WO2026038576A1 - Carte de circuit imprimé en céramique - Google Patents

Carte de circuit imprimé en céramique

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Publication number
WO2026038576A1
WO2026038576A1 PCT/JP2025/028717 JP2025028717W WO2026038576A1 WO 2026038576 A1 WO2026038576 A1 WO 2026038576A1 JP 2025028717 W JP2025028717 W JP 2025028717W WO 2026038576 A1 WO2026038576 A1 WO 2026038576A1
Authority
WO
WIPO (PCT)
Prior art keywords
inclined portion
metal plates
metal plate
circuit board
ceramic circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/028717
Other languages
English (en)
Japanese (ja)
Inventor
寛正 加藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Niterra Materials Co Ltd
Original Assignee
Toshiba Materials Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toshiba Materials Co Ltd filed Critical Toshiba Materials Co Ltd
Publication of WO2026038576A1 publication Critical patent/WO2026038576A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate

Definitions

  • the embodiments described below generally relate to ceramic circuit boards.
  • Ceramic circuit boards are used as circuit boards on which semiconductor elements are mounted. Examples of ceramic substrates include silicon nitride substrates, aluminum nitride substrates, and aluminum oxide substrates.
  • Patent Document 1 discloses a ceramic circuit board in which a ceramic substrate and a metal plate are bonded via a bonding layer.
  • the size and hardness of the protruding portion of the bonding layer are controlled.
  • Patent Document 2 discloses a ceramic circuit board in which the width of the inclined portion is 0.1 to 0.5 times the thickness of the metal plate.
  • Patent Document 3 An etching process is used to control the size of the protruding portion of the bonding layer and the sloped shape of the side surface of the metal plate.
  • Patent Document 3 an etching process is shown in Japanese Patent No. 7278215 (Patent Document 3).
  • Patent Document 3 the protruding portion of the bonding layer and the metal plate are etched by combining the etching process of the bonding layer containing Ag and Cu, the etching process of the titanium nitride layer, and chemical polishing.
  • Patent Document 4 describes a metal-ceramic circuit board in which a recess is formed in the lower portion of the metal circuit board, carved out so as to curve inward on the side of the circuit pattern, and the distance between the upper ends of the linear portions of the opposing side surfaces of adjacent circuit patterns is greater than the distance between the lower ends of the linear portions.
  • the patent document also provides a metal-ceramic circuit board in which the ratio of the thickness T of the circuit patterns to the bottom-to-bottom distance D B of adjacent circuit patterns is 0.3 or more, more preferably 0.8 or more, 1 or more, and most preferably 2 or more.
  • the problem that this invention aims to solve is to provide a ceramic circuit board in which the gap between metal plates is narrowed.
  • a ceramic circuit board having multiple metal plates bonded to at least one surface of a ceramic substrate has a portion where T ⁇ P, where T is the thickness of each of the multiple metal plates and P is the shortest distance between adjacent metal plates among the multiple metal plates; the side of the multiple metal plates that faces the adjacent metal plate has at least a first inclined portion and a second inclined portion with different inclination angles, in that order from the ceramic substrate side; and the protrusion width of the upper ends of adjacent metal plates is ⁇ 40 ⁇ m or less.
  • FIG. 1 is a side cross-sectional view showing an example of a ceramic circuit substrate according to an embodiment.
  • FIG. 4 is a side cross-sectional view showing another example of a ceramic circuit board according to an embodiment.
  • FIG. 2 is a side cross-sectional view showing an example of an inclined portion of a front metal plate in the ceramic circuit board according to the embodiment.
  • FIG. 3 is a side cross-sectional view showing an example of a contact point of an inclined portion of a front metal plate in a ceramic circuit board according to an embodiment.
  • FIG. 4 is a side cross-sectional view illustrating the protrusion width of the front metal plate in the ceramic circuit board according to the embodiment.
  • FIG. 10 is a cross-sectional side view showing another example of the inclined portion of the front metal plate in the ceramic circuit board according to the embodiment.
  • FIG. 2 is a side cross-sectional view showing an example of a front metal plate having a step portion in a ceramic circuit substrate according to an embodiment.
  • FIG. 4 is a cross-sectional view showing a bonded body and the like for explaining an example of an etching step in the method for manufacturing a ceramic circuit board according to the embodiment.
  • FIG. 4 is a side cross-sectional view showing another example of a front metal plate in the ceramic circuit board according to the embodiment.
  • a ceramic circuit substrate having a plurality of metal plates bonded to at least one surface of a ceramic substrate includes: When the thickness of each of the plurality of metal plates is T and the shortest distance between adjacent metal plates among the plurality of metal plates is P, there is a portion where T ⁇ P; a side surface of each of the plurality of metal plates facing an adjacent metal plate has at least a first inclined portion and a second inclined portion having different inclination angles in this order from the ceramic substrate side; The protrusion width 9 of the upper end portions of the adjacent metal plates is ⁇ 40 ⁇ m or less.
  • reference numeral 1 to 4 show an example of a ceramic circuit board according to an embodiment as a side cross-sectional view (X-Z cross-section).
  • reference numeral 1 denotes a ceramic circuit board
  • reference numeral 2 denotes a ceramic substrate
  • reference numeral 3 denotes a front metal plate among the metal plates
  • reference numerals 31 and 32 denote the front metal plates among the front metal plates
  • reference numeral 4 denotes a rear metal plate among the metal plates
  • reference numeral 5 denotes a bonding layer
  • reference numeral 6 denotes a first inclined portion
  • reference numeral 7 denotes a second inclined portion
  • reference numeral 8 denotes the upper end of the front metal plate 3
  • reference numeral 9 denotes the protrusion width of the upper end 8
  • reference numeral 10 denotes the inclined portion contact line (the inclined portion contact point in the side cross-sectional view)
  • reference numeral 11 denotes the height difference of the inclined portion contact point 10
  • reference numeral T denote
  • the metal plate to which a circuit pattern has been imparted is referred to as the front metal plate 3, and the metal plate used as a heat sink is referred to as the back metal plate 4.
  • a circuit pattern may also be imparted to the back metal plate 4.
  • Figures 1 to 4 and 8 illustrate examples in which two front metal plates 3 are arranged in one direction (X-axis direction), there may be three or more front metal plates 3 arranged in one direction. The same applies when a circuit pattern is imparted to the back metal plate 4.
  • Figures 1 to 4 illustrate examples in which the ceramic substrate 2 and the metal plates 3 and 4 are joined via a bonding layer 5, the ceramic substrate 2 and at least one of the metal plates 3 and 4 may be joined without a bonding layer 5.
  • the ceramic circuit board 1 has multiple front metal plates 31, 32 bonded to at least one surface of the ceramic substrate 2 (front metal plate 3 in Figures 1 to 4).
  • the front metal plates 3 are arranged in a one-to-multiple, multiple-to-one, or multiple-to-multiple configuration in the X-axis and Y-axis directions.
  • T thickness of the front metal plate 3
  • P shortest distance between adjacent front metal plates 31, 32
  • the shortest distance P is not limited to the lower end of the metal plate as in Figure 1, but may be the upper end 8 or another location.
  • the shortest distance P between adjacent front metal plates 31, 32 is sometimes simply referred to as the shortest distance P.
  • T ⁇ P indicate locations where the shortest distance P between adjacent front metal plates 31, 32 is the same or is smaller than the thickness T of the front metal plates 31, 32.
  • the bonding area of the front metal plate 3 can be ensured. It is also possible to make the ceramic circuit board 1 smaller than when the bonding area of the front metal plate 3 is the same. Furthermore, when the size of the ceramic substrate 2 is the same, the bonding area of the front metal plate 3 can be increased.
  • the thickness T of the front metal plate 3 is the thickness of a single metal plate. When a plurality of front metal plates are stacked, the thickness T is the thickness of the front metal plate 3 bonded to the ceramic substrate 2 or the bonding layer 4. Furthermore, of the side surfaces of the front metal plate 31, the side surface facing the adjacent front metal plate 32 has at least a first inclined portion 6 and a second inclined portion 7 which have different inclination angles, in that order from the ceramic substrate 2 side. The side surfaces of the adjacent front metal plates 31, 32 have the first inclined portion 6 and the second inclined portion 7. The first inclined portion 6 and the second inclined portion 7 only need to differ in inclination angle by 1° or more. In the plane of FIGS.
  • the side surface of the front metal plate 31 which faces the adjacent front metal plate 32 is the right side of the front metal plate 31.
  • the side surface of the front metal plate 32 which faces the adjacent front metal plate 31 is the left side of the front metal plate 32.
  • the tangent line (contact point in the side cross section) between the first inclined portion 6 and the second inclined portion 7 is the inclined portion contact point 10.
  • the inclined portion closer to the ceramic substrate 2 (or bonding layer 5) is referred to as the first inclined portion 6.
  • the inclined portion closer to the upper end 8 of the front metal plate 3 is referred to as the second inclined portion 7.
  • the first inclined portion 6 and the second inclined portion 7 have a substantially linear shape when viewed in side cross section. At least one of the first inclined portion 6 and the second inclined portion 7 may have an R-shape when viewed in side cross section.
  • the first inclined portion 6 and the second inclined portion 7 may also be an inclined portion that combines a substantially linear shape and an R-shape when viewed in side cross section.
  • the protrusion width 9 of the upper end portions 8 (shown in FIG. 3) of adjacent front metal plates 31, 32 is ⁇ 40 ⁇ m or less.
  • the protrusion width 9 of the upper end portions 8 of the front metal plates 31, 32 is the sum of the length ( ⁇ 40 ⁇ m) that the upper end portions 8 protrude from a line in the Z-axis direction passing through the inclined portion contact point 10 of the front metal plate 31 and the length (+40 ⁇ m) that the upper end portions 8 recede from a line in the Z-axis direction passing through the inclined portion contact point 10.
  • the protrusion width 9 will be a negative value.
  • the protrusion width 9 will be a positive value.
  • FIG. 5 shows only the inclined portion on the right side, but the same consideration can be given to the case where the inclined portion is on the left side, using the Z-axis line as the reference.
  • the protrusion width 9 of the front metal plate 31 will be 0 (zero).
  • the protrusion width 9 of the upper end 8 is a value that depends on the angle ⁇ 2. Therefore, a protrusion width 9 of ⁇ 40 ⁇ m or less indicates that the angle ⁇ 2 is close to 90°. This allows the width between the upper ends 8 of adjacent front metal plates 31, 32 to be wide, even if T ⁇ P, thereby suppressing discharge and maintaining insulation. For this reason, the protrusion width 9 is preferably ⁇ 40 ⁇ m or less, and even more preferably ⁇ 20 ⁇ m or less. Furthermore, it is preferable that the protrusion width 9 does not extend beyond the lower end of the front metal plate 3 in the X-axis direction. If the protrusion width 9 extends along the X-axis beyond the lower end of the front metal plate 3, the gap between the upper end 8 of the front metal plate 31 and the upper end 8 of the front metal plate 32 will narrow, potentially reducing insulation.
  • the shortest distance P, the presence or absence of inclined portions 6, 7, and the protrusion width 9 of the upper end portion 8 of the front metal plates 31, 32 are observed using a cross-sectional SEM photograph of the ceramic circuit board 1. A cross section perpendicular to the thickness direction of adjacent front metal plates 31, 32 is observed. SEM photographs should be taken at 50x magnification.
  • the upper end portions 8 of adjacent front metal plates 31, 32 preferably have a shape with a radius of curvature of 15 ⁇ m or less. Having a radius of curvature of 15 ⁇ m or less means that the upper end portions 8 of the front metal plates 31, 32 are hardly curved, allowing for a wider flat surface on the surface of the front metal plates 31, 32. A wider flat surface allows for a wider mounting area for semiconductor elements and the like. For this reason, the upper end portions 8 of adjacent front metal plates 31, 32 preferably have a shape with a radius of curvature of 15 ⁇ m or less, and even 7 ⁇ m or less.
  • the radius of curvature is measured using the aforementioned SEM photograph (50x magnification).
  • the angles ⁇ 1, ⁇ 2, protrusion width 9, radius of curvature, etc. may also be calculated using imaging software. ImageJ, for example, can be used as imaging software.
  • the angle ⁇ 1 of the first inclined portion 6 and the angle ⁇ 2 of the second inclined portion 7 satisfy the following formula (1).
  • the angle ⁇ 1 shown in Fig. 3 is the angle between the bottom surface of the front metal plate 31 and the first inclined portion 6.
  • the angle ⁇ 2 is the angle between the upper side (surface) of the front metal plate 31 and the second inclined portion 7. Note that the front metal plate 32 is not shown in Fig. 3. ⁇ 1 ⁇ 2 ... (1)
  • the angle of the first inclined portion 6 be within a range of 20° to 75°
  • the angle of the second inclined portion 7 be within a range of 80° to 110°.
  • the first inclined portion 6 is an inclined portion that starts from the lower end of the side of the front metal plate 3 that contacts the ceramic substrate 2 or the bonding layer 5.
  • the second inclined portion 7 is an inclined portion that starts from the upper end 8 of the front metal plate 3.
  • the angle ⁇ 1 of the first inclined portion 6 is preferably in the range of 20° to 75°.
  • the angle ⁇ 1 of the first inclined portion 6 is sometimes simply referred to as the angle ⁇ 1.
  • the angle ⁇ 1 is preferably in the range of 20° to 75°, and even more preferably in the range of 30° to 60°.
  • the angle ⁇ 2 of the second inclined portion 7 is preferably within the range of 80° to 110°.
  • the angle ⁇ 2 of the second inclined portion 7 is sometimes simply referred to as the angle ⁇ 2.
  • the angle ⁇ 2 is preferably within the range of 80° to 110°, and even more preferably within the range of 85° to 100°.
  • angles ⁇ 1 and ⁇ 2 are measured using the aforementioned SEM photograph (50x magnification). A straight line is drawn at the location of the first inclined portion 6 and the second inclined portion 7, and the respective angles are determined. In this case, even if there are small irregularities (for example, irregularities of 5 ⁇ m or less) on the surface of the first inclined portion 6 and the second inclined portion 7, they are treated as straight lines.
  • the ratio D/T of the combined width D of the inclined portions 6 and 7 of the front metal plate 3 to the thickness T of the front metal plate 3 satisfies the following formula (2). D/T ⁇ 0.5...(2)
  • width D is the distance from the intersection of a line in the X-axis direction passing through the top end 8 of the front metal plate 31 and a line in the Z-axis direction passing through the edge of the bottom end of the front metal plate 31 to the top end 8 of the front metal plate 31.
  • a ratio D/T of 0.5 or less indicates that width D is 1/2 or less of the thickness T of the front metal plate 3. While there is no lower limit for the ratio D/T, a ratio of 0.1 or greater is preferred. If the ratio D/T is less than 0.1, the small width D may make it difficult to provide the first inclined portion 6 and the second inclined portion 7.
  • Width D is measured using the SEM photograph (50x magnification) described above.
  • the thickness T of the front metal plate 3 satisfies the following formula (3). T ⁇ 0.5mm...(3)
  • the thickness T of the front metal plate 3 is preferably 0.5 mm or more, and more preferably 0.8 mm or more. Because the front metal plate 3 has the first inclined portion 6 and the second inclined portion 7 with different inclination angles, it is possible to create a portion where T ⁇ P even if the front metal plate 3 is thick.
  • the upper limit of the thickness T of the front metal plate 3 is not particularly limited, but is preferably 5 mm or less. For this reason, the thickness T of the front metal plate 3 is preferably within a range of 0.5 mm to 5 mm, and more preferably 0.8 mm to 3 mm.
  • the height difference between the inclined portion contact point 10 between adjacent front metal plates 31, 32 is within the range of 100 ⁇ m.
  • the height difference between the inclined portion contact point 10 between adjacent front metal plates 31, 32 is sometimes simply referred to as the height difference between the inclined portion contact point 10.
  • the inclined portion contact point 10, which is the point of contact between the first inclined portion 6 and the second inclined portion 7, is observed in the SEM photograph (50x magnification) mentioned above. A line is drawn in the X-axis direction from the inclined portion contact point 10 on front metal plate 31 to the inclined portion contact point 10 on the opposing front metal plate 32.
  • the height difference between the X-axis direction line relating to front metal plate 31 and the X-axis direction line relating to front metal plate 32 is defined as the height difference 11 of the inclined portion contact point 10.
  • the difference in height (in the thickness direction of the front metal plate 3) between a line in the X-axis direction passing through the inclined portion contact point 10 of the front metal plate 31 and a line in the X-axis direction passing through the inclined portion contact point 10 of the front metal plate 32 is measured.
  • the height difference 11 of the inclined portion contact points 10 is 100 ⁇ m or less, this indicates that the side shapes of the adjacent front metal plates 31, 32 are similar. This makes it possible to improve the TCT characteristics even if there are locations where T ⁇ P.
  • the similarity of the side shapes of the adjacent front metal plates 31, 32 makes it possible to homogenize the effects of thermal expansion. For this reason, it is preferable that the height difference 11 of the inclined portion contact points 10 be 100 ⁇ m or less, and even more preferably within the range of 0 ⁇ m to 50 ⁇ m.
  • the inclined portions 6 and 7 may each have an R-shape.
  • the point where the radii of curvature of the first inclined portion 6 and the second inclined portion 7 differ by 50 ⁇ m or more be set as the inclined portion contact point 10.
  • the radii of curvature of the first inclined portion 6 and the second inclined portion 7 satisfy the following formula (4). Radius of curvature of first inclined portion 6 ⁇ Radius of curvature of second inclined portion 7 (4)
  • the radius of curvature of the first inclined portion 6 is preferably within the range of 600 ⁇ m or more and 850 ⁇ m or less.
  • the radius of curvature of the second inclined portion 7 is preferably within the range of 350 ⁇ m or more and 550 ⁇ m or less. Note that the front metal plate 32 is not shown in Figure 9.
  • the radius of curvature of the first inclined portion 6 is large within the range of 600 ⁇ m or more and 850 ⁇ m or less, this means that the first inclined portion 6 has a gentler slope than the second inclined portion 7. As a result, the angle ⁇ 1 of the first inclined portion 6 can also be made smaller.
  • the radius of curvature of the second inclined portion 7 is within the range of 350 ⁇ m or more and 550 ⁇ m or less, the slope becomes steep (close to vertical), and the angle ⁇ 2 of the second inclined portion 7 becomes larger.
  • the above formula (1) is satisfied as described above, and the thermal stress relaxation effect at the lower end of the side surface of the front metal plate 3 can be improved.
  • the radius of curvature was measured by drawing a circle along the slope of the R-shaped portion of the first inclined portion 6 and the second inclined portion 7 using an SEM photograph (50x magnification), and the difference in the size of the radii of the circles was taken as the radius of curvature.
  • the number of inclined portions on the side surface of the front metal plate 3 is not limited to two, and may be three or more.
  • Figure 6 shows an example of a front metal plate 31 with three inclined portions.
  • reference numeral 31 denotes the front metal plate
  • reference numeral 6 denotes the first inclined portion
  • reference numeral 7 denotes the second inclined portion
  • reference numeral 12 denotes the third inclined portion.
  • the height difference 11 between the inclined portion contact points 10 is 100 ⁇ m or less.
  • Angle ⁇ 3 is the angle formed between the line in the X-axis direction passing through the contact point 10 between the first inclined portion 6 and the third inclined portion 12 and the contact point with the third inclined portion 12, and is greater than angle ⁇ 1 and smaller than angle ⁇ 2.
  • the fourth inclined portion is provided on the second inclined portion 7 side of the third inclined portion 12.
  • the inclination angle of the fourth inclined portion is the angle formed between the line in the X-axis direction passing through the junction of the third inclined portion 12 and the fourth inclined portion and the junction of the fourth inclined portion. As the number of inclined portions becomes n, the angle of the inclined portion is represented by ⁇ n.
  • FIG. 7 shows an example of a front metal plate 31 having a step.
  • reference numeral 31 denotes the front metal plate
  • reference numeral 6 denotes the first inclined portion
  • reference numeral 7 denotes the second inclined portion
  • reference numeral 8 denotes the upper end of the front metal plate
  • reference numeral 13 denotes the step (protrusion)
  • reference numeral T denotes the thickness of the front metal plate 31.
  • the step 13 is integrated with the front metal plate 31.
  • the step 13 is not formed by joining another metal plate to the front metal plate 31. Providing the step 13 can improve the heat dissipation and current-carrying capacity of that portion.
  • the thickness T of the front metal plate 31 having the step 13 is the thickness up to the upper end 8 of the front metal plate 31, which is the starting point of the second inclined portion 7.
  • the side of the step 13 itself may or may not have an inclined portion.
  • the range of 50% to 100% of the shortest distance P between adjacent front metal plates 31, 32 may satisfy T>P.
  • the total length in the Y-axis direction of the side surfaces of the front metal plates 31, 32 adjacent in the X-axis direction that face each other is set to 100%, and the ratio of the length in the Y-axis direction of the side surfaces that satisfy T>P is shown. This means that the following formula (5) is satisfied. 50% ⁇ (length of side surface that satisfies T>P/total length of adjacent side surface) ⁇ 100 ⁇ 100% ... (5)
  • the side length satisfying T > P refers to the length of the side surface of the front metal plate 31 facing the adjacent front metal plate 32 in the X-axis direction, when viewed from above, that satisfies T > P, among the lengths of the side surface in the Y-axis direction of the front metal plate 31 facing the adjacent front metal plate 32.
  • the length of the side surface facing the adjacent side refers to the length in the Y-axis direction of the side surface of the front metal plate 31 facing the adjacent front metal plate 32. Note that the side surface of the front metal plate 31 facing the adjacent front metal plate 32 is not necessarily straight when viewed from above, and may be bent.
  • the length in the Y-axis direction of the side surface of the front metal plate 31 facing the adjacent front metal plate 32 includes the length of the bent portion.
  • the case where the front metal plate 31 faces the adjacent front metal plate 32 in the Y-axis direction is the same as the case where the front metal plate faces the adjacent front metal plate in the X-axis direction.
  • the ceramic circuit board 1 can be made smaller by increasing the number of sides where the shortest distance P between adjacent front metal plates 31, 32 satisfies T>P in relation to the thickness T of the front metal plate 3.
  • the distance between adjacent front metal plates 31, 32 i.e., the inter-pattern distance S
  • the proportion of the inter-pattern distance S relative to the thickness of the front metal plate 3 that satisfies S ⁇ T may be 25% or more and 100% or less.
  • the proportion of areas where the inter-pattern distance S is wider than the metal plate thickness T may be within the range of 30% or more and 100% or less.
  • the ratio Mm/Mc of the area Mc of one surface of the ceramic substrate 2 to the total area Mm of the front metal plate 3 bonded to that surface satisfies the following formula (6).
  • Mm/Mc ⁇ 0.8...(6) Mm is the total area of the bonding surface of the front metal plate 3 bonded to one surface of the ceramic substrate 2.
  • An Mm/Mc ratio of 0.8 or more indicates that the bonding area of the front metal plate 3 is 80% or more. This means that even if the bonding area of the front metal plate 3 is set to 80% or more, a location that satisfies T ⁇ P can be created. Because a location that satisfies T ⁇ P can be created while increasing the bonding area of the front metal plate 3, the ceramic circuit board 1 can be made smaller than conventional ceramic circuit boards to which metal plates of the same size or area are bonded.
  • the ceramic substrate 2 and the front metal plate 3 are bonded via a bonding layer 5, and it is preferable that the bonding layer 5 have a protruding portion that protrudes beyond the edge of the front metal plate 3.
  • the protruding length of the bonding layer protruding portion is preferably within the range of 10 ⁇ m to 150 ⁇ m. If the protruding length is less than 10 ⁇ m, the stress relief effect may be insufficient. If the protruding length exceeds 150 ⁇ m, poor conductivity with the adjacent metal plate may occur.
  • the side surface that does not face the adjacent front metal plate may or may not have multiple inclined portions with different inclination angles. What is effective is to control the inclination of the side surface that faces the adjacent front metal plate.
  • the inclined portions according to the embodiment may be provided on both the front metal plate 3 and the back metal plate 4.
  • the ceramic substrate 2 is preferably one selected from a silicon nitride substrate, an aluminum nitride substrate, an aluminum oxide substrate, and a zirconium oxide substrate.
  • the silicon nitride substrate has a thermal conductivity of 50 W/m ⁇ K or more, and preferably 80 W/m ⁇ K or more.
  • the silicon nitride substrate also has a three-point bending strength of 600 MPa or more, and preferably 700 MPa or more.
  • the thermal conductivity of an aluminum nitride substrate is 150 W/m ⁇ K or higher, and even 200 W/m ⁇ K or higher.
  • the three-point bending strength of an aluminum nitride substrate is approximately 300 to 450 MPa.
  • the three-point bending strength of an aluminum oxide substrate is approximately 300 to 450 MPa, but aluminum oxide substrates are less expensive than other substrates.
  • the thermal conductivity of an aluminum oxide substrate is approximately 20 to 30 W/m ⁇ K.
  • the three-point bending strength of a zirconium oxide substrate is high, approximately 550 MPa, but its thermal conductivity is approximately 30 to 50 W/m ⁇ K.
  • the thickness of the ceramic substrate 2 is preferably in the range of 0.2 mm to 3 mm, and even more preferably 0.2 mm to 1 mm. If the ceramic substrate is thinner than 0.2 mm, it may lack strength. If the ceramic substrate is thicker than 3 mm, it may become a thermal resistor, reducing its heat dissipation properties. Furthermore, because silicon nitride substrates have high strength, their thickness can be set to 0.2 mm to 1.0 mm, and even more preferably 0.2 mm to 0.5 mm. From the perspective of making the substrate thinner, it is preferable to use a silicon nitride substrate.
  • the metal plates 3 and 4 are preferably copper plates (including copper alloy plates) or aluminum plates (including aluminum alloy plates). Furthermore, the copper plates are preferably oxygen-free copper plates. Oxygen-free copper has a copper purity of 99.96 wt% or higher, as specified in JIS-H-3100. The thermal conductivity of copper is approximately 400 W/m ⁇ K, while the thermal conductivity of aluminum is approximately 240 W/m ⁇ K. Because copper has a higher thermal conductivity than aluminum, it improves heat dissipation. Furthermore, the aluminum plates are preferably pure aluminum. Pure aluminum is specified in JIS-H-4000. JIS-H-4000 corresponds to ISO 6361. JIS-H-3100 corresponds to ISO 197 and other standards. For this reason, it is preferable that the ceramic substrate 2 is a silicon nitride substrate having a thickness of 1.0 mm or less, and the metal plates 3 and 4 are copper plates having a thickness of 0.5 mm or more.
  • the bonding layer 5 is preferably an active metal bonding layer.
  • the bonding layer 5 is preferably an active metal bonding layer whose main component is either Ag or Cu.
  • the active metal may be one or more selected from titanium (Ti), zirconium (Zr), hafnium (Hf), and niobium (Nb).
  • the active metal brazing material composition mainly composed of Ag or Cu preferably contains 0% by mass or more and 60% by mass or less of Ag (silver), 15% by mass or more and 70% by mass or less of Cu (copper), and 1% by mass or more and 15% by mass or less of Ti (titanium) or TiH 2 (titanium hydride).
  • Ti and TiH 2 the total amount is preferably in the range of 1% by mass or more and 15% by mass or less.
  • the Ag amount is preferably in the range of 20% by mass or more and 60% by mass or less and the Cu amount is preferably in the range of 15% by mass or more and 40% by mass or less.
  • one or both of Sn (tin) and In (indium) may be contained in an amount of 1% by mass to 50% by mass.
  • the content of Ti or TiH2 is preferably in the range of 1% by mass to 15% by mass.
  • C (carbon) may be contained in an amount of 0.1% by mass to 2% by mass.
  • brazing filler metal components include Ag-Cu-Ti, Ag-Cu-Sn-Ti, Ag-Cu-Ti-C, Ag-Cu-Sn-Ti-C, Ag-Ti, Cu-Ti, Ag-Sn-Ti, Cu-Sn-Ti, Ag-Ti-C, Cu-Ti-C, Ag-Sn-Ti-C, and Cu-Sn-Ti-C. In may also be used instead of Sn. Both Sn and In may also be used.
  • the active metal brazing material may contain one or more elements selected from tungsten (W), molybdenum (Mo), and rhenium (Re) in an amount of 0.1% by mass to 10% by mass. Tungsten, molybdenum, and rhenium can control the fluidity of the active metal brazing material. Magnesium (Mg) may also be added to the active metal brazing material.
  • the bonding layer 5 is preferably an active metal bonding layer containing Al as a main component.
  • the active metal may be one or more selected from silicon (Si) and magnesium (Mg).
  • the active metal brazing filler metal containing Al as a main component is preferably an Al-Si or Al-Mg brazing filler metal, and the content of one or both of Si and Mg in the active metal brazing filler metal is preferably in the range of 0.1 mass % to 20 mass %.
  • the active metal brazing material is made into a paste to prepare an active metal brazing material paste.
  • the active metal brazing material paste is applied to the ceramic substrate 2, and a metal plate is placed on top of the active metal brazing material paste. When joining metal plates 3 and 4 to both sides, the active metal brazing material paste is applied to both sides, and then the metal plates 3 and 4 are placed.
  • the ceramic circuit board 1 by heating and bonding at a temperature in the range of 600°C to 960°C, a bonded body of the ceramic substrate 2 and the metal plates 3 and 4 can be obtained. By subjecting the bonded body to an etching process, the ceramic circuit board 1 according to the embodiment can be produced. Also, a direct bonding method may be used instead of the active metal bonding method.
  • the method for manufacturing the ceramic circuit board 1 according to the embodiment is not limited as long as it has the above-described configuration, but the following methods can be mentioned as methods for obtaining the ceramic circuit board 1 with a high yield.
  • a manufacturing method in which an etching process is performed on a bonded body obtained by the active metal bonding method will be described as an example.
  • An example of the manufacturing process is shown in FIG. 8.
  • reference numeral 3 denotes a metal plate
  • reference numeral 13 denotes a bonded body
  • reference numeral 14 denotes a resist.
  • FIG. 8 is a side cross-sectional (X-Z cross-sectional) view illustrating a bonded body, etc., to explain the process of forming inclined portions 6, 7 between adjacent front metal plates 31, 32.
  • FIG. 8 shows two adjacent metal plates, this number can be increased as needed.
  • Figure 8(a) shows the process of applying resist 14 to the joined body.
  • Resist 14 is an etching resist.
  • Resist 14 is provided in the areas on the front metal plate 3 where it is desired to impart a circuit pattern.
  • resists 14 are positioned so that the gap W between them is within the range of 0.2 to 0.6 times the shortest distance P. Note that in areas where it is not necessary to satisfy T ⁇ P, the gap between resists 14 can be any size.
  • Resist 14 may be applied to both the front metal plate 3 and the back metal plate 4.
  • FIG. 8(b) shows a process of etching the gaps between the resists 14.
  • FIG. 8(b) shows a process of etching a portion of the thickness T of the front metal plate 3.
  • a method of etching a portion of the thickness of the front metal plate 3, but not all of it, is called half etching.
  • the depth of one half etching is preferably within a range of 0.2 to 0.7 times the thickness T of the front metal plate 3.
  • the depth of the first half etching serves to form the second inclined portion 7 of the front metal plate 3.
  • the gap between the resists 14 within a range of 0.2 to 0.6 times the shortest distance P between adjacent front metal plates after manufacturing, the shortest distance P between the front metal plates formed by the first half etching can be made to be T ⁇ P. This allows the final shape to satisfy T ⁇ P, or even T>P.
  • a known etching solution can be used.
  • the etching solution can be an etching solution containing copper (II) chloride or ferric chloride.
  • Figure 8(c) shows a second etching process performed on a bonded body that has been subjected to the first half-etching.
  • Figure 8 illustrates a process in which the front metal plate 3 is etched twice to expose the bonding layer 5.
  • the number of times the front metal plate 3 is etched is not limited to two, i.e., the number of inclined portions is not limited to two, and etching may be performed three or more times.
  • Figure 8(c) shows a process in which etching is performed until the bonding layer 5 is exposed.
  • the first inclined portion 6 is formed in the second etching step. Furthermore, if three inclined portions are formed in three etching steps to expose the bonding layer 5, the third inclined portion 12 (shown in FIG. 6) is formed in the second etching step, and the first inclined portion 6 is formed in the third etching step.
  • the number of inclined portions formed is equal to the number of times etching is performed. While there is no particular upper limit to the number of etchings, five or less is preferable. Increasing the number of etchings will not provide any further benefits and may actually result in increased costs. Although the description assumes that one etching is performed per inclined portion, this is not limited to this case. Multiple etchings may be performed per inclined portion.
  • the angle ⁇ 1 of the first inclined portion 6 and the angle ⁇ 2 of the second inclined portion 7 can be made different.
  • Etching conditions include the etching time, etching solution (etchant concentration and components), and the presence or absence of ultrasound.
  • etching solution etchant concentration and components
  • ultrasound etchant concentration and components
  • Figure 8(d) shows the step of etching the bonding layer 5.
  • the bonding layer 5 is an active metal bonding layer
  • the etching method described in Patent Document 3 can be used.
  • a silicon nitride substrate serving as the ceramic substrate 2 and a copper plate serving as the front metal plate 3 are bonded using an active metal brazing material containing Ti
  • a titanium nitride layer is formed on the surface of the silicon nitride substrate. Because the titanium nitride layer is conductive, removing it by etching can prevent poor conductivity between adjacent copper plates.
  • the etching step for the bonding layer 5 also serves to control the size of the protruding portion of the bonding layer.
  • the side surface of the front metal plate 3 may also be etched. By etching the side surface of the front metal plate 3, the size of the protruding portion of the bonding layer of the front metal plates 31 and 32 can be more precisely controlled.
  • At least one of a chemical polishing step and a water washing step may be provided between a plurality of etching steps. 7, there is a method of joining a front metal plate 3 having a step portion 13 in advance. There is also a method of forming the step portion 13 by subjecting the joined front metal plate 3 to etching or cutting.
  • the ceramic circuit substrate 1 according to the embodiment can be manufactured through the steps described above using Figure 8.
  • Example 1 (Examples 1 to 6, Comparative Examples 1 and 2) A silicon nitride substrate with a thermal conductivity of 90 W/m ⁇ K and a three-point bending strength of 650 MPa was prepared as the ceramic substrate 2.
  • An active metal brazing filler metal containing Ti was used as the brazing filler metal.
  • Copper plates (front and back copper plates) with a thickness of 0.5 mm or more were used as the metal plates 3 and 4.
  • Bonded bodies 1 to 4 were prepared in which copper plates were bonded to both sides of a silicon nitride substrate via an active metal bonding layer. Of bonded bodies 1 to 4, bonded body 4 had a step portion 13 provided on the front copper plate. The size of the bonded bodies is as shown in Table 1.
  • etching process was carried out on bonded bodies 1 to 4.
  • half-etching of the front copper plate was repeated two to four times to expose the bonding layer 5.
  • the bonding layer 5 was then etched. Each half-etching performed multiple times refers to a process (batch method) from immersion in the etching solution to removal from the etching solution.
  • the bonding layer 5 was washed with water between the previous and subsequent half-etching processes.
  • the front copper plate was etched once to expose the bonding layer.
  • half-etching was performed four times to form two sloped portions. The gaps between the resists are as shown in Table 2.
  • a ceramic circuit board was fabricated using an etching process.
  • the following parameters were measured for the resulting ceramic circuit board: the shortest distance P between adjacent metal plates, the protrusion width 9, the radius of curvature of the upper end of the front metal plate, the angle ⁇ 1 of the first inclined portion, the angle ⁇ 2 of the second inclined portion, the angle ⁇ 3 of the third inclined portion, the difference in height between the inclined portion contact points, the combined width D of the multiple inclined portions formed on the front copper plate/the metal plate thickness T, the percentage of adjacent metal plates where the shortest distance P between adjacent metal plates is greater than T, and the size of the protrusion portion of the bonding layer.
  • the results are shown in Tables 3 and 4.
  • the protrusion width in Table 3 is the lower limit when the protrusion width value is positive, and the upper limit when the protrusion width value is negative, is 0 (zero).
  • ceramic circuit boards were produced in which the side surfaces satisfying T>P accounted for 50% or more of the entire side surface. Furthermore, in examples 1, 2, 3, and 6, in which half etching was performed twice, a first inclined portion 6 and a second inclined portion 7 were formed. Furthermore, in example 4, in which half etching was performed three times, a first inclined portion 6, a second inclined portion 7, and a third inclined portion 12 were formed. In example 5, in which half etching was performed four times, a first inclined portion 6 and a second inclined portion 7 were formed.
  • Comparative Example 1 there are no locations where T>P. This is because the bonding layer is exposed in a single etching. In Comparative Example 1, the shortest distance P is large, so Mm/Mc cannot be made 0.8 or more. Furthermore, in Comparative Example 2, although T>P is satisfied, there are no first and second inclined portions with different angles.
  • Examples 3-4 and Comparative Examples 1 and 2 a bonded body 3 was used.
  • the number of locations where T>P was increased, which made it possible to increase the bonding area of the copper plates 3, 4 to the ceramic substrate 2. In other words, this shows that if the bonding area of the copper plates 3, 4 is the same, it is possible to reduce the size of the ceramic circuit substrate 1.
  • Example 6 the first inclined portion 6 and the second inclined portion 7 have an R-shape (see Figure 9).
  • the radius of curvature of the first inclined portion 6 in Example 6 was 450 ⁇ m, while the radius of curvature of the second inclined portion 7 was 700 ⁇ m. Therefore, Example 6 satisfies the above formula (4).
  • TCT was performed on the ceramic circuit boards of the examples and comparative examples. TCT was performed 3,000 times, with one cycle consisting of -40°C x 30 minutes ⁇ room temperature x 10 minutes ⁇ 170°C x 30 minutes ⁇ room temperature x 10 minutes. After TCT, the ceramic circuit boards were observed for defects. The results are shown in Table 5.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Structure Of Printed Boards (AREA)

Abstract

Selon un mode de réalisation de la présente invention, une carte de circuit imprimé en céramique comporte une pluralité de plaques métalliques liées à au moins une surface d'un substrat en céramique. La carte de circuit imprimé en céramique possède une partie satisfaisant T ≥ P, où T est l'épaisseur de chaque plaque métallique de la pluralité de plaques métalliques et P est la distance la plus courte entre des plaques métalliques adjacentes parmi la pluralité de plaques métalliques. Des surfaces latérales en regard l'une de l'autre entre des plaques métalliques adjacentes parmi des surfaces latérales de la pluralité de plaques métalliques comportent au moins une première partie inclinée et une seconde partie inclinée, qui présentent des angles d'inclinaison différents, dans cet ordre à partir du substrat en céramique, et la largeur de saillie d'extrémités supérieures des plaques métalliques adjacentes est de ± 40 µm ou moins. De plus, les extrémités supérieures des plaques métalliques adjacentes ont de préférence un rayon de courbure de15 µm ou moins.
PCT/JP2025/028717 2024-08-16 2025-08-14 Carte de circuit imprimé en céramique Pending WO2026038576A1 (fr)

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JP2024-135843 2024-08-16
JP2024135843 2024-08-16

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WO2026038576A1 true WO2026038576A1 (fr) 2026-02-19

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019221174A1 (fr) * 2018-05-16 2019-11-21 株式会社 東芝 Carte de circuit en cuivre céramique et procédé de fabrication associé
WO2020209121A1 (fr) * 2019-04-09 2020-10-15 日本碍子株式会社 Substrat lié et procédé de production de substrat lié
JP2023091914A (ja) * 2021-12-21 2023-07-03 Ｄｏｗａメタルテック株式会社 金属－セラミックス接合基板の製造方法、および、金属－セラミックス接合基板

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019221174A1 (fr) * 2018-05-16 2019-11-21 株式会社 東芝 Carte de circuit en cuivre céramique et procédé de fabrication associé
WO2020209121A1 (fr) * 2019-04-09 2020-10-15 日本碍子株式会社 Substrat lié et procédé de production de substrat lié
JP2023091914A (ja) * 2021-12-21 2023-07-03 Ｄｏｗａメタルテック株式会社 金属－セラミックス接合基板の製造方法、および、金属－セラミックス接合基板

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