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Patent Issued for Package Having MEMS Element and Fabrication Method

March 5, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Chan, Chang-Yueh (Taichung, TW); Huang, Chien-Ping (Taichung, TW); Ke, Chun-Chi (Taichung, TW); Chiu, Shih-Kuang (Taichung, TW), filed on June 28, 2011, was published online on February 18, 2014.

The assignee for this patent, patent number 8653661, is Siliconware Precision Industries Co., Ltd. (Taichung, TW).

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to semiconductor packages, and, more particularly, to a semiconductor package having a MEMS (micro-electro-mechanical system) element.

"MEMS elements have integrated electrical and mechanical functions and can be fabricated through various micro-fabrication technologies. A MEMS element can be disposed on a chip and covered by a shield or packaged with an underfill adhesive so as to form a MEMS package structure. FIGS. 1A to 1D show various types of MEMS package structures in the art.

"FIG. 1A shows a MEMS package structure as disclosed by U.S. Pat. No. 6,809,412. Referring to FIG. 1A, a chip 14 having a MEMS element 141 is disposed on a substrate 10 and electrically connected to the substrate 10 through a plurality of bonding wires 11. Then, a glass lid 12 is disposed on the substrate 10 to cover the chip 14, the MEMS element 141 and the bonding wires 11.

"FIG. 1B shows a MEMS package structure as disclosed by U.S. Pat. No. 6,303,986. Referring to FIG. 1B, a glass lid 12 is disposed on a chip 14 so as to cover a MEMS element 141 of the chip 14. Then, the chip 14 is disposed on a lead frame 10' and electrically connected to the lead frame 10' through bonding wires 11 Finally, an encapsulant 15 is formed to encapsulate the lead frame 10', the bonding wires 11, the glass lid 12 and the chip 14.

"However, the carriers of the above-described structures (the substrate 10 of FIG. 1A and the lead frame 10' of FIG. 1B) increase the thickness of the structures, thus adversely affecting miniaturization of the package structures. Therefore, carrier-free package structures were developed.

"FIG. 1C shows a MEMS package structure as disclosed by U.S. Pat. No. 7,368,808. Referring to FIG. 1C, a chip 14 having a plurality of conductive pads 140 and a MEMS element 141 is provided. A glass lid 12 having a plurality of through holes 120 is disposed on the chip 14 for covering the MEMS element 141. Each of the through holes 120 has conductive pads 122 disposed on the two ends thereof. The conductive pads 122 on the lower ends of the through holes 120 electrically connect with the conductive pads 140 of the chip 14, respectively, and the conductive pads 122 on the upper ends of the through holes 120 have solder balls 16 formed thereon so as for the chip 14 to be electrically connected to other electronic components.

"FIG. 1D shows a MEMS package structure as disclosed by U.S. Pat. No. 6,846,725. Referring to FIG. 1D, a chip 14 having a plurality of conductive pads 140 and a MEMS element 141 is provided, and the conductive pads 140 have solder bumps 142 disposed thereon. A glass lid 12 having a plurality of through holes 120 is disposed on the chip 14 for covering the MEMS element 141. Each of the through holes 120 has conductive pads 122 disposed on the two ends thereof. The conductive pads 122 on the lower ends of the through holes 120 electrically connect with the solder bumps 142, respectively, and the conductive pads 122 on the upper ends of the through holes 120 are used for electrically connecting the chip 14 to other electronic components.

"Although the last two above-described package structures eliminate the need of a carrier so as to achieve miniaturization, the cost for drilling through holes 120 in the lids 12 is quite high. Further, it is difficult to align the conductive pads 122 at the two ends of each of the conductive through holes 120 with a high degree of accuracy or stably secure the conductive pads 122 to the conductive through holes 120, thus easily leading to poor electrical connection and accordingly reducing the reliability of electrical connection between the chip 14 and an external electronic component.

"Therefore, it is imperative to provide a package having a MEMS element so as to overcome the above-described drawbacks."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "Accordingly, the present invention provides a package having a MEMS element, which comprises: a protection layer having opposite first and second surfaces and a plurality of openings in communication with the first and second surfaces; a plurality of conductors formed in the openings of the protection layer, respectively; a plurality of conductive pads formed on the first surface of the protection layer and the conductors for electrically connecting the conductors; a MEMS chip disposed on and electrically connected to the conductive pads; and an encapsulant formed on the protection layer for encapsulating the MEMS chip, wherein the conductors are exposed from the second surface of the protection layer and the encapsulant.

"The present invention further provides a fabrication method of a package having a MEMS element, which comprises the steps of: providing a carrier; forming on the carrier a protection layer having opposite first and second surfaces in a manner that the protection layer is attached to the carrier via the second surface thereof and forming in the protection layer a plurality of openings in communication with the first and second surfaces for exposing portions of the carrier; forming a plurality of conductors in the openings of the protection layer, respectively; forming a plurality of conductive pads on the first surface of the protection layer and the conductors such that the conductive pads electrically connect the conductors, respectively; disposing a MEMS chip on the conductive pads so as to electrically connect the MEMS chip and the conductive pads; forming an encapsulant on the first surface of the protection layer for encapsulating the MEMS chip; and removing the carrier to expose the conductors from the second surface of the protection layer.

"In the above-described package and the fabrication method thereof, a plurality of solder balls can be disposed on exposed surfaces of the conductors, respectively.

"In the above-described package and the fabrication method thereof, a solder mask layer can be formed on the first surface of the protection layer and have a plurality of openings for exposing the conductive pads, respectively.

"Further, a plurality of conductive bumps can be disposed on the conductive pads or on the MEMS chip for electrically connecting the conductive pads and the MEMS chip.

"Through the step of removing the carrier, the present invention obtains a carrier-free package. Compared with the conventional art that requires a substrate or lead frame that increases the package thickness, the present invention reduces the overall thickness of the package so as to achieve miniaturization. Further, by forming the conductors in the protection layer, the present invention avoids a conventional drilling process so as to simplify the fabrication process and reduce the fabrication cost.

"Furthermore, since the package can be fabricated through wafer-level packaging without the need of a conventional substrate or lead frame, a lot of fabrication steps can be avoided so as to save fabrication time and reduce costs."

For more information, see this patent: Chan, Chang-Yueh; Huang, Chien-Ping; Ke, Chun-Chi; Chiu, Shih-Kuang. Package Having MEMS Element and Fabrication Method. U.S. Patent Number 8653661, filed June 28, 2011, and published online on February 18, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=68&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=3351&f=G&l=50&co1=AND&d=PTXT&s1=20140218.PD.&OS=ISD/20140218&RS=ISD/20140218

Keywords for this news article include: Semiconductor, Microtechnology, Electronic Components, Siliconware Precision Industries Co. Ltd.

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Source: Electronics Newsweekly


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