JP5911231B2 - Method for manufacturing aluminum nitride-metal bonded substrate - Google Patents

Description

The present invention relates to a novel manufacturing method of an aluminum nitride-metal bonded substrate used as a mounting substrate or a circuit substrate for various electronic elements.

  Conventionally, ceramic substrates having excellent insulating properties, heat dissipation properties, mechanical properties, and the like have been used as substrates for mounting various electronic devices including semiconductor devices. In particular, an aluminum nitride sintered substrate having a high thermal conductivity is frequently used for a substrate on which a high-power semiconductor element such as a power transistor having a large calorific value or a laser element is mounted. When such an aluminum nitride sintered body substrate is used as a mounting substrate or a circuit substrate, it is indispensable to form a metal layer constituting an element mounting portion or a circuit portion on the surface thereof. In addition, as a method for forming the metal layer, a method in which an aluminum nitride sintered body substrate and a metal substrate are joined via a brazing material to form a joined body is performed.

By the way, in the manufacturing process of the aluminum nitride sintered body substrate, usually, the sintering is performed by stacking a plurality of formed bodies, and therefore a release material (BN powder or the like) is used to prevent the substrates from being bonded to each other. This remains on the aluminum nitride sintered substrate surface after firing. In the joining of the aluminum nitride sintered body substrate and the metal substrate, the remaining release material induces problems such as lowering the joining strength between the aluminum nitride sintered body substrate and the metal substrate. For this reason, after performing a cleaning process that removes deposits (foreign matter) such as a release material from the sintered aluminum nitride substrate after firing, for example, a surface process with low impact force such as a honing process is performed, and then the metal substrate Has been proposed (see Patent Document 1). The above honing process is superior in mass productivity and less impact force than polishing, so if polishing is performed, grinding marks of the grindstone may remain on the substrate surface and the substrate strength in a specific direction may decrease. On the other hand, it is frequently used as a pretreatment when bonding metal substrates without causing a decrease in substrate strength.

  Various types of abrasive grains are used for the honing treatment of the aluminum nitride sintered substrate, as described in Patent Document 1, but depending on the processing conditions of the honing treatment, damage to the substrate surface increases. There is a problem that the strength of the aluminum nitride sintered body substrate, the thermal cycle characteristics of the joined body (joined substrate) of the aluminum nitride sintered body substrate and a metal substrate such as a copper plate, and the like are degraded.

For the above problem, using abrasive grains having a lower hardness than the aluminum nitride sintered body substrate,
It has been proposed to reduce the damage given to the substrate surface by limiting the impact force when the abrasive grains collide with the object to be processed to the minimum so as to remove the release material (see Patent Document 2). .

  On the other hand, when constituting a bonded body with the metal substrate, the aluminum nitride sintered body substrate is not sufficient in mechanical properties, particularly bending strength and fracture toughness value, and further improvement is required. That is, when the bending strength or fracture toughness value is small, the aluminum nitride sintered substrate is caused by stress or heat when the semiconductor element is mounted on the metal circuit layer formed by the metal substrate bonded to the aluminum nitride sintered substrate. May be damaged, or repeated thermal cycles accompanying the operation of the semiconductor element may cause cracks in the sintered aluminum nitride substrate near the joint of the metal circuit layer, resulting in reduced heat cycle characteristics and reliability. Problem arises.

  In particular, recent ceramic substrates for power modules are increasingly used under severer heat cycles than before, and there is a strong demand for improvement in thermal shock resistance, as well as bending strength and fracture toughness.

  However, according to the conventional honing treatment techniques disclosed in Patent Documents 1 and 2, the bonding strength between the aluminum nitride sintered body substrate and the metal substrate is strengthened, but the entire bonding substrate obtained by the honing treatment is obtained. There was room for further improvement in the improvement of the strength and thermal cycle characteristics.

JP 2002-171037 A JP 2005-89265 A

  Therefore, the present invention not only exhibits the effect of improving the bonding strength between the aluminum nitride sintered body substrate and the metal substrate, but also stably provides an aluminum nitride-metal bonded substrate having high strength and excellent thermal cycle characteristics. An object of the present invention is to provide a method of manufacturing an aluminum nitride-metal bonded substrate that can be obtained with good reproducibility.

  As a result of repeated researches to achieve the above object, the present inventors have conducted processing conditions that were conventionally considered to lead to a decrease in strength of the aluminum nitride sintered body substrate itself, that is, a hardness higher than that of the aluminum nitride sintered body substrate. The substrate surface is made by using a high-abrasive grain and causing the abrasive grain to exist in a liquid in a specific amount and colliding it with the compressed air and the surface to be processed of the aluminum nitride sintered body substrate at a specific pressure. Compressive residual stress can be imparted to the aluminum nitride crystal particles existing on the surface to be processed while reliably removing the release material attached to the metal substrate, and by performing such a specific processing amount, the metal substrate It has been found that the bending strength and thermal cycle characteristics can be remarkably improved in the bonded aluminum nitride-metal bonded substrate, and the present invention has been proposed.

That is, according to the present invention, the abrasive grains collide with the surface to be processed of the aluminum nitride sintered body substrate for modification, and then when the metal substrate is joined to the surface to be processed of the aluminum nitride sintered body, A liquid having higher hardness than the aluminum nitride sintered body and containing the abrasive grains at a concentration of 10 to 30% by volume (hereinafter, the liquid containing the abrasive grains is also referred to as “abrasive slurry”). ) Together with compressed air to the surface to be processed of the aluminum nitride sintered substrate so that the pressure applied to the surface to be processed is 0.10 to 0.25 MPa, and X-ray diffraction is used. Aluminum nitride metal characterized in that the residual stress value of the (112) plane of the aluminum nitride of the treated surface obtained by the sin ² ψ method was −50 MPa or less and the surface roughness was 0.2 μm or less Manufacturing method of bonded substrate A.

  In the method for producing an aluminum nitride-metal bonded substrate of the present invention, the abrasive grains preferably have a Vickers hardness of more than 1060 and 2500 or less.

  According to the manufacturing method of an aluminum nitride-metal bonded substrate of the present invention, the surface of the aluminum nitride sintered body substrate is sprayed by the abrasive slurry selected with the specific condition and the specific abrasive grain not adopted in the conventional honing process. (Hereinafter, this process is also referred to as “wet spraying process”) gives the aluminum nitride-metal bonded substrate high bending strength and high heat cycle characteristics that cannot be achieved by conventional honing processes. It becomes possible to do.

  That is, the residual stress value shows the effect of improving the bending strength and thermal cycle characteristics of the aluminum nitride-metal bonded substrate after thermal cycling, as shown in the examples described later, for the aluminum nitride-metal bonded substrate. In addition, the surface roughness also exhibits the effect of the bending strength of the aluminum nitride-metal bonded substrate after the thermal cycle and the thermal cycle characteristic in cooperation with the residual stress value. This is an important characteristic.

  The manifestation of the effect of the present invention is achieved by applying a compressive residual stress to the surface to be processed of the aluminum nitride sintered substrate by the specific wet spraying process and performing a smoothing process on the conventional surface. It is presumed that the occurrence of large cracks, extension, etc., which were sacrificed when obtaining such effects in the treatment, are suppressed.

In addition, the method of the present invention ejects abrasive slurry from the nozzle as described later,
Since the surface to be processed of the aluminum nitride sintered substrate can be processed uniformly over a relatively wide range, the processing efficiency is good, and the effects of the present invention can be exhibited with good reproducibility, so that the industrial implementation Is advantageous.

  Hereinafter, modes for carrying out the present invention will be described.

(Sintered aluminum nitride)
As the aluminum nitride sintered body used in the production method of the present invention, the average crystal grain size of the aluminum nitride sintered body is 0.5 to 0.5 because it can be easily obtained or obtained in a desired shape. It is preferable to use an aluminum nitride sintered body of 20 μm, more preferably 2 to 7 μm. Such an aluminum nitride sintered body can be obtained by firing a molded body made of an aluminum nitride raw material powder having an average particle diameter of 0.1 to 15 μm, preferably 0.5 to 5 μm.

The molded body may contain a sintering aid, an organic binder and the like as necessary. For example,
As the sintering aid, a sintering aid commonly used according to the type of aluminum nitride raw material powder can be used without any particular limitation. Specifically, rare earth metal oxides such as yttrium oxide (Y ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), and ytterbium oxide (Yb ₂ O ₃ ), and alkaline earth metal elements such as Ca, Ba, and Sr Among these, it is particularly preferable to use yttrium oxide. The blending amount of the rare earth metal oxide is preferably in the range of 1 to 10% by mass with respect to the aluminum nitride sintered powder. If the blending amount of the rare earth oxide exceeds 10% by mass, the thermal conductivity of the aluminum nitride sintered body may be lowered. On the other hand, if the blending amount of the rare earth oxide is less than 1% by mass, the sinterability of the aluminum nitride sintered body may be reduced, leading to an increase in pores.

  Further, as the organic binder, polyvinyl butyral, ethyl celluloses, and acrylic resins are used, and acrylic resins and polyvinyl butyral are particularly preferably used because the moldability of the molded article is improved.

  The shape of the aluminum nitride sintered body used in the present invention is not particularly limited as long as it has a surface on which a metal substrate such as a copper (Cu) plate can be bonded, and is a plate or plate. It is also possible to use a part obtained by cutting or punching a part of the material or a sintered body having a curved surface.

  Further, the size of the aluminum nitride sintered body is not particularly limited, and may be appropriately determined according to the size of the metal substrate bonded to the surface.

  Furthermore, the thickness of the aluminum nitride sintered body is generally about 0.1 to 2.0 mm, preferably about 0.3 to 1.5 mm. That is, when the plate thickness of the aluminum nitride sintered substrate exceeds 1.5 mm, the thermal resistance increases and the metal substrate is easily peeled off when a thermal cycle is applied. Further, when the thickness of the aluminum nitride sintered body substrate is less than 0.3 mm, the deterioration of the substrate strength is increased, and the dielectric breakdown voltage of the aluminum nitride sintered body substrate is lowered. The reliability of the bonded substrate may be reduced.

  In addition, the surface roughness of the aluminum nitride sintered body is not particularly limited, and the surface after sintering may be the same as it is, or deposits (foreign matter) such as a release material (BN, etc.) used during sintering For example, a surface subjected to surface processing such as a known honing process, or a surface subjected to grinding / polishing.

Furthermore, the aluminum nitride sintered body used in the present invention preferably has a heat conductivity at room temperature of 100 W / mK or more, more preferably 150 W / mK or more. When the thermal conductivity of the aluminum nitride sintered body is less than 100 W / mK, it is possible to ensure the heat dissipation required for a substrate on which a semiconductor element, particularly a high-power semiconductor element such as a power transistor or a laser element is mounted. In other words, the advantage of applying the aluminum nitride-metal bonded substrate to a mounting board or circuit board for various electronic elements is impaired. The aluminum nitride sintered body preferably has a volume resistivity of 10 ¹² Ωcm or more.

(Surface treatment of aluminum nitride sintered substrate)
In the production method of the present invention, abrasive grains having hardness higher than that of the aluminum nitride sintered body are used, and a liquid containing the abrasive grains at a concentration of 10 to 30% by volume together with compressed air is sintered with the aluminum nitride. The pressure applied to the surface to be processed of the body substrate is sprayed from the nozzle so that the pressure is 0.10 to 0.25 MPa, and the aluminum nitride (112 of the surface to be processed is obtained by the sin ² ψ method using X-ray diffraction. ) The residual stress value of the surface is −50 MPa or less, and the surface roughness is 0.2 μm or less.

  In order to achieve the object of the present invention, the material of the abrasive grains used in the present invention is higher in hardness than the aluminum nitride sintered body. That is, when the hardness of the abrasive grains is lower than the above range, it is possible to remove the deposits on the surface of the aluminum nitride sintered body substrate as in the conventional honing treatment, but the compression residual by combining with the spraying conditions described later. The application of stress is not sufficient, and it becomes difficult to impart high bending strength and high heat cycle characteristics to the resulting bonded body.

  The material of the abrasive grains is not particularly limited as long as the material of the aluminum nitride sintered body is higher than that of the aluminum nitride sintered body, but in order to achieve the effects of the present invention, the aluminum nitride sintered body is not limited. A hardness having a picker hardness of more than 50 Hv, preferably 100 Hv or higher is used. Examples of the material of the abrasive grains include alumina, zirconia, and silicon carbide. Among these, alumina is easily available and industrially preferable.

  The average particle diameter of the abrasive grains is not particularly limited, but is 10 to 50 μm, preferably 20 to 30 μm. That is, if the grain size of the abrasive grains is too small, the effect of improving the strength and thermal cycle characteristics of the bonded substrate tends to be reduced. On the other hand, if the grain size is too large, the local impact force increases and the damage increases. Tend to be.

  The shape of the abrasive grains is not particularly limited, but is preferably spherical. That is, when the abrasive grains having corners are used, when the abrasive grains collide with the surface to be processed, the local impact force tends to increase and the damage tends to increase.

  The abrasive used in the present invention is used in a state of being contained in a liquid at a concentration of 10 to 30% by volume. When the concentration of the abrasive grains is less than 10% by volume, the effect of improving the bending strength and thermal cycle characteristics of the bonded substrate is insufficient, and when the concentration of the abrasive grains exceeds 30% by volume, the nozzle holes are clogged. It tends to occur, and poor circulation of abrasive grains tends to occur.

  Further, the liquid is not particularly limited as long as abrasive grains can be dispersed. For example, water is typical, but in addition, an organic solvent liquid such as alcohol can be used.

  In the production method of the present invention, in order to achieve the above object, the abrasive slurry is sprayed so that the pressure applied to the surface to be processed of the aluminum nitride sintered body substrate is 0.10 to 0.25 MPa. is necessary.

That is, in the present invention, when the pressure applied to the surface to be processed of the aluminum nitride sintered substrate is less than 0.10 MPa, it is determined by the sin ² ψ method using X-ray diffraction even if the processing time is increased. It is difficult to apply a compressive residual stress with a residual stress value of the (112) plane of aluminum nitride on the surface to be processed being -50 MPa or less, and the effect of improving the strength and heat cycle characteristics of the resulting bonded substrate is obtained. hard.

  On the other hand, when the pressure applied to the treated surface of the aluminum nitride sintered substrate exceeds 0.25 MPa, the AlN crystal particles on the treated surface of the aluminum nitride sintered substrate can be used even if abrasive grains having a small particle size are used. Graining becomes prominent, the surface roughness exceeds 0.2 μm, and the effect of improving the bending strength and thermal cycle characteristics of the bonded substrate becomes insufficient.

In the present invention, on the surface to be processed of the aluminum nitride sintered body substrate, the residual stress value of the (112) plane of the aluminum nitride of the surface to be processed obtained by the sin ² ψ method using X-ray diffraction is −50 MPa or less, And in order to make surface roughness into 0.2 micrometer or less, what is necessary is just to adjust the pressure concerning the to-be-processed surface of the said abrasive slurry to become the said range, but to the to-be-processed surface of the said abrasive slurry. If the contact time is too short or too long, the desired characteristics may not be obtained.

  Accordingly, the time for spraying the abrasive slurry onto the surface to be processed (processing time) is generally preferably 0.02 seconds to 1.0 seconds, and preferably 0.05 seconds to 0.2 seconds. More preferred. That is, when the treatment time is shorter than 0.02 seconds, the removal of the release material is insufficient, and the effect of improving the strength and heat cycle characteristics of the obtained bonded substrate is also insufficient.

  On the other hand, if the treatment time exceeds 1.0 seconds, the AlN crystal grains on the surface to be treated of the aluminum nitride sintered substrate become prominent and the surface roughness exceeds 0.2 μm, and the joint substrate is bent. The effect of improving strength and thermal cycle characteristics becomes insufficient, and productivity is also lowered.

Here, the pressure applied to the surface to be processed of the aluminum nitride sintered substrate is a pressure applied to the surface of the surface to be processed when the abrasive slurry is pressurized with compressed air and sprayed from the nozzle. It is a converted value. Specifically, the pressure for pressurizing the abrasive slurry is P ₁ [MPa], the opening area of the nozzle through which the abrasive slurry is injected is S ₁ [m ² ], and the area where the abrasive slurry acts is S ₂ [m ² ], the pressure P ₂ [MPa] acting per area of the surface to be processed is represented by the following formula.
P ₂ = P ₁ × S ₁ / S ₂
The area of the surface to be treated is obtained by actually measuring a stripe pattern that is a collision mark of abrasive grains formed on the surface of an aluminum nitride sintered body substrate to which a fluid containing abrasive grains is sprayed.

Incidentally, in the processing apparatus used in Examples of the present invention, the nozzle opening area is 90 mm ² to be S _1, the area acting on the target surface of the S ₂ become sintered aluminum nitride substrate is 95 mm ² there were.

  Further, the distance between the nozzle and the surface to be processed when spraying the abrasive slurry onto the surface to be processed of the aluminum nitride sintered substrate is preferably 100 mm or less, and more preferably 50 mm or less. When the distance between the nozzle and the surface to be processed is larger than 100 mm, unevenness in the pressure distribution applied to the surface to be processed is likely to occur, and the effect of improving the bending strength and thermal cycle characteristics of the bonded substrate becomes insufficient. There is a risk of

  In the method of the present invention, a known abrasive jetting device such as a blasting machine is used without particular limitation as the device used for jetting the abrasive slurry and compressed air. Further, the shape and number of nozzle holes in such an apparatus are not particularly limited, but the use of a nozzle having a wide rectangular opening composed of a short side of about 1 to 4 mm and a long side of about 1 to 630 mm is the object to be processed. This is preferable from the viewpoint of uniformity of surface treatment effect and productivity.

  In the present invention, when the above treatment is performed, the aluminum nitride sintered body substrate does not need to be in a fixed state, and the entire surface of the aluminum nitride sintered body substrate is processed efficiently and uniformly. In addition, the aluminum nitride sintered substrate may be conveyed by a belt conveyor or the like in the processing zone to which the wide nozzle is fixed. Moreover, the said process may perform only one side of an aluminum nitride sintered compact board | substrate, or may process both sides by processing one side alternately, and may perform both sides simultaneously. Alternatively, high-speed wet processing may be performed by moving the nozzle while the aluminum nitride sintered body is fixed.

In the present invention, the residual stress of the aluminum nitride sintered substrate that has been subjected to the above-described wet jet treatment is measured by the sin ² ψ method using the X-ray diffractometer on the (112) plane of aluminum nitride on the surface to be processed And it evaluated by the average value of arbitrary four points (n = 4).

(Metal substrate bonding)
In the present invention, the aluminum nitride sintered body substrate whose surface to be treated has been modified by spraying the abrasive slurry is joined to the aluminum nitride sintered body-metal joint by joining the metal substrate onto the surface to be treated. A substrate is obtained. Further, as described above, the surface roughness of the treated surface of the aluminum nitride sintered body substrate is set to 0.2 μm or less in terms of arithmetic average roughness Ra defined by JIS B0601-1994. When the surface roughness Ra of the treated surface of the aluminum nitride sintered substrate exceeds 0.2 μm, the aluminum nitride crystal particles existing on the surface to be treated are markedly grained, and the strength and heat cycle characteristics of the resulting bonded substrate are obtained. The effect of improving is not obtained.

  The metal substrate constituting the aluminum nitride sintered body-metal bonded substrate is appropriately selected according to the use application or usage of the bonded substrate, for example, a Cu or Cu alloy plate, an Al or Al alloy plate, Ni or a Ni alloy plate is used. However, the metal substrate is not limited to these, and an alloy with a refractory metal such as W or Mo or a clad material may be used as necessary. In particular, when the active metal method is applied to the bonding method, a metal substrate made of various metal materials can be bonded to the aluminum nitride sintered body substrate. In the present invention, the metal substrate preferably has a thickness in the range of 0.2 to 0.4 mm. Further, the metal substrate may have either a circuit structure or a simple plate shape.

  In the above description, the state in which the metal substrate is bonded to only one surface of the aluminum nitride sintered substrate is shown for convenience, but the metal substrate can also be bonded to both surfaces of the aluminum nitride sintered substrate. .

  The joining method of the aluminum nitride sintered body substrate and the metal substrate is not necessarily limited, but a joining method using an active metal brazing material layer is preferably applied. In the joining method (active metal method) using the active metal brazing material layer, the manufacturing method of the present invention is particularly applied because the properties of the substrate surface have a great influence on the strength and thermal cycle characteristics of the joined substrate. By doing so, a sound aluminum nitride sintered body-metal bonded substrate can be obtained. In addition to the active metal method, it is also possible to apply the DBC method in which the aluminum nitride sintered body substrate and the Cu plate are directly joined by heat treatment, but in the case of the DBC method, the surface of the aluminum nitride sintered body substrate Since it is common to form an oxide film, the properties of the substrate surface are not so affected. Thus, this invention is suitable with respect to the manufacturing method of the aluminum nitride sintered compact-metal joining board | substrate which applied the active metal method.

  For the active metal brazing material layer, for example, at least one active metal selected from Ti, Zr, Hf, Nb, Al, etc. is used, an Ag—Cu eutectic composition (72 wt% Ag-28 wt% Cu) or a composition in the vicinity thereof. It is preferable to apply an active metal brazing material blended with a brazing filler metal component such as an Ag-Cu brazing filler metal or a Cu brazing filler metal. The amount of active metal in the active metal brazing material is preferably in the range of 0.5 to 10% by weight with respect to the total amount of the brazing material. The active metal brazing material may contain an appropriate amount of Sn or In (for example, 2 to 7% by weight based on the total amount of the brazing material). An aluminum nitride sintered body substrate and a metal substrate are laminated through such an active metal brazing material coating layer, and the laminate is heat-treated at a temperature of about 700 to 900 ° C., for example. A body-metal bonded substrate is obtained. The heat treatment at the time of bonding is preferably performed in an inert atmosphere or in a vacuum.

  The aluminum nitride sintered body-metal bonded substrate obtained by the manufacturing method as described above is based on the properties of the substrate surface of the aluminum nitride sintered substrate, that is, the treated surface that has been subjected to the wet spraying process. It has excellent heat cycle characteristics.

  Next, specific examples of the present invention and evaluation results thereof will be described.

  In Examples and Comparative Examples described later, the surface roughness and bending strength of the surface-modified aluminum nitride sintered body substrate before joining the metal substrate were first measured. The bending strength of the aluminum nitride sintered body substrate was evaluated by an average value of a three-point bending test performed on 10 (n = 10) aluminum nitride sintered bodies.

  Next, the aluminum nitride-metal bonded substrate was subjected to measurement of the bending strength of the aluminum nitride-metal bonded substrate after thermal cycling, and measurement and evaluation of thermal cycle characteristics. The bending strength of the aluminum nitride-metal bonded substrate after the thermal cycle is 10 times (n = 10) after repeating the thermal cycle test with 1 cycle of 380 ° C. × 10 minutes 3 times. A three-point bending test was performed, and the average value was evaluated.

In addition, the thermal cycle characteristics are 10 aluminum nitride sintered bodies-Cu bonded substrates,
A thermal cycle test with 380 ° C. × 10 minutes as one cycle was repeated 35 times, and then evaluated based on a pass rate based on the number of cracks generated.

  A pass rate of 100% for thermal cycle characteristics evaluation means that no cracks are generated. On the other hand, a pass rate of 0% means that all the aluminum nitride sintered substrates have cracks. It means that I was doing.

Example 1
First, 5.0 parts by mass of Y2O3 powder having an average particle diameter of 1.0 μm is added as a sintering aid to aluminum nitride powder having an average particle diameter of 1.0 μm, and an appropriate amount of an organic binder and a solvent are added. And mixed to form a slurry. This raw material slurry was formed into a plate shape by the doctor blade method. A plurality of such aluminum nitride molded bodies were prepared, and the plurality of aluminum nitride molded bodies were overlapped with BN powder (release material) interposed between the molded bodies.

In this state, the aluminum nitride molded body was degreased at a temperature of 530 ° C. Next, these aluminum nitride degreased bodies after degreasing are fired under a condition of 1760 ° C. × 5 hours in a nitrogen gas atmosphere, whereby an aluminum nitride sintered body substrate (thermal conductivity = 170 W / mK, volume resistivity = 10 ¹² Ωcm, plate thickness 0.635 mm).

  Next, 0.15 MPa of abrasive slurry containing alumina (composition: Al 2 O 3) abrasive grains having an average particle diameter of 25 μm at a concentration of 15% by volume on both surfaces (all surfaces) of the obtained aluminum nitride sintered body. By subjecting the surface of the sintered body to a wet spraying process for 0.05 seconds by spraying from the nozzle so that the pressure applied to the treated surface of the aluminum nitride sintered body is 0.14 MPa. A surface-modified aluminum nitride sintered body substrate was obtained.

  Next, after applying an active metal brazing paste on both surfaces of the surface-modified aluminum nitride sintered body substrate, a Cu plate having a thickness of 0.3 mm is disposed, and this laminate is placed in a vacuum atmosphere at 800 ° C. Heat treatment was performed under the conditions of × 0.5 hours, and the target aluminum nitride sintered body-Cu bonded substrate was obtained by bonding the aluminum nitride sintered body substrate and the Cu plate via the active metal brazing material. . Such an aluminum nitride sintered body-Cu bonded substrate was subjected to the characteristic evaluation described later.

  In addition, the active metal brazing material paste used is an Ag-Cu eutectic brazing material (active metal brazing material) containing 4.0% by mass of Ti, which is made into a paste by adding an appropriate amount of an organic binder and a solvent. Such an active metal brazing paste was screen-printed on both surfaces of the surface-modified aluminum nitride sintered substrate so that the coating thickness was 30 μm.

Example 2
In Example 1 described above, the abrasive slurry containing alumina abrasive grains was pressurized with 0.20 MPa compressed air in the wet spraying process of the aluminum nitride sintered body substrate, and the treated surface of the aluminum nitride sintered body was An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure applied to was 0.19 MPa.

Example 3
In Example 1 described above, an abrasive slurry containing alumina (composition: Al 2 O 3) abrasive grains having an average particle diameter of 50 μm at a concentration of 15% by volume was applied to the wet jet treatment of the aluminum nitride sintered body substrate with a concentration of 0.1%. Aluminum nitride sintered body in the same manner as in Example 1 except that the pressure is applied with compressed air of 13 MPa and the pressure applied to the treated surface of the aluminum nitride sintered body is 0.12 MPa. A Cu bonded substrate was produced.

Comparative Example 1
In Example 1 mentioned above, the abrasive slurry containing alumina abrasive grains is pressurized with 0.22 MPa compressed air in the wet jet treatment of the aluminum nitride sintered body, and the aluminum nitride sintered body is treated on the surface to be treated. An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure was 0.21 MPa.

Comparative Example 2
In Example 1 described above, the abrasive slurry containing alumina abrasive grains is pressurized with 0.25 MPa compressed air in the wet spraying process of the aluminum nitride sintered body, and the surface to be treated of the aluminum nitride sintered body is applied. An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure was 0.24 MPa.

Comparative Example 3
In Example 1 described above, zircon abrasive grains having an average particle diameter of 60 μm were used for wet injection treatment of the aluminum nitride sintered body, and the abrasive slurry containing zircon abrasive grains was pressurized with 0.20 MPa compressed air, An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure applied to the treated surface of the aluminum nitride sintered body was 0.19 MPa.

Comparative Example 4
In Example 1 described above, the abrasive slurry containing alumina (composition: Al 2 O 3) abrasive grains having an average particle diameter of 50 μm at a concentration of 15% by volume was applied to the nozzle opening in the wet jet treatment of the aluminum nitride sintered body substrate. Using a nozzle with an area of 3 mm 2 and an area acting on the treated surface of the aluminum nitride sintered body substrate of 159 mm 2, the abrasive slurry is pressurized to 0.3 MPa with only a slurry pump without using compressed air, and aluminum nitride An aluminum nitride sintered body-Cu bonded substrate was produced in the same manner as in Example 1 except that the pressure applied to the treated surface of the sintered body was 0.06 MPa.

  As shown in Table 1, since the aluminum nitride sintered bodies according to Examples 1 and 2 collide with alumina abrasive grains having a hardness higher than that of aluminum nitride as the object to be processed with a higher impact force than before. It can be seen that a large compressive residual stress of −50 MPa or less is applied. Furthermore, in Example 3, a compressive residual stress of −50 MPa is obtained even when the pressure applied to the surface to be processed is low by using abrasive grains having a larger particle diameter than those in Examples 1 and 2. It can be seen that the sintered aluminum nitride-Cu bonded substrates according to Examples 1, 2, and 3 are excellent in bending strength and thermal cycle characteristics. On the other hand, in Comparative Examples 1 and 2 in which the wet abrasive treatment was performed by causing the alumina abrasive grains to collide with a stronger impact force, the aluminum nitride crystal particles on the surface to be treated were given a large compressive residual stress of −50 MPa or less. The surface roughness exceeds 0.2 μm, and both the bending strength and thermal cycle characteristics of the aluminum nitride sintered body-Cu bonded substrate are inferior. Furthermore, in Comparative Example 3 in which wet spraying was performed using zircon abrasive grains having a hardness lower than that of aluminum nitride, the surface roughness of the aluminum nitride sintered body surface is small, but a residual stress of −50 MPa or less is applied. Therefore, it can be seen that the bending strength and thermal cycle characteristics of the aluminum nitride sintered body-Cu bonded substrate are insufficient. Comparative Example 4 is a conventional honing process condition with a low impact force. Since the slurry slurry cannot be sufficiently pressurized only by the slurry pump, the pressure applied to the surface to be processed is small and a large compressive residual stress is applied. The aluminum nitride sintered body-Cu bonded substrate is inferior in both bending strength and thermal cycle characteristics.

Claims (5)

The treated surface of the aluminum nitride sintered body substrate, a liquid containing the abrasive grains that have a higher hardness than the aluminum nitride sintered body at a concentration of 10 to 30 vol%, together with the compressed air, against the surface to be processed was sprayed so that the pressure acting is 0.10 to 0.19 MPa, after modifying the target surface of the aluminum nitride sintered body substrate, and characterized in that bonding the metal substrate to the surface to be processed to, aluminum nitride - method for producing a metal junction board. 2. The method of manufacturing an aluminum nitride-metal bonded substrate according to claim 1, wherein the surface roughness of the surface to be processed is set to 0.1 μm or less by the spraying. By the jetting, sin using X-ray diffraction ² The method for producing an aluminum nitride-metal bonded substrate according to claim 1 or 2, wherein a residual stress value of the (112) plane of aluminum nitride on the surface to be processed obtained by the ψ method is set to -50 MPa or less. . The abrasive grains are at higher and 2500 or less than Vickers hardness 1060, wherein the average particle diameter of 10~50μm inorganic particles, aluminum nitride according to any one of claims 1 to 3 - metal A method for manufacturing a bonded substrate. The bonding between the metal substrate and the target surface of the aluminum nitride sintered body substrate, and performing through the brazing material having a melting point of 700 to 900 ° C., nitride according to any one of claims 1 to 4 A method for producing an aluminum-metal bonded substrate.