1. Field of the Invention
The present invention relates a method of filling and sealing a fluorescent layer in a slot space defined by two optical lenses and a partition ring, and especially to a method of completely sealing a fluorescent layer in a slot space defined by two optical glasses and a fastening frame, so that the moisture is prevented from permeating into the fluorescent layer, and thus the optical performance can be maintained over a long period, and the method of the present invention can be applied to a light emitting diode (LED) array package.
2. The Prior Arts
An LED is a solid-state semiconductor device, which operates based on the recombination of carriers (electrons and holes) in a semiconductor. When an electron in the conduction band combines with a hole in the valence band, it loses energy equal to the bandgap of the semiconductor in the form of an emitted photon, i.e., light. The LED has advantages of compact volume, fast start-up time and high efficiency so that it has been applied to various fields.
Referring to FIG. 1, which is a cross sectional view showing a conventional array-type LED package structure, which includes a substrate 10a, a package module 12a, a lead frame 14a, and a packaging cover 16a. The substrate 10a is installed at the bottom of the package structure. The package module 12a is served to integrate the substrate 10a and the lead frame 14a. The LED dices 18a are arranged on the substrate 10a in an array form, and the substrate 10a is made of a metal material. The LED dices 18a are electrically connected to the lead frame 14a. The packaging cover 16a is closely engaged with the package module 12a. An insulating protective layer 20a is formed on the LED dices 18a for covering the LED dices 18a. Then, a fluorescent layer 22a is formed on the insulating protective layer 20a. 
However, one disadvantage of the prior art is that the fluorescent layer of the LED dice is directly in contact with moisture in the air. It is known that a fluorescent material can absorb moisture and would result in the deterioration of light property, and an initially white light would gradually decays while changing its hue. Moreover, the fluorescent layer can directly absorb heat generated by light irradiation. In general, the heat resistant temperature and thermal stability of a fluorescent layer are relatively low, and thereby once heat generated by light irradiation is conducted to the fluorescent layer, the fluorescent material would deteriorate and the illumination efficiency is affected and the chromaticity is altered.
Moreover, if a fluorescent material is formed on an LED chip by filling or coating, an extra amount of the fluorescent material has to be provided for ensuring that the fluorescent material will form substantially uniformly on a LED chip, which will increase the manufacturing cost. Moreover, if the fluorescent layer has flaws, the LED chip can not be recycled and reused. In a conventional method, various optical tests can only be carried out after the formation of the fluorescent layer. Therefore, there is a need to provide an LED package structure which can be optically tested in advance, has relatively low manufacturing cost, and has excellent heat dissipation.