JP2004014827A - Manufacturing method of package for high frequency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a package for high frequencies, in which a warping is prevented, a process yield is improved, the cost is low and no joining failure occurs. <P>SOLUTION: There is provided a manufacturing method of a package 10 for high frequencies, in which an upper surface of a nearly rectangular plate shaped heat dissipating metallic plate 11 made from a copper tungsten based composite metallic material and a lower surface of a frame shaped insulating body 12 made of ceramic are joined together, and an external connecting terminal 14 is joined to the upper surface of the insulating body 12, wherein the method comprises two processes: a process for brazing the heat dissipating metallic plate 11 with the insulating body 12 and the insulating body 12 with an external connecting terminal 14 using a high temperature brazing material 13 to form a joined body 15 and a process for correcting the warp by pressing the joined body 15 being heated at a temperature lower than the melting temperature of the high temperature brazing material 13. <P>COPYRIGHT: (C)2004,JPO

Description

【００２２】
【表２】

【００２３】
（１）の常温中で押圧して反りを矯正したものについては、４００℃５分間加熱した後の反りが矯正する前の反りの値に戻っており、反りの矯正効果がなくなっている。これに反して、（２）の３００℃で加熱しながら３秒押圧して反りを矯正したものについては、４００℃５分間加熱した後も反りが矯正する前の反りに戻ることなく、反りの矯正効果を維持することができる。
【００２４】
【発明の効果】
請求項１及びこれに従属する請求項２記載の高周波用パッケージの製造方法は、放熱用金属板と絶縁体、及び絶縁体と外部接続端子を高温ろう材でろう付け接合して接合体を形成する工程と、接合体を高温ろう材の溶融温度以下で加熱しながら押圧して反りを矯正する工程を有するので、接合体に発生した反りを容易に矯正するすることができ、修正後の反りの発生を防止して歩留まりを向上させて安価に高周波用パッケージを作製できる。また、再加熱工程があったとしても矯正した反りが元に戻ることなく、高周波用パッケージに接合される部材の接合不良の発生がない高周波用パッケージの製造方法を提供できる。
【００２５】
特に、請求項２記載の高周波用パッケージの製造方法は、接合体の放熱用金属板の長手方向両端部が、円柱体側部形状からなる凹部を有する反りの矯正を行うための台板の凹部内に当接するように載置し、接合体の上部から放熱用金属板の下面が凹部に接触するまで加熱しながら押圧して反りを矯正するので、接合体の曲げすぎや、曲げ不足による高周波用パッケージの反りの矯正不良の発生がなく、また、曲げすぎによる絶縁体の破壊を防止して高周波用パッケージの反りを矯正することができる。
【図面の簡単な説明】
【図１】（Ａ）、（Ｂ）はそれぞれ本発明の一実施の形態に係る高周波用パッケージの製造方法で作製された高周波用パッケージの平面図、正面図である。
【図２】同高周波用パッケージの製造方法で作製された高周波用モジュール基板の斜視図である。
【図３】（Ａ）、（Ｂ）はそれぞれ同高周波用パッケージの製造方法の説明図である。
【図４】（Ａ）〜（Ｃ）はそれぞれ同高周波用パッケージの他の製造方法の説明図である。
【図５】（Ａ）、（Ｂ）はそれぞれ従来の高周波用パッケージの製造方法で作製された高周波用パッケージの平面図、正面図である。
【符号の説明】
１０：高周波用パッケージ、１１：放熱用金属板、１２：絶縁体、１３：高温ろう材、１４：外部接続端子、１５：接合体、１６：キャビティ部、１７：固定用切り欠き部、１８：半導体素子、１９：ボンディングワイヤ、２０：蓋体、２１：接着材、２２：高周波用モジュール基板、２３：台板、２４：凹部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a high-frequency package formed by bonding a heat-dissipating metal plate and an insulator, and an insulator and an external connection terminal.
[0002]
[Prior art]
The high-frequency package is used for mounting, for example, silicon used for an RF base station or the like, or a high-frequency, high-output semiconductor element such as a gallium arsenide field effect transistor. In this high-frequency package, the cavity for mounting the semiconductor element is formed on a substantially rectangular heat-dissipating metal plate having a high heat-dissipation characteristic so as not to deteriorate the electric characteristics of the semiconductor element in a high-frequency region. The semiconductor element mounting area thus formed is joined so as to be surrounded by a ceramic frame-shaped insulator. After the semiconductor element is mounted on the high-frequency package, the cavity is hermetically sealed with a lid joined to the upper surface of the insulator. The high-frequency signal is input / output via an external connection terminal joined between the upper surface of the insulator and the lid.
[0003]
If a semiconductor element that generates a large amount of heat from a semiconductor element, such as a power transistor module, is mounted on a high-frequency package by an ordinary method, the semiconductor device may not operate normally due to heat generation. Therefore, as a high-frequency package that satisfactorily dissipates heat generated during operation of a semiconductor element into the atmosphere, for example, a metal having a coefficient of thermal expansion close to that of ceramic and having excellent thermal conductivity A package formed by joining a frame-shaped insulator made of ceramic to a plate-shaped heat-dissipating metal plate made of
[0004]
An example of a conventional method for manufacturing the high-frequency package 50 will be described with reference to FIGS. A ceramic made of alumina (Al ₂ O ₃ ) or the like is placed on a plate-shaped heat-dissipating metal plate 51 made of a copper-tungsten (Cu-W) -based composite metal material having a thermal expansion coefficient similar to that of a ceramic and having good heat dissipation characteristics. A frame-shaped insulator 52 is placed on a metallized pattern formed on the back side of the insulator 52 via an Ag-Cu solder 53. Next, the heat-dissipating metal plate 51 and the insulator 52 are joined by brazing by heating in a heating furnace. Further, an external connection terminal 54 made of a metal member for connection to the outside via a metallized pattern formed on the front surface side is brazed to the insulator 52 with an Ag-Cu braze 53. Next, Ni plating and Au plating are applied to the metal surfaces of the heat dissipating metal plate 51, the insulator 52, and the external connection terminals 54. At both ends in the longitudinal direction of the heat dissipating metal plate 51, fixing notches 55 for attaching to a board or the like are provided.
[0005]
[Problems to be solved by the invention]
However, the conventional method for manufacturing a high-frequency package as described above has the following problems.
(1) Although the thermal expansion coefficients of the heat-dissipating metal plate and the external connection terminal are close to the thermal expansion coefficients of the insulator, it is difficult to completely match them, so a high-temperature brazing material such as Ag-Cu brazing material is used. Therefore, it is not possible to prevent the occurrence of stress in the joint when brazing is performed, and to prevent warping of the joined body formed by joining. Therefore, a warp exceeding a predetermined allowable range occurs, and the warpage of the manufactured high-frequency package is subjected to a screening inspection to detect only non-defective products, so that a screening process is required and the yield is lowered at the same time. Therefore, the cost of the high-frequency package is high.
(2) Forcibly correcting the warpage of the bonded body at room temperature is considered to be a correction without releasing the stress. However, it is considered that the warpage is corrected when the semiconductor element is bonded or the lid is bonded. The heating returns to the state of the warpage before the correction, and the bonding failure of the semiconductor element and the lid occurs.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a high-frequency package that prevents warpage, improves yield, and is inexpensive and does not generate defective bonding. I do.
[0006]
[Means for Solving the Problems]
A method for manufacturing a high-frequency package according to the present invention, which meets the above object, comprises joining an upper surface of a substantially rectangular plate-shaped heat-dissipating metal plate made of a copper-tungsten composite metal material and a lower surface of a frame-shaped insulator made of ceramic. A method for manufacturing a high-frequency package in which an external connection terminal is formed by bonding an external connection terminal to an upper surface of an insulator, wherein the heat-dissipation metal plate and the insulator, and the insulator and the external connection terminal are connected by brazing with a high-temperature brazing material. And a step of pressing the joined body while heating it below the melting temperature of the high-temperature brazing material to correct the warpage. Thereby, the warpage generated in the joined body can be easily corrected, the occurrence of the warpage after the correction can be prevented, the yield can be improved, and the high-frequency package can be manufactured at low cost, and the high-frequency package can be joined to the high-frequency package. It is possible to provide a method for manufacturing a high-frequency package free from occurrence of defective joining of members.
[0007]
Here, both ends in the longitudinal direction of the heat-dissipating metal plate of the joined body are placed so as to be in contact with the concave portion of the base plate for performing warp correction having a concave portion having a cylindrical side portion shape, and It is preferable to correct the warpage by pressing while heating until the lower surface of the heat-dissipating metal plate contacts the concave portion from the upper portion. This prevents the bonded body from being excessively bent or insufficiently corrected for warping of the high-frequency package due to insufficient bending. In addition, it is possible to correct the warpage of the high-frequency package without breaking the ceramic insulator due to excessive bending.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
1A and 1B are a plan view and a front view, respectively, of a high-frequency package manufactured by a method for manufacturing a high-frequency package according to an embodiment of the present invention, and FIG. FIGS. 3A and 3B are explanatory views of a method of manufacturing the high-frequency package, and FIGS. 4A to 4C are views illustrating the high-frequency module substrate manufactured by the method of FIGS. FIG. 7 is an explanatory view of another method of manufacturing a package for use.
[0009]
As shown in FIGS. 1A and 1B, a high-frequency package 10 manufactured by a method for manufacturing a high-frequency package according to one embodiment of the present invention has a high temperature generated from a semiconductor element to be mounted, and A ceramic frame-shaped insulator 12 is brazed and joined with a high-temperature brazing material 13 on the upper surface of a substantially rectangular plate-shaped heat-dissipating metal plate 11 for dissipating a large amount of heat. The high-frequency package 10 has a lead frame-shaped external connection terminal 14 electrically connected to a semiconductor element 18 (see FIG. 2) on the upper surface of the insulator 12 for transmitting electric power to the outside. 13 and brazed. The heat dissipating metal plate 11, the insulator 12, and the external connection terminal 14 form a joined body 15. Further, as shown in FIG. 2, in the high-frequency package 10, a semiconductor element 18 is die-bonded to the cavity portion 16, and the semiconductor element 18 and the external connection terminal 14 are connected by a bonding wire 19, and then a resin, ceramic, or the like is formed. A lid 20 made of metal or the like is bonded with an adhesive 21 such as resin or glass, and hermetically sealed to form a high-frequency module substrate 22. At both ends in the longitudinal direction of the heat-dissipating metal plate 11, fixing notches 17 for attaching the high-frequency module substrate 22 to a board or the like are provided.
[0010]
Next, a method for manufacturing the high-frequency package according to one embodiment of the present invention will be described in detail.
The heat-dissipating metal plate 11 for forming the high-frequency package 10 is made by impregnating copper into porous tungsten, for example, which has a coefficient of thermal expansion close to that of ceramic and has high heat-dissipation characteristics with high thermal conductivity. It is formed from a copper-tungsten (Cu-W) -based composite metal material which is produced by the following method. Then, a fixing notch 17 for screwing and fixing to a mounting member such as a board using a method such as cutting or powder metallurgy is provided, and is formed in a substantially rectangular shape. Incidentally, the thermal conductivity of Cu-W is about 230 W / mk, and the heat generated from the semiconductor element 18 can be efficiently radiated.
[0011]
The ceramic for forming the frame-shaped insulator 12 is made of Al ₂ O _3, which is an example of ceramic, and is obtained by adding an appropriate amount of a sintering aid such as magnesia, silica, and calcia to Al ₂ O ₃ powder. , A plasticizer such as dioctyl phthalate, a binder such as an acrylic resin, and a solvent such as toluene, xylene, and alcohols are sufficiently kneaded and defoamed to prepare a slurry having a viscosity of 2000 to 40000 cps. Next, for example, a roll-shaped sheet having a thickness of 0.25 mm is formed by a doctor blade method or the like, and a ceramic green sheet cut into a rectangular shape having an appropriate size is manufactured.
[0012]
Next, a hollow portion is punched into one or more ceramic green sheets so as to form a window frame, and a metal conductor paste made of a high melting point metal such as tungsten or molybdenum is used. Is screen-printed so as to be on the lower surface side and the upper surface side of the metal conductor pattern. When there are a plurality of ceramic green sheets, they are laminated and screen printed so that the lower surface side and the upper surface side of the laminate become metal conductor patterns. Then, the refractory metal and the ceramic green sheet are simultaneously fired in a reducing atmosphere to produce a frame-shaped insulator 12 having a metal conductor pattern on the lower surface side and the upper surface side. In addition, the metal conductor pattern on the lower surface side is formed on the entire lower surface of the insulator 12 so as to be brazed to the metal plate 11 for heat radiation over the entire periphery of the frame. In addition, the thermal expansion coefficient of Al ₂ O ₃ is about 6.7 × 10 ⁻⁶ / k, and the thermal expansion coefficient of Cu—W is about 6.5 × 10 ⁻⁶ / k. Thermal expansion coefficients are similar.
[0013]
The external connection terminal 14 having a lead frame shape joined to the upper surface of the insulator 12 is made of KV (Fe—Ni—Co alloy, trade name “Kovar”), 42 alloy (Fe—Ni alloy), or the like. And a metal member having a coefficient of thermal expansion similar to that of the ceramics, and is formed into a predetermined shape by cutting, etching, punching, or the like. Incidentally, the coefficient of thermal expansion of KV is approximately 5.3 × 10 ⁻⁶ / k, and the coefficient of thermal expansion of Al ₂ O ₃ is approximately 6.7 × 10 ⁻⁶ / k. ing.
[0014]
Next, a method of manufacturing the high-frequency package 10 from the joined body 15 formed by joining the heat-dissipating metal plate 11, the insulating plate 12, and the external connection terminal 14 will be described.
First, a first Ni plating made of Ni, a Ni alloy, or the like is applied to the surface of the metal plate 11 for heat radiation, the surface of the metal conductor pattern on both surfaces of the insulator 12, and the surface of the external connection terminal 14, respectively. Next, on the upper surface of the central part of the heat-dissipating metal plate 11, for example, a high-temperature brazing material 13 made of Ag-Cu brazing such as BAg-8 (a eutectic alloy composed of 72% Ag and the balance of Cu) is used. The lower surface of the insulator 12 is placed in contact with the insulator 12, and the insulator 12 is heated at about 780 to 900 ° C. and brazed. Next, the lower surface of the distal end of the external connection terminal 14 is placed on the upper surface of the insulator 12 via a high-temperature brazing material 13 made of, for example, Ag-Cu brazing such as BAg-8. It is heated at 780 to 900 ° C. and brazed. The joined body 15 is formed by joining the heat-dissipating metal plate 11 to the insulator 12 and joining the insulator 12 to the external connection terminal 14. The bonding body 15 can also be formed by simultaneously bonding the heat-dissipating metal plate 11 and the insulator 12 and bonding the insulator 12 and the external connection terminal 14.
[0015]
In the joined body 15 formed by the brazing, warpage occurs due to the mismatch of the thermal expansion coefficients of the metal plate for heat radiation 11, the insulator 12, and the external connection terminal 14. Therefore, as shown in FIGS. 3A and 3B, the bonded body 15 is warped by being pressed at a temperature lower than the melting temperature of the high-temperature brazing material 13, that is, at a temperature lower than about 780 ° C. The straightened high-frequency package 10 is manufactured. The shape of the warpage before the correction is the general shape of the high-frequency package 10 and the difference between the thermal expansion coefficients of the heat-dissipating metal plate 11, the insulator 12, and the external connection terminal 14 that form the joint 15. Therefore, since the shape is substantially convex on the upper surface side of the joined body 15, the pressing is performed from the upper surface side of the joined body 15. The pressing is performed until the shape of the joined body 15 becomes slightly concave in consideration of the backlash generated when the pressing is released.
[0016]
Next, another method of manufacturing the high-frequency package 10 according to the embodiment of the present invention will be described with reference to FIGS. 4A and 4B are a plan view and a front view, respectively, before pressing the joined body 15, and FIG. 4C is a front view after pressing the joined body 15, respectively.
[0017]
As shown in FIGS. 4A and 4B, in the same manner as described above, the junction formed between the metal plate 11 for heat dissipation and the insulator 12 and the junction between the insulator 12 and the external connection terminal 14 are formed. The body 15 is a recess of a base plate 23 in which a ridge at a longitudinal end of the heat-dissipating metal plate 11 of the joint body 15 has a groove-shaped recess 24 having a radius of curvature like a side shape of a cylindrical body. 24 so as to be in contact with each other.
[0018]
Next, as shown in FIG. 4 (C), a metal body for heat dissipation is used from above the joined body 15, for example, by using a pressing body having a convex curved surface shape or the like in cross section capable of pressing the surface of the cavity portion 16. The high-frequency package 10 is preferably formed by pressing while heating at a temperature equal to or lower than the melting temperature of the high-temperature brazing material 13 until the lower surface of the plate 11 contacts the concave portion 24.
[0019]
The base plate 23 is formed of a metal member such as stainless steel, and the radius of curvature of the concave portion 24 can be selected depending on the size and shape of the joined body 15, but is preferably about 700 to 800 mm, and warpage occurs below 700 mm. If it is corrected too much, and if it exceeds 700 mm, the correction of the warp is insufficient. The heating temperature can be selected depending on the size and shape of the joined body 15 and the type of the high-temperature brazing material. However, the heating temperature is preferably about 250 to 400 ° C., and if the temperature falls below 250 ° C., the warping occurs when the high-frequency package 10 is reheated. The rate at which corrections revert is increased.
[0020]
【Example】
The present inventors have made Cu-W, Dimensions 41 × 10 mm, and the radiating metal plate having a thickness of 1.2 mm, made of _Al 2 _{O 3,} outer dimensions 31 × 9.5 mm, inner dimensions 27.5 × 6 mm, a frame-shaped insulator having a thickness of 0.25 mm, and four external connection terminals made of KV and having outer dimensions of 11.5 × 5 mm and a thickness of 0.15 mm are prepared, and Ag-Cu made of BAg-8 is prepared. A joined body was prepared by brazing and joining. Then, on a base plate having a concave portion with a radius of curvature of 750 mm, (1) pressing at room temperature to correct the warp, and (2) pressing at 3 seconds while heating at 300 ° C. to correct the warping, for high frequency Six samples of each package were prepared. With respect to these samples, the degree of warpage before the warp was corrected, after the warp was corrected, and after heating at 400 ° C. for 5 minutes was measured. The measurement of the warpage after heating at 400 ° C. for 5 minutes is based on the assumption that the semiconductor element is mounted or that the cavity after mounting is sealed with a lid. Table 1 shows the measurement result of each sample of (1) as a line graph, and Table 2 shows the measurement result of each sample of (2) as a line graph.
[0021]
[Table 1]

[0022]
[Table 2]

[0023]
In the case of (1) in which the warpage was corrected by pressing at room temperature, the warp after heating at 400 ° C. for 5 minutes returned to the value of the warp before the correction, and the effect of correcting the warp was lost. On the other hand, in the case of (2) in which the warpage was corrected by pressing for 3 seconds while heating at 300 ° C., the warpage did not return to that before the warp was corrected even after heating at 400 ° C. for 5 minutes. Corrective effect can be maintained.
[0024]
【The invention's effect】
According to the method for manufacturing a high-frequency package according to the first and second aspects of the present invention, a joined body is formed by brazing a metal plate for heat radiation and an insulator, and an insulator and an external connection terminal with a high-temperature brazing material. And a step of correcting the warpage by pressing the joined body while heating it at or below the melting temperature of the high-temperature brazing material, so that the warpage generated in the joined body can be easily corrected, and the corrected warpage can be easily obtained. The generation of high frequency can be prevented, the yield can be improved, and a high-frequency package can be manufactured at low cost. Further, even if there is a reheating step, it is possible to provide a method for manufacturing a high-frequency package in which the corrected warpage does not return to the original state and no joining failure of members joined to the high-frequency package occurs.
[0025]
In particular, the method for manufacturing a high-frequency package according to claim 2 is characterized in that both ends in the longitudinal direction of the heat-dissipating metal plate of the joined body are formed in the recesses of the base plate for performing warp correction having a recess having a cylindrical side shape. The package is placed so as to be in contact with the package, and it is pressed while heating from the upper part of the joined body until the lower surface of the metal plate for heat radiation contacts the concave part to correct the warpage. In addition, it is possible to correct the warpage of the high-frequency package by preventing occurrence of a defect in correcting the warpage of the package and preventing breakage of the insulator due to excessive bending.
[Brief description of the drawings]
FIGS. 1A and 1B are a plan view and a front view, respectively, of a high-frequency package manufactured by a method for manufacturing a high-frequency package according to an embodiment of the present invention.
FIG. 2 is a perspective view of a high-frequency module substrate manufactured by the method for manufacturing a high-frequency package.
FIGS. 3A and 3B are diagrams illustrating a method of manufacturing the high-frequency package.
FIGS. 4A to 4C are diagrams illustrating another method of manufacturing the high-frequency package.
FIGS. 5A and 5B are a plan view and a front view, respectively, of a high-frequency package manufactured by a conventional method for manufacturing a high-frequency package.
[Explanation of symbols]
10: High frequency package, 11: Heat dissipation metal plate, 12: Insulator, 13: High temperature brazing material, 14: External connection terminal, 15: Joint, 16: Cavity, 17: Notch for fixing, 18: Semiconductor element, 19: bonding wire, 20: lid, 21: adhesive, 22: high-frequency module substrate, 23: base plate, 24: recess

Claims (2)

The upper surface of a substantially rectangular plate-shaped heat-dissipating metal plate made of a copper-tungsten composite metal material is joined to the lower surface of a frame-shaped insulator made of ceramic, and an external connection terminal is joined to the upper surface of the insulator. In the method for manufacturing a high-frequency package,
A step of brazing and joining the heat-dissipating metal plate and the insulator, and the insulator and the external connection terminal with a high-temperature brazing material,
A method of manufacturing a high-frequency package, comprising a step of pressing the joined body while heating it at a temperature equal to or lower than the melting temperature of the high-temperature brazing material to correct the warpage. 2. The method of manufacturing a high-frequency package according to claim 1, wherein the longitudinal ends of the heat-dissipating metal plate of the joined body have concave portions having a cylindrical side shape. Manufacturing a high-frequency package, wherein the package is placed so as to be in contact with the inside, and is pressed while heating from the upper part of the joined body until the lower surface of the metal plate for heat radiation contacts the concave part to correct the warp. Method.

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