Each of a plurality of semiconductor light-emitting element has, on an upper surface thereof that has a quadrilateral shape, a pair of connecting portions having different polarities from each other. The pair of connecting portions are aligned on a diagonal of the quadrilateral shape. The diagonal intersects a row direction along which the semiconductor light-emitting elements within a row are arranged. Connecting portions having identical polarity are positioned on an imaginary line parallel to the row direction. Metal wires intersect two sides extending from a corner, on the diagonal, of the upper surface of each of the semiconductor light-emitting elements when viewed from a direction perpendicular to a mounting surface of a substrate for mounting the semiconductor light-emitting elements.

RELATED APPLICATIONS

This application is a national phase of International Application No. PCT/JP2013/005224, filed on Sep. 4, 2013, which in turn claims the benefit of Japanese Application No. 2012-212865, filed on Sep. 26, 2012, the disclosures of which Applications are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to light-emitting modules in which a plurality of semiconductor light-emitting elements are mounted in rows on a substrate.

BACKGROUND ART

LEDs have the advantages of having long life, good luminance efficiency in a compact form, and vivid light-emission colors, and are widely used in illumination devices, as backlights of display devices, etc. Further, a light-emitting module used in a high capacity illumination device such as a downlight has been developed in which a plurality of LED chips are mounted in a plurality of rows on one substrate, each row sealed over by a sealing member.

As such a light-emitting module, a light-emitting module has been proposed in which the LED chips mounted in rows are connected in parallel by using metal wires (bonding wires) (for example, Patent Literature 1).

Further, in recent years, technology has been proposed in which adjacent LED chips are connected directly to each other by metal wires (for example, Patent Literature 2).

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Publication 2012-9622

Patent Literature 2: Japanese Patent Application Publication 2011-9298

SUMMARY OF INVENTION

Technical Problem

However, when electrically connecting adjacent LED chips by using metal wires there is a problem in that light extraction efficiency is reduced.

A typical LED chip is quadrilateral in plan view, having a pair of connecting portions of different polarity on a center line connecting midpoints of two opposing sides. Such an LED chip is mounted on a substrate such that the center line and row direction are perpendicular, and metal wires connect the connecting portions of adjacent LED chips in the row direction.

In such a case, the metal wires necessarily intersect an upper surface of the LED chip, causing light extraction efficiency from the LED chip to be reduced.

The present invention, in view of the above technical problem, has an aim of improving light extraction efficiency in a light-emitting module composed of a plurality of semiconductor light-emitting elements connected in parallel by using metal wires that electrically connect adjacent semiconductor light-emitting elements.

Solution to Problem

To achieve the above aim, in one aspect of the present invention, a light-emitting module comprises: at least one row of a plurality of semiconductor light-emitting elements mounted on a substrate; metal wires connecting in parallel adjacent ones of the semiconductor light-emitting elements within the at least one row; and at least one line-shaped sealing member sealing the semiconductor light-emitting elements, wherein each semiconductor light-emitting element has, on an upper surface thereof that has a quadrilateral shape, a pair of connecting portions having different polarities from each other, the pair of connecting portions being aligned on or near a diagonal of the quadrilateral shape, the diagonal intersects a row direction along which the semiconductor light-emitting elements within the at least one row are arranged and connecting portions having identical polarity are positioned on an imaginary line parallel or substantially parallel to the row direction, and the metal wires intersect two sides extending from a corner, on the diagonal, of the upper surface of each of the semiconductor light-emitting elements when viewed from a direction perpendicular to a mounting surface of the substrate for mounting the semiconductor light-emitting elements.

To achieve the above aim, in one aspect of the present invention, a light-emitting module comprises: at least one row of a plurality of semiconductor light-emitting elements mounted on a substrate; metal wires connecting in parallel adjacent ones of the semiconductor light-emitting elements within the at least one row; and at least one line-shaped sealing member sealing the semiconductor light-emitting elements, wherein each semiconductor light-emitting element has, on an upper surface thereof that has a quadrilateral shape, a pair of connecting portions having different polarities from each other, a diagonal intersects a row direction along which the semiconductor light-emitting elements within the row are arranged and connecting portions having identical polarity are positioned on an imaginary line parallel or substantially parallel to the row direction, the metal wires intersect sides extending from a corner, on the diagonal, of the upper surface of each of the semiconductor light-emitting elements when viewed from a direction perpendicular to a mounting surface of the substrate for mounting the semiconductor light-emitting elements, the upper surface of each of the semiconductor light-emitting elements has sides of length a and sides of length b and is a quadrilateral shape having four right angles, a connecting portion of the connecting portions is within an area enclosed by an imaginary line perpendicular to the diagonal that passes through a position on the diagonal and two sides extending from a corner of the upper surface nearest the position, where x is a distance between the position and the corner of the upper surface nearest the position and the distance x satisfies x<a2b/(a2+b2).

Advantageous Effects of Invention

According to the light-emitting module of the above aspects, lengths of portions of the metal wires intersecting upper surfaces of the semiconductor light-emitting elements are shorter when compared to a light-emitting module in which a center line of semiconductor light-emitting elements is perpendicular to the row direction and adjacent ones of the semiconductor light-emitting elements are connected by metal wires that extend in the row direction. In this way, light extraction efficiency is improved.

EMBODIMENT

Overview of One Aspect of the Present Invention

A light-emitting module pertaining to one aspect of the present invention is a light-emitting module comprising: at least one row of a plurality of semiconductor light-emitting elements mounted on a substrate; metal wires connecting in parallel adjacent ones of the semiconductor light-emitting elements within the at least one row; and at least one line-shaped sealing member sealing the semiconductor light-emitting elements, wherein each semiconductor light-emitting element has, on an upper surface thereof that has a quadrilateral shape, a pair of connecting portions having different polarities from each other, the pair of connecting portions being aligned on or near a diagonal of the quadrilateral shape, the diagonal intersects a row direction along which the semiconductor light-emitting elements within the at least one row are arranged and connecting portions having identical polarity are positioned on an imaginary line parallel or substantially parallel to the row direction, and the metal wires intersect two sides extending from a corner, on the diagonal, of the upper surface of each of the semiconductor light-emitting elements when viewed from a direction perpendicular to a mounting surface of the substrate for mounting the semiconductor light-emitting elements.

Further, the upper surface of each semiconductor light-emitting element may be square, and x may be less than a/2 where a is a length of one side of the upper surface of the semiconductor light-emitting element and x is a distance between a center of a connecting portion of the connecting portions and a corner of the upper surface nearest said connecting portion. In this way, length is reduced of portions of the metal wires intersecting the upper surfaces of the semiconductor light-emitting elements.

Further, among the semiconductor light-emitting elements within the at least one row, a connecting portion of at least one semiconductor light-emitting element not positioned at an end of the at least one row may be connected by two of the metal wires to connecting portions having identical polarity of two other semiconductor light-emitting elements adjacent to the at least one semiconductor light-emitting element, and a second bond of one of the two of the metal wires and a first bond of the other one of the two of the metal wires may overlap when viewed from above the at least one semiconductor light-emitting element. In this way, surface area of the connecting portions is reduced when viewed from above the semiconductor light-emitting elements. Note that here, “overlap” may mean that the first bond and the second bond completely overlap (the first bond is substantially the same size as the second bond or smaller and is positioned on the second bond), and may mean that a portion of the first bond and the second bond overlap.

Further, among the semiconductor light-emitting elements within the at least one row, a connecting portion of at least one semiconductor light-emitting element not positioned at an end of the at least one row may be connected by two of the metal wires to connecting portions having identical polarity of two other semiconductor light-emitting elements adjacent to the at least one semiconductor light-emitting element, and a second bond of one of the two of the metal wires and a first bond of the other one of the two of the metal wires may be configured to not overlap when viewed from above the at least one semiconductor light-emitting element. In this way, the metal wires and the connecting portions are directly connected.

Further, the upper surface of each semiconductor light-emitting element may be rectangular, and x may be less than a2b/(a2+b2) where a and b are lengths of sides of the upper surface of the semiconductor light-emitting element, x is a distance between a center of a connecting portion of the connecting portions and a corner of the upper surface nearest said connecting portion, and sides of length b of semiconductor light-emitting elements that are adjacent within the at least one row face each other. In this way, length is reduced of portions of the metal wires intersecting the upper surfaces of the semiconductor light-emitting elements.

Further, among the semiconductor light-emitting elements within the at least one row, a connecting portion of at least one semiconductor light-emitting element not positioned at an end of the at least one row may be connected by two of the metal wires to connecting portions having identical polarity of two other semiconductor light-emitting elements adjacent to the at least one semiconductor light-emitting element, and a second bond of one of the two of the metal wires and a first bond of the other one of the two of the metal wires may overlap when viewed from above the at least one semiconductor light-emitting element. In this way, surface area of the connecting portions is reduced when viewed from above the semiconductor light-emitting elements. Note that here, “overlap” may mean that the first bond and the second bond completely overlap (the first bond is substantially the same size as the second bond or smaller and is positioned on the second bond), and may mean that a portion of the first bond and the second bond overlap.

Further, among the semiconductor light-emitting elements within the at least one row, a connecting portion of at least one semiconductor light-emitting element not positioned at an end of the at least one row may be connected by two of the metal wires to connecting portions having identical polarity of two other semiconductor light-emitting elements adjacent to the at least one semiconductor light-emitting element, and a second bond of one of the two of the metal wires and a first bond of the other one of the two of the metal wires may be configured to not overlap when viewed from above the at least one semiconductor light-emitting element. In this way, the metal wires and the connecting portions are directly connected.

A light-emitting module pertaining to one aspect of the present invention is a light-emitting module comprising: at least one row of a plurality of semiconductor light-emitting elements mounted on a substrate; metal wires connecting in parallel adjacent ones of the semiconductor light-emitting elements within the at least one row; and at least one line-shaped sealing member sealing the semiconductor light-emitting elements, wherein each semiconductor light-emitting element has, on an upper surface thereof that has a quadrilateral shape, a pair of connecting portions having different polarities from each other, a diagonal intersects a row direction along which the semiconductor light-emitting elements within the row are arranged and connecting portions having identical polarity are positioned on an imaginary line parallel or substantially parallel to the row direction, the metal wires intersect sides extending from a corner, on the diagonal, of the upper surface of each of the semiconductor light-emitting elements when viewed from a direction perpendicular to a mounting surface of the substrate for mounting the semiconductor light-emitting elements, the upper surface of each of the semiconductor light-emitting elements has sides of length a and sides of length b and is a quadrilateral shape having four right angles, a connecting portion of the connecting portions is within an area enclosed by an imaginary line perpendicular to the diagonal that passes through a position on the diagonal and two sides extending from a corner of the upper surface nearest the position, where x is a distance between the position and the corner of the upper surface nearest the position and the distance x satisfies x<a2b/(a2+b2).

Further, among the semiconductor light-emitting elements within the at least one row, connecting portions having identical polarity may be connected by at least one of the metal wires. In this way, connections between the connecting portions are easily performed. Further, the at least one row may be provided in a plurality, and spacing between the semiconductor light-emitting elements may be different for each row of the plurality of rows. In this way, when adjacent ones of the semiconductor light-emitting elements are connected by the metal wires, wiring is not required in the substrate and freedom of mounting of the semiconductor light-emitting elements is increased.

Further, the plurality of rows may be connected in series. In this way, luminance consistency is easily ensured.

Embodiment

Pertaining to the embodiment, a light-emitting module, a lamp unit including the light-emitting module, and an illumination device are described with reference to the drawings.

FIG. 1is a cross-section illustrating an illumination device1incorporating a light-emitting module10pertaining to the embodiment.

The illumination device1is a so-called downlight mounted to be embedded in a ceiling2. The illumination device1includes a fixture3, a circuit unit4, and a lamp unit6.

The fixture3is metal, and has a lamp housing portion3a, a circuit housing portion3b, and an outer flange portion3c. The lamp housing portion3ais a bottomed cylindrical shape and the lamp unit6is detachably attached to the inside (bottom) thereof. The circuit housing portion3bis extended from the bottom side of the lamp housing portion3aand the circuit unit4is housed therein. The outer flange portion3cis annular, and extended outward from an opening of the lamp housing portion3a.

In other words, the fixture3has a cylindrical shape having a partition wall3dat a central portion in a direction perpendicular to the ceiling2. The lamp unit6is housed in an internal space from the partition wall3dof the fixture3to an end portion (lower portion) on a side close to the ceiling2. The circuit unit4is housed in an internal space from the partition wall3dto an end portion (upper portion) on a side far from the ceiling2.

The fixture3is attached to the ceiling2in a state in which the lamp housing portion3aand the circuit housing portion3bare embedded in an embedding hole2athat passes through the ceiling2, and the outer flange portion3cis in contact with a lower surface2bof the ceiling2at a periphery of the embedding hole2a.

The circuit unit4includes a circuit that causes the lamp unit6to be lit. Further, the circuit unit4includes a power supply line4athat is electrically connected to the lamp unit6. A connector4bthat is detachably attached to a connector72of leads71of the lamp unit6is attached to an end of the power supply line4a.

The circuit includes an AC/DC converter, is electrically connected to an external commercial AC power source (not illustrated), converts power inputted from the commercial AC power source to DC voltage (DC electricity) suitable for the light-emitting elements12, and supplies converted power to the lamp unit6. In this way, all of the light-emitting elements12are collectively controllable to be lit.

Note that in the illumination device1, the lamp unit6and the circuit unit4are separate units, but the illumination device1may include a circuit corresponding to the circuit unit4integrated into a lamp unit. Further, the circuit unit4is housed inside the fixture3, but may be positioned outside a fixture.

FIG. 2is a perspective view of the lamp unit6andFIG. 3is an exploded perspective view of the lamp unit6.

The lamp unit6includes the light-emitting module10as a light source. The lamp unit6, aside from the light-emitting module10, includes a base80, a holder30, a decorative cover40, a cover50, a cover pressing member60, a wiring member70, etc.

The base80is, for example, made from a material having a high thermal conductivity. As such a material, a metal material such as aluminium may be used. The base80is disk-shaped die-cast aluminium, and has a mounting portion81in a central area of an upper surface thereof. The light-emitting module10is mounted on the mounting portion81.

A securing means is provided on an upper surface of the base80for securing the holder30. Here, the securing means uses a threaded structure. Specifically, the securing means includes assembly screws35for securing the holder30and screw holes82for threading the assembly screw35. The screw holes82are provided on both sides of the mounting portion81.

Insertion holes83, boss holes84, and a cut-out portion85are provided in a peripheral portion of the base80. The insertion holes83are for attaching the lamp unit6to the fixture3. The boss holes84are a securing means used when securing the cover pressing member60(details are provided later). The cut-out portion85is for the wiring member70to pass through.

The holder30is, for example, made from resin material. The holder30is a bottomed cylindrical shape and includes a pressing plate31having a disk shape and a peripheral wall portion32having a cylindrical shape that extends towards the base80from a peripheral edge of the pressing plate31. The light-emitting module10is secured to the base80by being pressed to the mounting portion81by the pressing plate31.

A window hole33is present in a central area of the pressing plate31, allowing light from the light-emitting module10to pass through. The window hole33is formed to correspond to a mounting area20on the light-emitting module10on which the light-emitting module12is mounted. Here, the window hole33is circular in plan view.

Openings34are formed in the pressing plate31that are contiguous with the window hole33. The openings34prevent the leads71that are connected to the light-emitting module10from interfering with the holder30.

Insertion holes36are formed through a peripheral portion of the pressing plate31of the holder30at a position corresponding to the screw holes82of the base80, for insertion of the assembly screws35.

When the holder30is being attached to the base80, initially, the light-emitting module10(a portion of the light-emitting module10excluding the sealing members13, etc.) is sandwiched between the base80and the holder30in a state in which the sealing members13, etc., of the light-emitting module10are exposed from the window hole33of the holder30. Subsequently, the assembly screws35are inserted into the insertion holes36from above the pressing plate31of the holder30, and screwed into the screw holes82of the base80. In this way, the holder30and the base80are attached.

The decorative cover40is, for example, made from a non-light-transmissive material such as a white, opaque resin, and has an annular shape. The decorative cover40is positioned between the holder30and the cover50, and covers and conceals the assembly screws35, the leads71exposed by the openings34in the holder30, etc. The decorative cover40also has a window hole41in a central area thereof. The window hole41allows light from the light-emitting module10to pass through the decorative cover40.

The cover50is made from a light-transmissive material such as silicone resin, acrylic resin, glass, etc. In other words, light emitted from the sealing members13of the light-emitting module10is transmitted through the cover50and emitted from the lamp unit6. The cover50has an overall shape of a dome. The cover50includes a main body51having an optical function, described later, and an outer flange portion52extending outward from a peripheral portion of the main body51. The main body51has a function of diffusing light from the light-emitting module10. Specifically, diffusing material is mixed into the light-transmitting material from which the main body51is composed. The outer flange portion52is used when securing the cover50to the base80.

The cover pressing member60is made from a non-light-transmissive material such as a metal such as aluminium or a white, opaque resin. The cover pressing member60has an annular shape to avoid obstructing light emitted from the main body51of the cover50. The outer flange portion52of the cover50is sandwiched between the cover pressing member60and the base80. In this way, the cover50is secured to the base80.

Boss portions61are cylindrical and protrude from a lower side surface of the cover pressing member60towards the base80. Corresponding to the boss portions61, cutouts53that are semicircular are formed in the outer flange portion52of the cover50and boss holes84are formed in a peripheral portion of the base80.

When securing the cover pressing member60to the base80, the boss portions61of the cover pressing member60are inserted into the boss holes84of the base80, and end portions of the boss portions61that extend from a lower side of the base80are exposed to laser light, plastically deforming the end portions to a shape that does not come out of the boss holes84. In this way, the cover pressing member60is secured to the base80, forming a single unit.

Cut-out portions54and62, which are semicircular in shape, are formed in the outer flange portion52of the cover50and a peripheral portion of the cover pressing member60in positions corresponding to the insertion holes83of the base80. Attachment screws (not illustrated) that are inserted into the insertion holes83do not contact the cover pressing member60or the cover50.

By screwing such attachment screws into screw holes (not illustrated) formed in the partition wall3dof the fixture3, the lamp unit6is detachably attached to the lamp housing portion3aof the fixture3.

The wiring member70has a pair of leads71that are electrically connected to the light-emitting module10. The leads71lead out of the lamp unit6via the cut-out portion85of the base80, and ends of the leads71are attached to the connector72.

Ends of the leads71opposite to the connector72are joined to terminal portions14and15of the light-emitting module10by, for example, soldering.

FIG. 4is a plan view illustrating an example of the light-emitting module10.FIG. 5is a plan view of the light-emitting module10in which the sealing members13are removed. In these drawings, the paper surface vertical direction is considered a vertical direction and the paper surface lateral direction is considered a lateral direction.

As shown inFIG. 4andFIG. 5, the light-emitting module10includes a substrate11, a plurality of the light-emitting elements12arranged in a plurality of rows on the substrate11, the sealing members13covering the light-emitting elements12in each row, the terminal portions14and15, wiring16,17, and18, etc.

As shown inFIG. 4andFIG. 5, the light-emitting elements12are arranged in rows in a mounting area20(indicated by a two-dot chain line inFIG. 5) on an upper surface of the substrate11. In other words, the light-emitting elements12are lined up in single rows in the lateral direction in the mounting area20in light-emitting element rows21,22, and23, and the light-emitting element rows21,22, and23are lined up in the vertical direction parallel to each other.

Twelve light-emitting elements are arranged in the lateral direction in each of the light-emitting element rows21, eight light-emitting elements are arranged in the lateral direction in each of the light-emitting element rows22, and four light-emitting elements are arranged in the lateral direction in each of the light-emitting element rows23. The direction in which the light-emitting elements12in each of the light-emitting element rows21,22, and23are arranged is also referred to as a row direction. The row direction matches the lateral direction.

There are eight rows of the light-emitting element rows21, two rows of the light-emitting element rows22, and two rows of the light-emitting element rows23. In the light-emitting element rows21, as shown inFIG. 5, as distance from the center of the mounting area20to the position of the light-emitting element rows21increases, spacing between the twelve light-emitting elements12decreases (as shown inFIG. 4, length of the sealing members13in the lateral direction decreases).

The light-emitting element rows22and23are composed of light-emitting elements12arranged in regions at either end in the vertical direction of the light-emitting element rows21, and length (length of the sealing members covering the light-emitting elements) of the light-emitting element rows22and23is shorter than length of the light-emitting element rows21.

By adjusting length of the light-emitting element rows21,22, and23in this way, the mounting area20having an overall circular shape is obtained.

Light-emitting elements (twelve) in each of the light-emitting element rows21are connected in parallel, and each of the light-emitting element rows21is connected in series to other light-emitting element rows21(including the light-emitting element rows22) that are adjacent in the vertical direction.

Light-emitting elements12in one of the light-emitting element rows22and one of the light-emitting element rows23(twelve in total) are connected in parallel, and the light-emitting element rows22are connected in series to adjacent ones of the light-emitting element rows21. Thus, light-emitting elements12(120in total) mounted on the mounting area20are connected in ten serial rows in each of which twelve light-emitting elements are connected in parallel.

The substrate11includes an insulating layer composed of insulating material such as a ceramic or a thermally-conductive resin. The substrate11may be entirely the insulating layer, or may be configured as two layers including the insulating layer and a metal layer composed of an aluminium sheet.

Shape of the substrate11has no particular limitation, but here is considered to be rectangular.

The terminal portions14and15, and the wiring16,17, and18, are in the insulating layer. The terminal portions14and15are on a surface of the insulating layer, which is a surface layer. Wiring16and17connects the terminal portions14and15to the light-emitting element rows23positioned at both ends of the ten serial rows in each of which twelve light-emitting elements are connected in parallel. Each wiring18connects two rows among the light-emitting element rows21,22, and23.

Only portions of the wiring16,17, and18that connects to the light-emitting elements12(shown as solid lines inFIG. 5) appears on the surface. Other portions of the wiring16,17, and18(shown as broken lines inFIG. 5) are inside the insulating layer.

The light-emitting elements12are, for example, LED chips that are GaN-based and emit blue light having a dominant wavelength of approximately 430 nm to 470 nm. The light-emitting elements12are mounted on the surface of the substrate11using chip on board (COB) technology.

Each of the light-emitting elements12has a square or rectangular shape in plan view. Here, the light-emitting elements12have a square shape.

Note that although the light-emitting elements12are here described as LED chips and the light-emitting module10is described as an LED module, the light-emitting elements12may be laser diodes (LD) or electroluminescence elements (EL elements).

FIG. 6is a perspective view for describing mounting and connection of the light-emitting elements12, and illustrates a mounted state of the light-emitting elements12before connection by metal wires19.FIG. 7is a perspective view for describing mounting and connection of the light-emitting elements12, and illustrates a connected state connected by the metal wires19.

Each of the light-emitting elements12, as shown inFIG. 6, has a pair of connecting portions12aand12bon an upper surface thereof that have different polarities from each other. Each pair of the connecting portions12aand12bare electrically connected to a P-type electrode and an N-type electrode sandwiching a light-emitting layer in each light-emitting element12.

Each pair of the connecting portions12aand12bis, in plan view, positioned on a diagonal T1, which is one of two diagonals of the square that is an external shape of each of the light-emitting elements12. Note that here, “connecting portions are positioned on the diagonal” means that, in plan view, the connecting portions12aand12bhave an overlap with the diagonal T1, and the center of the connecting portions need not be positioned on the diagonal.

The light-emitting elements12, as shown inFIG. 5, are mounted on the substrate11such that the diagonal T1(seeFIG. 8), on which the connecting portions12aand12bare positioned, is perpendicular to the row direction (the lateral direction).

The light-emitting elements12in each of the light-emitting element rows21,22, and23(excluding light-emitting elements at both ends of the light-emitting element rows) are, as shown inFIG. 7, electrically connected without a connection pad (a type of wiring formed in insulating layers but not formed in the insulating layers of the present embodiment) by the metal wires19to other adjacent ones of the light-emitting elements12within the same light-emitting element row21,22, or23.

Each of the light-emitting elements12not positioned at ends of the light-emitting element rows21,22, and23(hereafter, “center-side light-emitting elements”) is connected to each connecting portion12aor12bhaving identical polarity of two adjacent light-emitting elements12in the row direction by two of the metal wires19and19. In other words, center-side light-emitting elements12are connected to two adjacent light-emitting elements12by four of the metal wires19.

The two of the metal wires19of each of the connecting portions12aand12bof the center-side light-emitting elements12are bonded to the connecting portion12aor12bsuch that a second bond19bof one of the two metal wires19overlaps with a first bond19aof the other of the two metal wires19when viewed from above the light-emitting element12.

A technique for connecting adjacent ones of the light-emitting elements12by the metal wires19may be the same bonding technique used to connect the wiring16,17, and18of the light-emitting elements12to the metal wires19.

Among the light-emitting elements12in the light-emitting element rows21,22, and23, one of the two of the connecting portions12aand12bof each of the light-emitting elements12positioned at both ends of each of the light-emitting element rows21,22, and23is, as shown inFIG. 7, connected to an adjacent one of the wiring16,17, and18by one of the metal wires19.

Each of the light-emitting element rows21,22, and23are provided with one of the sealing members13, which cover a plurality of the light-emitting elements12and have line-shapes extending in the lateral direction (seeFIG. 4). By providing each row with the sealing members13, optical path length of light emitted from the light-emitting elements12is made uniform when transmitted through the sealing members13and color irregularities are suppressed.

The sealing members13are made of light-transmissive material into which wavelength conversion material is mixed, and a portion of light emitted from the light-emitting elements12is converted into light of a different wavelength. Further, each of the light-emitting elements12is sealed by the sealing members13.

As the wavelength conversion material, phosphor particles may be used. As the light-transmissive material, for example, a silicone resin, a fluorine resin, a silicone/epoxy hybrid resin, a urea resin, etc., may be used.

A portion of blue light having a dominant wavelength of approximately 430 nm to 470 nm emitted from the light-emitting elements12is converted to light having a dominant wavelength of, for example, approximately 540 nm to 640 nm by the wavelength conversion material in the sealing members13. As a result, white light is emitted due to mixing of light in the wavelength range after conversion and blue light that is not converted.

4. Light Extraction Efficiency

FIG. 8is a plan view of a portion of a light-emitting module pertaining to the embodiment, illustrating light extraction efficiency.FIG. 9is a plan view of a portion of a light-emitting module pertaining to conventional technology, illustrating light extraction efficiency. Note that in connections between connecting portions and metal wires inFIG. 8andFIG. 9, the first bond and the second bond overlap.

Here, light-emitting elements pertaining to conventional technology are assigned a sign “912”, metal wires are assigned a sign “919”, and connecting portions of the light-emitting elements912are assigned signs “912a” and “912b”. Note that inFIG. 8andFIG. 9, the sealing members13are not shown in order that the metal wires19and919connecting adjacent ones of the light-emitting elements12and912in the row direction can be seen.

The light-emitting elements12and912that are adjacent in the row directions are connected as shown inFIG. 8andFIG. 9by the metal wires19and919.

The light-emitting elements12pertaining to the present embodiment have a square shape in plan view as shown inFIG. 8. The connecting portions12aand12bof the light-emitting elements12are positioned on the diagonal T1, which is one of two diagonals of the square shape.

Here, when a is one side of the square shape in plan view of the light-emitting elements12and x is a distance from the connecting portions12aand12bto a nearest corner on the diagonal T1,
x<a/2  (Equation 1)

Further, the light-emitting elements912pertaining to conventional technology also have a square shape in plan view and a length of one side is also “a”, as shown inFIG. 9.

As shown inFIG. 8, the metal wires19intersect upper surfaces of the light-emitting elements12and connect connecting portions12aand12bof adjacent ones of the light-emitting elements12.

In the same way, as shown inFIG. 9, the metal wires919intersect upper surfaces of the light-emitting elements912and connect connecting portions912aand912bof adjacent ones of the light-emitting elements912.

Thus, light emitted from the upper surfaces of the light-emitting elements12and912is hindered by the metal wires19and919and light extraction efficiency is correspondingly reduced. Of course, reduction in light extraction efficiency is decreased as length in plan view of the metal wires intersecting the light-emitting elements decreases.

Comparing the light-emitting module pertaining to the present embodiment (seeFIG. 8) and the light-emitting module pertaining to conventional technology (seeFIG. 9), a length of the metal wires19intersecting the upper surfaces of the light-emitting elements12is shorter in the light-emitting module pertaining to the present embodiment.

In the light-emitting module pertaining to the present embodiment, the connecting portions12aand12bof the light-emitting elements12are positioned on the diagonal T1of the upper surfaces of the light-emitting elements12, the diagonal T1is perpendicular to (intersected by) the row direction of the light-emitting element rows on the substrate11, and Equation 1, above, is satisfied.

Thus, the metal wires19intersect corner portions of the upper surfaces of the light-emitting elements12(in other words, intersect two sides either side of corners positioned on the diagonal T1), and “L1” is the length of intersecting portions of the metal wires19, as shown inFIG. 8. Because the upper surfaces of the light-emitting elements12are square-shaped, L1 is equal to 2×. According to Equation 1, L1, which is equal to 2×, is less than a.

On the other hand, in the light-emitting module pertaining to conventional technology, the connecting portions912aand912bof the light-emitting elements912are positioned on a center line T2on the upper surfaces of the light-emitting elements912, and the center line T2is perpendicular to a row direction of light-emitting rows on a substrate. Note that the center line T2is perpendicular to the row direction and connects center points of two opposite sides of the square shape.

Thus, the metal wires919intersect opposite sides of the upper surfaces of the light-emitting elements912, and “L2” is the length of intersecting portions of the metal wires919, as shown inFIG. 9. L2 is equal to a, which is one side of the square shape in plan view of the light-emitting elements912.

In this way, the length of the portions of the metal wires19intersecting the upper surfaces of the light-emitting elements12in the light-emitting module10pertaining to the embodiment is “L1”, the length of the portions of the metal wires919intersecting the upper surfaces of the light-emitting elements912in the light-emitting module pertaining to conventional technology is “L2”, and L1 is less than L2. In this way, the light-emitting module10pertaining to the present embodiment obtains a higher light extraction efficiency than the light-emitting module pertaining to conventional technology.

Modifications

Description is provided above based on an embodiment of the present invention, but the present invention is not limited to the above embodiment. For example, the light-emitting module may be an appropriate combination of a configuration described in the embodiment and configurations described in the modifications below. Further, additional modifications may be made to the light-emitting module without departing from the scope of the technical idea of the present invention.

(1) Overall Shape

The light-emitting module10pertaining to the above embodiment is described as having an overall shape in plan view that is a rectangular shape. As other shapes, for example, the overall shape in plan view may be polygonal such as square, triangular, pentagonal, etc., or may be circular, elliptical, or oval.

In the light-emitting module10pertaining to the above embodiment, the (120) light-emitting elements12are in the ten serial rows in each of which twelve light-emitting elements are connected in parallel. However, the light-emitting elements12may have other connection forms, and the number of the light-emitting elements12is not limited to 120 and may be other numbers.

Further, the light-emitting element rows are composed of three types of light-emitting element rows having different numbers of the light-emitting elements included therein. However, there may be only one type of light-emitting element row having an equal number of the light-emitting elements, or two, four, or more types of light-emitting element rows having different numbers of the light-emitting elements.

However, the number of the light-emitting elements in one of the light-emitting element rows is necessarily a plurality, and the plurality of the light-emitting elements in one of the light-emitting element rows are necessarily connected in parallel by the metal wires.

(3) Mounting Area

The mounting area20, as shown inFIG. 5, uses three types of light-emitting element rows, the light-emitting element rows21,22, and23, and in plan view has an overall external shape that is circular. However, the mounting area20may use one type of light-emitting element row that in plan view has an overall external shape that is a quadrilateral shape such as a square or rectangle, or a polygonal shape such as a hexagon.

However, each of the light-emitting element rows is necessarily sealed by one of the sealing members such that pairs of the metal wires that connect adjacent ones of the light-emitting elements in parallel are not exposed (not exposed to air).

The materials described for the substrate11and the sealing members13in the embodiment are examples, and other materials may be used.

For example, as the substrate, a ceramic sheet (one layer) may be used, and after forming the wiring on a surface thereof, the surface may be covered (coated) by an insulating resin material such that only the light-emitting elements and portions of the surface at which the light-emitting elements are bonded are exposed.

The sealing material, when conversion of the wavelength of light from the light-emitting elements is not required, need not include the wavelength conversion material. Further, ceramics, etc., may be used as the light-transmissive material that is the primary material of the sealing material.

The semiconductor light-emitting elements12in the embodiment have a square shape in plan view, but may have other shapes. As an example of other shapes, the light-emitting elements12may have a rectangular shape in plan view.

FIG. 10is a diagram illustrating mounting and connection of semiconductor light-emitting elements101having a rectangular shape in plan view. Note that in connections between connecting portions and metal wires inFIG. 10, the first bond and the second bond overlap.

The semiconductor light-emitting elements101have a rectangular shape having a length “a” of a short side and a length “b” of a long side, as shown in the illustration. Here, long sides (side of length b) of the semiconductor light-emitting elements101face each other, and a plurality of the semiconductor light-emitting elements101are arranged in the lateral direction. The lateral direction is the row direction.

The semiconductor light-emitting elements101have pairs of connecting portions101aand101bon positions on a diagonal T3that is one diagonal on upper surfaces of the semiconductor light-emitting elements101. The semiconductor light-emitting elements101are mounted on a substrate such that the diagonal T3is substantially perpendicular to the row direction. Note that here, the connecting portions101aand101boverlap with the diagonal T3in plan view, and centers of the connecting portions101aand101bneed not be positioned on the diagonal T3.

Here, when x is a distance from the connecting portions101aand101bof the semiconductor light-emitting elements101to a nearest corner on the diagonal T3, the following relationship is satisfied.
x<a2b/(a2+b2)  (Equation 2)

Adjacent ones of the semiconductor light-emitting elements101in the row direction, as shown inFIG. 10, are electrically connected (connected in parallel) by metal wires103that extend in the row direction. Upper surfaces of the semiconductor light-emitting elements101are, as shown inFIG. 10, intersected by the metal wires103, and a length L3 of portions of the metal wires103intersecting the upper surfaces satisfies the following relationship.
L3=(b/a+a/b)×x

Because “x” satisfies Equation 2, “L3” is less than “a”.

In the embodiment and above examples, the semiconductor light-emitting elements are quadrilateral in plan view and have diagonals. For example, when a four-sided shape has rounded corners, the four-sided shape does not have diagonals, but in such a case, a point of intersection derived by extending adjacent sides may be used as virtual corners.

When the semiconductor light-emitting elements having a rectangular shape are arranged in rows, the long sides of the semiconductor light-emitting elements may face each other in the row direction, as shown inFIG. 10, or the short sides of the semiconductor light-emitting elements may face each other in the row direction.

In a case in which the long sides face each other in the row direction, as shown inFIG. 10, the metal wires connecting adjacent ones of the semiconductor light-emitting elements can be short. In this way, disconnection of the metal wires can be minimized. Further, as the metal wires are shorter, hindrance of light emitted from adjacent ones of the semiconductor light-emitting elements and light emitted from other ones of the semiconductor light-emitting elements is reduced, and overall absorption loss of light due to the metal wires is reduced.

On the other hand, in a case in which the short sides face each other in the row direction, light emitted from sides of the semiconductor light-emitting elements is less likely to be absorbed by adjacent ones of the semiconductor light-emitting elements, and re-absorption loss of light is reduced. In other words, in a case in which the short sides face each other, facing surface areas of adjacent ones of the semiconductor light-emitting elements are reduced. Light emitted radially sideways from the semiconductor light-emitting elements proceeds in the direction of emission. Such light is less likely to be absorbed in correspondence with a reduction in area of side surfaces (facing surfaces) of adjacent ones of the semiconductor light-emitting elements.

In this way, even in a case in which the semiconductor light-emitting elements are mounted such that the short sides are facing each other in the row direction and the connecting portions are positioned on the diagonal, light extraction efficiency is improved over a case in which the semiconductor light-emitting elements are mounted such that the short sides are perpendicular to the row direction and the metal wires intersect two of the short sides that are facing each other.

(4) Position of Connecting Portions

The connecting portions12a,12b,101a, and101bof the light-emitting elements12and101are described as being positioned on the diagonals T1and T3. However, the connecting portions need not be positioned on the diagonals, and may be positioned near the diagonals or near opposing corners.

A range near the diagonals or near the opposing corners is defined as follows. In a case in which upper surfaces of the semiconductor light-emitting elements have a quadrilateral shape having four right-angled corners (a square or rectangular shape) and lengths of two sides sandwiching a corner are lengths a and b, an area R is enclosed by an imaginary line perpendicular to the diagonal that passes through a position on the diagonal and the two sides a and b sandwiching a corner nearest the position, where x is a distance between the position and the corner nearest the position, the distance x satisfying the following relationship within the area R.
x<a2b/(a2+b2)

Note that here, the semiconductor light-emitting elements are mounted on the substrate such that sides of length b face sides of length b of adjacent ones of the semiconductor light-emitting elements.

In a case in which sides of length a and b are equal, the upper surfaces of the semiconductor light-emitting elements have a square shape. In such a case, the area R is equivalent to a hatched portion R1shown inFIG. 8(only the semiconductor light-emitting element12on the right edge of the figure is hatched). On the other hand, in a case in which sides of length a and b are different, the upper surfaces of the semiconductor light-emitting elements have a rectangular shape. In such a case, the area R is equivalent to a hatched portion R2shown inFIG. 10(only the semiconductor light-emitting element101at a center of the figure is hatched).

(5) Element Orientation

The light-emitting elements12in the embodiment and the light-emitting elements101in the modifications are mounted on the substrate in a position in which the diagonals T1and T3are substantially perpendicular to the row direction. However, even when not perpendicular, a result of improved light extraction efficiency may be obtained.

In other words, the semiconductor light-emitting elements may be positioned such that the diagonal is inclined relative to a direction perpendicular to the row direction so as to satisfy a predefined condition. The predefined conditions are that length of a portion of the imaginary line above a semiconductor light-emitting element (“L1” inFIG. 8and “L3” inFIG. 10), the imaginary line passing through a connecting portion, extending parallel to the row direction, and passing through two sides sandwiching a corner on the diagonal (the two sides extending from a corner, on the diagonal, of the upper surface having a quadrilateral shape) is shorter than a length of a side (“L2” and “a” inFIG. 9, and “a” inFIG. 10) parallel to the row direction of semiconductor light-emitting elements arranged such that sides of the light-emitting elements facing adjacent semiconductor light-emitting elements are perpendicular to the row direction.

In the embodiment, the two of the metal wires19electrically connecting identical polarities of semiconductor light-emitting elements12adjacent on both sides of the center-side semiconductor light-emitting elements12in the light-emitting element rows21,22, and23are bonded such that the first bond19aof one of the two of the metal wires19and the second bond of the other one of the two of the metal wires19overlap.

However, at the connecting portions, the first bond of one of the metal wires and the second bond of the other one of the metal wires may be bonded so as to not overlap when the semiconductor light-emitting elements are viewed from above.

FIG. 11andFIG. 12illustrate examples in which the first bond and the second bond do not overlap.

Semiconductor light-emitting elements151, as shown inFIG. 11, have a square shape in plan view and have connecting portions153and155on a diagonal T4. Here, only one of the semiconductor light-emitting elements151is shown, but a plurality of the semiconductor light-emitting elements151are arranged in a single line to the left and right ofFIG. 11. In other words, the row direction extends left and right.

The semiconductor light-emitting elements151are mounted on a substrate (not illustrated) such that the diagonal T4is substantially perpendicular to the row direction. Center-side ones of the semiconductor light-emitting elements151in light-emitting element rows are connected to the connecting portions153and155having identical polarities of two adjacent ones of the semiconductor light-emitting elements151by two of the metal wires157and159.

Here, the connecting portions153and155have an elongated shape (laterally elongated) in a direction perpendicular to the diagonal T4. Specifically, the connecting portions153and155have an elliptical shape having a major axis perpendicular to the diagonal T4. Thus, the two of the metal wires157and159are bonded to the connecting portions153and155, respectively, second bonds157band159bof one of the metal wires157and159and first bonds157aand159aof the other of the metal wires157and159lined up left and right (directions perpendicular to the diagonal T4) and not overlapping when the semiconductor light-emitting elements151are viewed from above.

In other words, each of the connecting portions153and155of the center-side ones of the semiconductor light-emitting elements151has a first bonding area and a second bonding area that are separated to the left and right for the metal wires157and159that connect adjacent ones of the semiconductor light-emitting elements151.

Semiconductor light-emitting elements201, as shown inFIG. 12, have a square shape in plan view and have connecting portions203and205on a diagonal T5. Here, only one of the semiconductor light-emitting elements201is shown, but a plurality of the semiconductor light-emitting elements201are arranged in a single line to the left and right ofFIG. 12. In other words, the row direction extends left and right.

The semiconductor light-emitting elements201are mounted on a substrate (not illustrated) such that the diagonal T5is substantially perpendicular to the row direction. Center-side ones of the semiconductor light-emitting elements201in light-emitting element rows are connected to the connecting portions203and205having identical polarities of two adjacent ones of the semiconductor light-emitting elements201by two of the metal wires207and209.

Here, the connecting portions203and205have an elongated shape (vertically elongated) in a direction along the diagonal T5. Specifically, the connecting portions203and205have an elliptical shape having a major axis along the diagonal T5. Thus, the two of the metal wires207and209are bonded to the connecting portions203and205, respectively, and second bonds207band209bof one of the metal wires207and209and first bonds207aand209aof the other of the metal wires207and209are lined up and down (directions along the diagonal T5) and not overlapping when the semiconductor light-emitting elements201are viewed from above.

In other words, each of the connecting portions203and205of the center-side ones of the semiconductor light-emitting elements201has a first bonding area and a second bonding area that are separated up and down for the metal wires207and209that connect adjacent ones of the semiconductor light-emitting elements201.

As described above, because the first bonding area and the second bonding area of the connecting portions153and155of the semiconductor light-emitting elements151are separated, the metal wires157and159are connected to the connecting portions153and155without overlapping, and therefore reliability of electrical connections of the semiconductor light-emitting elements151is increased.

Further, because the semiconductor light-emitting elements151have connecting portions153and155having connection areas (bonding areas) for two of the metal wires157and159, firmer connections can be made than when compared to, for example, connecting one of the metal wires157or159to a single connection area after another one of the metal wire157or159is already connected (i.e. when a first bonding overlaps a second bonding).

Note that the connecting portions203and205of the semiconductor light-emitting elements201also, in the same way, have the first bonding area and the second bonding area, and therefore firm connections can be made with the metal wires207and209and reliability of electrical connections with the metal wires207and209is increased.

In the embodiment and present example, one of the semiconductor light-emitting elements has two of the connecting portions that are connected to the metal wires in the same form, but the two of the connecting portions may be connected to the metal wires in different forms. For example, one of the two of the connecting portions may be connected to the metal wires in the form described in the embodiment, and the other of the two of the connecting portions may be connected to the metal wires in any of the forms described in the present example. Further, among the connecting portions, one of the connecting portions may be connected to the metal wires in any of the forms described in the embodiment and the present example.

(2) Relay Point

In the embodiment and the modifications, the semiconductor light-emitting elements12,151, and201in the light-emitting element rows are all connected by the metal wires19, but, for example, a configuration is possible in which only one polarity of the semiconductor light-emitting elements is connected by the metal wires.

Further, when a mounting pitch of the semiconductor light-emitting elements in the row direction is large, relays lands (relay pads) may be provided between adjacent ones of the semiconductor light-emitting elements, and the semiconductor light-emitting elements may be connected via the metal wires connecting the semiconductor light-emitting elements and the relay lands (relay pads).

REFERENCE SIGNS LIST