JP7370192B2 - Method for manufacturing circuit boards for electronic devices - Google Patents

Description

The present invention relates to a method for manufacturing circuit boards for electronic devices by dividing a collective board into individual pieces.

Circuit boards for electronic devices are manufactured by separating a collective substrate sheet on which circuit boards are formed into individual pieces. When separating a collective substrate into individual pieces, a method is known in which dividing grooves are provided using a dicer or laser, and then the pieces are separated into pieces using a press.

Specifically, in Patent Document 1, in order to prevent the occurrence of burrs etc. during cutting, a method is described in which dividing grooves are formed using a laser beam and then pressing is performed while applying vibration to separate the substrate into pieces. Disclosed.

Patent Document 2 discloses that a substantially trapezoidal first groove is formed on one surface of a substrate, and a substantially V-shaped notch that extends in the direction in which the first groove extends in the bottom surface of the first groove. A method is disclosed for dividing a three-dimensional circuit board by forming a groove, sandwiching an elastic body from both sides of the groove, and pressing. Furthermore, an embodiment is disclosed in which a substantially trapezoidal second groove is formed on the other side of the three-dimensional circuit board, on the opposite side of the first groove.

Japanese Patent Application Publication No. 2005-294523 Japanese Patent Application Publication No. 2006-339459

However, although the method described in Patent Document 1 can reduce the occurrence of burrs and the like during cutting, burrs still occur at the edges of the back surface of the substrate due to pressing.
In addition, in Patent Document 2, although it is possible to prevent burrs from occurring at the edges of the back surface of the substrate by forming grooves on both sides of the substrate, the side surfaces of the substrate that have been cut into individual pieces are still sagged due to cutting by pressing. In some cases, sharp points were formed. If a sharp edge occurs, it may damage the clamping jig when pinching the side of the board, and the sharp edge may break during clamping, resulting in foreign matter, reducing work efficiency. There were cases where I was forced to do so.
The present invention solves the above problems, and provides a method for manufacturing a circuit board for electronic devices that suppresses the occurrence of burrs and has excellent workability.

The inventors of the present invention have conducted extensive research to solve the above problems, and found that in order to suppress the occurrence of burrs on the back side and sagging on the side surfaces, dividing grooves were formed on the back side, and the dividing grooves were cut using laser irradiation. We found that it is useful to do so. However, if the dividing groove does not have a flat bottom surface, such as when the dividing groove is V-shaped, problems may occur such as the cut surface becoming slanted due to misalignment of the point when cutting by laser irradiation. . Therefore, the present inventors have discovered that by forming a dividing groove with a substantially flat bottom surface, the problems that may occur during laser irradiation can also be solved, and have completed the present invention.

In one embodiment of the present invention, the back surface of a collective board on which a circuit board for electronic devices is formed, which has a main surface on which an electronic device is installed and a back surface opposite to the main surface, is divided into sections having a substantially flat bottom surface. This is a method of manufacturing a circuit board for an electronic device, including a step of forming a dividing groove to form a groove.

Preferably, the method includes a cutting step of cutting the collective substrate along the dividing grooves formed in the dividing groove forming step, and it is preferable that the cutting step cuts the collective substrate by laser irradiation. Laser irradiation can suppress the occurrence of sagging on the side surfaces of individual substrates.

Further, the main surface of the circuit board has an insulating material (hereinafter also referred to as resist), and the dividing groove forming step further includes forming a substantially flat bottom surface that opens toward the main surface on the main surface. Preferably, the first dividing groove is formed in a substantially trapezoidal shape. Burning and scattering of the resist caused by the laser can be prevented, and stress generated due to the difference in thermal expansion coefficient between the resist and the substrate can be released by forming the first dividing groove.
Further, it is preferable that the insulating material is not formed at the location where the first dividing groove is formed. With this configuration, even if stress occurs due to a difference in coefficient of thermal expansion between the substrate and the resist, the stress can be released, and therefore it is possible to prevent the resist from peeling off from the substrate.

Further, it is preferable that the length of the dividing groove bottom in the direction perpendicular to the extending direction of the dividing groove formed in the dividing groove forming step is 0.05 mm or more and 0.5 mm or less. By setting the length of the bottom of the dividing groove within the above range, the tolerance during laser beam irradiation can be relaxed.
Further, in the substantially trapezoidal dividing groove formed on the main surface in the dividing groove forming step, it is preferable that the angle formed between the tapered surface forming the trapezoid and the main surface of the circuit board is 45° or more and smaller than 90°. By forming the dividing groove on the main surface into the above shape, a creeping distance between the electronic device on the substrate and the substrate can be ensured.

Moreover, it is preferable to include a step of installing an electronic device on the main surface after the dividing groove forming step and before the cutting step. Even if an electronic device is installed on the main surface before the cutting step, the dividing grooves formed on the main surface prevent heat generated between the resist and the substrate from being generated during the installation of the electronic device. Stress can be released and peeling of the resist can be suppressed.

Furthermore, another form of the present invention is a rectangular electronic device having an electronic device, a main surface on which the electronic device is installed, a back surface opposite to the main surface, and a side surface sandwiched between the main surface and the back surface. an electronic component including a device substrate, wherein at least one side surface of the electronic device substrate includes a convex portion having a side top surface that is a surface substantially orthogonal to the main surface; This is an electronic component having an upper tapered portion extending toward the rear surface, and a lower side surface portion extending from the convex portion toward the back surface, and the perpendicularity of the side top surface is 50 μm or less.
Further, it is preferable that the lower side portion has a tapered shape.

According to the present invention, it is possible to provide a method for manufacturing a circuit board for an electronic device that suppresses the occurrence of burrs and has excellent workability. Furthermore, it is possible to provide an electronic component with excellent workability and suppressed generation of burrs.

It is a sectional view showing one form of a division groove formed in a circuit board for electric devices. It is a sectional view showing one form of a division groove formed in a circuit board for electric devices. FIG. 1 is a cross-sectional view showing one form of an electronic component.

The present invention will be explained in more detail below.
One embodiment of the present invention is a method for manufacturing a circuit board for an electronic device, in which a collective substrate is formed with a circuit board for an electronic device, the main surface having an electronic device installed thereon, and the back surface facing the main surface. a dividing groove forming step of forming a dividing groove having a substantially flat bottom surface on the back surface of the apparatus.

The electronic device is a device driven by current from a conductive circuit, and includes, but is not limited to, a transistor and an optical element. Hereinafter, the present invention will be mainly explained using an example in which the electronic device is an optical element. In this specification, the surface of the electronic device board on which the electronic device is installed is referred to as the main surface, and the surface facing the main surface is referred to as the back surface.

The collective board is a board on which a circuit board for an electronic device is formed, and is formed by providing a base material with wiring made of a conductor. A collective board is usually formed by integrating multiple electronic device circuit boards, but depending on the size of the electronic device circuit board, the collective board may consist of one electronic device circuit board and a blank space that does not become a product. In some cases.
The base material is typically a metal material, such as copper and aluminum, but is not limited to these materials, and may also be ceramic materials such as alumina, aluminum nitride, silicone, and glass.
The wiring provided on the substrate is provided by a known method, and after forming a conductor film by a method such as sputtering, vacuum evaporation, or ion plating, unnecessary portions other than the wiring portion may be removed by etching or the like.
A material ensuring insulation is placed between the metal material and the wiring. The insulating material may be an epoxy-based organic resin such as a resist, a polyimide-based organic resin, or an inorganic material such as ceramics.
The collective board may be formed only of circuit boards for electronic devices, or may be formed using blank areas that do not form a product. Since the margins can be touched by hand, the handling of the collective board is improved. Further, by having a margin, it is only necessary to hold the margin when using a jig or the like, and since the jig does not come into contact with the electronic device circuit board, it is not damaged. If there is a margin, its size is not particularly limited, but is usually about several mm.

In the dividing groove forming step, dividing grooves each having a substantially flat bottom are formed on the back surface of the collective substrate. By making the bottom part of the dividing groove on the back side substantially flat, it is possible to suppress the occurrence of burrs on the back side edge of the substrate due to cutting in the cutting step described later, and furthermore, when cutting with laser light, Problems that may occur can be resolved.
The method for forming a dividing groove with a substantially flat bottom surface is not particularly limited as long as a groove with a substantially flat bottom surface can be formed, and the dividing groove may be formed with a laser, or the dividing groove may be formed with a groove processing machine. However, it is preferable to form the dividing grooves using a groove processing machine because it is easy to make the bottom surface of the groove portion substantially flat. Furthermore, the dividing grooves may be formed by a wet method or by a dry method. Further, when forming the dividing groove into a curved line, an end mill may be used as the groove processing machine.
The dividing groove having a substantially flat bottom is typically rectangular or trapezoidal, but is not limited to these shapes. When forming a trapezoid, it is easier to form a groove if the trapezoid opens toward the back surface.

In the dividing groove forming step, in addition to grooves with substantially flat bottoms provided on the back surface of the collective substrate, grooves with substantially parallel bottoms, for example, approximately trapezoidal dividing grooves, are formed on the main surface of the collective substrate. It is preferable. By forming dividing grooves on the main surface of the collective substrate, it is possible to prevent the organic insulating material from being scorched by the laser beam in the laser beam cutting step described later, and it is also possible to prevent organic and inorganic insulating material fired products, etc. can be prevented from scattering and adhering to the substrate.
Furthermore, when installing electronic devices such as optical elements after the dividing groove forming step and before the cutting step described below, processes such as die bonding and wire bonding are performed, but the substrate is exposed to heat during this process. There is a risk that the board may warp or the insulating material or wiring may peel off from the base material. This warping and peeling is caused by the difference in thermal expansion coefficient between the base material and the insulating material. By forming dividing grooves on the main surface of the substrate, it is possible to release stress caused by the difference in coefficient of thermal expansion between the base material and the insulating material. It is possible to prevent the wiring from peeling off from the base material.

Note that when an organic insulating material such as a resist is laminated on the substrate, it is preferable to form the dividing grooves using a groove processing machine from the viewpoint of preventing the organic insulating material such as the resist from burning. Hereinafter, the shape of the dividing groove will be explained with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a substrate in which dividing grooves are formed in a dividing groove forming step.
As shown in FIG. 1, a substrate 10, which is a collective substrate, has a main surface 11 on which an insulating material 16 is laminated, an optical element (not shown) is installed, and a back surface 12 opposite to the main surface 11. It has a trapezoidal first dividing groove 13 that opens toward the main surface 11 and a trapezoidal second dividing groove 14 that opens toward the back surface 12. The first dividing groove 13 and the second dividing groove 14 are formed to face each other. The first dividing groove 13 and the second dividing groove 14 have a substantially flat bottom surface.
Due to the formation of the first dividing groove 13 and the second dividing groove 14, the substrate 10 has a thin portion 15.
The sizes of the first dividing groove 13, the second dividing groove 14, and the thin portion 15 may be appropriately set depending on the size of the optical element to be manufactured.

FIG. 2 is a cross-sectional view of FIG. 1 with the reference numerals removed for explaining the size of the dividing groove.
In the first dividing groove, the dividing groove depth D1 is approximately 0.3 mm as an example, and may normally be 0.05 mm or more, 0.1 mm or more, or 2 mm or less, It may be 1 mm or less.
In the second dividing groove, the dividing groove depth D2 is approximately 0.3 mm as an example, and may normally be 0.05 mm or more, 0.1 mm or more, or 2 mm or less, It may be 1 mm or less.
Further, the groove angle θ1 of the first dividing groove is the angle (dihedral angle) formed between the main surface of the substrate and the tapered surface of the dividing groove, and is approximately 75° as an example, but is usually 90° or less. Yes, it may be smaller than 90°, may be less than or equal to 85°, and may be greater than or equal to 45°, may be greater than 45°, and may be greater than or equal to 60°. From the perspective of ensuring the creepage distance between conductive parts such as circuit wiring and the conductive parts of the board, the creepage distance (L2 = resist thickness) is the shortest when the groove angle θ1 is 90°, and when it is smaller than 90°, the creepage distance is the shortest. Since the creepage distance (L3=L2÷cos(90-θ1)) is longer, it is preferably within the above range. This is because the creepage distance becomes longer and the dielectric strength voltage of the electronic device becomes higher. Furthermore, when the electronic device is an optical product, a material with high reflective performance is used for the substrate. If the groove angle θ1 is smaller than 45°, the laser light may be diffusely reflected when cutting the substrate with a laser because the substrate is made of a material with high reflective performance, so it is preferably within the above range. In the dividing groove forming step, when the groove bottom is substantially flat, the laser beam is uniformly irradiated and the laser beam is not diffusely reflected. The inner wall of the dividing groove may be treated to prevent diffuse reflection of laser light. Note that the groove angle of the second dividing groove may be the same as the groove angle of the first dividing groove, but for example, when the substrate is greatly warped due to thermal contraction of the insulating material, D1<D2, When the thin portion is provided on the insulating material side, the strength of the base material is increased, so that warping of the board can be suppressed. Further, the thin portion width L1 may be made larger on the main surface side of the collective substrate in order to ensure heat capacity of the base material to facilitate laser irradiation. On the other hand, if the area on which the finished product is placed is small, the back side of the collective substrate may be made larger. When the laser beam is irradiated from the main surface side, the molten material of the base material may be scattered to the back surface side, so the bottom surface of the first dividing groove 13 and the bottom surface of the second dividing groove 14 have the same size. Alternatively, it is preferable that the bottom surface of the second dividing groove 14 is larger than the bottom surface of the first dividing groove 13. Note that when the first dividing groove 13 and the second dividing groove 14 have the same bottom surface size, the shape of the groove is preferably tapered. This is because the melt does not adhere.
Further, the groove angle θ2 of the second dividing groove is the angle formed between the back surface of the substrate and the tapered surface of the dividing groove, and is approximately 75° as an example, but is usually 90° or less, and is smaller than 90°. The angle may be 85° or less, 45° or more, greater than 45°, or 60° or more.

Further, the thin portion width L1 is the length of the bottom surface of the dividing groove in the direction perpendicular to the extending direction of the dividing groove, and is approximately 0.3 mm as an example, and may usually be 0.05 mm or more. It may be 0.1 mm or more, 1 mm or less, or 0.5 mm or less. It is preferable that the thin portion width L1 be a substantially flat portion within the above range, from the viewpoint of being able to relax tolerances when cutting the collective substrate using a laser, which will be described later. Since the laser beam has a diameter of approximately 0.05 mm, if the diameter is smaller than 0.05 mm and the cross-sectional view is approximately V-shaped, the laser beam will be diffusely reflected and the quality will be unstable.
Further, the thin part thickness T1 is, for example, about 0.2 mm, and usually may be 0.05 mm or more, 0.1 mm or more, and 0.1 mm or less, and may be 0.5 mm or more. It may be the following. When the thin portion thickness T1 is within the above range, the workability of the collective substrate is improved, and energy consumption can be suppressed during laser cutting, which will be described later.

The cutting step is a step of cutting the collective substrate by irradiating a laser beam from the main surface side to the bottom of the substantially trapezoidal dividing groove formed in the dividing groove forming step. The laser beam only needs to be able to cut the collective substrate, and a YAG laser, an excimer laser, a fiber laser, or the like can be used.
Laser cutting is performed by irradiating a laser beam onto the thin portion of the collective substrate in which the dividing grooves are formed. By cutting the thin portions by laser irradiation, the cutting distance can be shortened without using a press, so it is possible to suppress the formation of burrs on the substrate when cutting. Furthermore, since cutting is not done by press, it is possible to prevent the cut surface from sagging and creating sharp points.

By suppressing the formation of burrs on the board in this way, the bottom surface of the board can be evenly attached to the heat dissipation member, etc., so the heat generated by the electronic device can be efficiently used for the heat dissipation member, etc., improving heat dissipation performance. In addition, deterioration of the member can be suppressed.

After the dividing groove forming step and before the cutting step, the method may include an installing step of installing an electronic device on the main surface of the substrate. In the installation step, if the electronic device is an optical element, the optical element may be installed on the main surface of the substrate by die bonding, wire bonding, etc., and then the optical element may be sealed from above with a transparent resin.
When the installation step is performed before the cutting step, by forming dividing grooves not only on the back side but also on the main surface, the resist on the main surface can be removed at the same time. Even if stress is generated due to a difference in coefficient of thermal expansion during the process, the stress can be released, making it possible to prevent the resist from peeling off from the substrate.

Note that the resist on the main surface of the substrate may be formed over the entire main surface of the collective substrate, or may not be formed in the portion of the main surface of the collective substrate where the first dividing groove is formed. If the resist is not formed at the location where the first dividing groove is formed, even if stress occurs due to the difference in coefficient of thermal expansion between the substrate and the resist, the stress can be released, thereby preventing the resist from peeling off from the substrate. It can be prevented.

An electronic component in which an electronic device is installed on a circuit board for an electronic device manufactured by the above manufacturing method is another embodiment of the present invention. That is, another embodiment of the present invention provides a rectangular electronic device having an electronic device, a main surface on which the electronic device is installed, a back surface opposite to the main surface, and a side surface sandwiched between the main surface and the back surface. an electronic component including a device substrate, wherein at least one side surface of the electronic device substrate includes a convex portion having a side top surface that is a surface substantially orthogonal to the main surface; The electronic component has an upper tapered portion extending toward the rear surface, and a lower tapered portion extending from the convex portion toward the back surface, and the perpendicularity of the side top surface is 50 μm or less. FIG. 3 shows a schematic diagram of one form of the electronic component.

FIG. 3 shows a semiconductor light emitting device 20, which is one form of an electronic component, in which a semiconductor light emitting element 21 is installed. A semiconductor light emitting element 21 is installed on the light emitting element substrate 22 with an insulating layer 24 interposed therebetween. The semiconductor light emitting element 21 is sealed with a sealing material (not shown), and the sealing material remains on the semiconductor light emitting element 21 by dam members installed on both sides of the semiconductor light emitting element 21, thereby sealing the semiconductor light emitting element 21. .

The side surface of the light emitting element substrate 22 includes a convex portion 25 having a side top surface substantially orthogonal to the mounting surface of the semiconductor light emitting device 21, and an upper tapered surface 26a and a lower tapered surface 26b extending from the convex portion to the main surface and back surface of the substrate. Consisting of
The convex portion 25 is composed of dividing grooves formed on the main surface and the back surface of the collective substrate described above, and the side top surface of the convex portion 25 is formed by cutting with a laser, so that the surface has a sharp point. There are no parts and it is smooth. In one example, the maximum squareness f of the side top surface measured according to JIS-B-0621 is 21 μm, preferably 100 μm or less, more preferably 50 μm or less, and 40 μm or less. It is more preferable that the particle size is 30 μm or less, and it is particularly preferable that the particle size is 30 μm or less. Variations in product external size are reduced, making it easier to guarantee product external size. The perpendicularity f was determined using an image dimension measuring instrument LM-1100 manufactured by Keyence Corporation, and measured at five points in the cross-sectional height direction (board thickness direction) of the apex surface of the convex portion 25, and in the cross-sectional lateral direction (board length direction). ) measurements were taken at a total of 35 locations. The squareness f of the side top surface of the electronic device substrate cut by the laser had an average value of 8.8 μm and a maximum value of 21 μm. On the other hand, the squareness f of the side top surface of the electronic device substrate cut by pressing was 52.8 μm on average and about 100 μm at the maximum. Note that the sharp portion that does not exist on the side top surface may be a sharp portion with a height of 500 μm or more, a sharp portion with a height of 100 μm or more, or a sharp portion with a height of 50 μm or more.

The angle θ3 formed by the upper tapered surface 26a forming the convex portion 25 and the main surface of the substrate is, for example, about 105°, usually 90° or more, may be larger than 90°, and may be 95° or more. It may also be less than or equal to 135°, less than 135°, and less than or equal to 120°. When the angle is larger than 90°, the volume of the base material becomes large and the heat capacity also becomes large, so that heat dissipation performance is improved. The angle may be 90° if the heat dissipation is sufficient. That is, the upper tapered surface 26a and the lower tapered surface 26b may be connected by a straight line with an angle of 90 degrees, or the entire surface may be substantially straight. Note that the angle formed between the lower tapered surface 26b and the back surface of the substrate may be the same as the angle formed between the upper tapered surface 26a and the main surface of the substrate. Further, the upper tapered surface 26a and the lower tapered surface 26b may be asymmetrical. When irradiating the laser beam from the main surface side, the melted material of the base material may scatter to the back surface side. The angle θ4 formed between the lower tapered surface 26b and the back surface of the substrate is preferably larger than 90°. This is because the melt does not adhere.

The length of the convex portion 25 in the substrate thickness direction corresponds to the thickness of the thin portion of the substrate in which the dividing groove is formed. An example is about 0.2 mm, and usually it may be 0.05 mm or more, 0.1 mm or more, 0.1 mm or less, and 0.5 mm or less.
Further, the distance between the main surface and/or back surface of the substrate and the convex portion (the distance in the direction perpendicular to the main surface or back surface of the substrate) corresponds to the depth of the dividing groove of the substrate in which the dividing groove is formed. An example is about 0.3 mm, and usually it may be 0.05 mm or more, 0.1 mm or more, 2 mm or less, and 1 mm or less.

Note that the above description is an example of an embodiment of the present invention, and those skilled in the art can implement various modifications within the scope of the gist of the present invention.

10 Collective substrate 11 Main surface 12 Back surface 13 First dividing groove 14 Second dividing groove 15 Thin part 16 Insulating material (resist)
20 Semiconductor light emitting device 21 Semiconductor light emitting element 22 Light emitting element substrate 23 Dam material
24 Insulating layer 25 Convex portions 26a, 26b Tapered surface

Claims (5)

A dividing groove having a substantially flat bottom surface is formed on the back surface of the collective board on which a circuit board for electronic devices is formed, which has a main surface on which an electronic device is installed and a back surface opposite to the main surface. forming a dividing groove, and the dividing groove forming step further includes forming, in the main surface, a first dividing groove having a substantially trapezoidal shape with a substantially flat bottom surface that opens toward the main surface; The trapezoidal first dividing groove has an angle (dihedral angle) between the tapered surface forming the trapezoid and the main surface of the circuit board of 45° or more and smaller than 90°, and the main surface of the circuit board is insulating. A method for manufacturing a circuit board for an electronic device, wherein the insulating material is not formed at a location where the first dividing groove is formed . 2. The method of manufacturing a circuit board for an electronic device according to claim 1, further comprising a cutting step of cutting the collective substrate along the dividing grooves formed in the dividing groove forming step. 3. The method for manufacturing a circuit board for an electronic device according to claim 2, wherein in the cutting step, the collective substrate is cut by laser irradiation. The dividing groove formed in the dividing groove forming step has a bottom length of 0.05 mm or more and 0.5 mm or less in a direction perpendicular to the extending direction of the dividing groove. A method for manufacturing a circuit board for an electronic device according to any one of the items. 3. The method of manufacturing an electronic device circuit board according to claim 2, further comprising an installation step of installing an electronic device on the main surface after the dividing groove forming step and before the cutting step.

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