HK1112115B - Method of making a memory card by injection molding - Google Patents

Abstract

Memory Card (10) containing Integrated Circuits and other electronic components is made by means of injection molding. External surfaces of e.g. polycarbonate, synthetic paper, PVC or the like are used to house the Memory Card (10) or similar device prior to the injection molding step. After a thermosetting material is injection molded the Memory Card (10) is removed from the two (2) mold halves and is trimmed.

Description

Method for manufacturing memory card by injection molding

Background

In recent years, consumer electronics devices such as digital cameras, Personal Digital Assistants (PDAs), smart phones, and digital audio video recorders have driven a strong market demand for removable data storage elements. The electronics industry responds to this need by a product known as a "memory card". Memory cards typically contain one or more semiconductor memory chips within an industry standard housing having dimensions that allow them to be connected to different devices of various manufacturers. Memory cards also typically have connection terminals on an outer surface for making electrical connections with the circuitry of the consumer electronic device. Examples of types of memory cards include PC cards, multimedia cards, compact flash cards, and secure digital cards. These devices conform to standards promulgated by industry associations such as the personal computer memory card international association ("PCMCIA") and the multimedia card association ("MMCA").

An exemplary memory card, or multi-media card ("MMC") 10 is illustrated in top, cutaway side, and bottom views in fig. 1-3, respectively. The MMC shown has standard dimensions of 32mm long, 24mm wide, 1.4mm thick, and typically contains a memory capacity of 2 to 256 megabytes ("MB") that is accessed through 7 contacts 11 located on the bottom surface of the MMC using, for example, a standard serial interface ("SPI"). A simple chamfer 12 at the corner of the MMC prevents incorrect insertion of the MMC into the connection terminal of the host device.

The exemplary prior art MMC illustrated in fig. 1-3 includes a rectangular substrate 13, such as a printed circuit board, and one or more semiconductor memory dies (die)14 or "chips" mounted and electrically connected to the substrate 13 using, for example, an adhesive layer 15 or conventional wire bonds 16, respectively. Surface mounted passive components such as resistors may also be mounted and connected to the substrate 13. The contacts 11 are connected through a substrate 13 to a memory circuit defined by the aforementioned elements, serving as input and output terminals of the card 10.

When the components have been mounted and attached to the substrate 13, the prior art method includes the step of protectively encapsulating the chip 14 by a "glob-top" process. This step is necessary because high pressure, high temperature injection molding of the thermoset material will occur at a later stage. High pressure injection molding and high temperatures can damage microchips and other small electronic components, particularly wire bonds. In the glob-top step, a viscous glob of encapsulant is placed over the top surface of the chip and allowed to flow over the sides of the chip to the surface of the substrate. The encapsulant solidifies to form a protective shell 18 over the chip. An outer covering or housing 19 (shown by dotted outline in fig. 1) of thin sheet metal or plastic is mounted over the substrate 13 assembly by embedding the top surface of the substrate 13 assembly into a bed of adhesive contained in the housing 19.

Prior art methods for manufacturing memory cards are largely concerned with properly positioning and securing electronic components, modules or assemblies within the memory card. This correlation results from the fact that: if the electronic components are not properly secured, they will move to random positions during the injection of the thermoset material into the card-forming cavity. This is a significant problem in prior art processes because injection molding is subject to relatively high pressures. Existing methods of manufacturing memory cards include the use of relatively large, mechanical clamping devices having a rigid, clear body for holding the electronic components in place during injection molding of a thermoset material. The use of such clamping devices limits the options for positioning the electronic components in the memory card. Positioning limitations also compress the size and number of electronic components that can be placed in such memory cards. This limitation may also limit the amount of memory that can be placed into an MMC.

In addition, due to the different coefficients of expansion of the materials used to make these relatively large holding devices, relative to the coefficients of expansion of the other components in such cards, deformations often occur on the outer surface of the finished cards containing such electronic component holding devices. That is, the deformation of the surface is caused only by the presence of the clamping parts in the card body, which are subjected to different temperatures and pressures in the manufacture. These deformations are, at best, merely unsightly; in the worst case, the card may be prevented from lying completely flat in the card-receiving slot of the card reader.

Some memory card manufacturers have addressed this problem by reducing the size of such clamping devices or by using glue to securely position their electronic components during the thermosetting injection molding process in the card-forming cavities. However, the use of glue to protect the electronic components causes another series of problems. These problems are caused by the fact that: most commercially available fast setting adhesives used to secure such electronic components in place typically have high shrinkage characteristics. Furthermore, a relatively large amount of glue is required for fixing the electronic components. The use of relatively large amounts of high shrinkage glue may tend to wrinkle or otherwise deform the area of the plastic sheet, layer to which such glue is applied. This corrugation may be transmitted through the thinner body of the memory card, causing the outer surface of the card to exhibit a locally wavy character. If certain tolerances are exceeded, these undulations are unacceptable to the memory card industry because the deformed memory card will not be usable in a particular device.

An additional limitation noted above that exists in the manufacture of prior art memory cards is that the memory cards are typically made in a prior art process involving the injection molding of a filled epoxy or high temperature, high pressure thermoset material into a shape. In addition to the fact that the injected material at high pressure and high temperature can stress or damage the electronic components of the card, it also needs to be solidified and cooled in the compression mold for a relatively long time. The epoxy can chemically react after injection, which can damage the electronic components of the memory card. What is needed is a method of manufacturing a memory card that does not require the provision of a "mass capping" for the memory die assembly, has a shorter set time and shorter manufacturing cycle time, and does not use internal clamping devices that could damage the memory card electronics.

Disclosure of Invention

It is therefore an object of the present invention to provide a memory card or similar device having a thickness in the range of from about 0.76mm (the thickness of a conventional credit card) to about 5.0mm, containing an integrated circuit and/or other electronic components (such as resistors) in a secure package, and having a high quality exterior surface on which complex graphics can be printed. The bottom surface of the memory card must include external contacts to make electrical connections with other devices. It is another object of the present invention to securely enclose electronic components in a memory card using a low pressure, low temperature process, thereby eliminating the need for "glob-top" of the electronic components. Removing the glob-top process will save time in processing the memory card and will provide additional valuable space within the memory card for additional memory or other electronic components. It is still another object of the present invention to shorten the manufacturing cycle time with a low temperature process that can improve production efficiency. The low temperature process allows the memory card to be manufactured with less energy and can significantly reduce the production cycle time, thereby improving manufacturing yield.

This and other objects of the present invention are achieved by providing a multi-layer memory card with, for example, Teslin^TMOr other synthetic paper or suitable material (e.g., PVC, PC) and with a core layer of an infusion polymer material with Teslin for securely encapsulating an integrated circuit (e.g., a multimedia card die assembly)^TMOr other suitable material, to be securely bonded.

The electronic components are cushioned above the bottom layer of the device with a low shrinkage glue to facilitate even flow and complete encapsulation of the electronic components by the injected polymeric material. A low shrinkage cement mound placed on the bottom layer of the device creates and maintains a void of about 0.1 to 0.15mm, allowing the injected polymer to fill the void and cover the top surface of the bottom layer as well as the bottom surface of the top layer, uniformly and completely distributing the polymeric material in the void under or over the electronic component without voids or pockets. Alternatively, the electronic component may be directly placed on the bottom mold without using a primer layer. In this manner, the bottom of each electronic component constitutes the bottom surface of the device.

Teslin^TMThe purpose of the insert design of PVC, or other suitable material is to enable the production of inlays, i.e. electronic components, in a plurality of inlays per piece. For example, FIG. 6 illustrates a 16 × 10 inlay array (160 total banks)A memory card).

The inlay is fabricated on a single continuous sheet, which is then cut with a mechanical tool into a form that allows the periphery of the memory card to be covered with the injected polymer.

Drawings

Fig. 1-3 depict a prior art memory card in a cutaway top view, cutaway side view, and bottom view, respectively.

FIG. 4 is a synthetic paper (e.g., Teslin) used to make prior art memory cards^TM) Or a layer or sheet of plastic material (e.g., PVC). This view shows the state before (fig. 4(a)) and after (fig. 4(b)) a small amount of the prior art "high shrinkage" glue is allowed to set on the synthetic paper or plastic material.

Fig. 5 is a cross-sectional side view of a memory card manufactured in accordance with the teachings of the present disclosure.

Fig. 6 and 7 are cross-sectional side views of a mold for making a first preferred embodiment of the memory card of the present disclosure, showing certain memory card components (e.g., a multi-media card die assembly) in a state prior to injection of liquid polymeric material between the top and bottom layers of the memory card (see fig. 6), and after injection of polymeric material into the space between the top and bottom layers to fill the space with polymeric material and cold form the top layer of the memory card into the memory card molding cavity contours of the top mold (see fig. 7).

Fig. 8 is a cross-sectional side view showing a mold removed from a memory card body precursor formed using the system of fig. 7.

Fig. 9 depicts a mold system that is capable of simultaneously manufacturing 160 memory cards (which are about 24mm x 32mm in size).

Fig. 10 is a cross-sectional side view of the completed memory card without a separate bottom layer.

Fig. 11 and 12 are cross-sectional side views of a mold for manufacturing a first preferred embodiment of the memory card of the present disclosure, showing a memory card component (e.g., a multi media card die assembly) prior to injecting a liquid polymeric material between the top layer of the memory card and the electronic component. A polymeric material is injected into the space between the top layer and the electronic component to fill the space with the polymeric material and cold form the top layer of the memory card to the contours of the memory card molding cavity of the top mold.

Fig. 13 is a cross-sectional side view showing a mold removed from a memory card body precursor formed using the system of fig. 12.

Detailed Description

Fig. 4(a) and 4(b) illustrate problems involved in a prior art method of manufacturing a memory card. Fig. 4(a) illustrates a sheet or layer of plastic material 40 (e.g., polyvinyl chloride, polyurethane, etc.) having a top surface 41 and a bottom surface 42 in a cross-sectional view. Such sheets will generally have a thickness 43 in the range of from about 0.075mm to about 0.25 mm. A state in which a mound, drop or block of liquid or semi-liquid high shrinkage glue 44 is newly dispensed on the top surface 41 of the plastic sheet 40 as shown in fig. 4(a) will be described. The mound of freshly dispensed glue 44 depicted in FIG. 4(a) is shown having an initial width W₁. Fig. 4(b) (in exaggerated form) shows the result of the dune of glue 44 shown in fig. 4(b) solidifying into a smaller dune of solidified glue 44'. The width W of the mound of set adhesive 44' depicted in FIG. 4(b)₂Than the width W of the mound of liquid or semi-liquid glue 44 newly applied in FIG. 4(b)₁Much smaller. For simplicity, the initial width W of the newly dispensed high shrinkage cement mound is measured₁To width W₂The reduction or shrinkage (i.e., aw) of (a) is indicated in fig. 4(b) by the dimension "1/2 aw" on the left side of the mound of cured cement 44' and the equivalent "1/2 aw". Such solidification may also be indicated by a reduction in volume of the original mound of cement 44. For example, in many high shrinkage cementsIn (e), the volume reduction may be as much as 20% to 30%.

As previously mentioned, the concept of "high shrinkage" glue versus "low shrinkage" glue can also be illustrated by the reduction in volume of the set glue relative to the volume of the glue in the freshly applied state.

The curing process associated with the high shrinkage glue allows the mound of glue 44 depicted in FIG. 4(a) to be considered as having an initial width W₁(wherein the glue mound is in a semi-liquid or tacky state) shrinks in initial dimension to a final width W₂(where the set glue 44' is in fact in a solid state) and the high degree of shrinkage (e.g. above about 15% -typically up to 20% -30%) causes the top surface 41 of the layer or sheet of plastics material to "wrinkle" or otherwise deform, such as to form wrinkles 45 in fig. 4 (b). Such a deformation action may generate a force in a relatively thin layer (e.g., 0.075 to 0.25mm thick) of the plastic material 40. These forces are transferred to the bottom surface 42 of the layer of plastic material 40. These transmitted forces, in turn, produce deformations 46 (curves, bends, waves, ripples, wrinkles, etc.) in the bottom surface 42 of the plastic layer 40. Any such deviation from a flat, smooth surface is considered by the memory card industry to be a highly unacceptable deformation, and thus is minimized to the greatest extent possible. One of the primary goals of the process disclosed herein is to obtain a memory card surface that is free of undulations, bends, wrinkles or other imperfections.

Fig. 5 illustrates a cross-sectional side view of a memory card 50 manufactured in accordance with the teachings of the present disclosure. In its final form, such a memory card 50 will consist of a top layer 51, a bottom layer 52, and an intermediate or core layer 53, wherein the electronic components of the memory card (e.g., multimedia die assembly, which includes a substrate 55 and contact pads 56, etc.) are embedded in a thermoset polymeric material 57 (e.g., a pristine liquid or semi-liquid thermoset resin) in the core layer 53, wherein the material 57, when solidified, constitutes the intermediate or core layer 53 of the completed memory card 50. Thermoset material 57, which ultimately becomes core layer 53 of memory card 50, fills the void between top layer 51 and bottom layer 52.

The void has a height 58 and extends from one side of the card to the other. As noted above, prior art methods of manufacturing memory cards include injecting epoxy, wherein the epoxy chemically reacts to solidify and form the body of the memory card. These reactions are potentially dangerous for sensitive electronic components such as microprocessors. Alternatively, the prior art methods involve high pressure injection of high temperature thermoplastic materials. The high pressures and temperatures of injection of the prior art methods are also dangerous for the electronic components, which is why "glob-top" protection of the electronic components is common when using the prior art methods. The configuration of the electronic component shown in fig. 5 that does not include a protective "glob top" is not suitable for use with either epoxy or high-pressure injected high-temperature thermoplastic materials. Finally, the epoxy resin and high temperature thermoplastic material injected into the mold take a longer time to cure. The lengthy set and cool down times required using high temperature thermoplastic and high pressure injection slows the production process of the device.

To this end, injection of the polymeric material 57 under the relatively low temperature, low pressure molding conditions used in the applicant's process can provide significant benefits.

In general, such a thermoset polymeric material will infuse and fill the void 58 between the inner surface 59 of the top layer 51 and the inner surface 60 of the bottom layer 52. Upon solidification, the polymeric material 57 of the core layer 53 bonds or adheres to the inner surface 59 of the top layer 51 and the inner surface 60 of the bottom layer 52 to produce a unified memory card body. The inner surfaces 59 and 60 of the top and bottom layers may be treated in one of several ways to assist in completing the bond. For example, adhesives known in the art (e.g., chlorinated polyolefin fibers) can be used to enhance the adhesion between the thermoset material forming the core layer and the materials making up the top and bottom layers (e.g., Teslin, PVC). By way of example only, the primary prime product 4475RTM from minnesota mining and manufacturing may be used for this adhesion enhancement purpose, especially when the material of the top or bottom layer is PVC. Other treatments that may be used for the inner surface of the top layer and/or the bottom layer include plasma corona treatment and acid etching.

With the thermoset material injected into void 58 as part of the low temperature, low pressure molding process disclosed herein, the thickness 61 of the memory card is limited by the placement of the mold surfaces (not shown in fig. 5). In fact, the thermoset material injected into the void 58 between the top and bottom layers fills all portions of the void 58 not occupied by the mounds of the electronic component or low shrinkage glue 62 on which the electronic component is placed.

Next, it should be noted that the electronic components of the memory card (e.g., multimedia die assembly substrate 55, memory chip 54, etc.) are preferably placed over the inner surface 60 of bottom layer 52 by using one or more drops or chunks of applicants' low shrinkage glue 62. As noted above, prior art methods of manufacturing memory cards do not use glue to cushion the electronic components of the memory card. This is because the prior art methods involve the operation of injecting epoxy or high pressure high temperature thermoplastic materials, both of which can damage the adhesive. Furthermore and more importantly, since the prior art methods involve the operation of injecting epoxy or high pressure high temperature thermoplastic materials, the electronic components must be "glob-topped" and thus do not need to be bumped up.

In applicants' method, the electronic components are most preferably placed on top of two or more mounds of glue 62 in the manner suggested in FIG. 5, such that the introduced liquid or semi-liquid polymeric material flows under the electronic components while they are submerged from above and from the sides of the electronic components. In other words, in a more preferred embodiment of the present invention, the mounds of glue 62 will serve as one or more "pads" upon which the electronic components are placed so that the underside of the electronic components are not in direct contact with the top surface 60 of the bottom layer 52, but are immersed in the incoming thermoplastic material 57. This design allows the electronic components to better resist bending or twisting forces that the memory card may experience on either of its major outer surfaces or one of the four outer lands. In some more preferred embodiments of the invention, the electronic components (e.g., memory chip 54) are placed above the inner surface 60 of the bottom layer 52 by a distance of about 0.075mm to 0.13mm using an adhesive.

FIG. 6 and FIG. 7 are related to the description of the applicationA first preferred embodiment of a method for manufacturing memory cards and similar devices. That is, FIG. 6 shows a particularly preferred embodiment of the present invention, which is illustrated by synthetic paper such as Teslin^TMOr a flat top layer or sheet 51 of plastic material such as PVC, prior to being low temperature and low pressure formed in accordance with the teachings of the present disclosure. In other words, fig. 6 shows the mold arrangement prior to injection of the polymeric material, showing a flat top layer 51 (e.g., a flat sheet of PVC) initially placed under the memory card molding cavity of top mold 64, and a bottom layer 52 (e.g., another flat sheet of PVC) placed over bottom mold 65. However, in some less preferred but still feasible embodiments addressed by applicants, top layer 51 preferably can be pre-molded, or at least partially pre-molded, to the general contour of the memory card-forming cavity in top mold 64.

By comparison, the bottom mold 65 does not have a cavity similar to the cavity in the top mold 64. Figure 7 illustrates the effect of injecting a thermoset polymeric material 57 into the space between the top layer 51 and the bottom layer 52. Thus, fig. 7 shows top layer 51 after thermoset polymeric material 57 has been molded into memory card molding cavity 66 in top mold 64. Referring to FIG. 6, a nozzle 67 for injecting a liquid or semi-liquid thermoplastic or thermoset polymeric material 57 is shown inserted into a cavity 68, wherein the cavity 68 opens into a void defined between the inner surface 59 of the top layer 51 and the inner surface 60 of the bottom layer 52. The distance between the top surface 69 of the top layer 51 and the bottom surface 70 of the bottom layer 52 is represented by distance 78. The void is shown expanding from the cavity opening 68 to the other end of the juxtaposed top and bottom layers 51, 52. In other words, in fig. 6, a portion of the outer surface 69 of the top layer 51 is not in contact with the inner surface 72 of the memory card forming cavity 66 of the top mold 64. In contrast, the outer surface 70 of the bottom layer 52 is shown in substantially flat abutting contact with the inner surface 74 of the bottom mold 65.

In fig. 6 and 7, the electronic components of the memory card (e.g., its substrate 55, memory chip 54, etc.) are shown above the inner surface 60 of the bottom layer 52. By way of example only, these electronic components are shown as being cushioned on two or more blocks 62 of applicants' low shrinkage glue. These glue pads hold the electronic component a sufficient distance (e.g., about 0.075mm to about 0.13mm) above the inner surface 60 of the bottom layer 52 so that the incoming thermoset polymeric material 57 can flow into both the area above the electronic component and the area 75 below the electronic component. Further, such a glue pad structure is preferred because the presence of the thermoset polymeric material underneath the electronic components enhances the protection of these electronic components from any forces or impacts that may be received by the outer surface of the memory card (i.e., the outside of the bottom layer and/or the outside of the top layer).

In fig. 6, the top mold 64 is shown with a cavity 66 that limits the top surface profile of the memory card that will be formed during the injection process. For this purpose, the injection of the liquid or semi-liquid thermosetting polymeric material 57 should be under pressure and temperature conditions that cause the top layer 51 to be formed into the cavity 66 of the top mold 64 at a low temperature and pressure. Fig. 7 illustrates how the low temperature, low pressure forming process of the present disclosure actually conforms the top surface 69 of top layer 51 to the configuration of the memory card forming cavity in top mold 64. Also, a condition in which the bottom surface 70 of the bottom layer 52 is molded onto the substantially flat inner surface 74 of the bottom mold 65 is shown in fig. 7. This is a particularly preferred configuration of the memory card of the present disclosure.

In fig. 6 and 7, front lip region 76 of top die 64 and front lip region 77 of bottom die 65 are shown spaced from each other by a distance 78 '(taking into account the thickness of top layer 51 and bottom layer 52), which distance 78' effectively limits the distance of the gap width of top layer 51 and bottom layer 52 at lip regions 76 and 77 of die 64 and die 65, respectively. This distance enables thermoset polymeric material 57 to be injected into the void over the length of the entire memory card. The distance 58 and the distance 78' to the left of the corresponding portion of the mold apparatus shown in fig. 6 mounted to the right side of the system may be different. In any event, the distance 58 should be such that the distance 58' defined between the inner surface 59 of the top layer 51 passing through the rear lip 79 of the top mold 64 and the inner surface 60 of the bottom layer 52 passing through the rear lip 80 of the bottom mold 65 is small, but still limited. That is, this small distance 58' should be large enough to allow gases 81 (e.g., air, gases generated by the reaction of the polymeric components, etc.) initially present in the void space between the top layer 51 and the bottom layer 52 (see FIG. 6), respectively, and excess polymeric material to escape from the void space, but small enough to maintain the injection pressure for injecting the thermoset polymeric material 57. The distance 58' is preferably of a size large enough to allow the smooth thin layer of liquid polymeric material 57 to "blow out" or "fly" of the void itself-and thereby allow any gas remaining in, or generated in, the void to be removed from the void, and indeed from the mold system itself. In this way, all of the gas 81 is completely replaced by the incoming liquid thermoset material 57. This venting technique is used to prevent the formation of bubbles within the thermoset material 57 that ultimately (i.e., upon curing of the thermoset material) will form the core layer 53 as shown in fig. 7.

Fig. 8 illustrates a memory card blank or precursor of the type shown in fig. 7 removed from a mold system. Cross-sectional lines 84 and 86 show where the left and right ends of the memory card precursor body can be cut or trimmed to produce clear edges and precise dimensions of the finished memory card. In this case, the distance 82 is about 32 mm.

Fig. 9 illustrates a molding process according to certain preferred embodiments of the present disclosure, wherein 160 memory cards 50 having dimensions of about 24mm x 32mm are molded simultaneously.

Fig. 10 illustrates a completed memory card 122 manufactured using an alternative embodiment of the present invention, in which the electronic components (in fig. 10, the memory die assembly is comprised of substrate 126, memory die 134, external electronic contacts 133, and additional components) are used as an underlayer without the need for an additional underlayer.

Fig. 11 and 12 illustrate a second embodiment of applicants' method for manufacturing memory cards and similar devices. That is, FIG. 11 shows a particularly preferred embodiment of the present invention, which is illustrated by synthetic paper such as Teslin^TMOr a flat top layer or sheet 124 of plastic material 124 such as PVC, prior to being low temperature and low pressure molded in accordance with the teachings of the present disclosure. In other words, FIG. 11 illustrates the mold arrangement prior to injection of the polymeric material, wherein the memory card is shown as being formed with a flat top layer 124 (e.g., a flat sheet of PVC) initially placed in a top mold 144Below the cavity and the electronic components including the substrate 126, the memory die 134, and the external contacts 133 are placed on the bottom mold 146. However, in some less preferred but still feasible embodiments addressed by applicants, the top layer 124 preferably can be pre-molded, or at least partially pre-molded, to the general contour of the memory card-forming cavity 164 in the top mold 144.

By comparison, the bottom mold 146 does not have a cavity similar to the cavity in the top mold 144. Fig. 12 illustrates the effect of injecting a thermoset polymeric material into the gap 136 between the top layer 124 and the electronic component. Fig. 12 shows the top layer 124 after it has been molded into the memory card-forming cavity 164 in the top mold 144.

A nozzle 148 for injecting a liquid or semi-liquid thermoplastic or thermoset polymeric material 134 is shown inserted into a cavity 149, wherein the cavity 149 opens into the void 136 defined between the inner surface 138 of the top layer 124 and the inner surface of the electronic component. The distance between the top surface 155 of the top layer 124 and the bottom surface 158 of the memory card is represented by distance 125. The void 136 is shown extending from the top layer 124 and the left end of the electronic component side-by-side to the right end. In other words, in fig. 11, the outer surface 155 of top layer 124 is not in contact with the inner surface 156 of the memory card forming cavity 164 of top mold 144. In contrast, the outer surface 158 of the electronic component is shown in substantially flat abutting contact with the inner surface 160 of the bottom mold 146.

In fig. 11, the top mold 144 is shown with a cavity 164 that limits the top surface profile of the memory card that will be formed during the injection process. To this end, the injection of the liquid or semi-liquid thermoset polymeric material 134 should be under pressure and temperature conditions that cause the top layer 124 to be formed into the cavity 164 of the top mold 144 at a low temperature and pressure. Fig. 12 shows how the disclosed low temperature, low pressure molding process of the present invention actually conforms top surface 155 of top layer 124 to the configuration of memory card molding cavity 164 in top mold 144. Also, a state in which the bottom surface 158 of the electronic component is molded onto the substantially flat inner surface 160 of the bottom mold 146 is shown in fig. 12.

In fig. 11 and 12, the front lip region 166 of the top die 144 and the front lip region 168 of the bottom die 146 are shown spaced apart from each other by a distance 170 (taking into account the thickness of the top layer 124 and the electronic component), which distance 170 effectively limits the distance of the gap width of the top layer 124 and the electronic component at the lip regions of the dies 144 and 146, respectively. This distance 170 should enable the thermoset polymeric material 134 to be injected into the void 136 over the length of the entire memory card. The distance 170' of the corresponding portion of the mold apparatus mounted to the right of the mold system and the distance 170 to the left may be different. In any event, the distance 170' should be such that the distance 137 defined between the inner surface 138 of the top layer 124 through the rear lip 167 of the top mold 144 and the inner surface of the electronic component through the rear lip 169 of the bottom mold 146 is small, but still limited. That is, this small distance 137 should be large enough to allow gases 172 (e.g., air, gases generated by the reaction of the polymeric components, etc.) initially present in the void 136 between the top layer 124 and the electronic component (see fig. 11), respectively, and excess polymeric material to escape from the void 136, but small enough to maintain the injection pressure for injecting the thermoset polymeric material. Distance 137 is preferably of a size large enough to allow a smooth thin layer of liquid polymeric material 134 to "blow out" or "fly" of void 136 itself-and thereby allow any gas remaining in, or generated in, void 136 to be removed from the void, and indeed from the mold system itself. In this way, all of the gas 172 is completely replaced by the incoming liquid thermoset material 134. This venting technique is used to prevent the formation of bubbles within the thermoset material 134 that will eventually (i.e., upon curing of the thermoset material) comprise the core layer 128 (fig. 10).

Fig. 13 illustrates a memory card blank or precursor of the type shown in fig. 12 removed from a mold system. Cross-sectional lines 284 and 286 show where the left and right ends of the memory card precursor body can be cut or trimmed to produce a clear edge and precise dimensions of the finished memory card. In this case, the distance 274 is about 32 millimeters.

While the invention has been described in connection with various specific examples and orientations based on concepts using specific glues and gluing processes, it is to be understood that the invention described herein is limited in scope only by the claims.

Claims (43)

1. A method of manufacturing a memory card comprising a top layer of synthetic paper or plastic material, a bottom layer of synthetic paper or plastic material, and a core layer in which electronic components are located, the method comprising the steps of:

(1) building a bottom layer with precisely positioned openings for external electrical contacts;

(2) placing at least one mound of glue having a shrinkage of no greater than 15% on an inner surface of the bottom layer;

(3) mounting an electronic component with external electrical contacts on at least one glue mound having a shrinkage of no more than 15% to form a bottom layer assembly, wherein the external electrical contacts are in alignment with openings in the bottom layer;

(4) solidifying the at least one cement mound portion having a shrinkage of no greater than 15%, wherein the electronic component is fixed in a stable position;

(5) placing the bottom layer assembly in a bottom die;

(6) placing the top layer in a top mold;

(7) the top die is close to the bottom die in a mode of generating a gap between the top layer and the bottom layer;

(8) injecting a thermosetting polymeric material into the void space under temperature and pressure conditions such that: (a) the electronic component is held in place by the partially set adhesive while the electronic component and the partially set adhesive are submerged in the thermosetting polymeric material, (b) gas and excess polymeric material are expelled from the void, (c) the electronic component is encapsulated in the thermosetting polymeric material before the partially set adhesive becomes fully set, (d) the lower surface of the external electrical contact is flush with the bottom surface of the bottom layer as the shrinkage of the partially set adhesive fully sets, and (e) the thermosetting polymeric material bonds the top layer and the bottom layer to form a unified precursor to the memory card body;

(9) removing the unified precursor of the memory card body from the mold apparatus; and

(10) the precursor body of the memory card is trimmed to the desired dimensions to make the memory card.

2. The method of claim 1, wherein the electronic component is not in physical contact with the substrate.

3. The method of claim 1, wherein the electronic component is positioned at least 0.01mm above the bottom layer.

4. The method of claim 1, wherein said electronic component is an integrated circuit that is cushioned over at least two mounds of glue that hold said integrated circuit at least 0.01mm above a bottom layer.

5. The method of claim 1 wherein the glue having a shrinkage of no greater than 15% is a cyanoacrylate adhesive type glue capable of at least partial solidification in 5 seconds or less.

6. The method of claim 1 wherein the glue having a shrinkage of no greater than 15% is a UV curable glue capable of at least partial curing in 5 seconds or less.

7. The method of claim 1 wherein the glue having a shrinkage of no greater than 15% cures at 10% in 3 seconds or less.

8. The method of claim 1 wherein the glue having a shrinkage of no more than 15% solidifies 10% to 90% when submerged in the thermoset polymeric material.

9. The method of claim 1 wherein the inner surface of the top layer and the inner surface of the bottom layer are treated to facilitate a strong bond between the top layer and the thermosetting polymeric material and between the bottom layer and the thermosetting polymeric material.

10. The method of claim 1, wherein the top layer is treated by applying an adhesive to the inner surface of the top layer and the inner surface of the bottom layer, respectively.

11. The method of claim 1, wherein the inner surface of the top layer and the inner surface of the bottom layer are treated by corona discharge treatment.

12. The method of claim 1 wherein the thermoset polymeric material is injected into the void space at a pressure between ambient pressure and 500 psi.

13. The method of claim 1 wherein the thermoset polymeric material is injected into the void space at a pressure between 80 and 120 psi.

14. The method of claim 1 wherein the thermoset polymeric material is injected into the void space at a temperature between 56 ° f and 120 ° f.

15. The method of claim 1 wherein the thermoset polymeric material is injected into the gap between the top layer and the bottom layer at a temperature between 65 ° f and 70 ° f.

16. The method of claim 1 wherein the film carries alphanumeric/graphic information applied to the inner surface of the top layer.

17. The method of claim 1, wherein a layer of opaque protective material is applied to the inner surface of the top layer and the inner surface of the bottom layer.

18. The method of claim 1, wherein the electronic component is

(a) A multimedia card die assembly, or

(b) A secure digital card die assembly for use in a digital card,

the electronic component is electrically connected to the external contact.

19. The method of claim 1, wherein the top layer and the bottom layer are both formed from flat sheets of polymeric material.

20. The method of claim 1 wherein the top layer is preformed with at least one memory card molding cavity.

21. The method of claim 1 wherein the top layer is molded into the memory card molding cavity of the top mold and the bottom layer is molded against a substantially planar surface of the bottom mold.

22. The method of claim 1 wherein the thermoset polymeric material is polyurethane.

23. The method of claim 1 wherein the thermoset polymeric material is an epoxy.

24. The method of claim 1 wherein the thermoset polymeric material is an unsaturated polyester.

25. The method of claim 1 wherein said gap is filled by a door having a width that is at least 25% of the width of the front edge of the memory card served by the door.

26. A method of manufacturing a memory card, wherein the memory card includes a top layer, a core layer having electronic components embedded therein, and a bottom layer, the method comprising the steps of:

(1) building a bottom layer with precisely positioned openings for external electrical contacts;

(2) placing at least one mound of glue having a shrinkage of no more than 15% and a volume of less than 0.1cc on an inner surface of the bottom layer;

(3) mounting an electronic component with external electrical contacts on the at least one glue mound having a shrinkage of no more than 15% to form a bottom layer assembly, wherein the external electrical contacts are in alignment with openings in the bottom layer;

(4) setting 10% to 90% of the total amount of cement mounds having a shrinkage of no greater than 15% will be completed in less than 5 seconds, with the electronic component being secured in a stable position;

(5) placing the bottom layer assembly in a bottom die;

(6) placing the top layer in a top mold;

(7) the top die is close to the bottom die in a mode of generating a gap between the top layer and the bottom layer;

(8) injecting a thermoset polymeric material into the void space at a temperature between 65 ° f and 70 ° f and a pressure between 80psi and 120psi, the temperature and pressure conditions being such that: (a) the electronic component is held in place by the partially cured glue while the electronic component and the mound of partially cured glue are submerged in the thermosetting polymeric material, (b) gas and excess polymeric material are expelled from the void, (c) the electronic component is encapsulated in the thermosetting polymeric material before the partially cured glue becomes fully cured, (d) the lower surfaces of the external electrical contacts are flush with the bottom surface of the bottom layer as the shrinkage of the partially cured glue as it fully cures, and (e) the thermosetting polymeric material bonds the top layer to the bottom layer to form a unified precursor to the memory card body;

(9) removing the unified precursor of the memory card body from the mold apparatus; and

(10) the memory card precursor is trimmed to the desired dimensions to make the memory card.

27. A method of manufacturing a memory card comprising a top layer of synthetic paper or plastic material and a bottom layer on which electronic components are located, said method comprising the steps of:

(1) constructing an electronic component with external electrical contacts;

(2) placing the electronic component in the bottom die;

(3) placing the top layer in a top mold;

(4) bringing the top mold close to the bottom mold in such a way that a gap is created between the top layer and the electronic component;

(5) injecting a thermosetting polymeric material into the void space under temperature and pressure conditions which are such that: (a) the exposed electronic components are completely covered by the thermoset polymeric material to form a bottom layer, (b) gas and excess polymeric material are expelled from the voids, (c) the electronic components are encapsulated in the thermoset polymeric material, and (d) the thermoset polymeric material adheres to the top layer to form a unified precursor to the memory card body;

(6) removing the unified precursor of the memory card body from the mold apparatus; and

(7) the precursor body of the memory card is trimmed to the desired dimensions to make the memory card.

28. The method of claim 27 wherein the inner surface of the top layer is treated to facilitate a strong bond between the top layer and the thermoset polymeric material.

29. The method of claim 27, wherein the top layer is treated by applying an adhesive to the inner surface of the top layer.

30. The method of claim 27, wherein the inner surface of the top layer is treated by corona discharge treatment.

31. The method of claim 27 wherein the thermoset polymeric material is injected into the void space at a pressure between ambient pressure and 500 psi.

32. The method of claim 27 wherein the thermoset polymeric material is injected into the void space at a pressure between 80 and 120 psi.

33. The method of claim 27 wherein the thermoset polymeric material is injected into the void space at a temperature between 56 ° f and 120 ° f.

34. The method of claim 27 wherein the thermoset polymeric material is injected into the gap between the top layer and the electronic component at a temperature between 65 ° f and 70 ° f.

35. The method of claim 27, wherein the film carries alphanumeric/graphic information applied to the inner surface of the top layer.

36. The method of claim 27, wherein a layer of opaque protective material is applied to the inner surface of the top layer.

37. The method of claim 27, wherein the electronic component is

(a) A multimedia card die assembly, or

(b) A secure digital card die assembly for use in a digital card,

the electronic component is electrically connected to the external contact.

38. The method of claim 27, wherein the top layer is formed from a flat sheet of polymeric material.

39. The method of claim 27 wherein the top layer is preformed with at least one memory card molding cavity.

40. The method of claim 27 wherein the thermoset polymeric material is polyurethane.

41. The method of claim 27 wherein the thermoset polymeric material is an epoxy.

42. The method of claim 27 wherein the thermoset polymeric material is an unsaturated polyester.

43. The method of claim 27 wherein said void is filled by a door having a width that is at least 25% of the width of the front edge of the memory card served by the door.