JP6642146B2 - Silicon nitride based ceramic aggregate substrate and method of manufacturing the same - Google Patents

Description

  The present invention relates to a silicon nitride-based ceramic aggregate substrate for forming a large number of circuit boards and a method for manufacturing the same.

  Ceramic substrates are used for circuit boards used for semiconductor modules, power modules, etc. in terms of thermal conductivity, insulation, strength, and the like, and metal circuit boards such as Cu and Al and metal radiating plates are used for the ceramic substrates. Joined to form a circuit board. Alumina and aluminum nitride have been widely used as ceramic substrates for such circuits, but recently, silicon nitride with high strength and improved thermal conductivity has been used so that it can be used in more severe environments. It has become.

  The circuit board is made by bonding a metal plate such as a Cu plate to a single ceramic aggregate substrate large enough to cut out a large number of ceramic substrates for circuit by an active metal brazing method or a direct bonding method, and etching the metal circuit board. After forming a plate and a metal radiator plate, mass production is performed by a method of dividing a ceramic aggregate substrate into a predetermined size.

  As a method of dividing the ceramic aggregate substrate into individual circuit boards, a concave portion or a groove is formed in the ceramic aggregate substrate by laser processing before joining a Cu plate or the like, and the ceramic aggregate substrate with the circuit board is bent after joining, A method of dividing by a concave portion or a groove is employed.

  WO 2009/154295 (Patent Literature 1) discloses that a circuit board can be easily and reliably divided by bending to take a large number of circuit boards, but is continuously connected to one or both sides of a ceramic sintered substrate so as not to be carelessly divided during handling. Disclosed is a rectangular ceramic aggregate substrate in which a groove is provided by laser processing, and a difference Δd between a maximum depth portion and a minimum depth portion in a length direction of the continuous groove is within a range of 10 to 50 μm. . However, it was found that when the ceramic substrate was divided along a continuous groove formed by laser processing near the four sides of the ceramic substrate, cracks and chips were likely to occur at the corners of the resulting rectangular ceramic assembly substrate.

  Japanese Unexamined Patent Application Publication No. 2008-198905 (Patent Document 2) shows a collective substrate 300 for taking a large number of ceramic substrates 301, as shown in FIG. 13, from a plurality of non-through holes formed by laser scribing. A collective substrate 300 having a lattice-shaped divided groove 303 and a diamond-shaped chamfered through hole 304 formed at the intersection of the divided grooves 303 by laser cutting is disclosed. Reference numeral 302 denotes a surplus portion serving as a disposal allowance. However, when a large number of diamond-shaped chamfered through holes 304 are formed in the collective substrate 300, large thermal stress due to laser cutting is concentrated near the diamond-shaped chamfered through holes 304, and not only is the crack easily generated from the chamfered portion, Since the hollowed-out volume is large, the entire collective substrate 300 may be warped, and the alignment of the collective substrate 300 may be inaccurate. In addition, it takes time to form the diamond-shaped chamfered through-hole 304 by laser cutting, and there is a problem that productivity is not good. Further, the technology of Patent Document 2 is a technology for manufacturing individual circuit boards from a ceramic aggregate substrate, and is not a technology for manufacturing a ceramic aggregate substrate from a ceramic sintered substrate.

  Japanese Unexamined Patent Application Publication No. 2011-233687 (Patent Document 3) discloses, as shown in FIG. 14, a plurality of rectangular wiring board regions 403 (regions where wiring conductors 404 are provided) provided on a motherboard 401 and each wiring A dummy region 402 formed around the substrate region 403, a dividing groove 412 formed along a boundary between the wiring substrate region 403 and the dummy region 402, and a dummy region 402 formed over the wiring substrate region 403 and the dummy region 402. A multi-cavity wiring board having a triangular through hole 413 and a cut 414 penetrating the motherboard 401 from the through hole 413 to the division groove 412 (412x, 412y) is disclosed. However, it takes too much time to form the triangular through holes 413 and the cuts 414, and the productivity is not good. In addition, similarly to Patent Document 2, when the triangular through hole 413 is formed by laser processing, not only a large thermal stress is concentrated, but also a large volume is cut out, so that the entire mother substrate 401 is warped. . Further, the technique of Patent Document 3 is also a technique for manufacturing individual wiring boards from a collective board, and is not a technique for manufacturing a collective board from a sintered board.

WO 2009/154295 JP 2008-198905 A JP 2011-233687 A

  Accordingly, an object of the present invention is to provide a method for easily and reliably producing a silicon nitride-based ceramic aggregate substrate in which cracks and chips at corners are suppressed from a silicon nitride-based ceramic sintered substrate, and a silicon nitride-based substrate obtained by such a method. It is to provide a ceramic assembly substrate.

  In view of the above object, as a result of earnest research, the inventors formed continuous groove-shaped side break lines composed of scribe holes and slit-shaped corner break lines on a silicon nitride-based ceramics sintered substrate, The present inventors have found that, when the substrate is divided along the side break lines, the silicon nitride-based ceramic aggregate substrate can be separated without cracking or chipping, and arrived at the present invention.

That is, the method of the present invention for producing a silicon nitride-based ceramics aggregate substrate of a predetermined size from a rectangular silicon nitride-based ceramics sintered substrate includes:
On the outer edge of the silicon nitride-based ceramics sintered substrate, side break lines corresponding to the four sides of the silicon nitride-based ceramic aggregate substrate are formed, and both of the adjacent side break lines are located near the intersection of the adjacent side break lines. Form a corner break line that intersects with
The depth of the side break line is not more than half the thickness of the silicon nitride ceramic sintered substrate,
The corner break line is a slit penetrating the silicon nitride ceramic sintered substrate,
By folding the silicon nitride-based ceramic sintered substrate along the side break line, a portion corresponding to the silicon nitride-based ceramic aggregate substrate inside the side break line and the corner break line and an outer side margin portion are formed. It is characterized in that it is divided.

  The side break line is preferably the same length as the corresponding side (extends to the opposite side of the substrate), but there is no problem in removing the side margin as long as the adjacent side break lines intersect. Since it is not, it may be shorter than the corresponding side. This is particularly true when the width of the side margin is about 5% or less of the length of the substrate.

  Since the sintered substrate is a brittle material, small chips or cracks of up to several mm at maximum are likely to occur starting from corners and sides (edges). In addition, uneven heat shrinkage during sintering not only increases dimensional variation, but also tends to cause defects such as wavy edges. If the defects at the sides and corners are left as they are, new chips starting from the defects occur during handling, causing existing cracks to progress or missing chips to become foreign substances. In addition, there is a problem in the accuracy of positioning the substrate in the next step. In order to remove these sintering defects in advance, it is preferable to remove the side margins including the defects with a width of, for example, about 3 to 6 mm from the outer periphery of the substrate. The silicon nitride-based ceramic aggregate substrate is smaller than the sintered substrate by the amount corresponding to the removal of the side margin.

  Preferably, the side break lines and the corner break lines are formed by a fiber laser.

  It is preferable to form the angular break line by repeating scanning of the fiber laser beam spot a plurality of times.

  Preferably, both ends of the corner break line extend beyond the intersection with the side break line.

  The length of each end of the corner break line extending beyond the intersection with the side break line (the length of entry of the corner break line into the side margin) is larger than the diameter of the fiber laser beam spot. And less than 3.5 mm.

  The intersection angle between the corner break line and the side break line is preferably 30 to 60 °.

  The silicon nitride-based ceramic aggregate substrate of the present invention is a rectangular silicon nitride-based ceramic aggregate substrate having a silicon nitride-based ceramic substrate portion having a large number of circuit forming portions, an edge portion, and chamfered portions at four corners. The arithmetic mean surface roughness Ra of the chamfered portion is 0.1 μm or more and less than 0.3 μm.

The silicon nitride-based ceramic aggregate substrate of the present invention is a rectangular silicon nitride-based ceramic aggregate substrate having a silicon nitride-based ceramic substrate portion having a large number of circuit forming portions, an edge portion, and chamfered portions at four corners. ,
The wall surface of the chamfered portion has an arithmetic average surface roughness Ram at the substrate thickness direction center portion, has an arithmetic average surface roughness Rao at the substrate thickness direction opening side, and Ram is smaller than Rao. .

  According to the present invention, a side break line is formed at the outer edge of a silicon nitride-based ceramics sintered substrate, and a corner break line that intersects both of them is formed near an intersection of adjacent side break lines, and the depth of the side break line is Is set to less than half the thickness of the silicon nitride-based ceramics sintered substrate, and the corner break lines are slits penetrating the silicon nitride-based ceramics sintered substrate, so that the silicon nitride-based ceramics sintered substrate is folded along the side break lines. Thus, when the outer margin portion is divided and removed, the occurrence of cracks and chips at the corners of the silicon nitride-based ceramic aggregate substrate is suppressed, thereby improving the production yield of the silicon nitride-based ceramic aggregate substrate.

It is a top view which shows an example of the method of this invention which manufactures a silicon nitride type ceramic aggregate substrate. It is a partial enlarged plan view showing a corner break line. FIG. 4 is a partially enlarged plan view showing a state of forming a corner break line. FIG. 4 is a sectional view taken along line AA of FIG. 3. FIG. 3 is a partially enlarged cross-sectional view showing a chamfered surface of a silicon nitride-based ceramic aggregate substrate. FIG. 2 is a plan view showing a silicon nitride-based ceramics aggregate substrate in which a plurality of first copper plates serving as circuit boards are joined to one surface. FIG. 4 is a bottom view showing a silicon nitride-based ceramic aggregate substrate in which a plurality of second copper plates serving as heat sinks are joined to the other surface. It is a top view showing a circuit board. It is a partial enlarged plan view showing another example of a corner break line. FIG. 3 is a partially enlarged plan view showing a silicon nitride-based ceramics aggregate substrate having burrs in a side surface region near a chamfered surface. 9 is a plan view illustrating the manufacturing method of Comparative Example 1. FIG. FIG. 3 is a plan view showing a silicon nitride-based ceramics aggregate substrate in which cracks are formed. 13 is a plan view illustrating the manufacturing method of Comparative Example 2. FIG. FIG. 3 is a plan view showing a silicon nitride-based ceramic aggregate substrate in which cracks have occurred. FIG. 1 is a plan view showing a ceramic aggregate substrate disclosed in Japanese Patent Application Laid-Open No. 2008-198905. 1 is a plan view showing a wiring board disclosed in Japanese Patent Application Laid-Open No. 2011-233687.

  Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. Further, the description of each embodiment can be applied to other embodiments unless otherwise specified.

[1] Method for Manufacturing Silicon Nitride-Based Ceramics Assembly Substrate The method of the present invention for manufacturing a silicon nitride-based ceramics assembly substrate will be described with reference to FIGS.

(1) Formation of Side Break Line As shown in FIG. 1, a side break line 13 is formed at each outer edge 10 of the rectangular silicon nitride-based ceramics sintered substrate 1. In order to facilitate division of the silicon nitride-based ceramics sintered substrate 1, each side break line 13 preferably extends to the opposite side 11 (extends over the entire length of each side of the substrate 1). Adjacent side break lines 13 along four sides 11 of the rectangular silicon nitride-based ceramics sintered substrate 1 intersect at an intersection 15. A portion 16 between each side break line 13 and each side 11 of the silicon nitride-based ceramics sintered substrate 1 is a portion to be removed by division along each side break line 13, and is referred to as a "side margin portion". A triangular region 17 surrounded by adjacent side break lines 13 and one corner break line 14 (described later) intersecting both of them is referred to as a “corner margin portion”. A rectangular region having a chamfer surrounded by the four side break lines 13 and the four corner break lines 14 corresponds to the silicon nitride-based ceramic aggregate substrate 12.

Each side break line 13 is preferably formed by continuously irradiating the inside of each outer edge portion 10 of the silicon nitride-based ceramics sintered substrate 1 while slightly moving the beam spot of the fiber laser. Microscopically, the side break line 13 is a continuous groove in which a large number of scribe holes formed by the beam spot of the fiber laser overlap. The fiber laser can focus on a beam spot smaller than the CO ₂ laser and the YAG laser, and has a large depth of focus, high conversion efficiency, and high output. The continuous groove formed by the fiber laser has a smaller thermal effect than the intermittent hole formed by the YAG laser and the CO ₂ laser, and can reduce the surface oxidized region and the melting and scattered matter around the groove.

On the other hand, a relatively deep intermittent hole is formed by irradiation with the YAG laser and the CO ₂ laser, so that the periphery of the groove is greatly affected by heat. For this reason, the surface of the silicon nitride-based ceramics sintered substrate 1 is often widely oxidized, or the thermal energy of the laser causes oxides such as Si and SiO ₂ , and a melt such as a sintering aid to scatter around. . As a result, microcracks may occur on the substrate surface, which may cause a decrease in bonding reliability or a bonding failure due to void formation.

  The width of the side break line 13 is preferably 300 μm or less, more preferably 10 to 100 μm, and most preferably 20 to 80 μm. The width of each side break line 13 is measured at the same height as the substrate surface. Further, the depth of the side break line 13 is not more than half the thickness of the silicon nitride-based ceramics sintered substrate 1, preferably 1/8 to 1/2, more preferably 1/4 to 1/2. is there. When the thickness of the silicon nitride-based ceramics sintered substrate 1 is, for example, 0.32 mm, the depth of the side break line 13 is preferably 40 to 160 μm, more preferably 80 to 160 μm.

  Since the side break line 13 having the above-mentioned size is long, it is preferable to form the fiber laser beam spot by one scanning in consideration of productivity, but it is needless to say that the scanning of the fiber laser beam spot may be repeated plural times.

  In the illustrated example, the side break lines 13 are the same length as the corresponding sides 11 (extend to the opposing sides 11 and 11 of the substrate 1), but the adjacent vertical and horizontal side break lines 13 and 13 intersect. As long as it is possible, it may be shorter than the corresponding side 11. In this case, when attempting to fold one side margin portion 16, since the side break line 13 does not extend to a portion beyond the intersection 15, a part of the side of the substrate 1 is folded without the side break line 13. become. However, that portion is sufficiently separated from the corner break line 14 so that the surface roughness of the chamfered surface 140 formed by the corner break line 14 is not affected. When the side break line 13 is shorter than the corresponding side 11, the width of the side margin 16 is preferably about 5% or less of the length of the substrate.

(2) Formation of corner break lines When the silicon nitride-based ceramics sintered substrate 1 is divided into the silicon nitride-based ceramics-assembled substrate 12 and the side margin portion 16, cracks or chips are formed at the four corners of the silicon nitride-based ceramics-assembled substrate 12. In order to prevent the occurrence, each corner break line 14 that intersects both of the side break lines 13 is formed near each intersection 15 of the adjacent side break lines 13. Each corner break line 14 is a slit that penetrates the silicon nitride ceramic sintered substrate 1. By forming the slit-shaped corner break lines 14 on the substrate, stress concentration at the four corners of the silicon nitride-based ceramic aggregate substrate 12 is reduced.

  When the thickness of the silicon nitride-based ceramics sintered substrate 1 is, for example, 0.32 mm, the width of the corner break line 14 is preferably 10 to 200 μm, more preferably 20 to 150 μm, and most preferably 30 to 100 μm. The length of the corner break line 14 is preferably 2.8 to 8.4 mm, more preferably 3.0 to 8.0 mm, and most preferably 3.5 to 7.5 mm. The intersection angle, which is the inclination of the corner break line 14 with respect to the side break line 13, is preferably 30 to 60 °. If the intersection angle is too small, the ends of the side margins may remain without breaking when dividing, resulting in burrs. Further, since the corner break line 14 intersects the two orthogonal side break lines 13, the upper limit of the intersection angle is preferably set to 60 ° due to the extra angle. In particular, when the crossing angle is 45 °, the silicon nitride-based ceramics sintered substrate 1 can be used without waste.

  Although the step of forming the side break lines 13 may be performed after the step of forming the corner break lines 14, the step of forming the corner break lines 14 is preferably performed after the step of forming the side break lines 13. In the latter case, the intersection 15 of the side break lines 13 can be used as a reference point when forming the corner break lines 14, so that the processing accuracy of the corner break lines 14 is improved.

  As shown in FIG. 2, the corner break lines 14 preferably extend (extend) into the side margin portions 16 from the adjacent side break lines 13 by the length L1. The extension length L1 of the corner break line 14 is preferably larger than the diameter of the fiber laser beam spot used to form the corner break line 14 and less than 3.5 mm. If the extension length L1 is larger than the diameter of the fiber laser beam spot, it is possible not only to suppress the generation of burrs near the corner break line 14 but also to prevent the corner margin portion 17 from remaining on the chamfered portion 22 (corner margin). It is more preferable from the viewpoint of productivity because it is not necessary to fold the part manually and there is no need for reworking). As shown in FIG. 8, if there is a burr 27 on the edge 21 of the silicon nitride-based ceramics assembly substrate 12, it is not possible to perform accurate positioning at the edge 21 in the circuit board forming step. On the other hand, if the advance length L1 is 3.5 mm or more, the side margin portion 16 is likely to be divided into a plurality of pieces between the corner break lines 14, and the number of steps for removing the scattered pieces may increase.

  Each of the slit-shaped corner break lines 14 penetrating the silicon nitride-based ceramics sintered substrate 1 is preferably formed by repeating scanning of the fiber laser beam spot a plurality of times (for example, 10 times). By repeating the scanning of the fiber laser beam spot a plurality of times, the scribe holes are formed little by little until they penetrate the silicon nitride-based ceramics sintered substrate 1. For this reason, the formation of cracks and particulate protrusions due to thermal shock on the inner surface is suppressed, and when the silicon nitride-based ceramics sintered substrate 1 is divided into the silicon nitride-based ceramic aggregate substrate 12 and the side margin portion 16 and the angular margin portion 17, In addition, crack growth and chipping can be suppressed. The particulate projections are obtained by reattaching the silicon nitride-based ceramics removed by the irradiation of the fiber laser beam, and are likely to occur when the irradiation energy in one scan of the fiber laser beam spot is high. Since the particulate projections may fall off from the silicon nitride-based ceramic aggregate substrate 12 in the process of forming the circuit board and cause a problem in the circuit board, it is preferable to suppress the generation of the particulate projections as much as possible.

The inner surface of the corner break line 14 with few cracks and particulate protrusions (the wall of the chamfer)
When forming the angular break line 14 by multiple scans, fiber laser beam spots from low to relatively high incident energy to the processing part can be used, and when the incident energy is high, the scanning speed can be increased Therefore, the arithmetic average surface roughness Ra is as small as 0.1 μm or more and less than 0.3 μm, and the processing time can be shortened. On the other hand, under the condition that the angular break line 14 is formed by one scan, the arithmetic average surface roughness Ra of 0.5 μm or more and less than 1.0 μm is obtained by irradiating the fiber laser beam spot with the incident energy density to the processing portion suppressed. be able to. However, since the angle break line must penetrate the substrate, the scanning speed of the beam spot cannot be increased, so that many cracks and particulate protrusions due to thermal shock are likely to be formed. The arithmetic average surface roughness Ra is defined in JIS B0601: 2001.

  As shown in FIG. 3, the diameter of the beam spot 14a of the fiber laser forming the corner break line 14 is preferably 10 to 100 μm. When forming the corner break line 14 by performing multiple scans in order to smoothly finish the inner wall surface of the corner break line 14, the moving speed of the beam spot 14a (also referred to as a scanning speed) should be 150 mm / sec or more. And more preferably 150 to 550 mm / sec. The irradiation pitch of the beam spot 14a is, for example, 3 μm.

  Since the laser intensity distribution is close to a Gaussian distribution (the central part has high intensity) and the groove processing proceeds from the central part with high intensity, as shown in FIG. The part where the irradiation energy of the fiber laser is small is easy to be processed) is wider than the center part (the irradiation energy of the fiber laser is large). As shown in FIG. 4 (b), the wall surface (chamfered surface) 140 of the chamfered portion formed by the slit-shaped corner break line 14 is opened in the thickness direction of the substrate 1 at the side wall surface 140o (laser irradiation side) and the center. When the wall surface portion 140m and the through wall surface portion 140e (the side opposite to the opening side wall surface portion 140o) are divided into three equal parts, the arithmetic average surface roughness Rao of the opening side wall surface portion 140o is greater than the arithmetic average surface roughness Ram of the central wall surface portion 140m. It is preferable to satisfy the relationship of Rao> Ram. The arithmetic average surface roughness Rao is measured along the longitudinal direction of the corner break line 14 at a depth of 20 to 30 μm from the surface of the silicon nitride-based ceramics sintered substrate 1. The arithmetic average surface roughness Ram is measured along the longitudinal direction of the corner break line 14 at the center of the silicon nitride-based ceramics sintered substrate 1 in the thickness direction.

  The ceramic melt is discharged with the progress of the processing of the slit-shaped corner break line 14, but in the initial stage of the processing, the ceramic melt is discharged from the opening side which is the laser incident surface side, and the corner break line 14 is made of silicon nitride. When penetrating through the ceramic sintered substrate 1, the ceramic melt is also discharged from the penetrating side. Since the melting point of the ceramic melt is high, solidification starts before the ceramic melt is completely discharged, and reattaches to the opening side wall surface portion 140o and the penetrating side wall surface portion 140e to roughen the surface. In the opening side wall surface portion 140o, as the width of the angle break line 14 becomes wider, processing becomes easier in a portion where the energy density of the fiber laser beam is low. In the part 140m, the rate of processing in a portion where the energy density of the laser beam is high increases. As a result, the degree of melting and flattening of the silicon nitride-based ceramics sintered substrate 1 is larger in the central wall surface portion 140m than in the open side wall surface portion 140o, and it is estimated that the relationship Rao> Ram is established.

  When the slit is formed by repeating the scanning of the beam spot of the fiber laser a plurality of times, the heat input into the silicon nitride-based ceramics sintered substrate 1 per time is longer than when the slit is formed by one scanning of the beam spot. Therefore, the occurrence of fine cracks due to thermal shock at the central wall portion 140m is small, and the surface roughness is also small. Therefore, the dimensional accuracy and reliability of the corner break lines 14 are improved.

(3) Division of Silicon Nitride Ceramic Sintered Substrate When the silicon nitride ceramic sintered substrate 1 on which the side break lines 13 and the corner break lines 14 are formed is folded along each side break line 13, the silicon nitride ceramic The substrate 1 is divided into a silicon nitride-based ceramic aggregate substrate 12, a side margin portion 16 and a corner margin portion 17. The corner margins 17 formed by the adjacent side break lines 13 and the corner break lines 14 are connected to the side margins 16 via the respective side break lines 13, so that the silicon nitride-based ceramics assembly together with the side margins 16 It is separated from the substrate 12. Therefore, there is no need to separately provide a step of separating the corner margin portion 17.

[2] Silicon nitride-based ceramic aggregate substrate As shown in FIG. 5A, a silicon nitride-based ceramic aggregate substrate 12 of the present invention includes a silicon nitride-based ceramic substrate portion 20 having a large number of circuit forming portions 19 and an edge portion 21. And having chamfered portions 22 at the four corners, and the wall surface (chamfered surface) of the chamfered portion 22 obtained by the corner break line 14 also preferably has an arithmetic average surface roughness Ra of 0.1 μm or more and less than 0.3 μm. . The thickness of the silicon nitride-based ceramic aggregate substrate 12 is preferably 0.2 to 1.0 mm, more preferably 0.25 to 0.65 mm. The fracture toughness value of the silicon nitride-based ceramic aggregate substrate 12 is preferably at least 5.0 MPa · m ^1/2, more preferably 5.0 to 7.5 MPa · m ^1/2 .

  Further, since the corner break lines 14 are slit-shaped, deformation such as warpage of the silicon nitride-based ceramics sintered substrate 1 is smaller than that of the diamond-shaped or triangular through-holes described in Patent Documents 2 and 3. It is suppressed, and the alignment by the outer edge or the mark of the silicon nitride-based ceramics sintered substrate 1 can be performed accurately. Furthermore, by simply forming a continuous groove-shaped side break line 13 composed of scribed holes and a slit-shaped corner break line 14, the silicon nitride-based ceramics sintered substrate 1 can be accurately divided by dividing it along the side break line 13. Since the silicon nitride-based ceramic aggregate substrate 12 can be separated, the cost is low and the productivity is high.

[3] Method of Forming Circuit Board As shown in FIGS. 5 (a) and 5 (b), a plurality of first copper plates 23a forming a circuit are joined to one surface of the silicon nitride-based ceramic aggregate substrate 12. Then, a plurality of second copper plates 23b serving as heat radiating plates are joined to the other surface at positions matching the first copper plate 23a. On the surface of the silicon nitride-based ceramic aggregate substrate 12 to which the first copper plate 23a is bonded, a plurality of second break lines 24 for dividing into individual circuit forming portions (portions where circuit boards are provided) 19 are formed. The second break line 24 is formed of a scribe hole formed by continuously irradiating the beam spot of the fiber laser while moving it slightly, similarly to the side break line 13, and has the same width and depth as the side break line 13. It is sufficient if it has.

  By folding the silicon nitride-based ceramic aggregate substrate 12 along the second break line 24, the silicon nitride-based ceramic aggregate substrate 12 is divided into a silicon nitride-based ceramic substrate portion 20 and an edge portion 21. The edge 21 is removed as a margin, and the circuit board 28 shown in FIG. 6 is obtained. However, in FIG. 6, reference numeral 23a 'indicates a circuit board made of a first copper plate, and reference numeral 25' indicates a ceramic substrate obtained by dividing a ceramic substrate portion according to the circuit board 23a '.

  Hereinafter, the present invention will be specifically described based on examples. In addition, this invention is not necessarily limited to the following example.

Example 1
Sheet-shaped molding containing 20% by mass of binder resin component for 100% by mass of ceramic component consisting of 95% by mass of silicon nitride powder, 2% by mass of MgO powder, and 3% by mass of Y ₂ O ₃ powder The body was sintered at a maximum temperature of 1850 ° C. for 5 hours to produce a silicon nitride-based ceramics sintered substrate 1 having a thickness of 0.32 mm and a length of 150 mm and a width of 200 mm. Using a fiber laser (wavelength: 1.06 μm, output: 100 W, oscillation frequency: 50 kHz), four side break lines 13 having a width of 35 μm and a depth of 120 μm 13 are formed inside the outer edge 10 of the silicon nitride-based ceramics sintered substrate 1. Was formed. The width of the side margin 16 was 5 mm in the longitudinal direction of the silicon nitride-based ceramics sintered substrate and 6 mm in the lateral direction of the silicon nitride-based ceramics sintered substrate. Further, the same fiber laser was used to form a slit-shaped corner break line 14 under the following conditions.
Fiber laser beam spot diameter: 35μm
Beam spot scanning speed: 200 mm / s
Beam spot irradiation pitch: 4 μm
Number of beam spot scans: 10 Width of square break line: 35 μm
Total length of corner break line: 4.2 mm
Advance length L1 of square break line: 0.7 mm
Intersection angle of corner break line with side break line: 45 °

  The silicon nitride-based ceramics sintered substrate 1 was folded along each side break line 13 and divided into a silicon nitride-based ceramics aggregate substrate 12 having a chamfered portion 22 and side margin portions 16 and corner margin portions 17. The corner margin portion 17 was separated while being attached to the side margin portion 16, and did not become a separate scrap. After the above separation operation, the front and back surfaces of the silicon nitride-based ceramics aggregate substrate 12 were cleaned and the surface roughness was adjusted by wet blasting using alumina abrasive grains.

  The chamfered surface 140 of the silicon nitride-based ceramic aggregate substrate 12 obtained by dividing the five silicon nitride-based ceramic sintered substrates 1 was observed with a laser microscope. As a result, it was confirmed that there were no cracks, particulate protrusions, burrs, and cracks on the chamfered surface 140 and the side surfaces (laser processed surface and fractured surface) adjacent thereto. In the chamfered surface 140, the arithmetic average surface roughness Rao of the opening side wall surface was 0.2 μm, and the arithmetic average surface roughness Ram of the central wall surface was 0.16 μm. In the region 22a adjacent to the chamfered portion 22, the arithmetic average surface roughness Ra on the side surface of the substrate (composed of the laser processing surface and the fracture surface) formed by breaking the side break line 13 is 0.4 μm on the laser processing surface. In the fracture surface, Ra was 0.7 μm.

A brazing material paste was applied to both surfaces of the silicon nitride-based ceramic assembly substrate 12 by a screen printing method. For the brazing material, 0.3 mass parts of TiH ₂ was added to an alloy powder consisting of 70 mass% of Ag, 3 mass% of In, and 27 mass% of Cu (total of 100 mass parts), and further, an organic solvent and It was a paste to which a binder component was added. After the brazing material is dried, the first and second copper plates having a thickness of 0.3 mm are arranged on both surfaces of the silicon nitride-based ceramic assembly substrate 12, and heated at 800 ° C. for 20 minutes while applying pressure in a vacuum to form a silicon nitride-based material. The first and second copper plates were joined to the ceramic assembly substrate 12. The thickness of the brazing filler metal layer after joining was about 30 μm.

  After applying an ultraviolet curable alkali peeling type etching resist ink to the first and second copper plates of the obtained joined body, the etching resist ink is cured by irradiation with ultraviolet light to a pattern for a circuit board and a heat radiating plate. I let it. Etching is performed with a copper chloride base etchant (mixed solution containing copper chloride, hydrochloric acid and hydrogen peroxide) maintained at 30 ° C, and unnecessary copper plate portions other than the pattern of the circuit board and the heat sink (that is, coated with a resist). Copper part) was removed.

  A first brazing material etching process (etching process with an acidic solution containing carboxylic acid and / or carboxylate and hydrogen peroxide) and a second brazing material to remove unnecessary brazing material portions protruding from the copper plate. Etching treatment (etching treatment with a solution containing ammonium hydrogen fluoride and hydrogen peroxide) was sequentially performed.

  After the bonded body was immersed in a 3% by mass aqueous solution of sodium hydroxide to remove the remaining resist, a gloss treatment (chemical polishing) using a sulfuric acid-based general commercial solution was performed. After washing with ion-exchanged water, the surfaces of the first copper plate 23a and the second copper plate 23b (circuit board and heat sink) were plated with Ni. In this way, an assembly of a circuit board having a circuit board 23a 'plated with Ni on both sides and a heat sink was obtained.

  As shown in FIGS. 5 (a) and 5 (b), a second break line 24 is formed in the aggregate of the circuit boards, and is divided along the second break line 24 to correspond to a margin portion. The edge 21 was separated to obtain a plurality of circuit boards 28 each having a circuit board 23a 'and a heat sink (not shown) on both sides of a ceramic substrate 25' as shown in FIG.

Example 2
The same as in Example 1 except that the scanning speed of the beam spot of the fiber laser was 33 mm / s, and the irradiation energy density was higher than that in Example 1, and the corner break line 14 penetrating the front and back sides in one scan was formed. Thus, a silicon nitride-based ceramics sintered substrate 1 having a side break line 13 and a corner break line 14 was obtained.

  The silicon nitride-based ceramics sintered substrate 1 was folded along the side break lines 13 and divided into a silicon nitride-based ceramics aggregate substrate 12 having a chamfered portion 22 and a side margin portion 16 and a corner margin portion 17. No cracks, burrs, or cracks were formed on the chamfered portion 22 (chamfered surface 140) and side surfaces (laser-processed surface and fractured surface) of the silicon nitride-based ceramic aggregate substrate 12. However, fine particulate projections were formed on the chamfered surface 140. Since the particulate projections may fall off as foreign matter (dust) in the process of forming the circuit board, they were removed by washing. The arithmetic average surface roughness Ra is Rao = 0.8 μm, Ram = 0.5 μm on the chamfered surface 140, Ra2 = 0.5 μm on the laser-processed surface of the side break line 13, and Ra3 = 0.7 μm on the fractured surface, respectively. there were. After bonding the first and second copper plates 23a and 23b for the circuit board and the heat sink to both surfaces of the silicon nitride-based ceramics assembly substrate 12 with a brazing material, a second break line 24 was formed. By dividing the silicon nitride-based ceramics assembly substrate 12 along the second break line 24, a circuit board similar to that of Example 1 was obtained.

Example 3
The corner break line 14 of Example 1 was changed to a slit-shaped corner break line 34 (L1 = 0 mm) shown in FIG. The corner break line 34 terminated at the intersection with the side break line 13. The silicon nitride-based ceramics sintered substrate 1 having the side break lines 13 and the corner break lines 34 was folded along the side break lines 13 and divided into a silicon nitride-based ceramic aggregate substrate 12 and side margin portions 16 and corner margin portions 17. . No cracks or cracks occurred on the chamfered surface 140 of the silicon nitride-based ceramic aggregate substrate 12 and on the side surfaces (laser processed surface and fractured surface) adjacent thereto. As shown in FIG. 8, burrs 27 exceeding the tolerance were formed in the side surface region near the chamfered surface 140 of the silicon nitride-based ceramic aggregate substrate 12, and the ratio of the burrs 27 exceeding the tolerance was 1%. The first and second copper plates for the circuit board and the heat sink are joined to both surfaces of the silicon nitride-based ceramic aggregate substrate 12 on which the burrs 27 are not formed by brazing material, and are divided after the etching process, similar to the first embodiment. Circuit board was obtained. In the third embodiment, the rate at which burrs 27 are formed is 1% (yield: 99%), but this is a range that does not cause any problem.

Comparative Example 1
As shown in FIG. 9, both the side break lines 113 and the corner break lines 114 formed on the silicon nitride ceramic sintered substrate 101 are continuous grooves having a width of 35 μm and a depth of 120 μm (not penetrating the substrate). . The corner break line 114 was inclined by 45 ° with respect to the side break line 113 formed along the side 111. Other conditions were the same as in Example 1. In this comparative example, the number of steps for separating the corner margin portion 117 is increased as compared with the above-described embodiment.

  The silicon nitride-based ceramics sintered substrate 101 is folded along the side break lines 113, divided into a silicon nitride-based ceramic aggregate substrate 112 and a side margin portion 116, and then folded along the corner break lines 114 to form a triangular shape. The corner margin 117 has been separated. No burrs or cracks occurred on the chamfered surface and the side surface (laser-processed surface and fractured surface) adjacent to the chamfered surface of the silicon nitride-based ceramics assembly substrate 112, but the rate at which cracks 134 were formed as shown in FIG. (Yield 94%). This was lower than the target yield (more than 95%).

Comparative Example 2
As shown in FIG. 11, the silicon nitride-based ceramics sintered substrate 201 having only the side break lines 213 formed along the side 211 is folded along the side break lines 213 to form the silicon nitride-based ceramic aggregate substrate 212 and the side. It is divided into a margin part 216. Although no burrs were generated on the side surfaces (laser-processed surface and fractured surface) of the silicon nitride-based ceramic aggregate substrate 212, the rate of occurrence of cracks was 6%. The rate of occurrence of (split corners 217 separated) was 2%. Therefore, the yield of Comparative Example 2 was lower than the target yield.

1,101,201: Sintered silicon nitride ceramic substrate
10: Outer edge of silicon nitride ceramic sintered substrate
11, 111, 211: side
12, 112, 212: Silicon nitride based ceramic aggregate substrate
13, 113, 213: Side break line
14, 34, 114: Square break line
14a: Beam spot
140: Wall of chamfer (chamfer)
140o: Side wall of opening
140m: Central wall
140e: Through-wall surface
15, 115: Intersection of side break lines
16, 116: Side margin
17: Corner margin
19: Circuit formation unit
20: Silicon nitride ceramic substrate
21: Edge
22: chamfer
22a: Area adjacent to the chamfer
23a: First copper plate
23a ': Circuit board
23b: Second copper plate
24: The second break line
25: Each ceramic substrate
25 ': Ceramic substrate
27: Bali
28: Circuit board
117: Corner margin
134: Crack
216: Side margin
217: Broken corner
L1: Length of corner break line advance

Claims (6)

In a method of manufacturing a silicon nitride-based ceramic aggregate substrate of a predetermined size from a rectangular silicon nitride-based ceramic sintered substrate,
On the outer edge of the silicon nitride-based ceramics sintered substrate, side break lines corresponding to the four sides of the silicon nitride-based ceramic aggregate substrate are formed, and both of the adjacent side break lines are located near the intersection of the adjacent side break lines. Form a corner break line that intersects with
The depth of the side break line is not more than half the thickness of the silicon nitride ceramic sintered substrate,
The corner break line is a slit penetrating the silicon nitride ceramic sintered substrate,
The silicon nitride-based ceramics sintered substrate is folded along the side break lines to divide the silicon nitride-based ceramic sintered substrate into a portion corresponding to the silicon nitride-based ceramic aggregate substrate inside the side break lines and the corner break lines and an outside margin portion. A method for manufacturing a silicon nitride-based ceramics aggregate substrate.   2. The method for manufacturing a silicon nitride-based ceramic aggregate substrate according to claim 1, wherein the side break lines and the corner break lines are formed by a fiber laser.   3. The method for manufacturing a silicon nitride-based ceramic aggregate substrate according to claim 2, wherein the corner break lines are formed by repeating scanning of a fiber laser beam spot a plurality of times. Method.   4. The method for manufacturing a silicon nitride-based ceramic aggregate substrate according to claim 1, wherein both end portions of the corner break line extend beyond an intersection with the side break line. Method for manufacturing a ceramic-based assembly substrate.   In the method for manufacturing a silicon nitride-based ceramic aggregate substrate according to claim 4, the length of each end of the corner break line extending beyond the intersection with the side break line is larger than the diameter of a fiber laser beam spot. A method for producing a silicon nitride-based ceramic aggregate substrate, which is large and less than 3.5 mm.   The method for manufacturing a silicon nitride-based ceramic aggregate substrate according to any one of claims 1 to 5, wherein an intersection angle between the corner break line and the side break line is 30 to 60 °. Manufacturing method of ceramic aggregate substrate.

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