JP4819398B2 - Electronic module - Google Patents

Description

  The present invention relates to an electronic module, and more particularly to a multilayer microelectronic module.

  In particular, the invention relates to a three-dimensional module comprising electrically interconnected layers, at least one of which is equipped with a thin, small profile package (TSOP). The TSOP has been modified to have the area of an industry standard (eg, JEDEC) BGA package, with each TSOP layer being selectively thinned to minimize the height of the integration.

  The demand for computer memory in the form of a ball grid array package (BGA) is increasing due to the larger storage volume and speed and the smaller form factor of the BGA format.

  The BGA package utilizes solder ball interconnections on the lower side of the package and interconnects the power source from the semiconductor die and the input / output ends in the package to external electronic circuitry. Thus, the BGA package does not require externally protruding leads for interconnection as does TSOP. There is a tendency to use BGA packages for applications where a small factor is desirable.

  In addition, computer memory manufacturers are increasingly offering newer and more expensive memory products in BGA format. Thus, end product manufacturers, such as server manufacturers who design DIMMs or printed circuit boards, electronic units, etc., use BGA memory packages in or on the final product.

  In the previous generation of memory technology, the memory IC chip was equipped in a thin, small outline package called TSOP. As TSOP packaging technology and manufacturing processes are well developed, TSOP memory product groups tend to be of higher quality, cheaper and more accessible.

To improve TSOP memory circuit density, the industry utilizes the vertical integration and interconnection of two or more layers containing traces or other microelectronic circuits to form high-density three-dimensional modules. Yes. Integration of TSOP memory packages is well known in the art and is disclosed, for example, in US Pat. Nos. 6,026,352, 6,806,559, 6,706,971, and the like.
US Patent No. 6,026,352 US Patent No. 6,806,559 US Patent No. 6,706,971

  With respect to integrated BGA packages, available BGA packages are expensive and have unique internal and external design characteristics, and thermal problems make thinning, integration and interconnection difficult. On the other hand, TSOP is easy to obtain, thin, and inexpensive. However, it lacks the standard BGA form factor required by the industry.

  The present invention seeks to combine the advantages obtained in both types of packages by providing a BGA scale integration consisting of at least one modified / thinned or non-thinned TSOP layer.

  The present invention proposes a three-dimensional electronic module consisting of one or more layers containing a modified TSOP package.

  In one embodiment, two or more conventional TSOP packages and base rerouting substrates are integrated and interconnected to form an electronic module. The TSOP layer is modified by removing predetermined portions of the lead frame inside and outside the encapsulated package. Here, a cross-sectional portion of an existing TSOP internal lead frame is exposed on one or more longitudinal sides of the module to form one or more lead frame access leads.

  The routing board typically includes a printed circuit board, flex circuit or equivalent structure for routing electrical signals. The rerouting substrate has appropriate conductive traces and peripheral rerouting substrate access leads and is coupled to the underside of the TSOP integrated module. The rerouting board further has a solder ball pattern, whereby the module is electrically connected to an industry standard BGA connection, as found on a printed circuit board.

  Appropriate access leads from each layer are interconnected using metallized conductive traces forming a “T connector”. The T connector is disposed on one or more module peripheral sides. The TSOP access lead is also electrically connected to an appropriate access lead on the route changing board. The board routes power, ground and input / output signals from the layers to appropriate locations on the routing board solder ball pattern located on the underside of the module. A modified layer with an encapsulated integrated circuit chip or surface polished TSOP package can also be used in the layer.

  The combined and interconnected layers form a three-dimensional electronic module that has a high circuit density, is inexpensive, is easy to manufacture, and can be easily connected to an industry standard conductive pattern.

  The present invention utilizes the unique shape of the existing TSOP lead frame structure, which allows access leads to be formed and interconnected on the four peripheral sides of the module, while at the same time, standard BGA package shapes. A module that is precisely matched to is formed.

  In addition, the layers in this invention consist of TSOP layers, which are thinned to expose ball or wire bonds on the die, which are electrically rerouted to the edge to provide one of the modules. They are interconnected along these sides.

  In addition, the layers of the present invention have one or more integrated circuit dies having an active surface encapsulated and covered with a dielectric. The integrated circuit bond pad is exposed through the dielectric and is electrically rerouted to the edge using metalized traces. The trace is used for setting a route of a signal entering and leaving the route changing board.

  A conventional commercially available TSOP package 1 shown in FIGS. 1a and 1b is generally an integrated circuit chip molded in an encapsulating material and has a plurality of conductive leads depending outwardly from the encapsulating material. Shown in FIG. 1a is the internal structure of a TSOP having an integrated circuit die and a lead frame.

  The package 1 generally has a square planar shape, and has an upper surface 5, a lower surface 10, longitudinal first side portions 15 a and 15 b, and lateral second side portions 20 a and 20 b.

  In FIG. 2, an internal integrated circuit die 25 such as a memory chip is electrically connected to the lead frame 30 through a wire bond 35. The lead frame 30 is made of a conductive material such as copper, and electrically connects the integrated circuit die 25, the wire bond 35, and the lead frame 30 encapsulated in the encapsulating material 40. The outwardly projecting TSOP lead 45 has an outer projecting portion of the lead frame 30 and extends from the encapsulating material 40 and is electrically connected to the integrated circuit die 25 and the TSOP lead 45 to enable connection to an external circuit. Yes.

  In the embodiment shown in FIG. 3, the package 1 is thinned by removing predetermined portions of the encapsulating material 40 from the upper surface 5, the lower surface 10, or both surfaces by lapping or polishing. As known to those skilled in the art, upon removal of a predetermined portion from the lower surface 10, a portion of the inactive lower surface of the integrated circuit die 25 is removed to minimize the thickness of the TSOP package.

  As will be described in detail below, the substrate 50 shown in FIGS. 4 a and 4 b has a through hole through a group of conductive traces 55, solder ball connection pads 60 and connectors 65. Conductive trace 55 terminates at or near the longitudinal and lateral perimeter of substrate 50 and is substantially converted to a rerouting substrate access lead and interconnected to a side bus metallization to form a T connector. ing.

  FIG. 4 a shows a plurality of packages 1 and a substrate 50, which are substantially vertically integrated with the TSOP lead 45, and each of the rerouting substrate access leads 70 is substantially the same as the TSOP lead 45. It is arranged vertically. The plurality of packages 1 and the substrate 50 are bonded by an appropriate adhesive 72 such as epoxy to form an accumulation of TSOP layers, and the path changing substrate is on the lower surface thereof to form an integrated three-dimensional module 75. ing.

  In FIG. 5, after the module is assembled and joined, one or more longitudinal side portions 15a, 15b or predetermined portions 78 of the lateral side portions 20a, 20b are removed by saw cutting, polishing, lapping, etc. The cross-sectional area of the frame 30 is exposed to define one or more lead frame access leads 80, and the transverse area of the conductive traces of the substrate 50 is exposed to define one or more rerouting board access leads 70. ing.

  By forming the lead frame access lead 80 and the route change board access lead 70, a group of conductive connection points are formed around the longitudinal side and / or the lateral side of the module. As a result, a circuit is formed in each package layer to be rerouted to the connection pad 60 on the lower side of the substrate 50.

  Once a group of access leads are exposed on the selected side, metallization such as plating is applied to all sides, effectively shorting each exposed access lead contained thereon, An orthogonally disposed conductor metallized T-connector is formed where the metallized and access leads are interconnected.

  The selected metallized conductive trace is then formed in place on either side by removing selected portions of the metallization, such as by sawing or laser polishing. This creates conductive traces between user-selected access leads on the various sides. The lead is routed to a route-changed board solder ball pattern.

  In another embodiment, predetermined portions on both sides of the plurality of packages 1 are removed, and lead frame access leads are exposed on each side. An auxiliary rerouting board is provided and access leads are formed at desired locations near the periphery of the module.

  The advantage of the package 1 shown in FIG. 6 resides in the unique configuration of the lead frame 30, which minimizes the trace of the module itself, but maximizes the connection to the access leads. When the package 1 is modified in this way, a high-density module that can be used for BGA applications can be formed from an inexpensive and readily available TSOP package.

  In assembling the embodiment, solder balls are used for the connection pads 60 to be interconnected to an external electronic circuit.

  In the manufacturing method shown in FIGS. 7a to 7n, first, a substrate 50 such as a printed circuit board or a flex circuit is prepared as shown in FIG. 7a. It has one or more suitable conductive traces (not shown) for receiving solder balls for subsequent electrical connections and subsequent ball grid array connections.

  In the step shown in FIG. 7b, an adhesive such as thermoplastic is applied temporarily.

  Illustrated in FIG. 7 c is a substrate 50 with applied printed epoxy, the epoxy pattern for receiving one or more packages 1.

  In the step of FIG. 7d, a first sacrificial substrate or a removable positioning fixture 85 is prepared. The fixing material has one or more packages 1 thereon, and each package 1 has an upper surface 5 and a lower surface 10. It is desirable to fix the package 1 on the first positioning surface by soldering or bonding the TSOP leads. The lower surface 10 is disposed toward the first positioning surface.

  In the step of FIG. 7 e, the top surface 5 of the package 1 is bonded onto the printed epoxy area on the substrate 50 to form the manufacturing unit 90.

  FIG. 7f shows the manufacturing unit 90 during curling.

  FIG. 7g shows the manufacturing unit 90 after removing the first positioning fixture.

  As shown in FIG. 7h, a predetermined portion of the lower surface 10 of the package 1 is removed by polishing or the like, and an epoxy layer is disposed thereon.

  7i to 7m, the second positioning and fixing member 95 with the set of the second package 1 is coupled to the manufacturing unit 90, and the upper surface 5 of the package 1 of the second fixing member is the first set of packages. 1 is coupled to the lower surface 10.

  The fixing member 95 is removed, and a predetermined portion of the lower surface 10 of the second set of packages 1 is removed. These steps can be repeated at the user's discretion, thereby forming a TSOP aggregate with two or more TSOP layers or modifying a single TSOP package to conform to the BGA format. .

  Once the desired number of layers are integrated and combined, the multiple subunits are individualized into individual assemblies of thinned TSOP layers as shown in FIG. 7m, such as by cutting, on one or more sides of the module 75. The internal lead frame cross section is exposed.

  As described above, this individualization step utilizes the unique internal structure of the TSOP, ie, the die placement and lead frame placement. By cutting the TSOP so that its surface area is that of an industry standard BGA form factor, the external TSOP lead 45 is removed, the internal lead frame 30 is partially removed, and the lead frame cross-section near the periphery of the modified package 1 Is exposed. These exposed lead frame portions are used as connection points to allow vertical connection of one or more modified TSOP layers on the longitudinal and lateral sides of each pair of modules.

  As shown in FIG. 8, the stack is stacked as an “stack of stacks” to simplify processes such as subsequent side bus metallization.

  Appropriate conductive traces are formed on the stacked assembly to allow connection of exposed lead frame portions as shown in FIG.

  Note the potential use of the lead frame “unconnected” lead cross-section, and the unconnected lead frame portion in the TSOP structure is used to conduct on the longitudinal and lateral sides of the package 1 Form traces to allow more complex side bus designs.

  In the steps of FIGS. 10 and 11, the individualization of the integrated body and the solder ball attachment are performed to form the integrated structure of the thinned TSOP layer having the form factor and the layout of the industry standard BGA package.

  Alternatively, a semiconductor wafer having an integrated circuit die thereon can be purchased, cut, packaged in a TSOP format, and the above-described processing can be easily used. Repackaging integrated circuit dies into BGA packages is currently very expensive.

  FIG. 12 shows the TSOP lead frame structure before removal of the longitudinal side parts 15a, 15b and the lateral side parts 20a, 20b, the resulting structure and the formation of lead frame access leads on the four peripheral surfaces. is there.

  As shown, the resulting electronic module has a BGA form factor and can be used in a BGA with a very low vertical shape (ie 1.5 mm). The module has the advantages of proven industrial standard TSOP manufacturing techniques and methods and is inexpensive because it allows processing steps to be performed on multi-processing modules.

  If the vertical height is not an important factor in the module, the TSOP layer need not be thinned.

  Alternative embodiments utilize internal wire bonds or ball pads connected to the integrated circuit die 25 of the TSOP package. A method for forming such a layer is disclosed in the aforementioned US Pat. No. 6,706,971.

  As can be seen in FIG. 13, in this embodiment, a predetermined portion of the encapsulating material 40 is removed or polished from the upper surface 5 by lapping, polishing, etching, etc., and the wire bond is approximately the depth of the ball bond. 35 is exposed. Wire bond 35 is connected to integrated circuit die 25.

  The exposed ball bond is electrically rerouted to one or more sides of the modified TSOP by connecting metallized conductive traces on the top surface of the modified package that act as a dielectric surface. An access lead is then formed at the end of the conductive trace on the surface of the modified TSOP.

  In a further embodiment, module 75 comprises at least one plastic encapsulated microcircuit (PEM), such as TSOP, which includes an active surface that includes an integrated circuit, an active circuit that includes the integrated circuit, and a wire bond pad. It has (a) a microcircuit having a surface and (b) an enveloping material that contacts the small circuit, and a modified PEM having a modified surface is formed by modifying the PEM. A wire bond cross section is exposed on the modified surface, which is also referred to as a conductor, which has the ball bond portion of the wire bond or the wire bond cross section itself, which is electrically connected to the bond pad. Connected.

  In the present invention, the module has at least one PEM. The PEM encapsulates (a) a microcircuit having a bond pad, (b) a lead frame connected to the bond pad, and (c) at least a portion of the microcircuit, bond pad, and lead frame. And (d) polishing the upper surface of the PEM and the top surface of the PEM leaving at least a portion of the lead frame leaving a flat surface containing the microcircuit and bonding pads.

  Further, the module comprising at least one plastic encapsulated microcircuit (PEM) of the present invention comprises: (a) a microcircuit having an active surface including an integrated circuit and a bond pad; and (b) a bond pad and a lead. A wire bond connected to the frame; (c) a wire connecting the wire bond to the lead frame; and (d) a known microcircuit, a wire bond, a plastic body encapsulating at least a part of the wire and the lead frame. Have.

  The surface of the PEM is polished to remove the lead frame and wires to form a modified PEM. The PEM includes microcircuits, bond pads, and wire bonds. The modified PEM also has a modified surface on which a wire bond is exposed and connected to the bond pad. Thus, electrical leads are formed on the modified surface and extend from the wire bond to the periphery of the modified PEM.

  The module of the present invention further comprises (1) a rerouting lead on the modified surface of the modified portion of the plastic encapsulated microcircuit (PEM). The microcircuit initially includes (a) a known microcircuit with a bond pad, (b) a conductive lead unit connected to the bond pad, and (c) a known microcircuit, bond pad, and conductivity. It has a plastic body encapsulating the lead unit.

  A modified portion is formed by removing a portion of the conductive lead unit from the PEM. The modified portion has a modified surface, which has a known microcircuit, bond pads, and the remainder of the lead unit, the end of which is exposed on the modified surface. (2) The route changing lead connects the remaining exposed portion of the lead unit to the edge of the modified portion.

In yet another embodiment, the BGA scale module comprises a modified layer disclosed in US Pat. No. 6,797,537, US Pat. No. 6,784,547, and the like.
US Pat. No. 6,797,537 US Patent No. 6,784,547

  The retrofit layer generally includes a layer that includes one or more integrated circuit dies encapsulated in a plastic material. A dielectric is disposed on the active surface of the die. The die bond pad is exposed through the dielectric and a redirection metallization from the bond pad to the periphery of the modified layer is formed to form at least one modified layer access lead at the end of the layer.

  Multiple dies can be present in a single layer through the use of a retrofit layer that is bonded to a rerouting substrate to form a BGA scale module. The dies are heterogeneous or homogeneous in the stack. Support circuitry, FPGA dies or other ICs can be present in a modified TSOP or single layer BGA scale integration through the use of a modified layer.

It is a perspective view of the external structure of the conventional thin small outline package or TSOP. It is a perspective view of the internal structure of the conventional thin small outline package or TSOP. It is sectional drawing of TSOP of a of FIG. 1, b. It is sectional drawing of TSOP of this invention. It is sectional drawing of the module of this invention. It is a top view of a path change board similarly. It is sectional drawing of the left side part of a module similarly. It is sectional drawing of the other side part of a module similarly. a is a figure which shows one step of the manufacturing process of the module of this invention. b is a figure which shows one step of the manufacturing process of the module of this invention. c is a figure which shows one step of the manufacturing process of the module of this invention. d is a figure which shows one step of the manufacturing process of the module of this invention. e is a figure which shows one step of the manufacturing process of the module of this invention. f is a figure which shows one step of the manufacturing process of the module of this invention. g is a figure which shows one step of the manufacturing process of the module of this invention. h is a figure which shows one step of the manufacturing process of the module of this invention. i is a figure which shows one step of the manufacturing process of the module of this invention. j is a figure which shows one step of the manufacturing process of the module of this invention. k is a figure which shows one step of the manufacturing process of the module of this invention. 1 is a figure which shows one step of the manufacturing process of the module of this invention. m is a figure which shows one step of the manufacturing process of the module of this invention. n is a figure which shows one step of the manufacturing process of the module of this invention. FIG. 7 is a diagram showing an assembly of the assembly of FIGS. FIG. 9 is a diagram illustrating the definition of copper traces on the side of the stack of the stack of FIG. FIG. 6 is a diagram illustrating the isolation of an integration body into individual modules. It is a figure which shows the solder ball attached to the path | route change board | substrate. It is a figure which shows the internal structure of the conventional TSOP lead frame. It is a figure which shows a plastic envelopment micro circuit.

Explanation of symbols

1: Package 15, 20: Side 25: Integrated circuit die 30: Lead frame 40: Encapsulant 50: Substrate 75: Three-dimensional module 90: Manufacturing unit

Claims (12)

An electronic module having a thin small profile package (TSOP) having an upper surface and a lower surface, and a routing board coupled to the lower surface,
The package includes a pair of longitudinal sides, a pair of lateral sides, an integrated circuit die, and an internal lead frame that is at least partially sealed within the encapsulant ;
The encapsulant of which the longitudinal side or the lateral side is removed so as to define a lead frame access lead exposed on a surface of the longitudinal side or the lateral side . Have a part ,
The rerouting board has conductive traces and a rerouting board access lead ;
Pathway changes the substrate access lead is connected the electrically conductive traces and electrically,
The lead frame access leads, wherein the longitudinal sides one above or one metallized conductive traces defined on top of the lateral sides of are the reroute substrate access leads and electrical connections,
The routing board has a connection pad provided on the routing board surface; and
The conductive traces are electrically connected to the connection pads by through-hole interconnections;
An electronic module characterized by that. Furthermore an electronic module according to claim 1 having a metallized T connector, the metallized T connector, electrically connecting the lead frame and the metallized conductive traces, the electronic module. The electronic module of claim 1, wherein the metalized conductive trace has a metalized side bus. A further electronic module according to claim 1 having at least one T-connector to the longitudinal sides on the T connector, the electrically the lead frame access leads and the metallized conductive trace Electronic module to connect. A further module of claim 1 having at least one said lateral side T connector on the T connector, electrically connecting the lead frame access leads and the metallized conductive trace Electronic module. A further module of claim 1 having at least one said longitudinal side and at least one T-connector to the lateral sides on the said T connector, the said lead frame access leads metal An electronic module that electrically connects a conductive trace. Further a module according to claim 1 having a T connector to the two said longitudinal side and at least one of said lateral side on the T connector, said metallization and said lead frame access leads An electronic module that electrically connects conductive traces. A module according to claim 1 having a T connector to at least one of said longitudinal sides and two of the lateral side on the T connector, the metallized conductive and the lead frame access leads Electronic module that electrically connects the sex traces. A further module of claim 1 having two longitudinal sides and T connectors on two lateral sides, said T connector, the said lead frame access leads metallized conductive trace Electronic module that electrically connects with the. The electronic module according to claim 1, wherein the TSOP is thinned. Electronic module according to claim 1, further comprising a solder ball that electrically connects the connection pads and the external electronic circuitry. 2. The electronic module according to claim 1, wherein the top surface of the TSOP is modified to be substantially the same as the top surface of the BGA package.

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