1. Field
The present technology relates to fabrication of semiconductor devices.
2. Description of 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.
At times, it is desired to glue a portable storage device, such as a memory card, to a solid object, such as a hard-cover of a book, a binder or a wide variety of other objects. There are at least two good reasons for gluing a portable memory card to an object. The first reason is that the user of the card may want to create a physical linkage between some object and the digital data that is associated with it. Examples can be a paper book and the digital version of that book, an archive binder and the digital data of the information in the archive binder, and a student's paper notebook where he or she summarizes the lectures, and digital data that was handed out by the teacher. In these cases, the memory card may be glued to an external object.
The second reason is that the microSD card is very small and is easily lost. Thus, a user may want to glue it to a larger object for visibility—like a key chain for a single key. A visible flexible colorful ribbon can be glued to the grip area of the card by the user, will not disturb the insertion of the card into its slot, but will help not to lose it.
When permanently attaching a molded memory device to an object by gluing, the adhesion between the memory device and the object is generally weak, and the memory device may separate from the object. One reason the adhesion is weak is that there is typically a lubricant such as a wax or oil added to the molding material during the encapsulation process of the memory cards to facilitate removal of the encapsulated cards from the mold. This lubricant interferes with the ability of the glue to bond with the surface. Even where the lubricant is removed from a surface of the cards, it can happen thereafter that the lubricant beneath the surface migrates to the surface. If the glue has not properly bonded with the surface prior to any such migration, this migration of the lubricant can result in poor adhesion of the glue on the surface.
Embodiments will now be described with reference to
The following description uses the examples of glue and ink as fluids which may be bound to a surface of a memory device according to the present technology. However, it is understood that any of a wide variety of curable fluids may be used which are applied as a liquid onto a pre-treated surface of a memory device and then solidify on the surface as explained below.
The terms “top,” “bottom,” “upper,” “lower,” “vertical” and/or “horizontal” as may be used herein are for convenience and illustrative purposes only, and are not meant to limit the description of the invention inasmuch as the referenced item can be exchanged in position.
The molding compound 120 may be an epoxy resin such as for example available from Sumito Corp. or Nitto Denko Corp., both having headquarters in Japan. Other molding compounds from other manufacturers are contemplated. The molding compound 120 may be applied according to various processes, including by transfer molding or injection molding techniques. The molding compound 120 covers at least the memory die 112, the controller die 114 and the passive components 116. The contact fingers 106 may be left uncovered and exposed so that they may be mated with terminals in a host device.
In
The underlying memory die in the memory device 100 can take any suitable form; preferably solid-state memory (e.g., flash), although other types of memory can be used. While a memory device 100 is used to illustrate the pre-treatment techniques of these embodiments, these pre-treatment techniques can be adapted for use with other items, such as items used in conjunction with memory devices (e.g., memory device readers and memory device lids).
The embodiments of
As discussed above, it is often desired for a memory device to include visible indicia that provides information such as, for example, the manufacturer of the memory device and the memory device's internal characteristics, such as its storage capacity. In contrast to the prior methods discussed above that apply a sticker to the memory device or that use a pad printing process to print relatively simple indicia, embodiments of the method and system disclosed herein provide a mechanism to print more complex and/or colorful indicia, referred to herein as “graphical content,” onto one or more surfaces of memory devices in a batch. In particular, embodiments of the present technology relate to pre-treating one or more surfaces on memory devices 100 in a batch in preparation for receiving graphical content. As explained below, other embodiments relate to pre-treating one or more surfaces on memory devices 100 for receiving a glue to affix the memory device to another object.
“Graphical content” as used herein may refer to any indicia that can be printed onto a memory device. Examples of graphical content include, but are not limited to, pictures, photographs, decorative designs, logos, colors, symbols, text, and any combination thereof. It should be noted that graphical content can include text only and does not necessarily need to include a picture. Graphical content can convey information about an internal characteristic or property of the memory device, such as its storage capacity (e.g., 1 GB, 16 GB, etc.). The graphical content may reveal information relating to the type of content stored on the memory device, such as for example a picture of a musical note, to indicate the memory device is storing music, or a picture of a camera to indicate the memory device is storing pictures. The graphical content may alternatively be decorative, having no relation to the type of device or content, but provided so as to appeal to a certain segment of the market. The graphical content may be other indicia in further examples. Additional examples of the types of graphical content which may be provided on a surface of a memory device are set forth in U.S. Provisional Patent Application No. 61/253,271, entitled “Method and System for Printing Graphical Content onto a plurality of Memory Devices and for Providing a Visually Distinguishable Memory Device, filed Oct. 20, 2009, which provisional patent application is incorporated herein by reference in its entirety.
“Glue” as used herein may be a mixture in a liquid or semi-liquid state that adheres or bonds items together, such as for example a memory device to an object. Glue, also referred to herein as adhesive, may be applied as a liquid, semi-liquid or b-stage adhesive, and then may be cured to a solid by any of various methods. These methods include curing by heat, by UV light, by evaporation of a solvent in the glue or by a chemical reaction between components in the glue.
The following describes various embodiments for pre-treating one or more surfaces of a memory device 100 to facilitate application of a glue or graphical content to the one or more surfaces. As used herein, “pre-treating” may refer to roughening and/or texturing one or more surfaces of a memory device, chemically treating one or more surfaces of a memory device, or otherwise processing one or more surfaces of the memory device to increase the capability of the surface(s) to receive and hold a fluid such as a glue or ink.
In embodiments, pre-treatment of memory device surface(s) according to the various embodiments may be performed on surfaces of the molding compound 120 after a panel of memory devices has been encapsulated and before the panel has been singulated. However, it is contemplated that pre-treatment may alternatively be performed after singulation. For example, pre-treatment may be performed in the molding compound 120 of individual memory devices 100. In further embodiments, pre-treatment may be performed on lids in which encapsulated memory devices are housed. In at least one embodiment described below, the pre-treatment in accordance with the present technology occurs during the encapsulation process. In the embodiments described below, the pre-treatment process is performed on memory devices 100 while the devices are still part of panel 110. However, as noted, pre-treatment may be performed on individual memory devices after they are singulated from panel 110.
The present technology improves the ability to receive and hold a fluid such as glue or ink by at least two distinct pre-treatment operations. A first of these operations relates to a mechanical pre-treating of the surface of the molding compound and the second of these operations relates to chemical pre-treating of the surface of the molding compound. Mechanical pre-treating will next be described with reference to
Mechanical pre-treating of a surface 102 and/or 108 of the molding compound 120 is performed by providing a roughened texture to the surface by scoring, abrading or other mechanical process. A first embodiment of mechanical pre-treating is described with reference to
The pre-treating of the surfaces 102 and/or 108 by laser 130 may operate provide better adhesion of a glue or ink to the surface(s) by one or more principles.
Given the randomly formed undercuts and jutting surfaces, there may exist points (e.g., P1, P2 and P3) that “overhang” and are able to exert forces F normal to their surface on any glue or ink which fills the cavity 134, where these normal forces have a component directed toward the reference plane R. Again, the number and orientation of overhangs shown in
When a fluid such as glue or ink is applied to the surfaces 102/108 as explained hereinafter, the fluid fills each cavity 134 on the textured surface. When applied as a liquid, the glue or ink may flow into the cavities 134. When applied as a semi-liquid or b-stage adhesive, the glue or ink may be pressed into the cavities 134. Once the fluid hardens upon being cured, any overhangs in a cavity 134 will exert a force on the glue or ink in the direction of the reference plane R, consequently holding the fluid within the cavity 134. All such overhangs across the lasered-surface act to bind and hold the fluid on the surface of the card.
As noted in the Background section, the molding compound of memory device 100 includes a lubricant which can migrate to the surface and disrupt the ability in conventional devices to hold a glue or ink. However, the contour of a cavity 134 including overhangs and other angled surfaces is able to hold a fluid such as a glue or ink even in the presence of lubricant that has migrated to the surface.
Instead of or in addition to the amorphous cavities 134 described above, it is conceivable that a laser 130 may create lines 132 having relatively smooth, V-shaped sidewall cavities, such as shown for example in the representative drawing of
A third adhesion principle holding the fluid to the lasered-surface may be the increased surface area created by lasered-lines 132. There are adhesive forces that exist between the glue or ink and the lasered-surface of the memory device 100. This adhesive force may result from the above-described overhangs, a coefficient of static friction, or possibly other adhesive forces (such as for example wettability discussed below). By increasing the surface area of the surfaces 102/108 with lasered lines 132, the adhesive forces exist over a larger area, thereby also increasing the adhesive forces. Thus, the increased surface area may increase the adhesiveness of the glue or ink to the card.
A fourth adhesion principle which may hold the fluid to the lasered-surface may be a capillary action by which liquid glue or ink is drawn into cavities created on the surface 102/108 by the laser 130. In embodiments, the laser 130 may create lines 132 forming narrow enough cavities in the surface (such as shown in
Each of the above-identified principles occurs as a result of creating a roughened texture into the surface 102/108 of the memory device 100. It is understood that the laser 130 may create lines 132 which improve the adhesion of the glue or ink to the lasered-surface by any one of the above-identified principles, or by a combination of these principles acting together. It is conceivable that, at least to some extent, the adhesion may be further improved by improving the wettability of the surfaces 102/108. Wettability is discussed in greater detail below with respect to the chemical pre-treatment of the surfaces 102/108.
As indicated above, a glue or graphical content may be provided on an entire surface or a portion of a surface of memory device 100. In embodiments, only those portions of a surface receiving the glue or graphical content are pre-treated by the laser 130. In further embodiments, an entire surface of panel 110, or a memory device 100 on panel 110, may be pre-treated even where only a portion of that surface is to receive glue or graphical content. Following the scoring of a surface with laser 130, an ultrasonic cleaning process may be performed to remove burned particles from the surface. The cleaning process may be omitted in further embodiments.
One example of a system for sandblasting a surface is shown for example in U.S. Patent Publication No. 2010/0159699, entitled “Sandblast Etching For Through Semiconductor Vias,” which publication is incorporated herein by reference in its entirety. In a further embodiment, blasting may be performed with dry ice particles such as carbon dioxide crystals.
In such embodiments, the deformation of the surface may occur as a result of both thermal shock (the carbon dioxide crystals being at around −80° C.) and mechanical impact of the particles on the surface. In embodiments, the abrasive particles may be approximately 50 μm, though other sizes are contemplated.
As shown in the cross-sectional view of
The deformations 142 improve the adhesion of glue or ink to the surface 102/108 by one or more of the principles discussed above with respect to
In embodiments, only those portions of a surface receiving glue or graphical content are pre-treated by the particle blaster 140. In further embodiments, an entire surface of panel 110, or a memory device 100 on panel 110, may be scored even where only a portion of that surface is to receive glue or graphical content.
Following the scoring of a surface with blaster 140, an ultrasonic cleaning process may be performed to remove fractured particles and grit from the surface. The cleaning process may be omitted in further embodiments.
As seen, the interior surface 154 is provided with a surface roughness. The interior surface of lower mold plate 152 may additionally or alternatively be provided with a surface roughness. Moreover, only portions of upper mold plate 150 and/or lower mold plate 152 may have a surface roughness. In embodiments, this surface roughness may for example be in a range of Ra=2-10 μm, and in further embodiments, Ra=3-6 μm. It is understood that the surface roughness provided on one or both mold plates 150, 152 may be higher or lower than these ranges in further embodiments. The roughness pattern may be lines, parallel or otherwise, and/or discrete deformations.
As shown in
The embodiment of
As described above, in addition to mechanical pre-treating, embodiments of the present system relate to chemically pre-treating the surfaces 102 and/or 108 of the memory device 100. Embodiments of chemical pre-treatment will now be described with reference to
Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together.
Thus, the contact angle provides an inverse measure of wettability. The example of
ΔE=E1(1+cos (θ)), where E1 is the surface energy of the solid surface.
It can be seen that for small angles near 0°, the adhesion energy AE will be maximized and for large angles near 180°, the adhesion energy ΔE will be minimized. Surface adhesion energy and wettability may be improved by chemical pre-treatment of the surfaces of a memory device. It is also contemplated that mechanical texturing in one or more of the above-described embodiments improves surface adhesion energy and wettability. Examples of how mechanical abrading and other techniques may increase intermolecular surface adhesion are discussed in U.S. Patent Publication No. 2009/0181217, entitled “Ink Jet Printing On Sport Court And Other Polymer Tiles,” which application is incorporated herein by reference in its entirety.
One embodiment where one or more surfaces of a panel 110 or individual memory devices 100 are chemically pre-treated is shown schematically in
The bonding of plasma ions to the molding compound 120 roughens the surfaces to which the plasma ions bond to lower the contact angle and increase the surface energy of pre-treated surfaces for increased wettability of glue or ink on the pre-treated surfaces. In
It is understood that other chemical processes may be performed to pre-treat panel 110 or memory devices 100. These further chemical pre-treatment processes may either add ions, atoms or molecules onto the surface of molding compound 120, or they may break the bonds within the molding compound 120.
Once one or more surfaces 102 and/or 108 of a panel 110 or individual memory devices 100 have been pre-treated by any of the above-described embodiments, the surface is then able to receive and hold one or more layers of glue or ink. The one or more glue or ink layers which are printed on memory device 100 may be in the range of 10-20 μm in one example. The pre-treatment techniques described above provide sufficient adhesive forces to adhere thinner layers of glue or ink than was previously known. The strong adhesive forces of the pre-treated surfaces is able to compensate for the relatively weak adhesive force of the glue or ink for the surface. For example, in embodiments where the glue or ink mechanically binds in the amorphous-shaped cavities, the glue or ink is securely held and prevented from coming off of the surface.
With or without primer layer 202, the pre-treating of the surfaces of a memory device 100 allows any of a wide variety of graphical content to be printed on the front and/or back surfaces of the memory device 100, and possibly on the edges between the front and back surfaces of the memory device.
The pre-treatment of memory devices 100 allows printing of graphical content onto the pre-treated surfaces by a wide variety of printing technologies, including for example inkjet printing and flatbed printing. Other types of printing are disclosed in the above-incorporated U.S. Provisional Patent Application No. 61/253,271.
As noted above, a lubricant 135 may have migrated to the surface of the memory device 100. In a conventional, untreated surface, the lubricant 135 may fill the microscopic pores which naturally exist on the surface of the memory device 100. However, after the pre-treatment as described above, the cavities 134 are larger than the natural microscopic pores in the surfaces 102, 108. The cavities 134 are too large for the lubricant 135 to fill, thus leaving overhangs and contours described above which receive the glue and prevent the glue from leaving the cavities upon hardening. One the liquid glue enters a cavity 134 and hardens, the hardened glue will not pull out of the cavity.
In summary, the present technology relates to a memory device including at least one roughened surface, said surface comprising multiple cavities designed to collect and hold a layer of a fluid applied to the surface.
In another example, the present technology relates to a memory device, comprising: a molding compound for encapsulating internal components of the memory device; and a surface of the molding compound pre-treated to increase the surface energy of the surface to facilitate better gluing of the surface to another object.
In a further embodiment, the present technology relates to a memory device, comprising: one or more semiconductor die; molding compound encapsulating the one or more semiconductor die, the molding compound including first and second opposed sides, the first side including electrical contacts for coupling the memory device to a host device; and a pre-treated surface on at least one of the first and second sides of the molding compound, the pre-treated surface pre-treated to increase the surface energy of the pre-treated surface to facilitate better adhesion of a glue on the pre-treated surface.
In another example, the present technology relates to a memory device, comprising: one or more semiconductor die; molding compound encapsulating the one or more semiconductor die, the molding compound including first and second opposed sides, the first side including electrical contacts for coupling the memory device to a host device; and a surface on at least one of the first and second sides of the molding compound, the surface having at least one of scored lines or discrete deformations for increasing a roughness of the surface to facilitate better adhesion of glue on the surface.
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.
Number | Date | Country | Kind |
---|---|---|---|
PCT/CN2010/077567 | Oct 2010 | CN | national |
13129510 | May 2011 | US | national |
The present application is a continuation-in-part of International Application No. PCT/CN2010/077567, entitled “PRE-TREATMENT OF MEMORY CARDS FOR INK JET PRINTING,” which application was internationally under the Patent Cooperation Treaty on Oct. 4, 2010, and which application in incorporated by reference herein in its entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/CN2011/075434 | 6/8/2011 | WO | 00 | 10/21/2011 |