Abstract:
The disclosure relates to a stacked type power device module. May use the vertical conductive layer for coupling the stacked devices, the electrical transmission path may be shortened. Hence, current crowding or contact damages by employing the conductive vias or wire bonding may be alleviated.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 101146419, filed on Dec. 10, 2012. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     TECHNICAL FIELD 
     The disclosure relates to a semiconductor device module, and relates to a stacked type power device module. 
     BACKGROUND 
     Currently, the design of a commercialized power device module is that the device is arranged directly on the planar substrate having the heat dissipating effect and the electrical and signal connections of the device are achieved through wire bonding. Although such an arrangement may enhance heat dissipating efficiency, the area required by the module is also increased. Meanwhile, large amount of wire bonding may cause current crowding, which leads to the failure of the device module. 
     SUMMARY 
     An embodiment of the disclosure provides a stacked power device module, including at least one substrate having a first surface and a second surface, at least one first device, at least one second device, a circuit pattern, and at least one filler layer. The at least one first device is located on the first surface of the substrate and is electrically connected to the substrate; the at least one second device is located on the at least one first device and is electrically connected to the substrate; the at least one filler layer covers on the first surface of the substrate and encapsulates the at least one first device and the at least one second device, and the at least one filler layer includes a plurality of first conductive plugs and at least one second conductive plug. The circuit pattern is located on the at least one second device and is located on the at least one filler layer. The circuit pattern is connected to the at least one second device via the plurality of first conductive plugs. The circuit pattern is connected to the at least one first device via the at least one second conductive plug, wherein the height of the at least one second conductive plug is greater than the height of each of the at least one first conductive plug. 
     In order to make the aforementioned features of the disclosure more comprehensible, embodiments accompanying figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1H  illustrate a cross-sectional schematic view of manufacturing processes of a stacked type power device module according to an embodiment of the disclosure. 
         FIGS. 2A-2H  illustrate a cross-sectional schematic view of manufacturing processes of a stacked type device module according to another embodiment of the disclosure. 
         FIG. 3  is a schematic cross-sectional view of a stacked type device module in an embodiment of the disclosure. 
         FIG. 4A  is a schematic cross-sectional view of a stacked type device module in another embodiment of the disclosure. 
         FIG. 4B  is a schematic top view of an exemplary stacked type device module of the disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The disclosure relates to a three dimensional packaging process in which a plurality of chips and/or package structures may be joined together by way of vertically stacking, and therefore wire bonding joints can be reduced. Also, the overall volume and size of the package structure can be decreased, and an electrical connection path of the device may be shortened so that electrical property is improved. The design of the disclosed structure is compatible for additional heat dissipating module(s) to help the heat generated in the module to be dissipated. 
       FIGS. 1A-1H  illustrate a cross-sectional schematic view of manufacturing processes of a stacked type power device module according to an embodiment of the disclosure. 
     Referring to  FIG. 1A , a substrate  100  is provided for carrying a metal substrate  12 , and the substrate  100  may be unloaded or removed in the process. The metal substrate  12  is, for example, a lead frame  120  which is formed of a metal such as copper or aluminum alloy. The lead frame  120  includes at least one void region  122  and a plurality of half etching blocks  124  and a sidewall block  126 . The void region  122  exposes an upper surface  101   a  of an adhesive layer  101 . The adhesive layer  101  is disposed on the substrate  100 . The metal substrate  12  is disposed on the adhesive layer  101 . The half etching block  124  currently shown in the figure will become the electrically connection portion of the lead frame  120  (i.e. a bonding contact terminal) in the process. The sidewall block  126  of the lead frame may become an external electrical connection terminal in the subsequent process. The lead frame  120  may include more than one half etching block and/or more than one void region, even though only one is shown in the figure. 
     The relative disposing position between the void region and the lead frame or the number thereof described in the embodiment is not intended to limit the scope of this disclosure, and may be adjusted or changed depending on the type of the used chip and device or the package structure. 
     Referring to  FIG. 1B , a first device  20  is disposed on the upper surface  101   a  of the adhesive layer  101  exposed by the void region  122  of the metal substrate  12 . The first device  20  is, for example, a power device such as a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or diode, etc., or a packaged device. At least one device is disposed in each void region  122  of the metal substrate  12 . The size of the void region  122  of the metal substrate  12  is at least larger than the size of the correspondingly carried device or die thereby. The pattern design of the void region  122  may be adjusted according to the device used therein or depending on the requirement of heat dissipating efficiency. 
     Referring to  FIG. 1C , a first filler layer  202  is formed and disposed on the substrate  100 , covering the exposed upper surface  101   a  of the adhesive layer  101  as well as encapsulating the first device  20  and filling up the voids between the first device  20  and the sidewall block  126  of the lead frame  120 . A material of the first filler layer  202  is, for example, an ultraviolet curable polymer, a thermosetting polymer, epoxy resin, polyimide or benzocyclobutene (BCB), and may be formed by molding or lamination. During the molding process, generally a mold is used and at a specific position an encapsulation material is injected into the mold. After curing the encapsulation material by thermal treatment or ultraviolet light irradiation, the filler layer  202  is formed and the mold is removed. For the lamination, a dielectric material layer with a predetermined thickness is directly laminated onto the lead frame  120  and the substrate  100  to form the first filler layer  202 . For example, in one embodiment, the thickness of the first filler layer  202  is roughly equivalent to the thickness of the first device  20 , and the first filler layer  202  at least exposes a bonding pad  201  and a bonding pad  203  of the first device  20 . By equivalent thickness it means that an upper surface  202   a  of the first filler layer  202  is coplanar with an upper surface  20   a  of the first device  20 . For example, in one embodiment, the upper surface  202   a  of the first filler layer  202  is coplanar with an upper surface  124   a  of the half etching block  124 . After curing and forming the filler layer  202 , the substrate  100  may be removed with the mold or after removing the mold. 
     Referring to  FIG. 1D , a conductive adhesive layer  204  is formed on the upper surface  202   a  of the first filler layer  202  and the upper surface  20   a  of the first device  20 . A material of the conductive adhesive layer  204  is, for example, conductive adhesive, silver paste or solder paste, formed by coating, screen printing, or film lamination. The conductive adhesive layer  204  may be formed by plating metal layers at the to-be-contact positions of the first device  20  and a second device  30 . An inter-diffusion may occur between both metal layers after treating with the thermomechanical process, and then an intermetallic compound (IMC) may be formed at the interface to achieve the connection. 
     Referring to  FIG. 1E , the second device  30  is disposed on the conductive adhesive layer  204 , covering a portion of the upper surface  202   a  of the first filler layer  202  and a portion of the bonding pad  203  of the first device  20 . The second device  30  may partially overlap with the first device  20  to expose the wire bonding pads  201  and  301  on the first and second devices  20  and  30 . The electrical connection between the first and second devices  20  and  30  may be achieved via the conductive adhesive layer  204 . The second device  30  is, for example, a power device such as MOSFET, IGBT, diode, or a packaged device. 
     Referring to  FIG. 1F , a plurality of wires  32  and  34  formed by wiring are respectively connected to the first and second devices  20  and  30  as well as to the corresponding half etching block  124  of the lead frame  120 . A first end of the wire  32  is connected to the bonding pad  201  of the first device  20 , and a second end of the wire  32  is connected to the half etching block  124 . A first end of the wire  34  is connected to the bonding pad  301  of the second device  30 , and a second end of the wire  34  is connected to the half etching block  124 . 
     Referring to  FIG. 1G , a conductive block  38  is placed on a contact pad  302  of the second device  30  at an end of the second device  30 . The conductive block  38  may be fabricated by a metal material (such as copper) and connected in the same way for connecting the devices  20  and  30 , which may function as an electrode in the subsequent process. 
     Referring to  FIG. 1H , a second filler layer  310  is formed and disposed on the first filler layer  202 , encapsulating the second device  30 , wires  32  and  34 , conductive block  38  and covering the first device  20  and the first filler layer  202 . The second filler layer  310  fills up the space between the sidewall  126  of the lead frame  120  and the second device  30  as well as the conductive block  38 . The thickness of the second filler layer  310  is roughly equivalent to or slightly less than the thickness of the conductive block  38 , at least exposing a portion of an upper surface  38   a  of the conductive block  38  for electrical connection in the process. By equivalent thickness it means that an upper surface  310   a  of the second filler layer  310  is coplanar with an upper surface  38   a  of the conductive block  38 . For example, in one embodiment, the upper surface  310   a  of the second filler layer  310  is coplanar with an upper surface  126   a  of the sidewall  126  of the lead frame  120 . A material of the second filler layer  310  is, for example, an ultraviolet curable polymer, a thermosetting polymer, epoxy resin, polyimide, or benzocyclobutene (BCB), formed by molding or lamination, depending on the type of the device to be packaged. The first and second filler layers  202  and  310  may be formed of the same material or different materials. The material for forming the first and the second filler layers  202  and  310  may be a dielectric material with a high heat-dissipating efficiency or may further include one or a plurality of additives that enhance heat dissipation, such as boron nitride (BN) particles, silica (SiO 2 ) particles, alumina (Al 2 O 3 ) particles, and etc. 
       FIGS. 2A-2H  illustrate a cross-sectional schematic view of manufacturing processes of a stacked type device module according to another embodiment of the disclosure. 
     Referring to  FIG. 2A , a substrate  22  having an upper surface  22   a  is provided and a first device  20  is disposed on the upper surface  22   a . The substrate  22  may be a metallic substrate formed of a metal such as copper or aluminum alloy. The substrate  22  may also be a printed circuit board or even a ceramic substrate with metallic circuit. The substrate  22  at least includes a void region  222 . The void region  222  may be a hole, recess, or concave. The substrate  22  may include a plurality of patterns, of which some may be continuous or discrete, including at least a metallic block pattern  24  that is used for carrying the first device  20  and also for dissipating heat. An adhesive layer  230  may be selectively formed between the metallic block pattern  24  and the first device  20 . The adhesive layer  230  may be formed of the same material as that of the conductive adhesive layer  204  in the previous embodiment, such as conductive adhesive, silver paste, or solder paste, formed by coating, screen printing, or film lamination. The conductive adhesive layer  204  may be formed by plating metal layers at the to-be-contact positions of the first device  20  and a second device  30 . An inter-diffusion will occur between both metal layers after treating with the thermomechanical process, and then an intermetallic compound (IMC) is formed at the interface to achieve the connection. The first device  20  is, for example, a power device such as MOSFET, IGBT, diode, or etc. in the form of a chip or even a packaged device. 
     In  FIG. 2B , the first filler layer  202  is formed and disposed on the substrate  22 , encapsulating the exposed upper surface  22   a  and covering the first device  20 . The first filler layer may be formed of, for example, an ultraviolet curable polymer, a thermosetting polymer, epoxy resin, polyimide, or benzocyclobutene (BCB), formed by molding or lamination. With regard to the lamination, a dielectric material layer with a predetermined thickness is directly laminated onto the upper surface  22   a  of the substrate  22  and fills up the void region  222  to form the filler layer  202 . For example, in one embodiment, the thickness of the first filler layer  202  is greater than the thickness of the first device  20 . That is, the upper surface  202   a  of the first filler layer  202  may be higher than the upper surface  20   a  of the first device  20 . 
     In  FIG. 2C , an opening forming step is performed to the first filler layer  202 . A first via  206  is formed by drilling from the upper surface  202   a  of the first filler layer  202  downward until the upper surface  20   a  of the first device  20  is exposed. A second via  208  is formed by drilling from the upper surface  202   a  of the first filler layer  202  downward until the upper surface  22   a  of the substrate  22  is exposed. The first and second vias  206  and  208  may be formed at the same time or in turn by using mechanical drilling or laser drilling. 
     For example, when the laser drilling technique is adopted for fabricating the via, parameters such as, laser output power, processing speed and the repetition times of processing may be adjusted, avoiding damages to the underlying material of the opening. The laser via may be intact devoid of forming a protection layer on the pad. 
     In  FIG. 2D , a plating process is performed. A metallic conductive material  214  is plated to cover the upper surface  202   a  of the first filler layer  202  and filled in the first and second vias  206  and  208  to form first and second conductive plugs  216  and  218 . A first circuit pattern  220  is formed on the upper surface  202   a  of the first filler layer  202  through a patterning step. The metallic conductive material  214  is, for example, copper. The first circuit pattern  220  may be a metal circuit pattern for re-distribution and therefore may also be regarded as a re-distribution pattern. 
     Referring to  FIG. 2E , a second device  30  is disposed on a surface of the metallic conductive material  214 . Optionally, an adhesive layer  330  may be formed between the metallic conductive material  214  and the second device  30  by conductive adhesive, silver paste, solder paste, and etc., formed by coating, screen printing, or film lamination. The conductive adhesive layer  204  may be formed by plating metal layers at the to-be-contact positions of the first device  20  and a second device  30 . An inter-diffusion may occur between both metal layers after treating with the thermomechanical process, an intermetallic compound (IMC) is formed at the interface to achieve the connection. The second device  30  is, for example, a power device such as MOSFET, IGBT, diode, or etc., a chip, or even a packaged device. The first device  20  and the second device  30  may have different functions or may be formed of different materials. 
     In  FIG. 2F , a second filler layer  310  is formed and disposed on the substrate  22 , covering the metallic conductive material  214  and the exposed upper surface  202   a  of the first filler layer  202  as well as encapsulating the second device  30 . The second filler layer  310  is formed of, for example, an ultraviolet curable polymer, a thermosetting polymer, epoxy resin, polyimide, or benzocyclobutene (BCB), formed by molding or lamination. For example, in one embodiment, the height of the second filler layer  310  may be greater than the height of the second device  30 . That is, an upper surface  310   a  of the second filler layer  310  may be higher than an upper surface  30   a  of the second device  30 . 
     In  FIG. 2G , another opening forming step is performed to the second filler layer  310 . A third via  306  is formed by drilling from the upper surface  310   a  of the second filler layer  310  downward until the upper surface  30   a  of the second device  30  is exposed. A fourth via  308  is formed by drilling from the upper surface  310   a  of the second filler layer  310  until the metallic conductive material  214  is exposed. The third and fourth vias  306  and  308  may be formed at the same time or in turn by using mechanical drilling or laser drilling. 
     In  FIG. 2H , a plating process is performed. Another metallic conductive material  314  is plated to cover the upper surface  310   a  of the second filler layer  310  and filled in the third and fourth vias  306  and  308  to form third and fourth conductive plugs  316  and  318 . A second circuit pattern  320  is formed on the upper surface  310   a  of the second filler layer  310  through a patterning step. The second circuit pattern  320  may be a metal circuit pattern for re-distribution and therefore may also be regarded as a re-distribution pattern. 
     The relative disposing position between the via/conductive plug(s) and the device or the number thereof as described in the embodiments of the disclosure is exemplary and is not intended to limit the scope of the disclosure. The relative disposing position or the number thereof may be adjusted or changed depending on the type of device used or the design of the actual products. The pattern design of the re-distribution metal pattern may be changed depending on the electrical connection terminal or electrical requirement of the vertically stacked device. The conductive plug described in the embodiments of the disclosure may be a build-up conductive via depending on the size of the via and the filling level of the conductive material, may be formed by plating. 
       FIG. 3  is a schematic cross-sectional view of a stacked type device module in an embodiment of the disclosure. Referring to  FIG. 3 , a semiconductor package module  400  includes a substrate  410 , at least one first device  420 , at least one second device  430 , at least one filler layer  440 , at least one electrode  450 , and a plurality of wires  460 ,  461 . 
     A substrate  410  is designed to have at least one sinking region  412 , at least one platform region  414 , and a sidewall block  416  located at the side for external connection. The substrate  410  may be, for example, a multi-layer printed circuit board or a laminated circuit board, which is fabricated via laminating metal boards with dielectric layers, and the substrate  410  may further include an internal circuit and a metallic conductive plug or a through via. 
     Referring to  FIG. 3 , a first device  420  is disposed on an upper surface  412   a  of the sinking region  412  of the substrate  410 . A second device  430  is disposed on an upper surface  420   a  of the first device  420  and covers a portion of an upper surface  414   a  of the platform region  414 . The electrode  450  is disposed on an upper surface  430   a  of the second device  430 . The filler layer  440  covers over the substrate  410  and fills up the space between the device and the sidewall block  416  and also encapsulates the wires  460 ,  461 . Although the electrode  450  is located on the upper surface  430   a  of the second device  430 , at least one portion of an upper surface of the electrode  450  is exposed from the filler layer  440  for external connection. In one embodiment, all of an upper surface of the electrode  450  is exposed from the filler layer  440  for external connection. The electrode  450  may also be a part of the metal pattern or the circuit pattern and the shape of the electrode  450  varies depending on the design of the products. 
     Referring to  FIG. 3 , the second device  430  partially, instead of completely, overlaps with the first device  420  to expose the wire bonding pads  421  and  431  on the first and second devices. The depth of the sinking region  412  is roughly equivalent to the thickness of the first device  420  so that the second device  430  stacked on the first device  420  may partially rest on the platform region  414  without inclination. A plurality of wires  460 ,  461  respectively connect the first and second devices  420  and  430  to the corresponding sinking region  412  and the platform region  414  of the substrate  410 . A first end of the wire  460  is connected to the wire bonding pad  421  of the first device  420 , and a second end of the wire  460  is connected to the sinking region  412 . A first end of the wire  461  is connected to the wire bonding pad  431  of the second device  430 , and a second end of the wire  461  is connected to a half etching block of the platform region  414 . 
     In the embodiment, the functions of the sinking region  412 , the platform region  414  and the block  416  of the substrate  410  in  FIG. 3  approximately are similar to that the functions of the void region  122 , the half etching block  124 , and the sidewall block  126  of the lead frame  120  in  FIG. 1A . 
     The electrical connection between the first device  420  and second device  430  and between first device  420  and sinking region  412  may be achieved via the conductive adhesive layers  470  and  425 . The conductive adhesive layers  425  and  470  are formed of, for example, silver paste or other appropriate adhesives. The first and second devices  420  and  430  may independently and respectively be a power device such as MOSFET, IGBT, diode, or a packaged device. The first device  420  and second device  430  may have different functions or may be formed of different materials. The wire  460 / 461  is, for example, a gold wire, copper wire, or aluminum wire. The electrical connection between the first and second devices  420  and  430  may be achieved via solid liquid inter-diffusion (SLID) technique, for example. The SLID technique is to form metal layers respectively on the contact surfaces of both devices and perform the thermomechanical treatment to cause inter-diffusion between the contact surfaces. The metal layer(s) may include elements such as copper, nickel, tin, silver, gold, titanium, and etc. 
     The filler layer  440  is formed of, for example, an ultraviolet curable polymer, a thermosetting polymer, epoxy resin, ajinomoto built-up film (ABF film), polyimide, or benzocyclobutene (BCB), by molding or lamination, depending on the type of the device to be packaged. The material of the filler layer may be a dielectric material with high heat-dissipating efficiency or may further include additives that enhance heat dissipation. 
     The substrate  410  shown in  FIG. 3  further includes an external contact surface  418  located at the bottom layer of the substrate  410 . A filler material  415  and one or more through vias  417  are disposed between the external contact surface  418  and the sinking region  412  for electrical connection and heat dissipation. The first and second devices  420  and  430  are, for example, power devices. The electrode  450  as an emitter and the sidewall block  416  as a gate may be located at the same side, while the external contact surface  418  as a collector may be located at the opposite side. 
       FIG. 4A  is a schematic cross-sectional view of a stacked type device module in another embodiment of the disclosure.  FIG. 4B  is a schematic top view of an exemplary stacked type device module of the disclosure. 
     Referring to  FIG. 4A , according to another embodiment of the disclosure, the difference between a semiconductor package module  500  and the semiconductor package module  400  as shown  FIG. 3  lies in that all the circuits are connected by plating through vias without involving any wiring process. The semiconductor package module  500  includes a substrate  510 , at least one first device  520 , at least one second device  530 , at least one filler layer  540 , a plurality of conductive plugs  550 , and at least one circuit pattern  560 . 
     Referring to  FIG. 4A , the substrate  510  and the substrate  410  as shown  FIG. 3  are similarly designed, having at least one sinking region  512  and at least one platform region  514 . The substrate  510  is, for example, a multi-layer printed circuit board or a laminated circuit board which may be fabricated via laminating metal boards with dielectric layers, and may further include an internal circuit and metallic conductive plugs or through vias. The design of the sidewall may be omitted from the substrate  510  as the connection can be achieved via the conductive plugs. 
     Referring to  FIG. 4A , a first device  520  is disposed on the sinking region  512  of the substrate  510 , and a second device  530  is disposed on the first device  520 , covering a portion of an upper surface  514   a  of the platform region  514 . The filler layer  540  covers over the substrate  510  and encapsulates the first and second devices  520  and  530 . The first device  520  and the substrate  510  as well as the  520 / 530  may be connected by using the conductive adhesive layers  515  and  570 . The conductive adhesive layers  515  and  570  may be formed of, for example, solder paste or silver paste. Alternatively, the connection technique such as a solid liquid inter-diffusion (SLID) technique may also be used to achieve the electrical connection there-between. 
     Referring to  FIG. 4B , the second device  530  partially, instead of completely, overlaps with the first device  520  to expose contact pads  521  and  531  on the first and second devices  520  and  530 . The depth of the sinking region  512  may be equivalent to the thickness of the first device  520  so that the second device  530  disposed on the first device  520  may partially rest on the platform region  514  without inclination. 
     The circuit pattern  560  includes a central circuit pattern  562  as an emitter terminal and a gate contact terminal  564  in the periphery of the circuit pattern. The central circuit pattern  562  may be connected to the second device  530  via a plurality of conductive plugs  552 . The contact pads  521  and  531  on the first and second devices are electrically connected to the gate contact terminal  564  via the conductive plugs  556  and  554 . Since the first and second devices  520  and  530  may be vertically stacked, the length (depth) of the conductive plug  556  may be greater than that of the conductive plugs  554  and  552 . In one embodiment, through the conductive plugs  550  and the circuit pattern  560 , the electrodes of the first and second devices  520  and  530  are connected to the corresponding external connection terminals. The substrate  510  shown in  FIG. 4A  further includes an external contact surface  518  located at the bottom-most layer of the substrate  510 . Take a power device as an example, the circuit pattern  562  as an emitter and the gate contact terminal  564  as a gate are at the same side, while the external contact surface  518  as a collector is located at the opposite side. 
     Depending on the products, the outer-most portion of the circuit pattern may be used as a heat-dissipating structure through pattern design to enhance heat-dissipating efficiency. 
     The electrical connection between the first and second devices  520  and  530  may be achieved via the conductive adhesive layer  570 . The conductive adhesive layer  570  is formed of, for example, solder paste or silver paste. Connection techniques such as SLID technique may be used to complete electrical connection between the two devices. The first and second devices  520  and  530  may independently and respectively be a power device such as MOSFET, IGBT, or diode etc., or a chip, or a packaged device. The first device  520  and the second device  530  may have different functions or may be formed of different materials. The first device  520  and the second device  530  may be a semiconductor chip such as a transistor, a radio-frequency (RF) chip, or a light emitting diode (LED). The conductive plug  550  is formed of, for example, copper or copper alloys. 
     In the embodiments of the disclosure, in order to integrate one or more devices, a lead frame with at least a void region and a half etching block as well as a substrate with a sinking region and a platform region are provided for embedding devices, to reduce the overall size or volume of the package and promote electrical transmission. 
     In the embodiments of the disclosure, the connection between the device and substrate as well as the connection between the devices may be achieved by using conductive materials (such as solder paste, silver paste, and etc.) or other connection techniques (such as SLID technique and etc.). 
     In the embodiments of the disclosure, redistribution and fanning out the electrode contacts may be achieved by laminating dielectric layers and metal patterns (build-up layers). By using the laser drilling technique to fabricate a via, intact via openings are obtained and there is no need to fabricate a protection layer over the contact pad. Also, a plating process may be used to fill the via opened to form the conductive plug (such as copper or its alloy) therein. Upon the completion of the electrical connection, an intermetallic compound (IMC) may be formed between the conductive plug and the joint point following the subsequent thermal treatment process, which enhances long term reliability. 
     When the module is operated under a heavy current mode, a heat-dissipating structure or module may be required. The design of the disclosure may incorporate the heat-dissipating module. Since the dielectric layer or the filler material encapsulates and protects the device(s), the module of the disclosure may have better heat-conducting efficiency than the module using wire bonding. 
     Although the disclosure has been disclosed by the above embodiments, the embodiments are not intended to limit the disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosure without departing from the scope or spirit of the disclosure. Therefore, the protecting range of the disclosure falls in the appended claims.