1. Field of the Invention
Embodiments of the present invention relate to an electronic component formed of a plurality of coupled semiconductor packages, and a method of forming the electronic component.
2. Description of the Related Art
The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
While a wide variety of packaging configurations are known, flash memory storage cards may in general be fabricated as system-in-a-package (SiP) or multichip modules (MCM), where a plurality of die are mounted on a substrate. The substrate may in general include a rigid base having a conductive layer etched on one or both sides. Electrical connections are formed between the die and the conductive layer(s), and the conductive layer(s) provide an electric lead structure for integration of the die into an electronic system. Once electrical connections between the die and substrate are made, the assembly is then typically encased in a molding compound to provide a protective package.
In view of the small form factor requirements, as well as the fact that flash memory cards need to be removable and not permanently attached to a printed circuit board, such cards are often built of a land grid array (LGA) package. In an LGA package, the semiconductor die are electrically connected to exposed contact fingers formed on a lower surface of the package. External electrical connection with other electronic components on a host printed circuit board (PCB) is accomplished by bringing the contact fingers into pressure contact with complementary electrical pads on the PCB. LGA packages are ideal for flash memory cards in that they have a smaller profile and lower inductance than pin grid array (PGA) and ball grid array (BGA) packages.
A cross-section of a conventional LGA package 40 is shown in
The substrate may be coated with a solder mask 36, leaving the contact fingers 32 exposed, to insulate and protect the electrical lead pattern formed on the substrate. The solder mask covers the surfaces of the substrate, leaving the contact fingers 32 exposed. The die may be electrically connected to the substrate by wire bonds 34. Vias (not shown) are formed through the substrate to allow electrical connection of the die through the substrate to the contact fingers 32. Once the dice are electrically connected, the package may be encapsulated in a molding compound 38 to form the package 40. Further examples of typical LGA packages are disclosed in U.S. Pat. Nos. 4,684,184, 5,199,889 and 5,232,372, which patents are incorporated by reference herein in their entirety.
There is an ever-present drive to increase storage capacity while at the same time maintaining or even decreasing the package form factor, and in particular the height of the semiconductor package. In typical packages, the thickness of the encapsulated package may for example be approximately 0.65 mm, though this height may vary. Recent advances in packaging technology have resulted in reduction of the footprint (i.e., the length and width) of semiconductor packages. In particular, where memory cards in the past have included several individually packaged integrated circuits mounted on a printed circuit board, SiP and MCM packages have a much smaller footprint. Thus, while it may not be allowable or desirable to increase the height of a semiconductor package, advances in packaging technology have freed up footprint space on memory cards.
Embodiments of the invention, roughly described, relate to an electronic component including a plurality of semiconductor packages soldered together in a side-by-side configuration. The packages are batch processed on a substrate panel. The panel includes a plurality of through-holes drilled through the panel and subsequently filled with metal such as copper or gold. These filled through-holes lie along the cut line between adjacent packages so that, upon singulation, the filled through holes are cut and a portion of the filled through-holes are exposed at the side edges of the singulated packages. These exposed portions of the filled through-holes form vertical surface mount technology (SMT) pads. After the semiconductor packages are singulated and the SMT pads are defined in the side edges, SMT is used to solder the SMT pads of a first semiconductor package to the respective SMT pads of a second semiconductor package to structurally and electrically couple the two packages together side-by-side.
The conductance pattern(s) in a given semiconductor package are coupled to some or all of the SMT pads in that package. The conductance pattern(s) in semiconductor packages to be coupled are also configured such that, once the packages are coupled together via the SMT pads, the semiconductor die in one package are electrically coupled to the semiconductor die and/or contact fingers in the second package. Thus, once soldered together, the semiconductor packages may function as a single electronic component, such as for example a single flash memory device. The semiconductor packages which are coupled together may originate from the same panel, or from different panels.
After the electronic component is formed, it may be encased in an industry standard lid enclosure to form any of various known standard flash memory format devices, including a Secure Digital (SD) card, a Compact Flash, a Smart Media, a Mini SD Card, an MMC, an xD Card, a Transflash memory card or a Memory Stick.
Embodiments will now be described with reference to
Where substrate panel 100 is PCB, the substrate 100a may be formed of a core 106a, having a top conductive layer 108a formed on the top surface of the core 106a, and a bottom conductive layer 110a formed on the bottom surface of the core. The core 106a may be formed of various dielectric materials such as for example, polyimide laminates, epoxy resins including FR4 and FR5, bismaleimide triazine (BT), and the like. Although not critical to the present invention, core 106a may have a thickness of between 40 microns (μm) to 200 μm, although the thickness of the core may vary outside of that range in alternative embodiments. The core 106a may be ceramic or organic in alternative embodiments.
The conductive layers 108a and 110a may be formed of copper or copper alloys, plated copper or plated copper alloys, Alloy 42 (42Fe/58Ni), copper plated steel, or other metals and materials known for use on substrate panels. The layers 108a and 110a may have a thickness of about 10 μm to 24 μm, although the thickness of the layers 108a and 110a may vary outside of that range in alternative embodiments.
In accordance with embodiments of the present invention, substrate panel 100 may further include filled through-holes 120 as seen in
Referring to
Thus, an embodiment where the through-holes 120 were formed in an edge that is 15 mm long could for example have 18 through-holes 120. An embodiment where the through-holes 120 were formed in an edge that is 18 mm long could for example have 22 through-holes 120. And an embodiment where the through-holes 120 were formed in an edge that is 22 mm long could for example have 26 through-holes 120.
The layer 108a and/or layer 110a may be etched with a conductance pattern for communicating signals between one or more semiconductor die and an external device. The conductance pattern in layer 108a and/or layer 110a may also be coupled to filled through-holes 120 to allow electrical signals and current flow between soldered side-by-side semiconductor packages as explained hereinafter. One process for forming the substrate panel 100 including the conductance pattern on the upper and/or lower surfaces of substrate panel 100 is explained with reference to the flowchart of
Once the conductance pattern in formed, the through-holes 120 may be plated and filled in a step 256. In embodiments, the through-holes 120 may first be plated in a known through-hole plating process with a metal such a for example copper, copper alloys, Alloy 42 (42Fe/58Ni), copper plated steel, gold, silver or other metals and materials. Thereafter, the plated through-holes 120 may be filled with a metal such as for example copper, copper alloys, Alloy 42, gold, silver or other metals and materials.
Thereafter, the top and bottom conductive layers 108a, 110a may be laminated with a solder mask 112a in a step 258. In embodiments where substrate panel 100 is used for example as an LGA package, one or more gold layers may be formed on portions of the bottom conductive layer 110a in step 260 to define contact fingers 114 as is known in the art for communication with external devices. In embodiments, only one of the semiconductor packages formed of substrates 100a and 100b will directly couple with a host device via the contact fingers 114. Thus, only one of the substrates 100a, 100b may be formed with contact fingers 114. It is understood that contact fingers 114 may be formed in both substrates 100a and 100b in alternative embodiments. The one or more plated layers may be applied in a known electroplating process. It is understood that the present invention may be used with other types of semiconductor packages, including for example BGA packages.
After the substrate 100a is formed, semiconductor die 116a may be mounted to the surface of the substrate 100a.
The one or more die 116a may be mounted on the top surface of the substrate panel 100 using a known adhesive or eutectic die bond process, with a known die attach compound. The one or more die 116a in
Once the die are mounted and connected, the entire substrate panel 100 including die 116a and 116b may be encased within a molding compound 150 in a known encapsulation process to form finished semiconductor die packages 160a, 160b. Molding compound 150 may be an epoxy such as for example available from Sumitomo Corp. and Nitto Denko Corp., both having headquarters in Japan. Other molding compounds from other manufacturers are contemplated. The molding compound may be applied according to various processes, including by transfer molding or injection molding techniques, to encapsulate the substrate panel 100 and semiconductor die 116a and 116b.
After the panel 100 is encapsulated, the panel may be cut to singulate the respective semiconductor packages 160a, 160b from the panel. Each semiconductor package 160a, 160b may be singulated by sawing along straight cut line 162 (shown in phantom in
Once cut into packages 160a, 160b, the packages may be separately tested to determine whether the packages are functioning properly. As is known in the art, such testing may include electrical testing, burn in and other tests.
In embodiments, the semiconductor packages 160a, 160b may be singulated into square or rectangular shapes. However, in alternative embodiments, the packages 160a, 160b may have one or more curvilinear or irregular shaped edges, and the SMT pads 170 may be positioned along one or more of these curvilinear or irregular shaped edges.
Referring now to
Referring to
As an alternative to solder paste applied in a solder printing process, it is understood that solder balls of known construction may be used in a solder ball placement process to couple respective SMT pads on adjoining packages. The packages and solder balls may then be heated in a known reflow process. It is further contemplated that other electrically conductive materials may be used instead of solder paste or solder balls to electrically and structurally couple packages 160a and 160b together in alternative embodiments.
As would be appreciated by those of skill in the art, the conductance pattern(s) in a given semiconductor package are coupled to some or all of the SMT pads 170 in that package. The conductance pattern(s) in the respective semiconductor packages are also configured in a known manner such that, once the packages are coupled together via the SMT pads, the semiconductor die in one package are electrically coupled to the semiconductor die and/or contact fingers in the second package. Thus, once soldered together, packages 160a and 160b may function as a single electronic component 176, such as for example a single flash memory device. In this regard, it is understood that the types of semiconductor die in the respective packages 160a and 160b may vary in alternative embodiments.
For example, in one embodiment, package 160a may include one or more flash memory chips, and a controller such as an ASIC for communicating with a host device via contact fingers 114. Package 160b coupled thereto in this example may include only flash memory chips. Such a configuration would offer enhanced memory capabilities as compared to the package 160a by itself. In another configuration, package 160a may include one or more controllers and flash memory chips, and package 160b may include one or more controllers and flash memory chips. In a further embodiment, one of the packages 160a or 160b may include one or more controllers, and the other package 160b or 160a may include one or more flash memory chips.
It will be evident that the semiconductor packages which are coupled together need not originate from the same substrate panel. Thus, a first substrate panel may include all identical semiconductor packages, such as for example having a controller and one or more flash memory chips. And a second substrate panel may include all identical semiconductor packages, such as for example having only flash memory chips. Packages from these respective panels may then be coupled by solder paste 174 or solder balls as described above.
The electronic component 176 has been described thus far as two side-by-side soldered packages of at least approximately the same size and configuration. It is understood that other arrangements are contemplated. For example, as shown in
In a further embodiment shown in
In a further embodiment shown in
Any of the above-described embodiments may be encased within a lid as described above and function as an electronic device such as a flash memory device.
The flowchart of
After the solder mask is applied, the contact fingers may be plated. A soft gold layer is applied over certain exposed surfaces of the conductive layer on the bottom surface of the substrate panel, as for example by thin film deposition, in step 280. As the contact fingers are subject to wear by contact with external electrical connections, a hard layer of gold may be applied, as for example by electroplating, in step 282. It is understood that a single layer of gold may be applied in alternative embodiments.
The individual substrate panels may then be inspected and tested in an automated inspection process (step 284) and in a final visual inspection (step 286) to check electrical operation, and for contamination, scratches and discoloration. The substrate panels that pass inspection are then sent through the die attach process in step 288. The wire bonds and other electrical connections are then made on the substrate panel in a step 290, and the substrate panel and die are then packaged in step 292 in a known transfer molding process to form a JEDEC standard (or other) packages as described above.
A cutting device then separates the panel into individual packages 160 in step 294. The individual packages may undergo further electrical and burn in testing in step 296. Those that pass this inspection may be soldered together side-by-side as described above in step 298. The finished electronic component 176 may again be tested in step 300. Where the electronic component forms a flash memory device within lids 180, the packages may be enclosed within lids 180 in a step 302. It is understood that an electronic component 176 may be formed by other processes in alternative embodiments.
The foregoing detailed description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
This application is a divisional application of U.S. patent application Ser. No. 11/322,017 filed on Dec. 29, 2005 entitled “Interconnected IC Packages With Vertical SMT Pads”, which application is incorporated herein by reference.
Number | Date | Country | |
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Parent | 11322017 | Dec 2005 | US |
Child | 11782102 | Jul 2007 | US |