Patent Publication Number: US-2003227731-A1

Title: Surface mountable laminated circuit protection device

Description:
BACKGROUND OF THE INVENTION  
       [0001] The invention relates to a surface mountable laminated circuit protection device, more particularly to a surface mountable laminated circuit protection device with the characteristics of a positive temperature coefficient (PTC) thermal sensitive resistor.  
       [0002] PTC devices have been extensively used in the fields of temperature detection, safety control, temperature compensation, etc. In the past, a thermal sensitive resistance device primarily used ceramic as materials. However, ceramic needed to be manufactured at a higher temperature, usually higher than 900 degree centigrade. Much energy had to be consumed, and the process was more complex. A polymeric thermal sensitive resistance device was developed later. The manufacturing temperature of the polymeric thermal sensitive resistance device is below 300 degree centigrade, processing and molding are easier, less energy is consumed, process is easy, and costs are cheaper, and thus the application fields are becoming more extensive.  
       [0003] The conventional PTC circuit protection device can be made by using polymeric composite materials filled by conductive fillers. The polymeric composite material filled by the conductive fillers has the PTC characteristics, and it is in the low-resistance state at room temperature. When the current through the polymeric composite material is too large, causing the temperature of the polymeric composite material to reach a certain switching temperature, the resistance of the polymeric composite material filled by the conductive filler would rise rapidly to avoid critical components of a circuit being burned down. Therefore, it can be applied in the current overloading protection device and the design of the temperature switching device. This is due to the fact that the conductive filling particles in the polymeric composite material filled by the conductive filler are at the conducting state of connecting to each other at room temperature. When the temperature rises above the switching temperature, the volume of the resin material in the polymeric composite material expands, causing conductive filling particles in the polymeric composite material to transform from the state of connecting to each other to expand to break to become an discontinuous state so as to cause the resistance of the PTC circuit protection device to rise rapidly to cut off the current, thereby achieving the objectives of current overloading protection and temperature-controlled switch.  
       [0004] The conventional PTC laminated structure uses the conductive composite material component with a top layer and a bottom layer metal foils and an intermediate layer with the PTC characteristics. It arranges with a lateral conductive mechanism and an insulating material to electrically conduct the top layer and bottom layer metal electrodes of the conductive composite material component with the PTC characteristics to another plane to make the surface mountable circuit protection device.  
       [0005] The aforementioned prior art techniques use the conductance between the first electrode and second electrode to make the surface mountable polymeric circuit protection device. The difference between them resides in that the former uses a plated through hole to conduct and that the later uses the lateral conductive layer to make the conductive mechanism to conduct. No matter whether the plated through hole or the lateral conductive layer is used, the expansion of the conductive composite material with the PTC characteristics is limited as the temperature rises such that the conductive composite material sometimes cannot discontinuous characteristics be fully expanded and the optimum breakdown property cannot be achieved.  
       [0006] These techniques mainly adopt the metal foils and the conductive composite material components with the PTC characteristics. The PTC laminated structure is formed after the thermal laminating, then electroplating, etching, plated through hole, and dipping electroplating processes are conducted. First of all, the metal foils, the conductive composite material component with PTC characteristics, and the PTC laminated structure formed by thermal laminating metal foils have insufficient mechanical strength, and are prone to wrapping to deform during the above processes. After circuits are made, thermal laminating of other PTC laminated structures, the insulation reinforcement material or the metal electrode to form multiple-layer PTC laminated structure will cause the problem of how to align top and bottom layers accurately. When the metal foil and conductive composite material with the PTC characteristics are processed, because of the material is flexible so the shortcomings of possible wrapping during the processing, deformation, poor dimension stability, and uneasy processing are more likely to occur.  
       [0007] Secondly, how to design a surface mountable laminated circuit protection device to make the conductive composite material components with the PTC characteristics have the parallel connecting effect, thereby causing the surface mountable laminated circuit protection device to have more extensive application fields, is one of the industrial needs when solving these manufacturing and processing issues.  
       THE OBJECTIVE OF THE INVENTION  
       [0008] One main objective of the present invention is to provide a surface mountable laminated circuit protection device, using the conductive composite material component itself with the PTC characteristics along with the top layer electrode, the bottom layer electrode, and the lateral insulating material between electrodes to make the surface mountable polymeric circuit protection device without using the conductive mechanism between top layer and bottom layer electrodes.  
       [0009] The other objective of the present invention is to provide a surface mountable laminated circuit protection device to make the conductive composite material component with the PTC characteristics is expanded ed sufficiently due to the increased temperature so as to expand to break completely to become a discontinuous state, thereby allowing the conductive composite material component with the PTC characteristics to have an optimum break down characteristics property during the current overloading.  
       [0010] Another objective of the present invention is to provide a surface mountable laminated circuit protection device. The surface mountable laminated circuit protection device adopts double-sided metal foil clad substrate as the foundation during the structural manufacturing process, then use the mature process of the current printed circuit board so as to make the processing and manufacturing of the laminated circuit protection device easier.  
       [0011] Another objective of the present invention is to provide a surface mountable laminated circuit protection device in order to obtain better structural strength and dimension stability.  
       [0012] Another objective of the present invention is to provide a surface mountable laminated circuit protection device in order to be further developed into a parallel surface mountable laminated circuit protection device.  
       SUMMARY OF THE INVENTION  
       [0013] In order to achieve the above objectives of the invention, the present invention provides a surface mountable laminated circuit protection device, and it comprises a first portion of a first conductive electrode, a second portion of a first conductive electrode, a conductive first composite material component with the PTC characteristics, and a first conductive layer. Where in the first portion of the first conductive electrode and the second portion of the first conductive electrode are separated by a first isolation trench. The conductive first composite material component with PTC characteristics is provided above the first portion of the first conductive electrode and the second portion of the first conductive electrode. And the thickness of the conductive first composite material component with the PTC characteristics is smaller than the width of the first isolation trench. The first conductive layer is provided above the conductive first composite material component with the PTC characteristics, causing most currents flowing from the first portion of the first conductive electrode to the first conductive layer through the conductive first composite material component with the PTC characteristics, then flowing to the second portion of the first conductive electrode through the conductive first composite material component with the PTC characteristics.  
       [0014] Based upon the above description, the present invention provides a surface mountable laminated circuit protection device, in which most currents flow from the first portion of the first conductive electrode to the first conductive layer through the conductive first composite material component with the PTC characteristics, then flow to the second element of the first conductive electrode through the conductive first composite material component with the PTC characteristics. There are not any plated through holes or lateral conductive layers between the first conductive layer and the first portion of the first conductive electrode or between the first conductive layer and the second portion of the first conductive electrode such that the conductive first composite material component with the PTC characteristics can fully expand due to the increased temperature to expand to break completely to become an discontinuous state, thereby allowing the surface mountable laminated circuit protection device to have characteristics an optimum break down property during the current overloading.  
       [0015] In addition, the present invention can further provide a reinforcement insulating layer above the first conductive layer, and provide a second conductive layer above the reinforcement insulating layer. The first conductive layer, the reinforcement insulating layer, and the second conductive layer can be replaced by the double-sided metal foil clad substrate, and the mature process of the current printed circuit board can be used such that the processing and manufacturing of the surface mountable laminated circuit protection device are easier.  
       [0016] Furthermore, adopting the double-sided metal foil clad substrate as the foundation to manufacture, hardness and strength is superior, thereby having better structural strength and dimension stability.  
       [0017] Furthermore, the present invention can be further developed such that the conductive second composite material component with the PTC characteristics can be provided above the second conductive layer and the first portion of the second conductive electrode and the second portion of the second conductive electrode can be provided above the conductive second composite material component with the PTC characteristics. The first portion of the second conductive electrode and the second portion of the second conductive electrode are separated by a second isolation trench. The first portion of the second conductive electrode electrically conducts the first portion of the first conductive electrode by using a first conductive mechanism, and the second portion of the second conductive electrode electrically conducts the second portion of the first conductive electrode by using a second conductive mechanism, but the first conductive mechanism and the second conductive mechanism do not physically contact the first conductive layer and the second conductive layer.  
       [0018] The current can further flow to the second portion of the first conductive electrode through the first element of the first conductive electrode, the first conductive mechanism, the first portion of the second conductive electrode, the conductive second composite material component with the PTC characteristics, and the second conductive layer, then through the conductive second composite material component with the PTC characteristics, the second portion of the second conductive electrode, the second conductive mechanism; or the current can further flow to the second portion of the first conductive electrode to be electrically turned on through the first portion of the first conductive electrode, the conductive first composite material component with the PTC characteristics, and the first conductive layer, then through conductive first composite material component with the PTC characteristics. Therefore, the present invention can realize the parallel surface mountable laminated circuit protection device, and have more extensive applications.  
       [0019] The features and other effects of the present invention are described with the following embodiments. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020]FIG. 1 is the elements decomposing figure of the circuit protection device of the first embodiment of the present invention;  
     [0021]FIG. 2 is the design example of a first conductive electrode layer and a second conductive electrode layer being a cross-shaped interleaving pattern;  
     [0022]FIG. 3 is the design example of a first conductive electrode layer and a second conductive electrode layer being a z-shaped interleaving pattern;  
     [0023]FIG. 4 is the design example of a first conductive electrode layer and a second conductive electrode layer being an s-shaped interleaving pattern;  
     [0024]FIG. 5 is the circuit protection device of the second embodiment of the present invention;  
     [0025]FIG. 6 is the circuit protection device of the third embodiment of the present invention;  
     [0026]FIG. 7 is the circuit protection device of the fourth embodiment of the present invention; and  
     [0027]FIG. 8 is the circuit protection device of the fifth embodiment of the present invention.  
                               Reference Numerals of Major Parts in the Drawings:                                         10   laminated circuit protection device of the first embodiment of the           present invention        11   second conductive electrode layer        11A   first portion of the second conductive electrode layer        11B   second portion of the second conductive electrode layer        12   first conductive electrode layer        12A   first portion of the first conductive electrode layer        12B   second portion of the first conductive electrode layer        13   first conductive composite material component with the PTC           characteristics        14   top insulating layer        15   bottom insulating layer        17   first isolation trench        19   second isolation trench        21   third-terminal electrode        22   fourth-terminal electrode        23   first-terminal electrode        24   second-terminal electrode        30   laminated circuit protection device of the second embodiment of           the present invention        31   first conductive layer        32   second conductive layer        33   first conductive electrode layer        33A   first portion of the first conductive electrode layer        33B   second portion of the first conductive electrode layer        34   first conductive composite material component with the PTC           characteristics        35   reinforcement insulating layer        36   composite electroplating layer        37   bottom insulating layer        38   top insulating layer        41   first-terminal electrode        42   second-terminal electrode        50   laminated circuit protection device of the third embodiment of the           present invention        51   first conductive layer        52   second conductive layer        53   reinforcement insulating layer        54   first conductive electrode layer        54A   first portion of the first conductive electrode layer        54B   second portion of the first conductive electrode layer        55   upper-most layer metal electrode layer        55A   first portion of the upper-most layer metal electrode layer        55B   second portion of the upper-most layer metal electrode layer        56   first conductive composite material component with the PTC           characteristics        57   second conductive composite material component with the PTC           characteristics        58   bottom insulating layer        59   upper-most layer metal electrode layer first insulating layer        61   first-terminal electrode        62   second-terminal electrode        63   third-terminal electrode        64   fourth-terminal electrode       100   laminated circuit protection device of the fourth embodiment of the           present invention       101   first conductive layer       102   second conductive layer       102A   first portion of the first conductive layer       102B   second portion of the first conductive layer       103   reinforcement insulating layer       111   first conductive composite material component with the PTC           characteristics       112   first conductive electrode layer       112A   first portion of the first conductive electrode layer       112B   second portion of the first conductive electrode layer       113   first conductive mechanism       114   second conductive mechanism       120   laminated circuit protection device of the fifth embodiment of the           present invention       121   first conductive layer       122   second conductive layer       123   reinforcement insulating layer       124   first conductive composite material component with the PTC           characteristics       125   second conductive composite material component with the PTC           characteristics       126   first conductive electrode layer       126A   first portion of the first conductive electrode layer       126B   second portion of the first conductive electrode layer       127   second conductive electrode layer       127A   first portion of the second conductive electrode layer       127B   second portion of the second conductive electrode layer       129   first conductive mechanism       130   second conductive mechanism       131   bottom insulating layer       132   top insulating layer       133   first-terminal electrode       134   second-terminal electrode       135   third-terminal electrode       136   fourth-terminal electrode       141   top insulating layer       142   bottom insulating layer       151   third-terminal electrode       152   fourth-terminal electrode       153   first-terminal electrode       154   second-terminal electrode                  
 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0028] First Embodiment:  
     [0029] Please refer to FIG. 1, the surface mountable laminated circuit protection device of the first embodiment of the present invention, and it comprises a first-terminal electrode  23 , a second-terminal electrode  24 , and a bottom insulating layer  15  on the first layer location according to a bottom-up order. Going one layer up is a first conductive electrode layer  12 , and it can be further divided as a first portion  12 A of a first conductive electrode layer and a second portion  12 B of a first conductive electrode layer. Going further up are a conductive first composite material component  13  with a PTC characteristics, and a second conductive electrode layer  11 , which is further divided into a first portion  11 A of a second conductive electrode layer and a second portion  11 B of a second conductive electrode layer. Going further up are a third-terminal electrode  21 , a fourth-terminal electrode  22 , and a top insulating layer  14 .  
     [0030] The first portion  12 A of the first conductive electrode layer and the second portion  12 B of the first conductive electrode layer are separated by a first isolation trench  19 . The conductive first composite material component  13  with the PTC characteristics is provided above the first portion  12 A of the first conductive electrode layer and the second portion  12 B of the first conductive electrode. The thickness of the conductive first composite material component  13  with the PTC characteristics is smaller than the smallest width of the first isolation trench  19 . And the first portion  11 A of the second conductive electrode layer and the second portion  11 B of the second conductive electrode layer are separated by a second isolation trench  17 . And the conductive first composite material component  13  with the PTC characteristics is provided below the first portion  11 A of the second conductive electrode layer and the second portion  11 B of the first conductive electrode. And the thickness of the conductive first composite material component  13  with the PTC characteristics is smaller than the smallest width of the second isolation trench  17 .  
     [0031] Or, the smallest distance between the first portion  12 A of the first conductive electrode and the first portion  11 A of the second conductive electrode, the smallest distance between the first portion  12 A of the first conductive electrode and the second portion  11 B of the second conductive electrode, the smallest distance between the second portion  12 B of the first conductive electrode and the first portion  11 A of the second conductive electrode, and the smallest distance between the second portion  12 B of the first conductive electrode and the second portion  11 B of the second conductive electrode are all less than the smallest distance between the first portion  12 A of the first conductive electrode and the second portion  12 B of the first conductive electrode and the smallest distance between the first portion  11 A of the second conductive electrode and the second portion  11 B of the second conductive electrode.  
     [0032] The first conductive electrode layer  12  is provided below the conductive first composite material component  13  with the PTC characteristics, causing most currents to flow from the first portion  12 A of the first conductive electrode to the first portion  11 A of the second conductive electrode and the second portion  11 B of the second conductive electrode respectively through the conductive first composite material component  13  with the PTC characteristics, then flow to the second portion  12 B of the first conductive electrode through the conductive first composite material component  13  with the PTC characteristics.  
     [0033] The conductive first composite material component  13  with the PTC characteristics in this embodiment is a carbon black filled conductive crystalline polymeric composite material. And the crystalline polymeric material can be polyethylene, polypropylene, and polyvinyl fluoride and its co-polymers. Carbon black uses carbon black Raven 450 (a product of U.S. Columbian Corporation). In this embodiment, carbon black and crystalline polymeric composite material with the weight ratio of 1 to 1 are mixed with a brabender mixer at 210 degree centigrade for eight minutes, and are thermally molded with a heated press at 175 degree centigrade to form plate-shaped conductive composite laminated material with the PTC characteristics and a thickness of about 0.5 mm.  
     [0034] The conductive metal foils, such as nickel foil, copper foil, and their alloy, can be the first conductive electrode layer  12  and the second conductive electrode layer  11 . In this embodiment, nickel electroplated copper foil is used.  
     [0035] As for insulating layers  14  and  15 , materials with the insulating effect can be used. Normally, insulating solder mask is used.  
     [0036] In the above embodiment, a first portion  11 A of the second conductive electrode and a second portion  11 B of the second conductive electrode above, and the first portion  12 A of the first conductive electrode and the second portion  12 B of the first conductive electrode below can use the cross-shaped, z-shaped, and s-shaped interleaving patterns as shown in FIG. 2, FIG. 3, and FIG. 4, or similar pattern designs to make circuits more variable so as to adjust the resistance value.  
     [0037] Second Embodiment:  
     [0038] Please refer to FIG. 5, the second embodiment of the surface mountable laminated circuit protection device of the present invention, which comprises a first-terminal electrode  41 , a second-terminal electrode  42 , and a bottom insulating layer  37 , a first portion  33 A of a first conductive electrode, a second portion  33 B of a first conductive electrode, a conductive first composite material component  34  with a PTC characteristics, a first conductive layer  31 , a reinforcement insulating layer  35 , a second conductive layer  32 , and a top insulating layer  38  according to a bottom-up order.  
     [0039] The first portion  33 A of the first conductive electrode and the second portion  33 B of the first conductive electrode are separated by a first isolation trench (unmarked). The conductive first composite material component  34  with the PTC characteristics is provided above the first portion  33 A of the first conductive electrode and the second portion  33 B of the first conductive electrode. And the thickness of the conductive first composite material component  34  with the PTC characteristics is smaller than the width of the first isolation trench.  
     [0040] Or, the distance between the first portion  33 A of the first conductive electrode and the first conductive layer  31 , and the distance between the second portion  33 B of the first conductive electrode and the first conductive layer  31  are both smaller than the smallest distance between the first portion  33 A of the first conductive electrode and the second portion  33 B of the first conductive electrode.  
     [0041] The first conductive layer  31  is provided above the conductive first composite material component  34  with the PTC characteristics for such that the most currents flow to the first conductive layer  31  from the first portion  33 A of the first conductive electrode through the conductive first composite material component  34  with the PTC characteristics, then to the second portion  33 B of the first conductive electrode through the conductive first composite material component  34  with the PTC characteristics.  
     [0042] The first conductive layer  31 , the reinforcement insulating layer  35 , and the second conductive layer  32  can use a double-side metal foil substrate like the approximate 35 μm-thick double-side metal foil substrate in the present invention, such that the present invention can use the mature process of the current printed circuit board to make the processing and manufacturing of the circuit protection device easier.  
     [0043] In this embodiment, the conductive first composite material component  34  with the PTC characteristics is a carbon black filled conductive crystalline polymeric composite material. The crystalline polymeric material can be polyethylene, polypropylene, and polyvinyl fluoride and its co-polymers. Carbon black uses carbon black Raven 450 (a product of U.S. Columbian Corporation). In this embodiment, carbon black and crystalline polymeric composite material with the weight ratio of 1 to 1 are mixed with a brabender mixer at 210 degree centigrade for eight minutes, and are thermally molded with a heated press to the plate-shaped conductive composite material with the PTC characteristics and a thickness of about 0.5 mm.  
     [0044] The combining of the first conductive layer  31  and the conductive first composite material component  34  with the PTC characteristics can use carbon black composite electroplating process such that the composite electroplating layer  36  of the continuous porous structure with carbon black and metal is formed between the conductive first composite material component  34  with the PTC characteristics and the first conductive layer  31 . Good connections with the lower interface resistance between the metal electrode and the conductive composite material with the PTC characteristics can be formed by using this continuous porous structure.  
     [0045] As for insulating layers  37  and  38 , materials with the insulating effect can be used. Normally, insulating solder mask can be used.  
     [0046] Third Embodiment:  
     [0047] Please refer to FIG. 6, the third embodiment of the present invention.  
     [0048] The third embodiment symmetrically stacks two protection devices of the second embodiment, and further comprises a third-terminal electrode  63 , a fourth-terminal electrode  64 , a top insulating layer  59 , a first portion  55 A of the second conductive electrode, a second portion  55 B of the second conductive electrode, and the conductive second composite material component  57  with the PTC characteristics (but the top insulating layer  38 , which is the top insulating layer  38  of FIG. 5, is not added). And the double-sided metal foil clad substrate portion (including the first conductive layer  51 , the reinforcement insulating layer  53 , and the second conductive layer  52  portions) in between can be shared.  
     [0049] The formed laminated circuit protection device  50  can increase structural symmetry, have better structural strength, have better dimension stability, and are convenient in use.  
     [0050] Fourth Embodiment:  
     [0051] Please refer to FIG. 7, the fourth embodiment of the present invention, derived from the second embodiment (FIG. 5), but in which the second conductive layer  102  of the double-side metal foil is divided into two portions of a first portion  102 A of the second conductive layer and a second portion  102 B of the second conductive layer, and it is separated by a second isolation trench (unmarked).  
     [0052] The first portion  102 A of the second conductive layer electrically conducts the first portion  112 A of the first conductive electrode with a first conductive mechanism  113 . And the second portion  102 B of the second conductive layer electrically conducts the second portion  112 B of the first conductive electrode with a second conductive mechanism  114 . Furthermore, the first conductive mechanism  113  and the second conductive mechanism  114  do not physically contact the first conductive layer  101 .  
     [0053] Similarly, a first-terminal electrode  153 , a second-terminal electrode  154 , a third-terminal electrode  151  and a fourth-terminal electrode  152  can be provided respectively above the first portion of the first conductive electrode, the second portion of the first conductive electrode, the first portion of the second conductive electrode, and the second portion of the second conductive electrode. Insulating layers  141  and  142  can be provided between the terminal electrodes.  
     [0054] In this embodiment, the first conductive mechanism  113  and the second conductive mechanism  114  can use the conventional method of plated through holes.  
     [0055] Fifth Embodiment:  
     [0056] Please refer to FIG. 8, the fifth embodiment of the present invention.  
     [0057] This embodiment is derived from the design of the above third embodiment (FIG. 6), and further comprises a first conductive mechanism  129  and a second conductive mechanism  130 . The first portion  127 A of the second conductive electrode electrically conducts the first portion  126 A of the first conductive electrode with a first conductive mechanism  129 , and the second portion  127 B of the second conductive electrode electrically conducts the second portion  126 B of the first conductive electrode with a second conductive mechanism  130 . And the first conductive mechanism  129  and the second conductive mechanism  130  do not physically contact the first conductive layer  121  and the second conductive layer  122 .  
     [0058] The current can flow to the second portion  126 B of the first conductive electrode through the first portion  126 A of the first conductive electrode, the first conductive mechanism  129 , the first portion  127 A of the second conductive electrode, the conductive second composite material component  125  with the PTC characteristics, the second conductive layer  122 , then through the conductive second composite material component  125  with the PTC characteristics, the second portion  127 B of the second conductive electrode, and the second conductive mechanism  130 ; or flows to second portion  126 B of the first conductive electrode to be electrically conducting through the first portion  126 A of the first conductive electrode, the conductive first composite material component  124  with the PTC characteristics, and the first conductive layer  121 , then through the conductive first composite material component  124  with the PTC characteristics. Therefore, the parallel connecting surface mountable laminated circuit protection device can have more extensive applications.  
     [0059] Similarly, in this embodiment, the first conductive mechanism  129  and the second conductive mechanism  130  uses the conventional method of plated through holes.  
     [0060] Based upon the above description, the provided surface mountable laminated circuit protection devices of the first embodiment, the second embodiment, and the third embodiment of the present invention use the conductive composite material component with the PTC characteristics itself along with the top layer and bottom layer electrodes, and the insulating materials between electrodes to be able to make the surface mountable polymeric circuit protection device without using the conductive mechanism between the top layer and the bottom layer electrodes, such that the conductive composite material component with the PTC characteristics can fully expand due to the increased temperature to expand to break completely to reach a discontinuous state, thereby causing the conductive composite material component with the PTC characteristics to have the optimum break down characteristics during the current overloading, when the current overloads.  
     [0061] Since the first conductive layer, the reinforcement insulating layer and the second conductive layer of the present invention can use the existing double-sided metal foil clad substrate as the foundation, and can use the mature process of the current printed circuit board during the structural manufacturing, thereby making the processing and manufacturing of the laminated circuit protection device easier and having better structural strength and dimension stability.  
     [0062] What needs to be explained is, although the fourth embodiment and the fifth embodiment still use the method of plated through holes such that the conductive composite material with the PTC characteristics cannot fully expand due to the increased temperature to expand to break completely to become a discontinuous state during their applications like the first embodiment, the second embodiment, and the third embodiment, but they can use the mature process of the current printed circuit board to make the processing and manufacturing of the surface mountable laminated circuit protection device easier. In addition, they adopt the double-sided metal foil clad substrate as the foundation to manufacture, hardness and strength are superior, thereby having the advantages of better structural strength and dimension stability.  
     [0063] Although the present invention is described using the above embodiments, it does not mean that the scope of the present invention is limited to the above description. Persons skilled in the art can make all kinds of modifications, for example, changing the selected polymeric material, introducing different conductive particles, changing electroplating conditions, changing constituent weight ratio, increasing the numbers of layers, increasing the turn-on modes of different internal circuits, or using different pattern designs of the isolation trench on the metal layers to achieve the same effects. However, these modifications shall not deviate from the spirit of the present invention, and they still belong to the protective scope of the present invention. The protective scope of the present invention shall be limited to the description of the claims.