JP4376781B2 - Microchip package - Google Patents

Description

  The present invention relates generally to the field of semiconductor device manufacturing. In particular, the present invention relates to the packaging of microchip devices with integrated circuit chips used in electronic assemblies such as printed circuit boards.

  The electronics industry continues to pursue smaller electronic devices with lower cost and better performance. This trend is particularly evident in the field of mobile electronics devices and wireless communications, which have recently experienced rapid growth. In particular, as the size of microchips has decreased and the electronic functional density per chip area has improved, there is an increasing demand for very small microchip packages.

  Examples of conventional microchip device packaging include a thin small outline package (TSOP), a quad flap package (QFP), and the like. These packages have fixed package dimensions for the number of external electrical contacts for contacting the mounted microchip device and peripheral devices.

  As microchip sizes become smaller, the technical requirements necessary for microchip packaging also increase. In particular, the length of the electrical signal path needs to be reduced as much as possible in order to prevent delays in the transport of high-speed electrical signals.

  Microchip devices typically have very small electronic pads on the surface of the microchip. These electronic pads are known to be connected to external contacts of the package using very small wires ("wire bonding") or ribbons (e.g., tape automated bonding (TAB)). In any case, these conductors are very fragile and need to be protected from structural defects. Furthermore, it is known to provide pin-shaped or ball-shaped external electrical contacts to allow electrical contact from outside the package to the mounted microchip.

  In some packaging schemes, electronic pads arranged in a fixed layout to suit a particular packaging scheme are used as contacts on the surface of the microchip. A class of packaging scheme that includes such a technique is called chip size packaging (CSP). According to the CSP definition by the Institute for Interconnecting and Packaging Electronic Circuits (IPC), the final package surface area is more than 1.5 times the surface area of the microchip. must not. Furthermore, the final package must be easily accessible via external contacts exposed on the surface of the package.

  In a new subclass of CSP, interposers with multiple external contacts are used for packaging. The interposer includes an aperture having an external contact disposed outside and extending from the outside through the interposer. The aperture has a shape of a window or a frame (window chip scale packaging, wCSP) in particular, but may have a shape in which one side surface or a plurality of side surfaces in the longitudinal direction is open. The interposer is placed adjacent to or in close proximity to the microchip device so that it can contact electrical contacts on the microchip surface through the aperture from the outside. Thereafter, the contacts on the surface of the microchip are electrically connected to external contacts on the outside of the interposer via a conductor. At least some of the conductor is extended into the aperture and then encapsulated with an insulating material.

  This new subclass of CSP has the following advantages.

  Keep the length of the conductor connecting the electrical contacts on the surface of the microchip and the external contacts very short, especially when the end of the aperture is placed close to the contacts on the surface of the microchip device be able to.

  During the wiring process, it is possible to connect to an external contact located outside the interposer from the same side as the contact on the microchip surface.

  In this way, the component arrangement can be made very compact.

  The conductor is protected with an encapsulating material.

  The external contact of the package can be directly connected to the contact of the substrate. In addition, the microchip device is placed on or in close proximity to the opposite surface of the package for maximum heat dissipation to the surrounding environment.

  However, the positioning of the interposer relative to the microchip device needs to be performed very accurately. Failure to do so can result in contact failure and / or damage to the conductor, even if only slightly out of position. Furthermore, when using transfer molding when encapsulating a conductor with an insulating material, handling an interposer and a microchip device in preparation for transfer molding may cause contact failure or damage.

  One object of the present invention is to facilitate the handling of any of the microchip devices, interposers, mounted microchip devices, or any combination thereof, or all of them, and to reduce the percentage of rejected products in mass production. It is an object of the present invention to provide a microchip device packaging method that can be kept low.

  Another object of the present invention is to provide a corresponding interposer and mounted microchip device.

The microchip package according to claim 1 has a plurality of first electrical contacts on the upper surface of the microchip device, an upper surface and a bottom surface, and is disposed so that the bottom surface is in contact with the upper surface of the microchip device. A plurality of second electrical contacts on the top surface of the interposer, a plurality of first electrical contacts on the top surface of the microchip device and a plurality of second electrical contacts penetrating from the top surface of the interposer to the bottom surface. A longitudinal aperture that enables connection with the electrical contacts, and an aperture that is separated into a first portion and a second portion in the longitudinal direction and is in contact with the side wall of the aperture, the upper surface being from the upper surface of the interposer A low tie bar.

  A microchip package according to claim 2 is the material according to claim 1, which encapsulates connections between the plurality of first electrical contacts on the top surface of the microchip device and the plurality of second electrical contacts on the top surface of the interposer. Is further provided in the aperture.

  The microchip package according to claim 3 is the microchip package according to claim 2, wherein the material is an electrically insulating material.

  According to a fourth aspect of the present invention, there is provided a microchip package according to the first aspect, further comprising: a conductor that connects the plurality of first electrical contacts on the top surface of the microchip device and the plurality of second electrical contacts on the top surface of the interposer. Prepare.

Further , the following microchip device packaging method may be proposed.

  Providing a microchip device having a plurality of first electrical contacts, divided into at least two openings by an outer second electrical contact and a bridge extending from the outside through the interposer and connecting opposite side ends to each other An interposer with an aperture formed in the microchip device, wherein the interposer is disposed in the vicinity of the microchip device so that the first electrical contact can be accessed through at least the first opening of the opening divided from the outside. A method comprising electrically connecting one of the electrical contacts and one of the second electrical contacts.

In this way , the bridge strengthens the area of the interposer aperture, making it easier to handle the interposer and microchip devices. At least in the region adjacent to the bridge, the dimensions of the at least two openings are stable regardless of the handling of the interposer. In particular, when both openings are used to connect the first electrical contact to the second electrical contact, the stability is significantly higher compared to undivided apertures having the same or similar cross-sectional area or cross-sectional dimensions. Moreover, the dimension of the 2nd electrical contact located in the outer side of an interposer is also maintained stably. Therefore, it is possible to reduce the failure occurrence rate when the mounted microchip device is brought into contact with an external device such as an electronic substrate.

  The bridge is preferably located as close as possible to the first electrical contact. Thus, in a preferred embodiment in which the first opening defines the connection area used for positioning the conductor, the distance between the bridge and the nearest conductor among the conductors in the connection area is between the conductors in the connection area. It is desirable to arrange it so that it is 3 times the average distance, preferably 2 times or less.

  After applying the contact of the first electrical contact, it is desirable that at least the first opening is filled with an electrically insulating material by transfer molding.

  In a preferred embodiment, at least one electrical conductor is connected to extend from the microchip device through the first opening to the outside of the opening that is outside the interposer. The conductor according to the present embodiment is encapsulated by transfer molding at least outside the opening. During transfer molding, the interposer is at least partially surrounded by the mold so as to form a cavity into which the insulating material is injected. The cavity preferably further comprises an opening and a space located outside the opening so as to provide sufficient space to completely encapsulate the at least one conductor.

  A separation opening may be provided, which may be a groove that penetrates or does not penetrate the interposer, but is supplied from the direction in which the insulating material passes through the region of the separation opening before reaching the aperture. . The separation aperture stabilizes the transfer molding process for different aspects. First, the separation opening serves as a storage location for the electrically insulating material. As a result, there is sufficient material to fill the aperture when the initial amount of material is injected into the aperture. In particular, when the insulating material is an agglomerated material, the material already injected into the aperture can attract the material in the separation opening. Thus, even if the flow from the material source is temporarily insufficient, sufficient material will flow into the aperture. Second, the isolation aperture acts as a reflective shield when the insulating material is injected at a rate that is too fast or from the direction of backflow, thus preventing the next material from entering or filling the aperture. One explanation for this effect is that the insulating material first passes through the separation opening and at least a portion of the insulation material is temporarily stored in the separation opening. Thereafter, when the additional material arrives, at least a portion of the storage material escapes from the separation opening and is bonded to the subsequent material. As a result, the material flow has a sufficient flux density at a moderate flow rate. Alternatively, this temporary storage effect can be used to fill an extra cavity or space that can be placed in the flow path of the material with an insulating material.

  Such extra cavities or spaces for filling according to a preferred embodiment are longitudinal along the outer edges of the interposer and / or microchip device, or both, especially the interposer and / or microchip device, or both. Consists of regions. Such a configuration makes it possible to encapsulate at least part of the interposer and / or the microchip device. In this case, it is desirable that the isolation opening be dimensioned and positioned so that during transfer molding, the insulating material flows along the outer surface of the interposer and / or microchip device, or both, before reaching the aperture.

  The cross section of the separation opening may have any shape such as, for example, a circle, a slot, a square, or a rectangle. Furthermore, the separation opening may be partially divided, or may be constituted by a plurality of separation openings, or both.

  It is desirable to determine the shape and arrangement of the separation opening or openings so that the aperture and, preferably, the region including the adjacent portion of the cavity to be filled is completely filled with insulating material.

  The two main advantages of the proposed method of providing this separation opening are that the separation opening stabilizes the flow of the insulating material, thus facilitating transfer molding and thus handling of the interposer and microchip devices. And, as a result of satisfactory transfer molding, the final package is protected from damage and can be handled easily.

  A preferred embodiment comprises a plurality of separate apertures or separate aperture regions filled with an electrically insulating material, the apertures or aperture regions being aligned in series to form a passage through which the electrically insulating material passes during transfer molding. A separation opening is further arranged along the passage between two apertures or aperture regions. The additional separation aperture stabilizes the flow of insulating material to the second aperture in a manner similar to that described above.

  The aperture according to yet another preferred embodiment forms at least one passage extending along the outside of the interposer (ie, the side on which the aperture extends through the interposer). This passage allows the insulating material to be supplied to the interior of the aperture or to pass through the interior of the aperture. The separation opening according to this embodiment is arranged adjacent to the start position of the passage. This arrangement makes the flow to the aperture particularly stable.

  Yet another embodiment comprises a plurality of separation openings, each positioned adjacent to a starting or ending position of a particular passage or passages.

  A separation opening adjacent to the end of the passage also helps to completely fill the aperture or cavity. One explanation is that the separation opening serves as a storage location, and the material that flows into it deflects the material that was injected later. In this way, the flow rate of the subsequently injected material decreases at the end of the passageway, facilitating the accumulation of material in that region.

In addition, the following interposer may be provided for the packaging of microchip devices.

  A plurality of electrical contacts disposed on the outside of the interposer that are in electrical contact with and electrically connected to the mounted microchip device and an aperture extending from the outside to the interior of the interposer; The aperture is divided into at least two openings by a bridge connecting opposite ends of the aperture to each other, at least the first opening allowing the interposer from the outside to allow connection to a microchip device. An interposer that extends through.

  In particular, at least the first opening is an opening such as a frame or window.

  It is further desirable to have a plurality of apertures aligned in series so as to form passages through which the electrically insulating material passes during the transfer molding process. An opening extending from the outside to the inside of the interposer may be disposed between the two apertures along the passage.

Further , the following mounting microchip device may be provided.

  An interposer comprising: a microchip device comprising a plurality of first electrical contacts; a plurality of second electrical contacts; and an aperture extending from the outside through the interposer and divided into at least two openings by a bridge; A first electrical contact and a conductor electrically connecting the corresponding second electrical contact, the interposer being attached to the microchip device, wherein the at least one conductor extends into the aperture, And the separation opening is at least partially filled with an electrically insulating material, whereby at least one conductor is secured to the interposer.

In particular, the device may be composed of a plurality of mounted microchips, and the outline of the microchip defines a package area covering the surface of the microchip corresponding to the interposer, excluding the aperture package area,
The bridge extends substantially parallel to the surface of the microchip from the outside of one package area to the inside of the package area.

  FIG. 1 shows a cross section of the arrangement of the microchip device 1, the interposer 7, and the encapsulating resin 25. The interposer 7 is fixed to the microchip device 1 with a single layer of adhesive 27. The width of the microchip device 1 is wider than the width of the interposer 7 so that the edges of the microchip device 1 protrude outward from both sides of the microchip device / interposer arrangement. The surface of the microchip device 1 facing the interposer 7 includes a chip pad 3 in a region not covered by the interposer 7. The chip pad 3 serves as an electrical contact that enables contact and electrical connection between the microchip device 1 and the interposer 7. There is at least one electrical contact (not shown) for each chip pad 3 on the surface of the interposer (outside 10 of the interposer 7). These contacts are located on the surface of the interposer facing downward in FIG. That is, the chip pad 3 and the contact on the surface of the interposer face in the same direction. Each chip pad 3 is electrically connected to one of these contacts by a conductor 5. Furthermore, each contact is electrically connected to a contact ball 9 on the same interposer surface by an electrical connection (not shown). These electrical connections are part of the interposer 7. The contact ball 9 is an electrical contact that enables electrical connection of the mounted microchip device 1. The conductive wire 5 is encapsulated in the resin 25 by any one of potting, dispensing, direct printing, transfer molding, or an appropriate process combining these techniques. Resin 25 is the only conductor 5 to mechanically stabilize the package and to electrically insulate over the chip pad 3 as well as the contacts (not shown) on the interposer surface adjacent to the side edges. In addition, the end of the microchip device 1 is also encapsulated.

  The package design of FIG. 1 represents a CSP (chip scale packaging) class called fan-in design. The design according to the arrangement of FIG. 2 represents another CSP class called fanout design. The fan-in design differs from the fan-out design with respect to the arrangement of contacts on the surface of the microchip device 1 and the interposer 7 that are electrically connected by the conductor 5 or other suitable means. In the fan-in design, both contact groups are distributed over the surface area adjacent to the side edge of the microchip device 1 or interposer 7. In the fan-out design, these contacts are arranged on the surface area of the interposer 7 or microchip device 1 located in the central area of the cross-sectional view. It is also possible to combine fan-in and fan-out designs.

  FIG. 3 shows a variation of the fan-out design in which both the side end portion and the back surface (upward in FIG. 3) of the microchip device 1 are covered with the resin 25. Therefore, the microchip device 1 is encapsulated by the resin 25. This design produces a particularly stable package. Compared with this design, the resin 25 according to the design of FIG. 2 does not cover the back surface of the microchip device 1. Furthermore, the side end portion of the peripheral resin 25 according to the embodiment of FIG. 2 is aligned with the side end portion of the interposer 7.

  The present invention is not limited to only the design described with respect to FIGS.

  FIG. 4 shows a perspective view of the interposer 7 arranged adjacent to the plurality of microchip devices 1 so that the plurality of microchip devices 1 can be packaged simultaneously or in parallel in a single process. Yes. The arrangement of FIG. 4 comprises at least nine microchip devices 1 to be packaged, as indicated by the dotted package outline 8. To show the profile of this arrangement, a part of the arrangement on the right side is cut off.

  The interposer 7 having the arrangement shown in FIG. 4 is a single component. This facilitates the handling of the interposer and accelerates the mass production of a plurality of packages. However, an interposer 7 composed of a plurality of parts can be used instead. The interposer 7 has an aperture 11 having a plurality of aperture regions, and each aperture region corresponds to one package region of the microchip device 1. Each package region has a first longitudinal opening 15 having a longitudinal rectangular cross section with round corners. The first opening 15 extends from the outside (upper side in FIG. 4) through the interposer 7 to the surface of the corresponding microchip device 1. As an example of all the microchip devices 1 and other areas on the surface of this particular microchip device 1, eight chip pads 3 are shown on the left side of the mounting area in the central package of FIG. The interposer 7 is disposed on the surface of the microchip device so that the chip pad 3 can be accessed from the outside (upper side) through the first opening 15. After placing the interposer 7 next to the microchip device 1, the conductor 5 or other suitable conducting means is connected to the chip so that each chip pad 3 is electrically connected to one of the interposer pads 6. Provide and connect to pad 3 and corresponding electronic interposer pad 6. The interposer pad 6 is disposed on the surface area of the interposer 7 facing outward. Each interposer pad 6 is electrically connected to one of the contact balls 9 installed on the surface of the interposer (connection is not shown).

  The aperture 11 or the aperture region according to the embodiment of FIG. 4 is formed in a step shape so that the surface region where the interposer pad 6 is located and the surface region where the contact ball 9 is located are different. In particular, the height of the interposer pad 6 is low so that the aperture 11 can be filled up to the height of the surface area of the contact ball 9. However, the present invention is not limited to this specific embodiment. Rather, different interposer step profiles giving different surface heights are possible. Also, providing an interposer where the interposer pad or contact is located on the same height as the contact ball or other type of external contact (as in the example shown in the design of FIGS. 1-3) You can also.

  The first openings 15 having different aperture regions are separated from each other by a bridge 18 installed between the two first openings 15. Each bridge 18 includes two tie bars 19 that extend along the first opening 15 and extend from one side of the aperture 11 to the opposite side so as to connect the aperture-side ends 13 that face each other. Between the two tie bars 19 of each bridge 18, a second opening 16 extending from the outside of the interposer 7 through the interposer 7 to the height of the surface of the microchip device 1 is provided. . In an alternative embodiment, at least one of these second openings extends partially from the outside of the interposer to the interior of the interposer without penetrating the interposer. The second opening 16 according to both embodiments serves as a stabilizing means for stabilizing the flow of liquid or molten insulating material that is poured to at least partially fill the aperture 11 or aperture region. Therefore, the dimension of the first opening 15 and the distance D between the contact balls 9 arranged at opposite positions on both sides of the aperture 11 are kept stable, and handling of the interposer 7 is facilitated.

  The aperture 11 forms a passage for supplying an encapsulating material or filling material to the aperture region. The passage according to the embodiment of FIG. 4 has a longitudinal shape and is constituted by a series of subsequent apertures.

  5 and 6 show another arrangement of the interposer and the microchip device. FIG. 5 shows a top view of the contact surface on which the contact ball 9 is arranged. The interposer 7 consists of a single part and is used for packaging two microchip devices 1. This arrangement is similar to a fan-in design, but the resulting two packages of the microchip device 1 are split after packaging by being separated along the package contour 8. The aperture 11 has a longitudinal shape, and extends along the side end portion of the interposer in the central region of the interposer 7 where the interposer pad 6 is located. The aperture 11 is subdivided by a tie bar 19 located in the middle between both open ends (up and down in FIG. 5 and front and rear in FIG. 6). The tie bar 19 does not extend from the height of the surface of the microchip device 1 (as is most apparent from FIG. 6) to the height of the outer surface of the interposer 7 where the contact ball 9 is located. Rather, the tie bar 19 extends from the height of the surface of the microchip device 1 to a height of about two thirds of the difference from the height of the outer surface of the interposer 7. This allows the material to pass through the tie bar 19 when an insulating material or other filling material or encapsulating material is supplied from one open end of the aperture 11. Furthermore, the area of the open end where the material of the aperture 11 is supplied acts like one of the second openings 16 according to the embodiment of FIG. 4, ie stabilizes the flow of material to the aperture area on the opposite side of the tie bar 19. Let

  FIG. 7 shows a schematic diagram of a transfer molding process for packaging four microchip devices 1. On the right and left sides of FIG. 7, each two microchip devices 1 are aligned in a line with the material feed path that is fed during transfer molding. As shown in FIG. 7, the flow direction of the feed material is indicated by a plurality of arrows. The material is supplied from the material source 22 through the two supply paths 23 and led to one of the two regions where each of the two microchip devices 1 is aligned.

  FIG. 8 showing details of a part of the region where the supply path 23 ends shows a partial cross section of such a region. This arrangement includes a plurality of cavities that are completely filled with an encapsulating material. These cavities are subdivided as in the embodiment of FIG. 4, but with an aperture 11 that does not have a stepped profile and the longitudinal end of the package as in the embodiments of FIGS. Peripheral cavities 21 at both ends of each package that allow encapsulation, and front and rear cavities 24, 26 located at the front and rear of the package relative to the supply direction of the material to be supplied. Front and rear cavities 24, 26 allow for encapsulation of the front and rear of the package. For transfer molding, one or more molds (not shown) that at least cover the surface area of the interposer 7 in which the contact balls 9 are arranged as external contacts of the package can be provided. Each interposer 7 has a longitudinal shape and extends from the termination region of the supply path 23 through the first and second package regions of the two aligned microchip devices. The interposer 7 has one first opening 15 for each package of the microchip device. The first opening extends from the outside of the interposer 7 to the surface of the corresponding microchip device 1 through the interposer 7. Furthermore, the interposer 7 has a total of three in the supply direction, located in front of the first microchip device package, between the two microchip device packages, and behind the second microchip device package. A separation opening 17 is provided. All the separation openings 17 extend through the interposer 7 from the outside of the interposer 7. The separation opening 17 stabilizes the flow of the material supplied from the material source 22 through the supply path 23. Furthermore, the handling and dimensions of the interposer 7 are also stabilized by a total of four tie bars 19 arranged between one of the first openings 15 and one of the separation openings 17.

  When material is supplied from the material source 22 through the supply path 23, the material is separated from the end of the supply path 23 before reaching the first front cavity 24 and the first opening 15. 17 is reached. Thus, the filling material partially fills this separation opening 17 and other filling material can reach the peripheral cavity 21 before the first opening 15 is completely filled. Thus, sufficient material is provided in the peripheral cavity 21 to encapsulate the longitudinal ends of the microchip device 1 and interposer 7 during the transfer molding process. A similar effect is achieved by a separation opening 17 between two aligned microchip devices 1. However, it should be noted that the length of the separation opening 17 is particularly longer than the length of the separation opening 17 in front of the first microchip device 1 and behind the second microchip device 1. By appropriately changing the length of the separation opening 17 and the length of the first opening 15 as necessary, or appropriately changing the length of the first opening 15 instead of the length of the separation opening 17, Satisfactory filling results can be achieved by controlling the filling of all cavities 15, 21, 24, 26 to be filled.

The present invention will now be described based on non-limiting examples with reference to the following accompanying drawings.
Sectional drawing of a different mounting microchip device. Sectional drawing of a different mounting microchip device. Sectional drawing of a different mounting microchip device. FIG. 3 is a partial perspective view of an interposer disposed on a plurality of microchip devices. The top view of the contact surface of the interposer arrange | positioned next to two microchip devices. Sectional drawing by the VI-VI line of FIG. Schematic showing the arrangement of the encapsulating material that forms the microchip package by transfer molding. FIG. 8 is a partial cross-sectional view showing a part of the arrangement of FIG. 7.

1 to 8, the same reference numerals are used for parts and features having the same or similar functions.

Claims (4)

A microchip device having a top surface and a bottom surface;
A plurality of first electrical contacts on the top surface of the microchip device;
An interposer having a top surface and a bottom surface, wherein the bottom surface is disposed in contact with the top surface of the microchip device;
A plurality of second electrical contacts on the top surface of the interposer;
The plurality of first electrical contacts on the top surface of the microchip device and the plurality of second electrical contacts on the top surface of the interposer can be connected to penetrate from the top surface to the bottom surface of the interposer. A longitudinal aperture that
A tie bar that separates the aperture into a first portion and a second portion in the longitudinal direction and is in contact with a side wall of the aperture, and whose upper surface is lower than the upper surface of the interposer ;
A microchip package comprising:   The aperture further comprises a material that encapsulates the connections between the plurality of first electrical contacts on the top surface of the microchip device and the plurality of second electrical contacts on the top surface of the interposer. The microchip package according to claim 1.   The microchip package of claim 2, wherein the material is an electrically insulating material.   The micro of claim 1, further comprising a conductor connecting the plurality of first electrical contacts on the top surface of the microchip device and the plurality of second electrical contacts on the top surface of the interposer. Chip package.

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