Abstract:
A method for mounting a component to an electric circuit board ( 10 ), comprising: providing at least one cavity in the electric circuit board; arranging the component in the at least one cavity; and generating in the at least one cavity mechanical and/or electrical connections simultaneously to at least two locations of the component. 
     A method for making an electric circuit board arrangement comprising at least one electric circuit board, comprising: providing at least one cavity and/or through-hole in the at least one electric circuit board; arranging the component in the at least one cavity and/or in a through-hole, the component being mechanically and/or electrically connectable by contact in the at least one cavity and/or through-hole; and stacking one or more electric circuit boards on top of the at least one electric circuit board and coupling the electric circuit boards by solderable terminal pads of the component.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of co-pending U.S. Provisional Patent Application No. 61/524,774, filed on Aug. 18, 2011, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to the art of electronic devices and, more specifically, to a method for mounting electronic components to a circuit board, an electric circuit board and/or an electric circuit board arrangement. 
       BACKGROUND 
       [0003]    During assembly of electronic devices, components need to be interconnected to the circuit board and to other components. Some components, such as, for example, leaded devices, are placed onto the top of a circuit board pad and soldered to the substrate using reflow soldering. Other components, such as, for example, integrated circuits (ICs), are often wire bonded to a substrate. Many ICs and semiconductors require both active side and passive side connectivity. The bottom side of the device is often a ground connection or common node. In these cases, the assembly process can be complex, since two sides of the component, e.g., top and bottom, need to be attached to the substrate. 
         [0004]    Currently, wire bonding and ultrasonic ribbon bonding are used to attach active side terminals to a substrate while simultaneously needing a conductive adhesive or soldering process for common node or ground connections. Flip chip and direct chip attach processes often use sequential soldering processes for both top and bottom side nodes. 
         [0005]    Current methods require multiple manufacturing sequences to interconnect the top and bottom sides of the component. The required board real estate is typically large since wire bonds need encapsulated or overmolded post assembly. However, the known multi-step soldering processes are time consuming and require complex structures to connect the top and bottom sides of the die to the substrate. 
         [0006]    Current approaches require that each side or edge of a die be connected at different steps in the assembly process. For example, a die with a back side ground first requires that a conductive material, such as, for example, silver filled epoxy, be placed on a substrate and the die placed onto the epoxy and cured. The top side connections are then made in a series of other assembly steps, such as, for example, wire bonding. Finally, the assembly is encapsulated to protect the wire bonds. 
         [0007]    The present invention is directed toward overcoming one or more of the above-identified problems. 
         [0008]    It is an object of the invention to provide a method for mounting a component to an electric circuit board, which particularly allows for an attachment of the top and bottom of the component. 
         [0009]    A further object is to provide an electric circuit board comprising a component, particularly with the top and bottom ends of the component attached to the electric circuit board. 
         [0010]    A further object is to provide an electric circuit board arrangement comprising a plurality of electric circuit boards and at least one component, particularly with the top and bottom ends of the component attached to an electric circuit board. 
       SUMMARY 
       [0011]    These and other objects are achieved by the features of the independent claim(s). The other claims, the description and the drawing include favorable embodiments of the invention. 
         [0012]    A method for mounting a component an electric circuit board is proposed wherein the method comprises the steps of:
       providing at least one cavity in the electric circuit board;   arranging the component in the at least one cavity; and   generating in the at least one cavity mechanical and/or electrical connections simultaneously to at least two surfaces of the component.       
 
         [0016]    The cavity may be a pocket extending partially in the electric circuit board or may be a through-hole extending from top to bottom surface of the electric circuit board. 
         [0017]    The proposed method is particularly useful in surface mount technologies (SMT) where components, particularly electric components, are mounted to an electric circuit board. During SMT assembly, components need to be interconnected to the circuit board and other components. Traditionally, multilayer circuit boards are formed in which layer to layer connections are created by metalized vias and copper plating. Components such as discrete capacitors and the like are assembled to the top and bottom of the electric circuit board by soldering processes. 
         [0018]    Advantageously, the invention allows for the simultaneous interconnection of two sided, or top and bottom, metalized components, such as, for example, a die. In addition, the component may be placed in such a way that allows for a three dimensional use of the electric circuit board and space above the component. The inventive method replaces complex and expensive multiple sequential interconnections for top and bottom metal components. The invention removes the need to sequential assembly steps when connecting front and back side metalized components (such as, for example, a die) to a substrate (such as, for example, an electric circuit board). 
         [0019]    The component may be an electric device having an end and side terminal, such as chip resistors and capacitors and the like. The component&#39;s terminals can be electrically connected to the electric circuit board in one process step. Alternatively, the component may be a device without external terminals, for instance an inductance such as an RFID transponder or the like. 
         [0020]    In conventional electric circuit boards, the required board real estate made by conventional methods is larger than in the proposed method, since conventional wire bonds require encapsulated or overmolded post assembly. Multi-step soldering processes are time consuming and require complex structures to connect the top and bottom sides of the component to the electric circuit board. 
         [0021]    The proposed method allows for simplification of processes, simultaneous bulk or mass assembly, top and bottom side soldering of two sided die components, use of the space above the embedded component for other assemblies, miniaturization, and low cost assembly methods as well as high yield and reliable processes. 
         [0022]    According to a favorable development, the inventive method may further comprise the step of arranging the cavity adjacent at least one through-hole or via in the electric circuit board. Advantageously, the inventive method may further comprise the step of providing the at least one through-hole or via with an electrical conducting plating and connecting the component mechanically and/or electrically to the plating. Favorably, the metallic plating of the through-hole or via can be used as an electrical connection for connecting the terminals of the component to one or more electric contact pads of the electric circuit board. The through-hole penetrates the electric circuit board so that electrical connections to the component can be provided at the top as well as at the bottom surface of the electric circuit board. Alternatively, a via is a blind hole so that electric electrical connections to the component can be provided at the surface of the electric circuit board from where the via is accessible. 
         [0023]    According to a favorable development, the inventive method may further comprise the step of coupling the component to the at least one circuit board by at least one of reflow soldering, solder wave, selective solder, and/or solder fountain. Advantageously, simultaneous bulk or mass assembly, and particularly top and bottom side soldering of two sided die components, can performed. 
         [0024]    According to a favorable development, the inventive method may further comprise the step of arranging the component flush with at least one surface of the at least one electric circuit board or flush with a surface of a plating arranged at the at least one electric circuit board. Expediently, the space above the embedded component can be used for other assemblies. This allows for reduction of the required real estate of the electric circuit board. 
         [0025]    According to another aspect of the invention, an electric circuit board is proposed, the electric circuit board comprising:
       at least one cavity in the electric circuit board;   at least one component arranged in the at least one cavity; and   mechanical and/or electrical contacts to the component in the at least one cavity generated simultaneously to at least two surfaces of the component.       
 
         [0029]    It is of advantage that a compact device can be provided which allows for miniaturization of the device. Electrical connections can be established in one process step. 
         [0030]    The cavity may be a pocket extending partially in the electric circuit board or may be a through-hole extending from the top to bottom surface of the electric circuit board. 
         [0031]    According to a favorable embodiment, the at least one component may be an electric device, particularly a device with top and bottom and/or side terminals. Electric connections to the component&#39;s terminals can be established by using, for example, metallic plating of through-holed and/or vias in the electric circuit board. Particularly, the cavity may be arranged adjacent one or more through-holes or vias. Expediently, the number of through-holes corresponds to the number of terminals of the component. 
         [0032]    According to a favorable embodiment, the at least one component may be arranged flush with respect to a surface of the electric circuit board or may be arranged flush with respect to a surface of a plating on the electric circuit board. The arrangement is compact, as the space over the component may be used for arranging other components, such as, for example, electrical components at the surface of the electric circuit board. 
         [0033]    According to another aspect of the invention, a method for making an electric circuit board arrangement is proposed, comprising the steps of:
       providing at least one cavity in the at least one electric circuit board;   arranging the component in the at least one cavity being mechanically and/or electrically connectable by contacts in the at least one cavity; and   stacking one or more electric circuit boards on top of the at least one electric circuit board and coupling the electric circuit boards by solderable terminal pads of the component.       
 
         [0037]    During SMT assembly, components need to be interconnected to the circuit board and to other components. Traditionally, multilayer circuit boards are formed in which layer to layer connections are created by metalized vias and copper plating. Components, such as, for example, discrete capacitors, are assembled to the top and bottom of the circuit board by soldering processes. This invention uses the concept of stacking individual circuit boards on top of each other, and creating interconnects by soldering aligned features on each board. In particular, the present invention uses components embedded in the electric circuit boards to allow adjoined stacking of electric circuit boards. Stacked electric circuit boards allow unique three dimensional circuit configurations and provide higher assembly density and shape conformity than traditional SMT products. 
         [0038]    The present invention provides a method for the simultaneous interconnection of two or more independent circuit boards. This allows high component density and effective use of volume within unconventional three dimensional shapes. It removes post SMT processes needed in standards three dimensional PCB methods (PCB=Printed Circuit Board), such as, for example, folding. The use of rigid materials fastened together in multiple layers provides increased robustness. The inventive method replaces multiple sequential interconnections for top and bottom metal components. 
         [0039]    Currently, multilayer circuit boards are formed by traditional drill and plating of vias and through-holes to connect layers and surface mounting components on the top and bottom of the PCB. Embedding components inside PCBs is being done at board manufacture, however, it is an expensive and complicated process and the components cannot be changed or repaired once the board is laminated. The present invention allows for the use of lower cost high density circuit layer and uses an inexpensive and simple approach to embed components in the boards. Current methods for utilizing volume within three dimensional shapes involve folding flexible PCB material, which requires complicated process steps, and are more difficult and expensive to manufacture. 
         [0040]    Particularly, current methods require multiple manufacturing sequences to interconnect the top and bottom sides of the component. Multi-step soldering processes are time consuming and require complex structures to connect the top and bottom sides of the die to the substrate. 
         [0041]    Current approaches require components to be placed into the laminated structure of the electric circuit board during PCB manufacturing. This can potentially lead to component damage as lamination press temperatures and pressures are high. In addition, once the components are embedded in the laminate, they cannot be changed, reworked or probe tested directly. The present invention describes an alternative method for embedding components by using a stacked board structure and standard assembly processes. 
         [0042]    The present invention allows for simplification of processes for embedding components, simultaneous bulk or mass assembly of two circuit boards, top and bottom side soldering of two sided dies, use of the space inside a board to embed components, miniaturization, low cost assembly methods, and the ability to utilize unconventional volume shapes. 
         [0043]    According to a favorable development, the inventive method further comprises arranging the cavity adjacent at least one through-hole or via in the electric circuit board. A compact arrangement is achieved. Use can be made of existing electrical connections. Electric connections to the component&#39;s terminals can be established by using metallic plating of through-holed and/or vias in the electric circuit board. Particularly, the cavity may be arranged adjacent one or more through-holes or vias. Expediently, the number of through-holes corresponds to the number of terminals of the component. 
         [0044]    According to a favorable development, the inventive method further comprises providing the at least one through-hole or via with an electrical conducting plating and connecting the component mechanically and/or electrically to the plating. A compact arrangement is achieved. Use can be made of existing electrical connections. 
         [0045]    According to a favorable development, the inventive method further comprises coupling the component to the circuit board by at least one of reflow soldering, solder wave, selective solder, and/or solder fountain. Low cost assembly methods can be used. 
         [0046]    According to a favorable development, the inventive method further comprises interconnecting the electric circuit boards by reflow soldering. Simultaneous bulk or mass assembly of two or more circuit boards and low cost assembly methods can be used. 
         [0047]    According to another aspect of the invention, an electric circuit board arrangement is proposed, comprising at least one electric circuit board which comprises:
       at least one cavity in the at least one electric circuit board;   at least one component arranged in the at least one cavity being mechanically and/or electrically connectable by contacts in the at least one cavity; and   one or more electric circuit boards stacked on top of the at least one electric circuit board and coupled with adjacent electric circuit boards by solderable connections.       
 
         [0051]    The present invention allows for simplification of processes for embedding components, simultaneous bulk or mass assembly of two circuit boards, top and bottom side soldering of two sided dies, use of the space inside a board to embed components, miniaturization, low cost assembly methods, and the ability to utilize unconventional volume shapes. 
         [0052]    The cavity may be a pocket extending partially in the electric circuit board or may be a through-hole extending from top to bottom surface of the electric circuit board. 
         [0053]    According to a favorable development, the one or more electric circuit boards may be coupled by solderable terminations of the component. A very compact design is achieved as well as simultaneous bulk or mass assembly of two or more circuit boards. 
         [0054]    According to a favorable development, edges of the electric circuit boards may be arranged in a staggered arrangement. The stack of electric circuit boards can have unusual or unconventional volume shapes. 
         [0055]    Further features, aspects, objects, advantages, and possible applications of the present invention will become apparent from a study of the exemplary embodiments and examples described below, in combination with the Figures, and the appended claims. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0056]    The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the exemplary embodiments, but not restricted to the embodiments, wherein is shown in: 
           [0057]      FIG. 1  an exemplary embodiment of an electric circuit board in surface mount technology before mounting of a component; 
           [0058]      FIGS. 2A-2B  in side cut views method steps of preparing a cavity in an electric circuit board of  FIG. 1 ; 
           [0059]      FIGS. 3A-3D  in side cut views several method steps of mounting and connecting a component in an electric circuit board of  FIG. 2 ; 
           [0060]      FIG. 4  an alternative connection of a component in a cavity; 
           [0061]      FIGS. 5A-5D  in top views a cavity adjacent three through-holes ( FIG. 5A ), a component mounted in the cavity ( FIG. 5B ), a side cut view of the arrangement ( FIG. 5C ), and a top view of an alternative arrangement of the component in the cavity ( FIG. 5D ); 
           [0062]      FIGS. 6A-6B  in side cut views conventional surface mount components ( FIG. 6A ), and an exemplary embodiment of the invention; 
           [0063]      FIG. 7  in a side cut view an exemplary embodiment three stacked electric circuit boards according to the invention; 
           [0064]      FIG. 8  an exemplary embodiment of the invention showing two separated electric circuit boards before assembly; 
           [0065]      FIGS. 9A-9C  exemplary embodiments of interconnected electric circuit boards; and 
           [0066]      FIG. 10A-10B  in a side cut view and a perspective view stacked electric circuit boards with staggered edges. 
       
    
    
     DETAILED DESCRIPTION 
       [0067]    In the drawings, like elements are referred to with equal reference numerals. The drawings are merely schematic representations, and are not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and, therefore, should not be considered as limiting the scope of the invention. 
         [0068]      FIG. 1  depicts an exemplary embodiment of an SMT electric circuit board  10  before mounting of a component and  FIGS. 2A-2B  illustrate method steps of preparing a cavity  40  in the electric circuit board  10  of  FIG. 1 . 
         [0069]    On a top surface  16  of the electric circuit board  10 , two parallel through-holes  20  extending through body  12  of the electric circuit board  10  are arranged which are equipped with metallic platings  22  inside the through-holes  20  and on top of surface  16 , as well as on the opposite back surface  18 . By way of example, terminals  14  are arranged for placing and soldering electric components to surface  16  of the electric circuit board  10 . The through-holes  20  can be pin through-holes, for instance, which are provided for mounting pins of leaded components to the electric circuit board  10 . 
         [0070]    The inventive method involves creating a cavity  40  in the electric circuit board  10  by a tool  30 , such as an ablation or mechanical tool, e.g., a mill. The cavity  40  forms a pocket having a bottom  42  in body  12  of the electric circuit board  10  and is created between two or more adjacent plated through-holes  20  in the electric circuit board  10 . 
         [0071]    A component  50  is then placed into the cavity  40  (see  FIGS. 3A-3D ) and soldered or attached using conductive adhesive.  FIGS. 3A-3D  illustrate the placement of the component  50  in side cut views and several method steps of mounting and connecting the component  50  in the cavity  40  of the electric circuit board  10 . 
         [0072]    The cavity  40  becomes a mechanical resting place or placeholder for the component  50  during soldering. The component  50  may be placed into the cavity  40  by an automated process or by hand. The attachment process for terminals (not shown) on the component  50  can be created by a variety of methods, including, but not limited to, wave or bulk solder processes, printed solder and/or by using conductive adhesive. 
         [0073]    Cavity  40  forms a pocket which is deep enough to accommodate the component  50  so that the component  50  is flush with top surface  16  of the electric circuit board  10  ( FIGS. 3A-3B ). 
         [0074]    A solder print process can accomplish the electric connection between component  50  and the plating  22  of the through-holes  20 . Alternatively, the solder  60  can be dispensed on the respective regions. The component  50  is placed into the cavity  40  and then the electric circuit board  10  is printed by traditional stencil or screen printing to deposit solder paste onto the terminal/plated through-hole regions ( FIG. 3C ). 
         [0075]    A subsequent reflow process will cause the solder  60  to spread into the through-holes  20  and onto attachment pads of component  50  ( FIG. 3D ). Conductive adhesive could alternatively be applied to the plated through-hole/termination regions. 
         [0076]    Reflow soldering is a process in which the solder paste  60 , typically a sticky mixture of powdered solder and flux, is used to temporarily attach one or several electrical components to their contact pads, after which the entire assembly is subjected to controlled heat, which melts the solder, permanently connecting the electric joint. Heating may be accomplished, for example, by passing the assembly through a reflow oven or under an infrared lamp or by soldering individual joints with a hot air pencil or the like. 
         [0077]    For a simple approach, the component  50 , once placed into the cavity  40 , may be passed over a molten wave or selective solder wave. The solder  60  wets the plating  22  of the through-holes  20  and moves into gaps between component  50  and adjacent plating  22  and reacts with and attaches to terminal pads (not shown in the Figures) of component  50  that are adjacent to the plated through-holes  20 . Surface tension and capillary flow pulls the solder  60  into the through-holes  20  and the solder wetting force allows the solder  60  to flow onto the metal plating  22  to the component  50 , as indicated in  FIG. 4 . 
         [0078]    The wave approach may require the use of a non-conductive adhesive to prevent the component from falling out of the pocket during soldering. A reflow retaining fixture could also be used to retain component  50  in the cavity  40  during soldering. 
         [0079]      FIGS. 5A-5C  depict, in top views, a cavity  40  adjacent three through-holes  20  ( FIG. 5A ), and a component  50  mounted in the cavity  40  ( FIG. 5B ).  FIG. 5C  shows a side cut view of the arrangement with component  50  placed on edge in the cavity  40 .  FIG. 5D  shows an alternative arrangement of a component  50  in cavity  40 . 
         [0080]    The component  50  has a terminal pad  52  on one main surface and two terminals  54  on the opposite main surface. By placing component  50  on edge in the cavity  40 , the terminals  52 ,  54  are aligned with the respective through-holes  20  on each side of component  50  (one adjacent to terminal  52  and one adjacent to each of terminals  54 ). Component  50  is accommodated in the cavity  40  so that one side surface is flush with surface  24  of the plating  22  of the through holes  20 . 
         [0081]    In  FIG. 5D , component  50  has a terminal pad  56 ,  58  on opposing narrow sides of component  50 . The terminal pads  56 ,  58  align with two opposing through-holes  20  which can be pin through-holes  20  in the electric circuit board  10 . 
         [0082]      FIG. 6A  illustrates a side cut view of a conventional SMT circuit board where electric components  150   a,    150   b  are placed at the surface of the electric circuit board. Component  150   a  is a leaded component with leads  170   a  attached to terminal pads  14  on the top surface of the electric circuit board. A traditional wire bond component  150   b  is arranged next to component  150   a.  Component  150   b  has a bottom terminal pad  152   b  and front terminal pads  154   b.  The bottom terminal  152   b  is soldered or glued to the top surface of the electric circuit board while wires  156   a  are attached to the front surface terminal pads  154 . The wires  154   b  are soldered to terminal pads  14  arranged on the top surface of the electric circuit board. 
         [0083]      FIG. 6B  shows an exemplary embodiment of the invention. According to the invention, expensive real estate of the electric circuit board  10  is saved by arranging a component  50  beneath the leaded component  150  in a cavity  40  provided in the body  12  of the electric circuit board  10 . Terminal pads  52  and  54  on either side of component  50  are electrically connected to regions of plating  22  of through-holes  20  by solder  60 . The space above component  50  is available for component  150  on top of the electric circuit board  10 . Compared to a conventional arrangement as shown in  FIG. 6A , the inventive arrangement requires only about  50 % of the real estate on the electric circuit board  10  by making use of the space above the embedded component  50  for other assemblies. This allows for miniaturization of complex electric devices. 
         [0084]    To summarize, a simplification of the manufacturing process of the electric circuit board  10  can be achieved. The inventive method allows for simultaneous bulk or mass assembly. Top and bottom side soldering of two-sided dies can be achieved simultaneously. Low cost assembly methods and high yield and reliable processes can be employed to manufacture SMT devices. 
         [0085]      FIG. 7  illustrates an embodiment of an electric circuit board arrangement  200  according to another aspect of the invention. 
         [0086]    The electric circuit board arrangement  200  comprises a multitude of individual electric circuit boards  300 ,  400 ,  500  stacked on top of each other and electrically connected by way of through-hole soldering. Solder paste  60  is reflowed to create electrical connections between the individual electric circuit boards  300 ,  400 ,  500 . Within the individual bodies of the electric circuit boards  300 ,  400 ,  500 , some of the multiple through-holes  320 ,  420 ,  520  are interconnected by metallic paths  302 ,  402 ,  502 . 
         [0087]    During SMT assembly, components need to be interconnected to the electric circuit boards  300 ,  400 ,  400  and to other components. Traditionally, multilayer circuit boards are formed in which layer to layer connections are created by metalized vias and copper plating. Components such as, for example, discrete capacitors, resistors and the like, are assembled to the top and bottom of the circuit board by soldering processes. According to this aspect of the invention, the individual electric circuit boards  300 ,  400 ,  500  are stacked on top of each other, and interconnects are created by soldering aligned features on each electric circuit board  300 ,  400 ,  500 . Solder is indicated by reference numeral  60 . 
         [0088]    The present invention uses the embedded component concept as described in the preceding embodiments to allow adjoined stacking of boards. The stacked electric circuit board arrangement  200  allows for unique three dimensional circuit configurations and provides higher assembly density and shape conformity than traditional SMT products. 
         [0089]    The method according to this aspect of the invention allows for simultaneous interconnection of two or more independent electric circuit boards  300 ,  400 ,  500 . This concept allows high component density and effective use of the volume within unconventional three dimensional shapes. It removes post SMT processes needed in standards three dimensional PCB methods (PCB=Printed Circuit Board), such as, for example, folding. The use of rigid materials for the individual electric circuit boards  300 ,  400 ,  500  fastened together in multiple layers provides increased robustness of the arrangement. The inventive method replaces multiple sequential interconnections for top and bottom metal components. 
         [0090]    Currently, multilayer electric circuit boards are formed by traditional drill and plating of vias and holes to connect layers and surface mounting components on the top and bottom of the PCB. Embedding components inside PCBs is being done at board manufacture. However, it is an expensive and complicated process and the components cannot be changed or repaired once the PCB is laminated. The present invention allows for the use of lower cost high density circuit layer and uses an inexpensive and simple method to embed components in the individual electric circuit boards. Current methods for utilizing volume within three dimensional shapes involve folding flexible PCB material, thus requiring complicated process steps, and are more difficult and expensive to manufacture. 
         [0091]    Current methods require multiple manufacturing sequences to interconnect the top and bottom sides of the component. Multi-step soldering processes are time consuming and require complex structures to connect top and bottom sides of the die to the substrate. 
         [0092]    Current approaches require components to be placed into the laminated structure of the board during PCB manufacturing. This can potentially lead to component damage as lamination press temperatures and pressures are high. In addition, once the components are embedded in the laminate, they cannot be changed, reworked or probe tested directly. The inventive method describes an alternative method for embedding components by using a stacked electric circuit board arrangement  200  and standard assembly processes. 
         [0093]      FIG. 8  and  FIGS. 9A-9C  depict exemplary embodiments illustrating the inventive method. The inventive method involves taking individual electric circuit boards  300 ,  400  that have cavities  340 ,  440  and/or large plated through-holes  320 ,  420  and placing components  50  with solderable terminal pads  52 ,  54  into the cavities  340 ,  440  or through-holes  320 ,  420 . Once placed, solder paste  60  is applied to the terminal pads  52 ,  54  of the components  50  in one electric circuit board  300 . Another (likewise assembled) electric circuit board  400  is placed on top of the first assembled electric circuit board  300  and then the structure undergoes a reflow solder process as indicated in  FIGS. 9A-9C . Electric circuit board to electric circuit board interconnects can be achieved through a variety of methods, as will be appreciated by one skilled in the art. For instance, pins  26  can be used to create electric connections but also maintain alignment and create a structure for a reflow process. 
         [0094]    Electrical connections between the individual electric circuit boards  300 ,  400 ,  500  can be established for instance by a board-to-board connection tab ( FIG. 9A ) and a direct connect through through-holes  320 ,  420  by solder  60  ( FIG. 9B ). Components  50  can also be placed through the through-holes  320 ,  420  or cavities  340 ,  440  so that the component&#39;s terminal pads are accessible on each side of the electric circuit board ( FIG. 9C ). Solder paste  60  allows for forming a connection by direct component-to component connection. 
         [0095]    Alignment of the individual electric circuit boards  300 ,  400 ,  500  can be made by, for example, automated visual inspection or even by simple tooling pins  26 , as shown in  FIG. 8 . Expediently, multiple component types can be used in the present inventive method, including most two terminal devices, die with front/back side terminations, and other configurations. 
         [0096]    The assembly of stacked electric circuit boards  300 ,  400 ,  500  is processed once in a reflow process, creating a high density, rigid three dimensional electric circuit. 
         [0097]      FIGS. 10A-10B  illustrate an exemplary embodiment where shaped electric circuit boards are stacked, thus allowing the electric circuit to conform to unconventional shapes, e.g., an electric circuit board arrangement  200  having staggered edges, indicated by a broken line  210  in  FIG. 10A . The invention allows for new form factor designs while maintaining a high circuit density. 
         [0098]    To summarize, the invention allows, among other things, for simplification of processes for embedding components, simultaneous bulk or mass assembly of two or more circuit boards, and top and bottom side soldering of two sided dies. Use can be made of the space inside a board to embed components. Miniaturization of the arrangement, as well as low cost assembly methods, is possible. The invention also has the ability to utilize unconventional volume shapes. 
         [0099]    It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range.