Ti, Ag and Cu are mixed in a generally used weight ratio to prepare a metal powder, and as shown in the column of "AlN addition amount" in Table 1, the total amount of the metal powder is 100. 0 parts by weight of AlN powder for each part by weight,
0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 3 parts by weight, 5 parts by weight, 10 parts by weight, and 20 parts by weight were added, and an organic substance was added to the balance to prepare sample Nos. 1 to 8. Prepared the raw paste. The samples marked with * in the sample numbers in Table 1 are samples outside the scope of the present invention.

【００１４】[0014]

【表１】 [Table 1]

【００１５】つぎに、サンプルNo.１〜８のロウペース
トを用いてＡｌＮ基板と銅板の接合強度を測定した。す
なわち、サンプルNo.１〜８の各ロウペースト１３を厚
さ１００μｍの銅板１１に塗布し、６０℃のオーブン中
で乾燥させた後、銅板１１を２ｍｍ角のサイズにカット
した。この２ｍｍ角の銅板１１をペースト印刷面を接触
させてＡｌＮ基板１２に仮接着し、真空中において９５
０℃で１０分間熱処理を施し、ＡｌＮ基板１２と銅板１
１の接合体１４を作製した。ついで、図２に示すよう
に、サンプルNo.１〜８の各ロウペースト１３によって
ＡｌＮ基板１２に接合された各銅板１１にリード線１５
を半田１６によって固着し、このリード線１５をＬ形に
折り曲げて銅板１１の面に対して垂直に引っ張って接合
強度を測定した。こうして、各サンプルNo.１〜８毎に
接合体１４の接合強度（初期強度）を求めた。この結果
を表１の「初期強度」の欄に示す。Next, the bonding strength between the AlN substrate and the copper plate was measured using the wax pastes of Sample Nos. 1-8. That is, each of the wax pastes 13 of Sample Nos. 1 to 8 was applied to a copper plate 11 having a thickness of 100 μm and dried in an oven at 60 ° C., and then the copper plate 11 was cut into a 2 mm square size. This 2 mm square copper plate 11 is temporarily bonded to the AlN substrate 12 with the paste printing surface in contact with the paste printing surface,
Heat treatment is performed at 0 ° C for 10 minutes, and the AlN substrate 12 and the copper plate 1
The bonded body 14 of No. 1 was produced. Then, as shown in FIG. 2, a lead wire 15 is provided on each copper plate 11 joined to the AlN substrate 12 by each solder paste 13 of Sample Nos. 1 to 8.
Was fixed with solder 16 and the lead wire 15 was bent into an L shape and pulled perpendicularly to the surface of the copper plate 11 to measure the bonding strength. In this way, the bonding strength (initial strength) of the bonded body 14 was obtained for each of the sample Nos. 1 to 8. The results are shown in the column of "initial strength" in Table 1.

【００１６】つぎに、上記サンプルNo.１〜８のロウペ
ーストを用いてＡｌＮ基板と銅板のヒートサイクル後の
接合強度を測定した。すなわち、サンプルNo.１〜８の
各ロウペースト１３を用い、上記接合方法と同様にして
２ｍｍ角にカットした厚さ１００μｍの銅板１１をＡｌ
Ｎ基板１２に仮接着し、熱処理を施してＡｌＮ基板１２
と銅板１１の接合体１４を作製した後、−５５℃及び１
２５℃間で１００サイクルのヒートサイクルテストを行
なった。ついで、ヒートサイクル後に各接合体１４の銅
板１１に図２のようにリード線１５を半田付けし、この
リード線１５を銅板１１の面に対して垂直に引っ張って
接合強度を測定した。こうして、各サンプルNo.１〜８
毎に接合体１４のヒートサイクル後における接合強度を
求めた。この結果を表１の「ヒートサイクル後」の欄に
示す。Next, the bonding strength of the AlN substrate and the copper plate after the heat cycle was measured using the wax pastes of the above sample Nos. 1 to 8. That is, using each of the wax pastes 13 of Sample Nos. 1 to 8, a copper plate 11 having a thickness of 100 μm, which was cut into a 2 mm square in the same manner as the above joining method, was Al.
Temporarily adhere to the N substrate 12 and heat-treat the AlN substrate 12.
After producing a bonded body 14 of the copper plate 11 and
A 100-cycle heat cycle test was performed at 25 ° C. Then, after the heat cycle, the lead wire 15 was soldered to the copper plate 11 of each bonded body 14 as shown in FIG. 2, and the lead wire 15 was pulled perpendicular to the surface of the copper plate 11 to measure the bonding strength. In this way, each sample No. 1-8
The joint strength of the joined body 14 after the heat cycle was determined for each case. The results are shown in the column of "after heat cycle" in Table 1.

【００１７】表１から明らかなように、サンプルNo.１
のようにロウペースト中にＡｌＮ粉末が含まれない場
合、あるいはサンプルNo.２のようにＡｌＮ粉末の添加
量が０.５重量部よりも少ない場合には、接合体の初期
強度は強いが、その値のばらつきが大きく、ヒートサイ
クル後の接合強度の劣化が著しかった。一方、サンプル
No.８のようにＡｌＮ粉末の添加量が１０重量部よりも
大きい場合には、初期強度のばらつき及びヒートサイク
ル後の接合強度の劣化は少ないが、初期接合強度でも平
均１.０kgf／（２ｍｍ角）と小さく、十分な接合強度を
得られなかった。As is clear from Table 1, sample No. 1
When the AlN powder is not contained in the wax paste as in No. 2 or when the addition amount of AlN powder is less than 0.5 parts by weight as in Sample No. 2, the initial strength of the bonded body is strong, The variation in the value was large, and the deterioration of the bonding strength after the heat cycle was remarkable. Meanwhile, the sample
When the amount of AlN powder added is more than 10 parts by weight as in No. 8, there is little variation in the initial strength and deterioration of the bonding strength after the heat cycle, but even the initial bonding strength is 1.0 kgf / (2 mm on average. Corner), and sufficient bonding strength could not be obtained.

【００１８】これに対し、ＡｌＮ添加量が０.５重量部
〜１０重量部の範囲内にあるサンプルNo.３〜７のロウ
ペーストを用いた場合には、接合強度が２.０kgf／（２
ｍｍ角）と大きく、接合強度のばらつきも小さく、ヒー
トサイクル後の劣化も小さくなった。したがって、Ａｌ
Ｎ粉末の添加量は、金属粉末１００重量部に対してほぼ
０.５〜１０重量部の範囲内が最適であった。On the other hand, when the wax pastes of Sample Nos. 3 to 7 in which the added amount of AlN was within the range of 0.5 to 10 parts by weight were used, the bonding strength was 2.0 kgf / (2
mm square), variation in bonding strength was small, and deterioration after heat cycle was small. Therefore, Al
The optimum amount of N powder added was approximately 0.5 to 10 parts by weight per 100 parts by weight of metal powder.

【００１９】[0019]

【発明の効果】本発明によれば、ロウ材層の熱膨張率が
ＡｌＮ基板の熱膨張率に近くなり、熱処理後にＡｌＮ基
板にかかる残留応力が小さくなる。この結果、熱処理時
の冷却及びヒートサイクル時の熱衝撃に起因するＡｌＮ
基板側のクラックが発生しなくなり、ＡｌＮ基板と銅板
の接合体の接合強度のばらつきや、ヒートサイクル後の
接合強度の劣化を小さくすることができる。According to the present invention, the coefficient of thermal expansion of the brazing material layer is close to the coefficient of thermal expansion of the AlN substrate, and the residual stress applied to the AlN substrate after heat treatment is reduced. As a result, AlN caused by cooling during heat treatment and thermal shock during heat cycle
The cracks on the substrate side do not occur, and it is possible to reduce the variation in the bonding strength of the bonded body of the AlN substrate and the copper plate and the deterioration of the bonding strength after the heat cycle.

【図面の簡単な説明】[Brief description of drawings]

【図１】（ａ）（ｂ）はセラミック基板と銅板の接合方
法を示す断面図である。1A and 1B are cross-sectional views showing a method for joining a ceramic substrate and a copper plate.

【図２】接合体のピール強度を測定する方法を示す概略
断面図である。FIG. 2 is a schematic cross-sectional view showing a method for measuring the peel strength of a joined body.

【符号の説明】[Explanation of symbols]

１１銅板１２ＡｌＮ基板１３ロウペースト 11 Copper Plate 12 AlN Substrate 13 Wax Paste

───────────────────────────────────────────────────── フロントページの続き (72)発明者坂部行雄京都府長岡京市天神二丁目26番10号株式会社村田製作所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Sakabe 2 26-10 Tenjin Tenjin, Nagaokakyo City, Kyoto Murata Manufacturing Co., Ltd.

Claims

【特許請求の範囲】[Claims]

【請求項１】窒化アルミニウム基板と銅板を接合する
ためのロウペーストであって、金属粉末と、金属粉末合計１００重量部に対してほぼ
０.５重量部以上１０重量部以下添加された窒化アルミ
ニウム粉末と、有機ビヒクルとからなることを特徴とす
る窒化アルミニウム基板と銅板の接合用ロウペースト。1. A wax paste for joining an aluminum nitride substrate and a copper plate, wherein the metal powder and aluminum nitride are added in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the total of the metal powder. A brazing paste for joining an aluminum nitride substrate and a copper plate, comprising a powder and an organic vehicle.

【請求項２】前記金属粉末が、銀、銅及びチタン元素
を含むことを特徴とする請求項１に記載の窒化アルミニ
ウム基板と銅板の接合用ロウペースト。2. The brazing paste for joining an aluminum nitride substrate and a copper plate according to claim 1, wherein the metal powder contains elements of silver, copper and titanium.