Patent Application
20070108561
The present invention generally relates to IC (integrated circuit) chip packages, and more particularly to an image sensor chip package which is reduced in size and cost and still has high reliability.
Image sensors are widely used in digital camera modules in order to convert the optical image data of an object into electrical signals. In order to protect the image sensor from contamination or pollution (i.e. from dust or water vapor), the image sensor is generally sealed in a structural package.
A typical image sensor chip package 100 is illustrated in
In the foresaid package 100, the base 10 is essentially made from ceramic, which is expensive. In addition, during the process of forming the contacts 104, 105 and the interconnecting portions 106 on the base 10, a number of interconnection holes are punched in the base 10, then the base 10 is copper plated, via electroless or electrolytic deposition onto the surface of the base 10 and onto the surfaces created by the interconnecting holes. Finally, the contacts 104, 105 are formed by means of etching. Accordingly, the contacts 104, 105 and the interconnecting portions 106 are electrically connected with each other. It is obvious that this method of forming the contacts 104, 105 and the interconnecting portions 106 is complex and as a result it is expensive. Furthermore, water vapor can enter the cavity 103 via the interconnection portions 106. Thus, the chip 12 may be polluted, even be damaged.
Additionally, the cavity 103 of the base 10 must contain both of the top contacts 104 and the chip 12 therein, and there must define a space between an outer periphery of the chip 12 and an inner periphery of the frame portion 102 of the base 10 for allowing movement of a wire bonding tool, which accordingly results in a relative large volume of the package 100 relative to the volume of the chip 12.
Furthermore, the relative large volume of the package 100 results in more dust-particles adhering to the cover 15, the board portion 101 and the frame portion 102 of the base 10. Thus, more dust-particles will drop onto the chip 12. The dust-particles obscure the optical path and produce errors in the image sensing process. Accordingly, the quality and/or reliability of the package 100 may be affected.
Therefore, an improved image sensor chip package is desired in order to overcome the above-described shortcomings.
In one aspect, an image sensor chip package includes a carrier, an image sensor chip, a number of wires and a holder. The carrier includes a base and a leadframe embedded in the base. The base has a board, a sidewall extending from a top surface of the board and a cavity cooperatively defined by the board and the sidewall. The leadframe includes a plurality of conductive leads spaced from each other. Each conductive lead has a first terminal portion exposed from a top surface of the sidewall of the base, a second terminal portion exposed through a bottom surface of the board, and an interconnecting portion connecting the first and second terminal portion. The chip is mounted on the base and received in the cavity, and includes an active area and a plurality of contacts. The wires electrically connect the contacts of the chip and the first terminal portions of the leadframe. The holder is mounted on the carrier enclosing the cavity of the carrier, and allows light passing therethrough to reach the active area of the chip.
Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Many aspects of the present image sensor chip package can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the image sensor chip package. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Referring to
The carrier 20 of the package 200 includes a plastic base 21 and a leadframe (not labeled). The leadframe and the plastic base 21 cooperatively form the carrier 20 by injection molding.
The base 21 is essentially made from plastic materials such as polyphenylene oxide (PPO), polyphenylene sulfide (PPS) and the like. The base 21 may have various perimeter shapes, such as a square, rectangular, a circular etc. The base 21 includes a base board 211, a sidewall 213 upwardly extending from a periphery of the base board 211, and a cavity 24 cooperatively formed by the base board 211 and the sidewall 213 for receiving electronic components. As shown in
Referring to
During injection molding, the plastic base 21 encapsulates the leadframe, wherein the die pad 231 is disposed in a middle portion of the base board 211, an upper surface of each first terminal portion 235 is exposed from the top surfaces of the sidewall portions without a slot 217 defined therein, for example, the top surfaces of the front and rear sidewall portions 2131, 2133, and both of a lower surface of the die pad 231 and each second terminal portion 236 are exposed from the bottom surface of the base board 211. The first and second terminal portions 235, 236 both are configured for electrically connecting with other electronic components, for example the first terminal portions 235 can be used to electrically connect to a chip and the second terminal portions 236 can be used to electrically connect with a printed circuit board (PCB), thereby transmitting signals from the chip to the PCB via the leadframe.
The image sensor chip 30 is received in the cavity 24, and is attached to the base board 211. A top surface of the image sensor chip 30 is arranged with an active area 301 and a number of contacts 302. The active area 301 is disposed in a middle portion of the top surface of the chip 30. The contacts 302 are divided into two groups, and the two groups of contacts 302 are symmetrically disposed and formed at regular intervals along a peripheral portion of the top surface of the chip 30.
The wires 50 can be made of a conductive material with good electric conductivity, such as gold or aluminum alloy. One end of each wire 50 is connected/joined with a respective contact 302 of the image sensor chip 30, and the other end of the wire 50 is connected/joined with a respective top surface of a first terminal portion 235 of the leadframe.
The holder 60 is made from opaque material or transparent material with an opaque layer coated thereon. The holder 60 is a hollow case having an opening end and a half-closed end. The half-closed end of the holder 60 has a through hole 601 defined therein. A transparent board 602 can be received in or attached to a perimeter of the through hole 601 to close the half-closed end and allow light to pass therethrough. The opening end of the holder 60 has a first step portion 61 and a second step portion 62. An inner periphery of the first step portion 61 has a dimension equal to that of an outer periphery of the carrier 20. An inner periphery of the second step portion 62 has a dimension smaller than that of the outer periphery of the carrier 20. The second step portion 62 includes a step surface 621 from which the first step portion 61 extends. The step surface 621 has two grooves 623 defined therein for receiving the wires 50 and two ribs 624 projecting therefrom for engaging with the slots 217 of the carrier 20. The holder 60 receives the carrier 20 mounted with the chip 30 therein, wherein the inner periphery of the first step portion 61 is adhered to the outer periphery of the carrier 20, the step surface 621 of the holder 60 is adhered to the top surface of the sidewall 213, each groove 623 receives a group of wires 50, each rib 624 of the holder 60 is adhered to and engaged with a corresponding slot 217 of the carrier 20, and the transparent board 602 is positioned above the active area 301 of chip 30.
The base 21 of the carrier 20 is made of plastic material, which is much cheaper than ceramic, and the carrier 20 is formed by injection molding technology, which is a relative simple method for manufacturing the carrier 20, thus, the cost of the package 200 is accordingly decreased.
The leadframe of the barrier 20 is solid and substantially encapsulated by the base 21, so it is difficult for water vapor to penetrate into the package 200 to pollute the chip 30, thereby enhancing the reliability of the packaged 200.
The top surfaces of the first terminal portions 235 of the leadframe act as connecting pads, accordingly there is no space restriction on the wire bonding tools' movement. Thus, the size of the carrier 20 can be sufficiently minimized to approach the size of the chip 30, and the volume of the image sensor chip package 200 can also be minimized.
In addition, a relative small volume of the package 200 contains relatively little dust particles therein, the pollution and/or contamination of the active area 301 is reduced and the quality and reliability of the package 200 is much improved.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200510101505.8 | Nov 2005 | CN | national |
This application is related to a co-pending U.S. patent applications (Attorney Docket No. US7591), entitled “DIGITAL CAMERA MODULE”, by Steven Webster et al. Such application has the same assignee as the present application and has been concurrently filed herewith. The disclosure of the above identified application is incorporated herein by reference.
