Light source package structure

A light source package structure is provided. The light source package structure includes a substrate, an upper electrode layer and a lower electrode layer respectively disposed on two sides of the substrate, a light emitting unit mounted on the upper electrode layer, a surrounding wall disposed on the substrate and arranged to surround the light emitting unit, a conductive unit disposed on the surrounding wall and electrically connected to the lower electrode layer, a light permeable element disposed on the surrounding wall, a detection circuit formed on the light permeable element, and at least one conductive adhesive. The conductive adhesive includes a colloid and a plurality of fillers mixed with the colloid. The colloid and the fillers of the conductive adhesive are partially filled within the gap.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of priority to China Patent Application No. 202010004957.9, filed on Jan. 3, 2020, and No. 201910378781.0, filed on May 7, 2019, in People's Republic of China. The entire content of the above identified application is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a light source package structure, and more particularly to a light source package structure including at least one conductive adhesive that has a plurality of fillers.

BACKGROUND OF THE DISCLOSURE

Conventional light source package structures mostly use a TO-CAN (Transistor Outline-CAN) package structure. However, as there have been no major structural improvements in recent years, the conventional light source package structures have become increasingly difficult to meet various requirements.

SUMMARY OF THE DISCLOSURE

In response to the above-referenced technical inadequacies, the present disclosure provides a light source package structure to effectively improve on the issues associated with conventional light source package structures.

Therefore, the light source package structure of the present disclosure provides a structure that is different from a TO-CAN (Transistor Outline-CAN) package structure to meet different requirements nowadays. Specifically speaking, the fillers of the conductive adhesive are partially filled within the gap between the surrounding wall and the light permeable element. Accordingly, the conductive adhesive does not collapse from the gap, so that a bridge of the electrical connection can be improved through the fillers of the conductive adhesive.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring toFIG. 1toFIG. 16, an embodiment of the present disclosure provides a light source package structure100, and more particularly to a light source package structure100for a3D sensing, such as the light source package structure100applying a vertical cavity surface emitting laser (VCSEL) or an infrared light source, but the present disclosure is not limited thereto. For example, the light source package structure100can also apply a LED or a laser.

As shown inFIG. 1toFIG. 3, a light source package structure100is provided. That is, the light source package structure100can be adjusted according to design requirements, but it is not limited thereto. The light source package structure100includes a substrate1, an upper electrode layer2and a lower electrode layer3respectively disposed on opposite sides of the substrate1, a plurality of conducting pillars4embedded inside of the substrate1, a surrounding wall5disposed on the substrate1, a light emitting unit6mounted on the upper electrode layer2, a light permeable element8disposed on the surrounding wall5, and an adhesive9that is provided to fix the light permeable element8onto the surrounding wall5.

The substrate1is substantially a rectangular shape (such as a rectangle shape or a square shape) in the present embodiment. The substrate1of the present embodiment is a ceramic substrate and includes a first surface11and a second surface12that is opposite to the first surface11. The material of the substrate1is not limited to the ceramic, and the material of the substrate1can also be a circuit board or other insulating substrate.

The upper electrode layer2is disposed on the first surface11of the substrate1, and the lower electrode layer3is disposed on the second surface12of the substrate1. The conducting pillars4are embedded inside of the substrate1. Each of the conducting pillars4has two ends that are respectively connected to the upper electrode layer2and the lower electrode layer3, so that the upper electrode layer2can be electrically connected to the lower electrode layer3through the plurality of conducting pillars4.

The surrounding wall5is made of the liquid crystal polymer and disposed on the first surface11of the substrate1. An outer edge of the surrounding wall5is coplanar with an outer edge of the substrate1, and a peripheral part of the upper electrode layer2is sandwiched between the above-mentioned surrounding wall5and the substrate1. The surrounding wall5is annular with a step structure, and the surrounding wall5of the present embodiment is a one-piece molded structure, but the present disclosure is not limited thereto.

Specifically, the surrounding wall5includes an upper tread surface51, an upper riser surface52connected to an inner edge of the upper tread surface51, a lower tread surface53, each of the above mentioned element (i.e.,51-54) are sequentially arranged from an outside to an inside of the surrounding wall5. Furthermore, in the present embodiment, the surrounding wall5includes two inclined surfaces55that are respectively connected to the upper riser surface52and the lower tread surface53, and the two inclined surfaces55are respectively connected to two opposite sides of the lower tread surface53(e.g., two short edges of the lower tread surface53inFIG. 2).

The upper tread surface51is a square annular shape (such as a rectangular annular shape or a square annular shape) and is arranged away from the substrate1. The upper tread surface51in the present embodiment is a top surface of the surrounding wall5, and the upper tread surface51is preferably parallel to the first surface11of the substrate1. The upper riser surface52is a square annular shape and is vertically connected to the inner edge of the upper tread surface51. The lower tread surface53is a square annular shape and is disposed at an inner side of the upper riser surface52. The lower tread surface53is preferably parallel to the upper tread surface51, and a distance between the lower tread surface53and the first surface11is less than a distance between the upper tread surface51and the first surface11. The lower riser surface54is a square annular shape. The lower riser surface54is vertically connected to an inner edge of the lower tread surface53and is arranged away from the upper tread surface51. The lower riser surface54and the first surface11of the substrate1jointly define a receiving space S.

Furthermore, one side of each of the two inclined surfaces55(e.g., an inner edge of each of the inclined surfaces55inFIG. 3) is connected to the lower tread surface53to form an angle greater than 90 degrees, and the other side of each of the two inclined surfaces55(e.g., an outer edge of each of the inclined surfaces55inFIG. 3) and the upper riser surface52jointly form an accommodating groove56that has an angle less than 90 degrees. That is, positions of the two accommodating grooves56of the surrounding wall5are opposite to each other, but the present disclosure is not limited thereto. For example, in other embodiments not shown, the surrounding wall5can include at least one inclined surface55and at least one accommodating groove56corresponding in position to the at least one inclined surface55. That is, the accommodating groove56is disposed between the lower tread surface53and the upper riser surface52.

In addition, the surrounding wall5has two notches58that are recessed from the lower tread surface53and the lower riser surface54and that are in spatial communication with the receiving space S. The two notches58are arranged opposite to each other. The two notches58of the surrounding wall5are preferably and respectively disposed at a center of two long edges of the lower tread surface53. That is, the two accommodating grooves56of the surrounding wall5and the two notches58respectively correspond in position to four edges of the lower tread surface53, but the present disclosure is not limited thereto. For example, in other embodiments of the present disclosure, the surrounding wall5can also have at least one notch58.

As shown inFIG. 1toFIG. 3, in the present embodiment, the light emitting unit6is the vertical cavity surface emitting laser (VCSEL) that provides an infrared light. The light emitting unit6is disposed in the receiving space S, and the light emitting unit6preferably corresponds in position to a center of the first surface11.

In the present embodiment, the light permeable element8is a transparent glass plate and a light-diffusing layer disposed on the transparent glass plate. The light permeable element8is disposed on the lower tread surface53of the surrounding wall5and is spaced apart from the upper riser surface52(that is, the light permeable element8does not contact the upper riser surface52). Accordingly, each of the notches58defines an air flow channel that is in spatial communication with the receiving space S and an external space.

As shown inFIG. 4toFIG. 6, a light source package structure that is formed by adjusting the light source package structure shown inFIG. 1toFIG. 3is provided, and the same part of the light source package structure shown inFIG. 1toFIG. 3will not be reiterated herein. A main difference between the light source package structure shown inFIG. 1toFIG. 3and the light source package structure shown inFIG. 4toFIG. 6is described as follows. The lower electrode layer3includes a first lower electrode layer31and a second lower electrode layer32, and the light emitting unit6is electrically connected to the first lower electrode layer31through the upper electrode layer2. Furthermore, the light source package structure100further includes a conductive unit50disposed on the surrounding wall5and electrically connected to the second lower electrode layer32, at least one detection circuit80formed on the light permeable element8, and a least one conductive adhesive901.

The conductive unit50includes at least one upper pad501arranged away from the substrate1. The conductive unit50includes at least one transmission lines504on the surrounding wall5and the substrate1. In this embodiment, the conductive unit50includes a plurality of upper pads501and a plurality of transmission lines504. The transmission lines504are configured to respectively and electrically connect the upper pads501to the second lower electrode layer32. The detection circuit80is preferably a transparent conductive and includes a plurality of metal contacts801respectively arranged adjacent to the upper pads501. Specifically, each of the metal contacts801are substantially coplanar with each of the upper pads501, such that the metal contacts801are respectively and electrically connected to the upper pads501through the conductive adhesives901.

It should be noted that high-power laser packages are more widely used in consumer electronics, so that the eye safety has become an important issue. The detection circuit80is a protecting mechanism that protects eyes are not harmed by the vertical cavity surface emitting laser6, that is, a transparent conductive layer of the detection circuit80is formed on a top or a bottom surface of the light permeable element8. The transparent conductive layer may be an indium tin oxide (ITO) layer, but it is not limited thereto. The detection circuit80is formed on the light permeable element and is connected to the substrate1, when the light permeable element8falls off or breaks, an open circuit is formed by the detection circuit80and then a protection mechanism is triggered so as to protect the human eye.

As shown inFIG. 9toFIG. 11, a light source package structure that is formed by adjusting the light source package structure shown inFIG. 1toFIG. 3is provided, and the same part of the basic architecture shown inFIG. 1toFIG. 3will not be reiterated herein. The main difference between the light source package structure shown inFIG. 1toFIG. 3and the light source package structure shown inFIG. 9toFIG. 11is described as follows. The light source package structure100includes a substrate1, an upper electrode layer2and a lower electrode layer3respectively disposed on opposite sides of the substrate1, a plurality of conducting pillars4embedded inside of the substrate1, a light emitting unit6mounted on the upper electrode layer2, a surrounding wall5disposed on the substrate1and arranged to surround the light emitting unit6, a conductive unit50disposed on the surrounding wall5, a light permeable element8disposed on the surrounding wall5and covering the light emitting unit6, two detection circuits80formed on the light permeable element8, and a plurality of conductive adhesives90fixing the light permeable element8onto the surrounding wall5. Some of the above components that are similar or identical to the components shown inFIG. 1toFIG. 3, such as the substrate1, the surrounding wall5, the light emitting unit6, and the light permeable element8, will not be reiterated herein.

The lower electrode layer3is disposed on the second surface12of the substrate1and includes a first lower electrode layer31and a second lower electrode layer32both coplanarly disposed. The first lower electrode layer31includes two first lower electrode pads311, and the second lower electrode layer32includes two second lower electrode pads321. The two first lower electrode pads311of the first lower electrode layer31are electrically connected to the upper electrode layer2respectively through the conducting pillars4. The two second lower electrode pads321of the second lower electrode layer32are electrically connected to the conductive unit50. The light emitting unit6is mounted on the upper electrode layer2(substantially mounted on a central portion thereof) so as to be electrically connected to the first lower electrode layer31through the upper electrode layer2.

The conductive unit50is disposed on the surrounding wall5and is electrically connected to the second lower electrode layer32. In the present embodiment, the conductive unit50includes a plurality of lower pads502, a plurality of upper pads501that correspond in position to the lower pads502, a plurality of connecting lines503that are configured to connect the upper pads501respectively to the lower pads502, two transmission lines504respectively connected to the lower pads502, and two conductive pillars505respectively connected to the two transmission lines504.

The lower pads502and the upper pads501are disposed on the surrounding wall5, and a first height position of the lower pads502at the surrounding wall5is different from (e.g., lower than) a second height position of the upper pads501at the surrounding wall5. In the present embodiment, the lower pads502are disposed on the lower tread surface53of the surrounding wall5. The upper pads501are disposed on the at least one of the upper tread surface51and the upper riser surface52.

Specifically, the upper pads501are disposed on the upper riser surface52(and the upper tread surface51), and positions of the upper pads501are respectively arranged adjacent to positions of the lower pads502. The connecting lines503are embedded inside of the surrounding wall5, and two ends of each of the connecting lines503respectively connect one lower pad502and one upper pad501being adjacent to the one lower pad502, so that the lower pads502are respectively and electrically connected to the upper pads501(by the connecting lines503).

Furthermore, the two transmission lines504are embedded inside of the surrounding wall5. In the present embodiment, each of the transmission lines504are substantially located under the lower tread surface53, and two ends of the transmission lines504are respectively connected to the two lower pads502that are spaced apart from each other by the receiving space S. From another perspective, a third height position of each of the transmission lines504at the surrounding wall5is lower than the first height position of the lower pads502at the surrounding wall5.

Parts of each of the two transmission lines504are respectively located above the two second lower electrode pads321of the second lower electrode layer32. The two conductive pillars505are embedded inside of the substrate1and the surrounding wall5. One end of each of the two conductive pillars505is connected to each of the two transmission lines504, respectively. The other end of each of the two conductive pillars505is connected to each of the two second lower electrode pads321of the second lower electrode layer32. Accordingly, the two transmission lines504are respectively and electrically connected to the two second lower electrode pads321of the second lower electrode layer32.

In the present embodiment, it should be noted that the conductive unit50is described by the above-mentioned components, but the conductive unit50can also be adjusted according to design requirements. For example, in other embodiments not shown in the present disclosure, the lower pads502of the conductive unit50can be omitted.

The two detection circuits80are formed on an outer surface of the light permeable element8, and height positions of the two detection circuits80and the outer surface of the light permeable element8substantially correspond in position to the upper tread surface51of the surrounding wall5. Accordingly, the metal contacts801of the two detection circuits80can be connected to the upper pads501through the conductive adhesives90. Any one of the metal contacts801of the detection circuit80and the upper pad501corresponding thereof can be connected by filling within a gap G2between the light permeable element8and the upper riser surface52of the surrounding wall5through the conductive adhesives90(That is, a plurality of fillers902are located between an outer side edge of the light permeable element8and the upper riser surface52, and any one of the conductive adhesives90in the present embodiment does not contact the lower tread surface53), and then the metal contacts801are electrically connected with the upper pads501through the conductive adhesives90, but the present disclosure is not limited thereto.

As shown inFIG. 12toFIG. 16, the metal contacts801are respectively and electrically connected to the upper pads501through the conductive adhesives90of the present embodiment. In each of the conductive adhesives90and its corresponding metal contact801and upper pad501, the conductive adhesive90includes a colloid901and the plurality of fillers902mixed with the colloid901. The gap G2between the metal contacts801and the upper pads501are fully or partially filled within the fillers902. Each of the conductive adhesives90is filled within the gap G2through a part of the fillers902, so that a top edge of the colloid901is not arranged in the gap G2. Preferably, a (D90)<b and a (D10)>b/2. The a (D90) describes an equivalent outer diameter a of the fillers902where ninety percent of the distribution has a smaller particle size and ten percent has a larger particle size. The gap has a width defined as b. The equation a (D90)<b means that the equivalent outer diameter a is less than the width b of the gap G2with distribution size D90. Similarly, the equation a (D10)>b/2 means that the equivalent outer diameter a is greater than half of the width b of the gap G2with distribution size D10. The equivalent outer diameter of the filler902has a width of the size distribution span that satisfies 0.3<(D90−D10)/D50<1.6, and preferably (D90−D10)/D50=1.2. Furthermore, increasing the width of the size distribution indicates that since the fillers may have a varied distribution size, the gap G2may have a varied distribution by the fillers. Therefore, the particle size distribution of the fillers902is required to be a certain width of the size distribution; or if the gap G2is filled with too concentrated fillers, the fillers902cannot enter the small gap G2, and if the gap G2is filled with too dispersed fillers, a probability that the gap G2is filled by the fillers902would be decreased.

Furthermore, the fillers902of the conductive adhesives90are made of at least one of a metal, a metal alloy, a glass, a polymer, or the combination thereof. The fillers902of the conductive adhesives90have at least one of a spherical shape, a sheet shape, a strip shape, an irregular shape or the combination thereof, but the present disclosure is not limited thereto.

The colloid901may be a formed by low-temperature curing or photo curing, such as an epoxy-based silver adhesive. The epoxy-based silver adhesive has a mass fraction of silver powder in the epoxy resin within a range of 70% to 90%, and the silver powder has a particle diameter less than 2 μm. The fillers902are metal particles, and the mass fraction of the fillers in the901is within the range of 10%˜30%. For example, when the gap G2has the width b ranging from 20 μm to 60 μm, tin-silver-copper alloy particles with a melting point of 217° C. may be selected as the material of the fillers. The size distribution of the alloy particles may satisfied with the equations, i.e., D10=13.5 μm, D50=18 μm, D90=34.5 μm, and the width of size distribution is (D90−D10)/D50=1.17. The conductive adhesive90is formed by mixing the conductive silver adhesive and tin-silver-copper alloy particles after curing. The mass fraction of the tin-silver-copper alloy particles in the conductive silver adhesive is about 20%, and a curing temperature is a constant temperature at 100° C. for a half hour thereof.

From another perspective, the fillers902is preferably spherical metal particles, such as nickel balls, silver balls, tin-silver-copper alloys, gold-tin alloys, or other tin balls. Accordingly, the fillers902can be more easily squeezed into the gap G2by needles so that the colloid901in the gap G2is prevented from depression, and then a conductivity of the conductive adhesive90can be increased. Accordingly, the difference in impedance results from a shape variation of the conductive adhesive90is reduced.

In addition, in other embodiments not shown in the present embodiment, the detection circuit80can be formed on an inner side of the light permeable element8. The metal contacts801of the detection circuit80are respectively connected to the lower pads502of the conductive unit50.

In conclusion, in the light source package structure of the present embodiment, the fillers of the conductive adhesive are filled within the gap between the surrounding wall and the light permeable element. Accordingly, the conductive adhesive does not collapse from the gap through the fillers, so that a bridge of the electrically connection can be improved. Furthermore, since the fillers of the conductive adhesive are filled within the gap between the surrounding wall and the light permeable element, the conductive adhesive on the side wall can be prevented from being too thin which may result in rupture or an increase in impedance.