Package substrate and LED flip chip package structure
A package substrate includes: an insulating substrate, a first and a second soldering pads spacedly disposed on a first surface of the insulating substrate, a first and a second electrodes spacedly disposed on an opposite second surface of the insulting substrate. The first and the second soldering pads are electrically connected to the first and the second electrodes respectively. Moreover, a first and a second grooves are defined on the first surface of the insulating substrate, the first and the second grooves are spaced from each other and disposed between the first and the second soldering pads. The invention further provides a LED flip chip package structure including the package substrate, a LED flip chip and fluorescent glue. The invention adds the grooves in the spacing between the soldering pads as a buffer space for melted solder flowing during reflow soldering process and therefore can relieve short-circuit phenomenon.
1. A package substrate comprising: an insulating substrate, a first soldering pad and a second soldering pad disposed on a first surface of the insulating substrate, a first electrode and a second electrode disposed on a second surface opposite to the first surface of the insulting substrate; the first soldering pad and the second soldering pad being spaced apart, the first electrode and the second electrode being spaced apart, the first soldering pad and the second soldering pad being electrically connected to the first electrode and the second electrode respectively; wherein a first groove and a second groove are recessedly defined on the first surface of the insulating substrate, the first groove and the second groove are spaced from each other and located in a non-soldering-pad region between the first soldering pad and the second soldering pad, a bottom surface of each of the first groove and the second groove is lower than a bottom surface of each of the first soldering pad and the second soldering pad;
wherein each of the first groove and the second groove comprises an elongated main part and an extension part laterally protruding from the elongated main part in a widthwise direction of the elongated main part; the extension part of the first groove and the extension part of the second groove are located between the elongated main parts of the first groove and the second groove and further are staggeredly disposed in a lengthwise direction of the elongated main part intersecting with the widthwise direction.
2. The package substrate according to claim 1 , wherein a depth of each of the first groove and the second groove is in a range from 20 micrometers to 30 micrometers.
3. The package substrate according to claim 1 , wherein the extension part is substantially round.
4. The package substrate according to claim 1 , wherein the first groove is one of an L shape and a reversed L shape, and the second groove is the other one of the L shape and the reversed L shape.
5. The package substrate according to claim 1 , wherein a distance between the first groove and the second groove is 10%˜50% of a distance between the first soldering pad and the second soldering pad.
6. The package substrate according to claim 1 , wherein a length of the first groove is approximately 95% of a length of a side of the first soldering pad adjacent to the first groove, and a length of the second groove is approximately 95% of a length of a side of the second soldering pad adjacent to the second groove.
7. The package substrate according to claim 1 , wherein a depth of each of the first groove and the second groove is 10%˜15% of a thickness of the insulating substrate.
8. The package substrate according to claim 1 , further comprising a bowl-shaped structure disposed on the first surface of the insulating substrate; wherein the bowl-shaped structure is disposed surrounding the first soldering pad and the second soldering pad as well as the first groove and the second groove.
9. The package substrate according to claim 8 , wherein a material of the bowl-shaped structure is a silicone molding compound or an epoxy molding compound.
10. The package substrate according to claim 1 , wherein the insulating substrate is a ceramic substrate, the first groove and the second groove are formed by sintering directly, or formed by laser engraving after the ceramic substrate being sintered.
11. A LED flip chip package structure comprising: a LED flip chip, a fluorescent glue and a package substrate; the package substrate comprising: an insulating substrate, a first soldering pad and a second soldering pad disposed on a first surface of the insulating substrate, a first electrode and a second electrode disposed on a second surface opposite to the first surface of the insulting substrate; the first soldering pad and the second soldering pad being spaced apart, the first electrode and the second electrode being spaced apart, the first soldering pad and the second soldering pad being electrically connected to the first electrode and the second electrode respectively; wherein a first groove and a second groove are recessedly defined on the first surface of the insulating substrate, the first groove and the second groove are spaced from each other and located in a non-soldering-pad region between the first soldering pad and the second soldering pad, a bottom surface of each of the first groove and the second groove is lower than a bottom surface of each of the first soldering pad and the second soldering pad; wherein a positive electrode and a negative electrode of the LED flip chip respectively are electrically connected to the first soldering pad and the second soldering pad by solder, and the fluorescent glue is disposed covering the LED flip chip;
wherein each of the first groove and the second groove comprises an elongated main part and an extension part laterally protruding from the elongated main part in a widthwise direction of the elongated main part; the extension part of the first groove and the extension part of the second groove are located between the elongated main parts of the first groove and the second groove and further are staggeredly disposed in a lengthwise direction of the elongated main part intersecting with the widthwise direction.
12. The LED flip chip package structure according to claim 11 , wherein the first soldering pad and the second soldering pad respectively are electrically connected to the first electrode and the second electrode by metal-filled holes respectively located rightly below the positive electrode and the negative electrode of the LED flip chip.
13. The LED flip chip package structure according to claim 11 , wherein a depth of each of the first groove and the second groove is in a range from 20 micrometers to 30 micrometers.
14. The LED flip chip package structure according to claim 11 , wherein the extension part is substantially round.
15. The LED flip chip package structure according to claim 11 , wherein the first groove is one of an L shape and a reversed L shape, and the second groove is the other one of the L shape and the reversed L shape.
16. The LED flip chip package structure according to claim 11 , wherein a distance between the first groove and the second groove is 10%˜50% of a distance between the first soldering pad and the second soldering pad; a length of the first groove is approximately 95% of a length of a side of the first soldering pad adjacent to the first groove, and a length of the second groove is approximately 95% of a length of a side of the second soldering pad adjacent to the second groove; a depth of each of the first groove and the second groove is 10%˜15% of a thickness of the insulating substrate; the insulating substrate is a ceramic substrate, the first groove and the second groove are formed by sintering directly, or formed by laser engraving after the ceramic substrate being sintered.
17. The LED flip chip package structure according to claim 11 , wherein the package substrate further comprises a bowl-shaped structure disposed on the first surface of the insulating substrate, and the bowl-shaped structure is disposed surrounding the first soldering pad and the second soldering pad as well as the first groove and the second groove.
18. The LED flip chip package structure according to claim 17 , wherein a material of the bowl-shaped structure is a silicone molding compound or an epoxy molding compound.