Abstract:
The present invention generally provides a novel method for manufacturing an electronic module with crossed conducting lines and a novel electronic module with crossed conducting lines. In particular, an aspect of the present invention is to provide a thin, single layer electronic module. It is also an object of the present invention to provide an electronic module with an embedded jumper element having reliable high quality connections and contacts. To achieve at least some of the aspects of the present invention, an embedded pre-fabricated jumper module is placed inside a printed circuit board which allows the crossing of conducting lines within the module without manufacturing additional layers over the whole PCB board. The resultant PCB will have improved contacts and will not have surface deformation.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to a printed circuit board (PCB) or semiconductor package substrate and a method for allowing local crossing of conductor lines in a PCB or semiconductor package structure. The novel invention is particularly useful in single layer PCB&#39;s or semiconductor package structures where a local crossing of conductors may be useful, A single layer application where a conductor crossing must be used is, for instance, an RF antenna module or in a memory card. 
         [0002]    When designing a PCB it is advantageous to layout conductor lines so that they do not cross. However, there are certain instances where the crossing of conductor lines is either preferable or unavoidable. While there are several known methods of crossing conductor lines, they each have their own distinct disadvantages. 
         [0003]    In US publication US 2002/0135058 there is presented a component built-in module which includes a plurality of wiring patterns in a plurality of layers that are laminated with an electric insulation layer interposed between. Such a module is relatively thick and requires a large number of manufacture steps. Additionally, there is a substantial amount of unutilized space in the multiple layers if a small amount of crossings are present. 
         [0004]    In many applications it is preferable to have a printed circuit board with a single layer. This results in PCBs that are easier to manufacture and thinner overall. In order to accommodate conductor line crossing there are normally jumpers attached on top of the PCB. 
         [0005]    U.S. Pat. No. 6,665,193 presents an electronic circuit arrangement wherein an electronic jumper is connected to a substrate including two contacts spaced apart substantially a predetermined distance. The electronic jumper is placed on a surface of the substrate. There are several drawbacks to such a jumper. First, the resultant module is no longer fiat which can make its incorporation in to a system difficult. Second, the contact between the jumper, PCB and conductor lines is not optimal since it is often soldered or chemically adhered. 
         [0006]    Japanese patent publication JP 04-221879 describes a jumper on a printed circuit board which attempts to overcome the first problem mentioned above. By providing a concaved surface or a complex shape on the surface of the PCB, a jumper can be affixed without leaving a protrusion. While this overcomes one of the deficiencies in U.S. Pat. No. 6,665,193, it requires more complex manufacturing and still does not address the less than optimal contact of the jumper. 
         [0007]    Herein will be described a novel electronic module and method for making which overcomes the deficiencies of the prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    Generally, the present invention provides a novel method for manufacturing an electronic module with crossed conducting lines. Additionally, the present invention provides a novel electronic module with crossed conducting lines. 
         [0009]    In particular, an aspect of the present invention is to provide a thin, single layer electronic module. It is also an object of the present invention to provide an electronic module with an embedded jumper element having reliable high quality connections and contacts. 
         [0010]    To achieve at least some of the aspects of the present invention, an embedded pre-fabricated jumper module is described herein. The pre-fabricated jumper is placed inside a printed circuit board which allows the crossing of conducting lines within the module without manufacturing additional layers over the whole PCB board. The resultant PCB will have improved contacts over the prior art and will not have surface deformation like the prior art. 
         [0011]    The electronic module of the present invention is manufactured in an efficient and cost saving manner. One example of manufacturing is by way of pick and place assembly. Additionally, introducing a pre-fabricated horizontal jumper element in accordance with the present invention can be accomplished by utilizing embedded placing technology. 
         [0012]    The embedded jumper element can be manufactured by using PCB manufacturing processes and materials. According to an embodiment of the invention an FR4 laminate with Cu traces can be manufactured with conductive traces/surface on one or both sides of the core. The embedded jumper element can take the form of a line, rectangular, T-shape, L-shape, frame-like shape or any other geometric type of shape. The element can be placed or embedded in any location on a mother board or substrate and it can be used by one or more of several final products. The layout pattern of the conductor lines and pads can be standard or unique. 
         [0013]    Advantages of the present invention are that a pre-fabricated jumper element enables manufacturing of crossed conductor lines without manufacturing additional entire build-up layers or build-in layers. Also a jumper element according to an object of the invention may not cause any protrusions to an outer shape of an electronic module. Additionally, an embedded jumper element also provides reliability as the jumper element can be manufactured from the same material as the surrounding PCB or semiconductor package. 
         [0014]    An additional advantage is that the embedded jumper element provides reliable connections between the components and wiring layer. This is due to the connections being preferably both solder-less and metallurgic. 
         [0015]    A generous improved reliability can be achieved by an embedded jumper element. According to an embodiment of the invention an embedded jumper element of printed circuit board material with copper (Cu) traces are full and uniform metal and thus very reliable when exposed on thermal cycling or drop testing. 
         [0016]    By using a jumper element according to an object of the present invention, denser conductor structure can be achieved. Also by locating a jumper element precisely, alignment accuracy can be maintained at a high level. 
         [0017]    Due to the small component size of the embedded jumper element, compared to microcircuit chips, there can be several jumper elements inside a single electronic module. Furthermore, multiple jumper elements need not to be similar to each other and may vary a lot from, for example, a single conductor juniper element to a jumper element having plurality of jumper conductors. 
         [0018]    For a more complete understanding of the present invention and the advantages thereof, the invention is now described with the aid of the examples and with reference to the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1A  presents a schematic top view of an electronic module having an embedded jumper element. 
           [0020]      FIG. 1B  presents a schematic cross profile of the electronic module of  FIG. 1A . 
           [0021]      FIG. 2  presents a schematic cross profile of an electronic module without a solder mask. 
           [0022]      FIG. 3  presents a schematic top view of an electronic module with several embedded jumper elements at the four corners. 
           [0023]      FIG. 4  presents a partial enlargement of a corner of the electronic module in  FIG. 3 . 
           [0024]      FIG. 5  presents a schematic top view of a part of panel having several electronic modules. 
           [0025]      FIG. 6  presents a schematic top view of an electronic module having two embedded jumper elements recessed from the edges of the module. 
           [0026]      FIG. 7  presents a schematic top view of an electronic module having two embedded jumper elements, each having a unique design. 
           [0027]      FIG. 8  presents a schematic top view of an electronic module having a single, linear embedded juniper element 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0028]      FIG. 1A  presents a schematic top view of an electronic module having crossed conductor lines. The electronic module  1  contains a microcircuit chip  10 , which is embedded in a substrate  21 , connected to an embedded passive component  11  and contact areas  60 . There is one conductor  50  that must be jumped by two other conductors. All of the conductors are on the same level, i.e. at only one wiring layer  41 . 
         [0029]    Embedded in the electronic module  1  there is a jumper element  100 . The jumper element includes juniper conductors  110  embedded inside a substrate  21 . The jumper element  100  is aligned beneath conductor  50  so that the conductor can be jumped. 
         [0030]      FIG. 1B  presents a schematic cross profile of the same electronic module  1  presented in the  FIG. 1A . The microcircuit chip  10  and jumper element  100  are both embedded in the substrate  21 . The jumper element  100  contains two jumper conductors  110  and a supporting part  120 . Additionally, the single wiring layer  41  is shown and there is a soldering mask  24  covering at least a portion of the single wiring layer. 
         [0031]    The supporting part  120  is preferably an insulating material such as FR4, PI or similar insulating material. The insulating material  120  can be the same as, or similar to that used in the substrate  21 . Alternatively, the insulating material  120  can be different from that used in the substrate  21 . 
         [0032]    The jumper conductors  110  are shown on the supporting part  120 . However, jumper conductors  110  can also reside inside the supporting part  120  and have lands on surface of the supporting part  120 . Jumper conductors  110  comprise the actual jumping conductor but may also include lands at the ends of the jumping conductor. Jumper conductors  110  are ready made onto, or inside, the supporting part  120 . 
         [0033]    The embedding of components, i.e. the microcircuit chip  10 , passive component  11  and jumper element  100  can be accomplished by any known compatible method. Examples of useful methods for embedding are cavity embedding, face down and face up embedding, etc. Additionally, the conventional connecting of components and any contact pads  15  to the wiring layer  41  can be accomplished by any known compatible method. One useful method for connecting the components is using microvias  130 . Further examples of these methods are described in the following patents and patent applications: U.S. Pat. No. 6,991,966; U.S. Pat. No. 7,294,529; U.S. Pat. No. 7,299,546; U.S. Pat. No. 7,609,527; U.S. Pat. No. 7,663,215; U.S. Pat. No. 7,673,387; U.S. Pat. No. 7,696,005; U.S. Ser. No. 11/797,609; U.S. Ser. No. 11/878,557; U.S. Ser. No. 12/603,324; U.S. Ser. No. 11/570,673; U.S. Ser. No. 11/667,429; U.S. Ser. No. 11/791.547; U.S. Ser. No. 11/587,586; U.S. Ser. No. 11/917,724; U.S. Ser. No. 11/917,711; U.S. Ser. No. 11/917,737; U.S. Ser. No. 12/293,412; U.S. Ser. No. 12/506,519; U.S. Ser. No. 12/420,617 and U.S. Ser. No. 12/546,454 which are herein incorporated by reference. 
         [0034]      FIG. 2  presents a schematic cross section view of an electronic module similar to that of  FIG. 1B . However,  FIG. 2  shows the wiring layer  41  void of a soldering mask. The microcircuit chip  10  has contact pads  15  which are connected to the first wiring layer  41  by means of microvias  130 . Likewise the jumper element  100  is connected to the first wiring layer  41  by means of microvias  130 . There is also shown insulating material in-between the jumper conductors  110  and the conductor to be jumped  50 . This insulating material is preferably that of substrate  21 . However, the insulating material between the conductors can be similar to substrate  21 , the same or similar to supporting part  120 , or alternatively it can be a separate insulating material different from that of  21  and  120 . 
         [0035]      FIG. 3  presents a schematic top view of an electronic module  2  having multiple jumper elements  102  located at the corners of the module. A microcircuit chip  10  is embedded inside a substrate  21 . Each jumper element  102  contains one jumper conductor  110  and a supporting part  120 , in more complex electronic modules there can be multiple jumper conductors  110  in one or more of the jumper elements. 
         [0036]    The microcircuit chip  10  has contact pads  15  which are connected to the first wiring layer by means of microvias  130 . Likewise the conductor ends of each jumper element  102  are connected to the first wiring layer by means of microvias  130 . Placing the insulation between the conductors to be jumped  50 , and jumper conductors  110  can be accomplished through various methods. 
         [0037]    There has been a long felt need in the art to easily cross conductor lines at the corner of electronic modules such as that shown in  FIG. 3 . Locally embedding a jumper element at each corner where such a crossing is desired allows for the most compact and efficient module design. Though  FIG. 3  shows similar jumper elements at each of the four corners, there can be jumper elements at less than four corners. Additionally, each jumper element can be different so as to conform to the design requirements of each corner. 
         [0038]      FIG. 4  presents an enlargement of the lower left corner of the electronic module  2  shown in  FIG. 3 . The design in the present example requires that, from the microcircuit chip  10 , the lowest left-hand side contact pad  15 A should be coupled to the lowest contact area  60 A on left-hand side row of contact areas of the electronic module  2 . Likewise, the second lowest left-hand side contact pad  15 B of the microcircuit chip  10  should be coupled to the most leftward contact area  60 B on bottom side row of contact areas of the electronic module  2 . 
         [0039]    In traditional single wiring layer applications, this kind of design requirement is impossible to implement without manufacturing a build-up layer or the like. In the case that there is a build-up layer then the topography of the module surface can become uneven or the overall thickness of the module can increase to an undesirable size. Similar drawbacks as associated with each traditional method as described above. Particularly, in examples such as presented in  FIG. 4 , when there are only a small number of conductor lines to be jumped traditional methods are extremely inefficient and costly. 
         [0040]    In  FIG. 4 , the jumper element  102  is embedded inside a substrate  21 . All the microvias  130 , those associated with the component and the jumper element, can be manufactured at the same time. For example, the microvias can be created by first using chemical deposition metallization and then electrochemical plating. Other methods, as described in the patents and applications above, as well as those known in the art can be used to form the microvias. 
         [0041]    In certain instances, it is preferable to manufacture the microvias associated with the component and those associated with the jumper element in separate steps; sequentially, or at separate times using similar or different methods. In one embodiment, the microvias associated with the jumper element are prefabricated with the jumper element at a time separate from when the microvias associated with the component are formed. In such an embodiment, the microvias are often formed by different methods. 
         [0042]      FIG. 5  presents a schematic top view of a portion of a panel  30  of electronic modules  2 . One full electronic module  2  is shown in the center of the panel  30 . Surrounding the full module are portions of identical modules as shown in  FIG. 3 . It can be seen from  FIG. 5  that instead of embedding a jumper element in each corner of an electronic module, a single jumper element  101  can be embedded between four electronic modules in a panel, at position  200 . When the panel is cut along first cut lines  201  and second cut lines  202 , there are produced multiple electronic modules with a quarter of each jumper element  101  now disposed at each of its corners making up jumper elements  102  respectively. 
         [0043]    Utilizing the jumper elements of the present invention in a panel, designers of electronic modules can utilize the corners of said modules extremely efficiently. As noted earlier, it is often unavoidable to design crossing conductor lines around the corners of electronic modules. Traditionally, these corners have been problematic for designers and result in electronic modules that are unnecessarily thick or costly. By using the jumper elements as described here, designing crossing conductor lines at the corners becomes the most efficient place to put them. Other efficiencies of having embedded jumper elements at the corners of electronic modules will be readily apparent to those skilled in the art. 
         [0044]      FIG. 6  presents a schematic top view of an electronic module  3  having two jumper elements  103  embedded near two opposing corners of the module. A microcircuit chip  10  is embedded inside a substrate  21  of the module  3 . In the electronic module  3  there are embedded two jumper elements  103  slightly displaced from opposite corners of the electronic module  3 . The embedded jumper elements  103  do not extend to the edge of the electronic module  3 . Jumper elements  103  need not be shaped as a square or rectangular. One or more of the jumper elements  103  can be shaped such as a bar, line, T-shaped, L-shaped, frame-like, cross, cylinder, semi-cylinder or other non-enumerated geometric shape. 
         [0045]      FIG. 7  presents a schematic top view of an electronic module  4  having two unique jumper elements  103  and  104 . Juniper element  103  has a square shape and is deposed in a corner region of the electronic module  4  similar to electronic module  3 . Jumper element  104  is deposed in an opposing corner of the electronic module  4  and has a different geometric design than jumper element  103 .  FIG. 7  shows the substrate  21  separating both jumper elements from the component  10  and the outer edge of the electronic module. However, one or more of the jumper elements can be located at the corner as shown in  FIGS. 3-5 . 
         [0046]    Jumper element  103  connects one contact from component  10  to one contact area  60  using a single jumper conductor  110 . Jumper element  103  uses the single jumper conductor to jump a single conductor line  50 . Jumper element  104  connects two contacts from the same component  10  to two respective contact areas  60  using two separated jumper conductors  111  and  112 . 
         [0047]    The inner jumper conductor  111  of jumper element  104  is used to jump two conductor lines  50  extending from the component  10  across the jumper element. The outer jumper conductor  112  is used to jump three conductor lines  50  extending from the component  10  across the jumper element. Additionally, the outer jumper conductor  112  is used to jump conductor line  51  which extends from the inner juniper conductor  111  across the remaining portion of the jumper element. 
         [0048]      FIG. 8  presents a schematic top view of an electronic module  5  according to an embodiment of an RF antenna. A single jumper element  105  is located embedded in the substrate  21  away from any corner and at a distance from the edge of the electronic module. A single conductor line  50  extends from a first contact of a component  10  around the component in a squared spiral having several loops. The single conductor line  50  passes over the single embedded jumper element  105  several times in a local area. Then second end of conductor line  50  is connected to the outer contact of jumper conductor  113  which jumps the number of loops made by conductor line  50 . The inner contact of jumper conductor  113  is then connected via a second conductor line back to the second contact of component  10  firming an antenna. 
         [0049]    Jumper elements are shown in the figures as being smaller in size than the components. It is preferable to have small, local jumper elements to reduce material and manufacturing cost. 
         [0050]    In an embodiment embedding at least one microcircuit chip, each of the jumper elements in the final module has a surface area comparable to, or smaller than, the surface area of the largest microcircuit chip embedded in the module. The surface area of the jumper elements can be, for example, between 0.1 . . . 2 times the surface area of the largest microcircuit chip embedded in the module. In some embodiments, the above-stated ratio is typically less than 1 and can be even less than 0.5 for each jumper element in the final module. 
         [0051]    In an embodiment, the support substrate  120  forming the geometry of the jumper elements is not substantially larger than required to support any or all of the juniper conductors associated with the jumper element. Additionally, as shown in  FIG. 7 , the support substrate ideally corresponds to the path of the jumper conductors when aiming at small modules, for instance. Alternatively, the geometry of the jumper elements can be designed for easy mounting even though this may take up more space. For example, the shape of the jumper elements can be made to correspond to the shape of the components, i.e. be rectangular, for instance, even when the jumper conductors would not suggest such a rectangular shape. 
         [0052]    While it is often preferable for the surface area of the jumper elements to remain as small as possible and to confine the size of the jumper elements to local positions contoured to the path of the jumper conductors and around intersections or crossings, larger jumper elements can also have their benefit as will be discussed below. 
         [0053]    Single wiring layer electronic modules may also include one or more semiconductor chips. It should be noted that embodiments are not limited to be used in context with embedded component but can be actually utilized with “conventional” printed circuit boards and substrates where IC&#39;s, discrete and all other component are assembled in conventional methods such as surface mount technology, or SMT. Additionally, the present invention can be utilized within single wiring layers of multilayer electronic modules. 
         [0054]    In any embodiment of the invention a jumper element can be considered as an embedded component or a local build-in structure. The dimensions of conductor lands and microvias of a jumper element are typically, but not necessarily, 80 μm and 30-50 μm. Additionally, the alignment accuracy of a jumper element can easily achieve 90 μm or greater. 
         [0055]    While embedded jumper element  104  is shown with two jumper connectors, a jumper element can contain any number of jumper connectors, can jump any number of conductor lines and can connect any types of connections. The present invention provides the greatest benefits when the number of conductor lines needing to be jumped is either small. The present invention also provides substantial benefit when there are a larger number of conductor lines that need to be jumped but they are located relatively near each other in a localized portion of an electronic module. This is due to the fact that an entire addition wiring layer is made unnecessary by the present invention minimizing wasted space and wasteful manufacturing steps. 
         [0056]    Though the greatest benefits are in the situations described above, there are benefits associated with other embodiments where larger embedded jumper elements connect numerous contacts and jump larger numbers of conductor lines across vast regions of the electronic modules. Therefore, the present invention is not limited to the explicit examples shown in the figures and described herein. 
         [0057]    The advantages of the present invention are numerous. The outer shape of electronic modules can remain straight or flat on every surface, no jumper protrusions. In the manufacturing phase there can be savings in costs where otherwise a build-up layer or an outer jumper element would have otherwise been necessary to process. One of the most important advantages is that all of the conductors are substantially in one wiring layer and only in the point of conductor crossing are there conductors in separate layers. Additional advantages are that there are reliable electrical connections over the jumper element made by metallurgical contacts and the jumper elements can be prefabricated. 
       LIST OF REFERENCE NUMBERS 
       [0058]      1  Electronic module with single jumper element 
         [0059]      2  Electronic module with four jumper elements, one at each corner 
         [0060]      3  Electronic module with similar jumper elements at opposite corners 
         [0061]      4  Electronic module with different jumper elements at opposite corners 
         [0062]      5  Electronic module with antenna 
         [0063]      10  Component, microcircuit chip having several contact pads 
         [0064]      11  Component, passive component e.g. a resistor or capacitor 
         [0065]      15  Contact pad of a component  10   
         [0066]      15 A Specific contact pad of component  10   
         [0067]      15 B Specific contact pad of component  10   
         [0068]      21  Substrate, dielectric composite e.g. FR4, PI or similar 
         [0069]      24  Solder mask 
         [0070]      30  Panel 
         [0071]      41  First wiring layer 
         [0072]      50  Conductor line that is jumped across a jumper element 
         [0073]      51  Conductor line that crosses only a portion of a jumper element 
         [0074]      60  Contact area of an electronic 
         [0075]      60 A A specific contact area of an electronic module 
         [0076]      60 B Another specific contact area of an electronic module 
         [0077]      100  A jumper element 
         [0078]      101  An unbroken jumper element in a panel 
         [0079]      102  A piece of jumper element  101   
         [0080]      103  A jumper element located at but not touching a corner 
         [0081]      104  A jumper element with multiple jumper conductors at a corner 
         [0082]      105  A jumper element of an antenna 
         [0083]      110  Conductor of a jumper element 
         [0084]      111  Inner conductor of a jumper element having two conductors 
         [0085]      112  Outer conductor of a jumper element having two conductors 
         [0086]      120  Supporting part of a jumper element 
         [0087]      130  Microvia between an embedded component and a wiring layer 
         [0088]      200  Corner point of four different electronic modules 
         [0089]      201  First dicing street 
         [0090]      202  Second dicing street