Image sensor package and packaging method for the same

An image sensor package includes a substrate, a sensor chip, a frame, a lens element and at least a pair of guide pins. The sensor chip is mounted on the substrate, and has two opposite sides and a sensing region, which has a sensing region central axis. The frame is mounted on the substrate, and has an aperture and an inner space with the sensor chip disposed therein. The lens element is disposed inside the aperture and has a lens central axis. The guide pins locate oppositely inside the inner space of the frame with an interval between the tips of the guide pins substantially identical to the distance between the opposite sides of the sensor chip, wherein the central line of the interval between the tips of the guide pins defines a positioning line, which substantially coincides with the lens central axis; wherein the tip of each guide pin is aligned with one of the opposite sides of the sensor chip such that the positioning line is substantially coincided with the sensing region central axis.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan Patent Application Serial Number 096120666, filed on Jun. 8, 2007, the full disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a semiconductor package and packaging method thereof, and more particularly, to an image sensor package and a packaging method for the same.

2. Description of the Related Art

In a conventional solid-state image device, as disclosed in Japanese patent publication number 61-134187 and entitled “Solid-State Image Pickup Device” as shown inFIG. 1, a CCD image sensing chip303is attached to a substrate301by means of an adhesive302and the substrate301has erected side walls305at its surroundings. A frame307for carrying a lens element308is fixed on the side walls305by means of an adhesive306. However, in an actual packaging process, when the CCD image sensing chip303is attached to the substrate301by means of the adhesive302, a positional error of the CCD image sensing chip303may be introduced such that the central axis303cof the chip303may deviate from a predetermined central line300c, i.e. de-center caused by the die attachment process. In addition, when fixing the frame307with the adhesive306, a second positional error may be introduced such that the central axis308cof the lens element308may deviate from the predetermined central line300cto cause further de-center. In the solid-state image device300, the positional deviation between the central axis303cof the CCD image sensing chip303and the central axis308cof the lens element308is preferably controlled within 20 micrometers such that the imaging beams from the lens element308can fall onto the effective sensing region of the CCD image sensing chip303and the captured image can be fully displayed without the shading phenomenon.

In order to solve the aforementioned misalignment problem, many methods have been provided in the art to decrease the occurrence of de-center, as disclosed in Japanese patent publication number 9-232548 and entitled “Solid-State Image Pickup Device” as shown inFIG. 2. In this reference, a plurality of stepped positioning portions4,5and6are formed on a single supporting member2and then a solid-state image device7, a lens element8and a diaphragm plate9are sequentially mounted on those positioning portions so as to improve positioning accuracy during packaging and decrease the occurrence of de-center. However, in an actual packaging process, manufacturing errors still exist for the positioning portions4of the solid-state image device7and the positioning portions5of the lens element8. The accumulations of the manufacturing errors of the positioning portions4and5can still affect positioning accuracies of each element and introduce de-center. In addition, in this solid-state image pickup device, the supporting member2is directly formed on the leadframe3and thus the device is only applicable to a solid-state image device with a low pin count. As to a solid-state image device with a high pin count, the leadframe3cannot fulfill its requirement and therefore it is necessary to use the chip on board (COB) package. However, the supporting member2of the solid-state image device cannot be formed directly on the substrate.

According to the above reasons, it is necessary to further improve the above mentioned solid-state image device so as to solve the problem of positional deviation between the lens element and the chip in a COB-type image sensor package.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image sensor package and a packaging method for the same to solve the problem of positional deviation between the sensing region of a sensor chip and the lens element.

In order to achieve the above object, the image sensor package according to the present invention mainly includes a substrate, a sensor chip, a frame, a lens element, and at least a pair of guide pins. The sensor chip is mounted on the substrate, and has two opposite sides and a sensing region, which has a sensing region central axis. The frame is mounted on the substrate, and has an aperture and an inner space with the sensor chip disposed therein. The lens element is disposed inside the aperture and has a lens central axis. The guide pins locate oppositely inside the inner space of the frame with an interval between the tips of the guide pins substantially identical to the distance between the opposite sides of the sensor chip, wherein the central line of the interval between the tips of the guide pins defines a positioning line, which is substantially coincided with the lens central axis; wherein the tip of each guide pin is aligned with one of the opposite sides of the sensor chip respectively such that the positioning line is substantially coincided with the sensing region central axis.

The present invention also provides a packaging method for an image sensor package. The image sensor package includes a sensor chip, a frame, a lens element and at least a pair of guide pins, wherein the sensor chip has two opposite sides and a sensing region, which has a sensing region central axis; the frame has an inner space and an aperture for carrying the lens element, which has a lens central axis; the guide pins are located oppositely inside the inner space of the frame with an interval between the tips of the guide pins substantially identical to the distance between the opposite sides of the sensor chip; wherein the central line of the interval between the tips of the guide pins defines a positioning line, which is substantially coincided with the lens central axis. The packaging method includes the steps of: mounting the sensor chip on the substrate; mounting the frame on the substrate such that the sensor chip is disposed inside the inner space; and aligning the tip of each guide pin with one of the opposite sides of the sensor chip such that the positioning line is substantially coincided with the sensing region central axis.

In the image sensor package of the present invention, the lens central axis of the lens element carried by the frame is substantially coincided with the sensing region central axis of the sensor chip by forming at least one pair of guide pins inside the frame. Accordingly, the positional deviation between the sensing region of the sensor chip and the lens element can be decreased so as to improve the positioning accuracy in packaging.

According to the image sensor package of the present invention, the guide pins are formed integrally inside the frame by means of injection molding without increasing the manufacturing complexity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIGS. 3aand3b,FIG. 3aillustrates a sectional view of the image sensor package1according to one embodiment of the present invention andFIG. 3bshows a sectional view taken along the line3b-3bofFIG. 3a. The image sensor package1includes a substrate11, a sensor chip12, a frame13, at least a pair of first guide pins14and a lens element15, and all these elements together form the image sensor package1of the present invention. Imaging beams are incident from outside of the image sensor package1to penetrate the lens element15and are then captured by an image sensing region121of the sensor chip12.

Embodiments of the substrate11may be a printed circuit board or a ceramic circuit board, and the substrate11has a predetermined packaging line11cserved as a datum line for packaging the sensor chip12and the frame13thereon. Embodiments of the sensor chip12may be a Complementary Metal-Oxide-Semiconductor (CMOS) image sensing chip, a Charge Coupled Device (CCD) image sensing chip, or other kinds of image sensing chip for capturing images. The sensor chip12has two first opposite sides122,122and a sensing region121, which has a first sensing region central axis121c. The frame13is mounted over the sensor chip12and includes an upper frame132and a side wall131. The middle of the upper frame132has an aperture H for carrying the lens element15, which has a first lens central axis15c. The side wall131is erected from the edges of the frame13and thus an inner space133is formed inside the frame13, and the sensor chip12is disposed inside the inner space133. The frame13and the lens element15are, preferably, sealed hermetically so as to prevent dust from entering the image sensor package1and affecting the performance of the package. At least one pair of first guide pins14are formed on the side wall131inside the inner space133and are preferably formed integrally thereon by means of injection molding. The interval between the tips of the first guide pins14is substantially identical to or larger than, by a range from 1 to 2 micrometers, the distance between the first opposite sides122of the sensor chip12. The central line of the interval between the tips of the first guide pins14defines a first positioning line14c, which substantially coincides with the first lens central axis15c; meaning that, the lens element15is aligned with the interval between the tips of the first guide pins14. During packaging, the sensor chip12is inserted between the first guide pins14and the tips of the first guide pins14are aligned with the first opposite sides122of the sensor chip12such that the first sensing region central axis121cof the sensor chip12is substantially coincided with the first positioning line14c. In this manner, the first sensing region central axis121cis substantially coincided with the first lens central axis15cso as to eliminate the positional deviation between the sensing region121of the sensor chip12and the lens element15.

The packaging method for the image sensor package1of the present invention is illustrated hereinafter. First, the sensor chip12is attached to the substrate11and preferably it is die attached to the substrate11by means of an adhesive16. Then, the sensor chip12is connected to the substrate11through a plurality of bonding wires18, e.g. gold wires, so as to electrically connect to the leadframe (not shown). After the sensor chip12goes through the die attachment and wire bonding processes, a positional deviation “d” tends to form between the first sensing region central axis121cand the predetermined packaging line11c. Then, the frame13, which carries the lens element15, is mounted over the sensor chip12such that the sensor chip12is located inside the inner space133. After the tips of the first guide pins14are aligned with the first opposite sides122of the sensor chip12, the bottom of the side wall131of the frame13is attached to the substrate11by means of an adhesive17or the like. Alternatively, the frame13can be riveted to the substrate11by disposing rivets (not shown) on the bottom of the side wall131and inserting the rivets into the substrate11. Accordingly, although a first positional deviation “d” may be formed between the first sensing region central axis121cof the sensor chip12and the predetermined packaging line11cafter the sensor chip12is die attached and wire bonded, a second positional deviation is not formed between the first lens central axis15cof the lens element15and the first sensing region central axis121cof the sensor chip12by utilizing the frame13of the present invention. This is because the packaging of the frame13is positioned with reference to the first sensing region central axis121cof the sensor chip12. The sensing region121of the sensor chip12is indeed aligned to the lens element15, thereby improving the positioning accuracy.

In an alternative embodiment, two pairs of guide pins, e.g. first guide pins14and second guide pins14′, are disposed at different locations inside the frame13; for example in this embodiment, the guide pins14and14′ are perpendicular to each other; wherein the first positioning line14cdefined by the central line of the interval between the tips of the first guide pins14is substantially coincided with a first lens central axis15cof the lens element15, and a second positioning line14c′ defined by the central line of the interval between the tips of the second guide pins14′ is substantially coincided with a second lens central axis15c′ of the lens element15. The sensor chip12has a first sensing region central axis12cparallel to its first opposite sides122and a second sensing region central axis12c′ parallel to its second opposite sides122′. During packaging, the tips of the first guide pins14are aligned with the first opposite sides122of the sensor chip12such that the first sensing region central axis121ccan be substantially coincided with the first lens central axis15cwhile the tips of the second guide pins14′ are aligned with the second opposite sides122′ of the sensor chip12such that the second sensing region central axis121c′ can be substantially coincided with the second lens central axis15c′. In this manner, positional deviations between the lens element15and the sensing region121of the sensor chip12in different directions can be further decreased.

Referring toFIG. 3c, it shows an enlarged view of the alignment of the sensor chip12and one of the first guide pins14. In order to facilitate the alignment between the first guide pins14of the frame13and the first opposite sides122of the sensor chip12, it is preferable to form lead angles141on the tips of the first guide pins14, lead angles123on the sides of the sensor chip12, or lead angles on both the tips of the first guide pins14and the sides of the sensor chip12.

As described above, since conventional solid-state image devices shown inFIGS. 1 and 2have the problem of low positioning accuracy, it will decrease the yield of packaging. Compared with the conventional solid-state image devices shown inFIGS. 1 and 2, the image sensor package1and packaging method for the same (shown inFIGS. 3aand3b) according to the present invention can indeed improve the positioning accuracy during packaging by means of forming at least one pair of guide pins14inside the frame13. And because the guide pins14can be formed integrally on the frame13by means of injection molding, the manufacturing complexity will not be increased.

Although the invention has been explained in relation to its preferred embodiment, it is not used to limit the invention. It is to be understood that many other possible modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the invention as hereinafter claimed.