阅读说明：本技术 极薄封装 (Very thin package ) 是由 金龙宝 林伊国 陈嘉川 于 2013-09-20 设计创作，主要内容包括：公开用于实现极薄封装结构的技术。在某些实施例中,器件包含：集成电路,经由连接而连接到引线框或衬底；以及EMC(环氧树脂模制化合物),除了在集成电路的背侧和连接区域之外包围所述集成电路,所述集成电路经由所述连接区域连接到引线框或衬底。(Techniques for achieving extremely thin package structures are disclosed. In certain embodiments, a device comprises: an integrated circuit connected to a lead frame or substrate via a connection; and EMC (epoxy molding compound) surrounding the integrated circuit except at its backside and connection areas, via which the integrated circuit is connected to the leadframe or substrate.)

1. A device, comprising:

an integrated circuit connected to a lead frame or substrate via a connection; and

EMC (epoxy mold compound) surrounding the integrated circuit except at its backside and connection areas, via which the integrated circuit is connected to a lead frame or substrate.

2. The device of claim 1, wherein EMC between a backside of the integrated circuit and a top side of the device is removed during device assembly.

3. The device of claim 1, wherein grinding is used to remove EMC from the top side of the device and expose the backside of the integrated circuit during device assembly.

4. The device of claim 3, wherein grinding comprises subjecting the leadframe or substrate to topside grinding until a backside of the integrated circuit is exposed.

5. The device of claim 3, wherein grinding comprises subjecting the leadframe or substrate to top side grinding until a desired package thickness is achieved.

6. The device of claim 1, wherein the backside of the integrated circuit comprises exposed silicon.

7. The device of claim 1, further comprising: an adhesive film applied to the top side of the device to protect the exposed backside of the integrated circuit.

8. The device of claim 7, wherein the adhesion film is cured to improve adhesion to underlying EMC and integrated circuit backside.

9. The device of claim 1, wherein the device comprises an extremely thin DFN (dual flat no-lead) or QFN (quad flat no-lead) package.

10. The device of claim 1, wherein the device comprises an exposed silicon ultra-thin DFN (dual flat no-lead) or QFN (quad flat no-lead) package.

Background

A typical chip manufacturing assembly process includes: EMC (epoxy molding compound) is applied to cover the entire area of the device, the device is subjected to plating on the leads, and then the device is separated via a saw blade. EMC fillers protect the integrated circuit from light emission induced leakage and moisture penetration, but also contribute to overall package thickness. Fig. 1 illustrates a typical device structure resulting from the previously mentioned assembly process. As depicted, the EMC surrounding the integrated circuit (i.e., chip) contributes greatly to the resulting device size.

Drawings

Various embodiments of the invention are disclosed in the following detailed description and the accompanying drawings.

Fig. 1 illustrates a prior art device structure resulting from a typical assembly process.

Fig. 2A illustrates an embodiment of a package structure resulting from an assembly process that includes a grinding process.

Fig. 2B illustrates an embodiment of a package structure resulting from an assembly process that includes a grinding process.

FIGS. 3A-3Q illustrate an embodiment of an assembly process for creating extremely thin package structures.

Fig. 3R illustrates example dimensions of a device resulting from the disclosed assembly process.

Detailed Description

The invention can be implemented in numerous ways, including as a process, an apparatus, a system, a composition of matter, a computer program product embodied on a computer readable storage medium, and/or a processor, such as a processor configured to execute instructions stored on and/or provided by a memory coupled to the processor. In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention. Unless otherwise stated, a component such as a processor or a memory described as being configured to perform a task may be implemented as a general component that is temporarily configured to perform the task at a given time or as a specific component that is manufactured to perform the task. The term 'processor' as used herein refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions.

A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.

Various techniques for achieving thinner package thicknesses are disclosed herein. As further described, the disclosed assembly process includes a grinding process for reducing the overall device thickness. The grinding process facilitates various types of thinner package structures. In some embodiments, a grinding process is used to expose the backside of the integrated circuit (i.e., chip), which may be acceptable for insensitive light emitting devices. Alternatively, adhesive tape may be applied, for example, on the abrasive surface to protect the integrated circuit from luminescence-induced leakage and moisture penetration.

FIG. 2A illustrates an embodiment of a package structure resulting from an assembly process that includes a grinding process, As depicted, the package structure 200 includes an integrated circuit (i.e., chip) 202 that is partially surrounded by EMC (epoxy mold compound) 204 and connected to a leadframe (L/F) or substrate 206 via bumps 208. in some embodiments, the package structure 200 is produced by subjecting the entire leadframe or substrate to top side grinding after EMC injection until at least the backside of the chip is exposed and/or a desired thickness is achieved. in the given example, the package structure 200 includes an adhesive tape (i.e., a laminate film) 210 that is applied on top of the device (i.e., the backside of the flip chip 202) to protect the chip. the package structure 200 may include, for example, an extremely thin DFN (double Flat No leads) package or QFN (quad Flat No leads) package.

FIG. 2B illustrates an embodiment of a package structure resulting from an assembly process that includes a grinding process, as depicted, package structure 220 includes an integrated circuit (i.e., chip) 222 that is partially surrounded by EMC224 and connected to a leadframe (L/F) or substrate 226 via bumps 228. in some embodiments, package structure 220 results from subjecting the entire leadframe or substrate to top side grinding after EMC implantation until at least the backside of the chip is exposed and/or a desired thickness is achieved.

Fig. 3A-3Q illustrate an embodiment of an assembly process for generating extremely thin packaging structures, such as those described with respect to fig. 2A-2B. Fig. 3A illustrates dicing the wafer 300 to separate each die 302 in the wafer 300. As further depicted in fig. 3A, each chip 302 is then subjected to flip-chip, flux-dip, and mounted onto a leadframe or substrate 304. Fig. 3B illustrates flip chip mounting onto a lead frame or substrate 304. Fig. 3C illustrates a reflow step to connect the bumps between the chip 302 and the leadframe or substrate 304. The reflow temperature profile depends on the bump composition and characteristics. Fig. 3D illustrates a molding step, which is performed, for example, by an injection molding tool. As depicted, chip 302 is surrounded by EMC306 during this step.

Fig. 3A-3D also illustrate a backside adhesive tape 305, which may be applied to embodiments in which a chip 302 is mounted to a leadframe 304. Fig. 3E illustrates a step for removing the backside adhesive tape 305. Fig. 3F illustrates a lead plating step for providing lead trim 307 in an embodiment in which the chip 302 is mounted to the leadframe 304. In embodiments where chip 302 is mounted to substrate 304, the terminals/leads of the substrate have been pre-plated trimmed. Fig. 3G illustrates a leadframe/substrate mounting (i.e., backside lamination) step. As depicted, a backside mounting tape 308 is applied in preparation for subsequent topside grinding.

Fig. 3H illustrates the grinding step by which the top side grinding is performed using grinding wheel 310. This top side grinding process is specifically introduced into the assembly process to achieve the desired package thickness and is not used in other existing DFN/QFN processes. Fig. 3I illustrates continued top side grinding until a desired chip and/or total device thickness is achieved. In some embodiments, grinding is stopped once the backside of the chip 302 is exposed. Alternatively, as depicted in fig. 3I, grinding is stopped once the desired chip thickness is achieved. Once grinding is complete, the ground surface is polished, for example, to relieve shear stresses introduced during grinding and/or to increase adhesion between the ground surface and a top adhesive film (which is used for extremely thin DFN/QFN packages, such as the package structure 200 depicted in fig. 2A).

Fig. 3J illustrates a tape stripping step in which the backside mounting tape 308 is removed fig. 3K illustrates a lamination step in which a top side adhesive film 312 is placed to protect the device from light emission induced leakage (for devices sensitive to light emission) and moisture penetration fig. 3L illustrates a laminate curing 313 step in which the top side adhesive film 312 is treated to ensure adhesion to the underlying EMC and chip backside fig. 3M illustrates a marking step in which the top side is marked for device identification and traceability purposes and illustrates a top view 314 after marking.

Fig. 3N illustrates a mounting step in which the leadframe/substrate 304 is flipped and a mounting tape 316 is applied to hold the device in place during a subsequent package sawing step. A sawing process is performed on the leadframe/substrate 304. Fig. 3O illustrates a sawing step in which each device is separated via a saw blade 318. Fig. 3P illustrates the completion of the package saw singulation step. Fig. 3Q illustrates a step in which the mounting tape 316 is manually scrubbed and/or a pick-and-place manipulator is employed to remove devices from the tape 316 for batch packaging, (electrical) testing and/or taping/packaging 320.

While a particular order of steps is illustrated in the assembly process depicted in fig. 3A-3Q, the order of steps may be altered in other embodiments. For example, the grinding process of fig. 3H-3I may be performed at any suitable stage of the assembly process. Further, the inclusion of the top side adhesive film 312 is optional. That is, top-side adhesive film 312 is not included in an exposed silicon package structure, such as package structure 220 depicted in fig. 2B.

Fig. 3R illustrates example dimensions of a device resulting from the assembly process of fig. 3A-3Q. The given table provides example dimensions for an ultra-thin dfn (etdfn) and an ultra-thin qfn (etqfn) package, as well as an exposed silicon ultra-thin dfn (esetdfn) and an exposed silicon ultra-thin qfn (esetgfn) package. Overall, thinner packages can be achieved due to the grinding process involved.

Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided. There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative and not restrictive.