Abstract:
Disclosed is a connection structure for a circuit board using a solder bump to arrange circuit boards. The circuit board connection structure includes a solder bump prepared on one of two circuit boards and a perforated part formed at the other of the circuit boards to receive the solder bump. Facing both circuit boards towards each other and inserting the solder bump into the perforated part, the circuit boards are desirably arranged.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 2009-0024884, filed on Mar. 24, 2009 with the Korean Intellectual Property Office (KIPO), the entire contents of which are herein incorporated by reference. 
     BACKGROUND 
     1. Field 
     Example embodiments relate to a connection structure for a circuit board using a solder bump to connect two circuit boards. 
     2. Description of the Related Art 
     A printed circuit board (PCB) may serve to connect a plurality of electronic devices in a certain framework and is widely employed in a number of electronic products including, for example, electrical home appliances, e.g., digital TVs and advanced telecommunication devices. 
     In certain electronic devices, for example, a mobile phone or a digital camera, a thin folding type flexible printed circuit (FPC) is used for fabrication of an internal wiring. With increased miniaturization as well as enlargement of a movable part in the mobile phone, such FPC is increasingly used. When connecting the FPC to a rigid substrate used as a main board, a connector or an anisotropic conductive film (ACF) may be used. 
     Connectors are well known and widely used to provide a connection between boards and, in particular, may have a merit of repetitive attachment/detachment of FPC. However, it is difficult to employ connectors with complicated shapes in automatic connections thereof and to reduce a size of the connector due to three-dimensional space occupied thereby. 
     An ACF is a thermosetting resin film containing conductive single particles. In adhering the ACF at a terminal part of one substrate and laminating a terminal of another substrate over the adhered ACF, the laminate is pressed so that a conductive terminal is inserted between two opposite electrode faces, thereby guaranteeing electrical through-connection between terminals via the inserted conductive terminal. The ACF connection may have merits in connection of narrow pitches. However, as the conductive particle connects with the terminals, it may exhibit higher resistance at connection parts as compared to soldering connection. Because the resin hardens over time, the resin is duly removed using a particular solvent. Accordingly, the ACF described above has problems of increased time and/or cost, as compared to repairing of soldered products. 
     BRIEF SUMMARY OF THE INVENTION 
     Example embodiments provide a connection structure for a circuit board fabricated using a solder bump to connect two circuit boards. 
     Example embodiments provide a connection structure for a circuit board, fabricated using a solder bump to arrange two circuit boards and maintain the arrangement. 
     In accordance with example embodiments, a connection structure for a circuit board may include a first circuit board having at least one first connection terminal, a second circuit board having at least one second connection terminal, and at least one solder bump on the at least one first connection terminal. In example embodiments, the at least one second connection terminal may include a connecting part receiving at least a part of the at least one solder bump. 
     In accordance with example embodiments, a connection structure of a circuit board may include a first circuit board having at least one first connection terminal, a second circuit board having at least one second connection terminal corresponding to the first connection terminal, and at least one connecting protrusion electrically connecting the at least one first connection terminal to the at least one second connection terminal. In example embodiments, the at least one connecting protrusion may be on the first circuit board and the second circuit board may have a perforated part coupled with the at least one connecting protrusion. 
     In accordance with example embodiments, a process for connection of circuit boards using a solder bump to connect a first circuit board and a second circuit board may include preparing the solder bump on one of the first circuit board and the second circuit board and inserting the solder bump into the other of the first circuit board and the second circuit board. 
     In accordance with example embodiments, a connection structure for a circuit board may include a first circuit board having at least one first connection terminal, a second circuit board having at least one second connection terminal, and a solder bump placed at the first connection terminal. In example embodiments, the second connection terminal may have a connecting part to receive at least a part of the solder bump. 
     In this regard, the second circuit board may include a perforated part to receive at least a part of the solder bump and the connecting part may be placed in the perforated part. 
     In example embodiments, the connecting part may be positioned to enclose an inner side of the perforated part or, otherwise, to enclose the periphery of the perforated part. 
     In example embodiments, the solder bump may be smaller than the perforated part. 
     In example embodiments, the solder bump may include a part smaller than the perforated part. 
     In example embodiments, the perforated part may be formed in a round shape while the connecting part may be formed in a ring shape. 
     In example embodiments, the first connection terminal may comprise a plurality of connection terminals aligned in zig-zag form. Likewise, the second connection terminal may comprise a plurality of connection terminals aligned in zig-zag form. 
     In example embodiments, the connection structure may further include a first solder mask to prevent or reduce the plural first connection terminals from being interconnected. 
     In example embodiments, the connection structure may further include a second solder mask to prevent or reduce the plural connection terminals from being interconnected. 
     In example embodiments, the first connection terminal may comprise a plurality of connection terminals aligned in a row. Likewise, the second connection terminal may comprise a plurality of connection terminals aligned in a row. 
     In example embodiments, the connecting part may be fixed to the solder bump so as to arrange positions of the first circuit board and the second circuit board. 
     In accordance with example embodiments, a connection structure for a circuit board may include a first circuit board having at least one first connection terminal, a second circuit board having at least one second connection terminal which corresponds to the first connection terminal, and at least one connecting protrusion to electrically connect the first connection terminal to the second connection terminal. In example embodiments, the connecting protrusion may be placed on the first circuit board and the second circuit board may have a perforated part to be coupled with the connecting protrusion. 
     In example embodiments, the second connection terminal may include a connecting part in the perforated part and the connecting part may be coupled with the connecting protrusion. 
     In example embodiments, the perforated part and the connecting part may receive at least a part of the connecting protrusion. 
     In accordance with example embodiments, a process for connection of circuit boards performed using a solder bump to connect a first circuit board and a second circuit board may include preparing the solder bump on one of the first circuit board and the second circuit board, and inserting the solder bump into the other of the first circuit board and the second circuit board. 
     In example embodiments, the above connection process may further include fusing the solder bump. 
     In example embodiments, the above connection process may further include supplying fused solder between the first circuit board and the second circuit board. 
     In example embodiments, the second circuit board may have a perforated part to receive the solder bump. 
     As disclosed above, the circuit board connection structure according to example embodiments may arrange two circuit boards without additional equipment in a process for connection of circuit boards. 
     According to the example process for connection of circuit boards, the circuit board is not pushed during sliding a soldering iron tip so as to prevent or retard the arrangement of two circuit boards from being distorted and to inhibit an increase in transfer resistance due to lack of solder between two electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.  FIGS. 1-9  represent non-limiting, example embodiments as described herein. In accordance with example embodiments: 
         FIG. 1  is a plan view illustrating a first circuit board and a second circuit board in a circuit board connection structure according to example embodiments, before connection thereof; 
         FIG. 2  is a cross-sectional view taken along the line A-A shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along the line B-B shown in  FIG. 1 ; 
         FIG. 4  is a plan view illustrating the first circuit board and the second circuit board connected to each other using the circuit board connection structure according to example embodiments; 
         FIG. 5  is a cross-sectional view taken along the line C-C shown in  FIG. 4 ; 
         FIG. 6  is a cross-sectional view taken along the line D-D shown in  FIG. 4 ; 
         FIG. 7  shows a second connection terminal according to example embodiments; 
         FIG. 8  shows a first circuit board according to example embodiments; and 
         FIG. 9  shows alignment of a first connection terminal and a second connection terminal according to example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings, in which example embodiments are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the sizes of components may be exaggerated for clarity. 
     It will be understood that when an element or layer is referred to as being “on”, “connected to”, or “coupled to” another element or layer, it can be directly on, connected to, or coupled to the other element or layer or intervening elements or layers that may be present. In contrast, when an element is referred to as being “directly on”, “directly connected to”, or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments. 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     Example embodiments described herein will refer to plan views and/or cross-sectional views by way of ideal schematic views. Accordingly, the views may be modified depending on manufacturing technologies and/or tolerances. Therefore, example embodiments are not limited to those shown in the views, but include modifications in configuration formed on the basis of manufacturing processes. Therefore, regions exemplified in figures have schematic properties and shapes of regions shown in figures exemplify specific shapes or regions of elements, and do not limit example embodiments. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” if used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. 
     Reference will now be made in detail to example embodiments of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     A connection structure for a circuit board according to example embodiments will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a plan view illustrating portions of a first circuit board and a second circuit board in a circuit board connection structure according to example embodiments, before a connection thereof.  FIG. 2  is a cross-sectional view taken along the line A-A shown in  FIG. 1 .  FIG. 3  is a cross-sectional view taken along the line B-B shown in  FIG. 1 . 
     As shown in  FIGS. 1 to 3 , a circuit board connection structure may be employed for connection of circuit boards with a variety of types and shapes. Such a structure may include a first circuit board  10  having at least one first connection terminal  11 , a second circuit board  20  having at least one second connection terminal  22 , and a solder bump  30  in order to connect the first connection terminal  11  to the second connection terminal  22 . Each of the first circuit board  10  and the second circuit board  20  may comprise a rigid circuit board or a flexible circuit board. Because the solder bump  30  connects the first connection terminal  11  to the second connection terminal  22 , the solder bump  30  may allow current to pass from the first connection terminal  11  to the second connection terminal  22  and from the second connection terminal  22  to the first connection terminal  11 . 
     The first connection terminal  11  may be integrated into the first circuit board  10 . The first connection terminal  11  may have a first connecting part  12  in a flat form with the solder bump  30  on the flat first connecting part  12 . The solder bump  30  may be fixed to the first connecting part  12  of the first connection terminal  11  and may be protruded to a certain height. In example embodiments, the height may or may not be predetermined.  FIGS. 1 to 3  illustrate the solder bump  30  in an approximately spherical form, however, the shape of the solder bump  30  is not particularly limited thereto and may be embodied in a variety of forms. 
     In  FIG. 1 , a plurality of first connection terminals  11  may be used. In order to perform general functions of the first circuit board  10 , it may be necessary to prevent the plurality of first connection terminals  11  from being interconnected during connection of the circuit board. Therefore, the first connection terminals  11  may be spaced from one another at a certain interval. When a large number of first connection terminals  11  are used, that is, when a pitch spacing between adjacent first connection terminals  11  is relatively small, aligning the first connection terminals  11  in a zig-zag form as shown in  FIG. 1  may prevent them from being interconnected or may reduce an interconnection that may form therein. Also, a first solder mask  13  may be integrated into the first circuit board  10  in order to enclose the plurality of first connection terminals  11  so that interconnection of the first connection terminals  11  optionally caused by impurities may be prevented or reduced. 
     In example embodiments, it may be required that the first connecting part  12  of each of the first connection terminals  11  be connected with a second connecting part  23  of each of the second connection terminals  22  and, therefore, the first solder mask  13  may not cover the first connecting part  12  of the first connection terminal  11  and surroundings thereof. The first connecting parts  12  of the plurality first connection terminals  11  may be spaced from one another and the first solder mask  13  may be formed between and around the first connecting parts  12  so that interconnection of the first connection parts  12  of the first connection terminals  11  by fused solder during connection of the circuit board may be prevented or reduced. 
     The second connection terminal  22  may be formed or placed on the second circuit board  20 . The second connection terminal  22  may have the second connecting part  23  in a ring form, into which the solder bump  30  may be inserted. In other words, the second circuit board  20  may include a perforated part  26  opening in a vertical direction and the second connecting part  23  of the second connection terminal  22  may be in the perforated part  26 . The second connecting part  23  of the second connection terminal  22  may be formed on an inner side  27  of the perforated part  26 . Such second connecting part  23  of the second connection terminal  22  may be constructed so that the solder bump  30  may be inserted into the perforated part  26 , thereby being easily connected with the solder bump  30 .  FIGS. 1 to 3  illustrate a ring type second connecting part  23  of the second connection terminal  22 , however, a shape of the second connecting part is not particularly limited thereto and may be embodied in a variety of forms. 
     A plurality of second connection terminals  22  may be used. In order to perform general functions of the second circuit board  20 , it may be necessary to prevent the plurality of second connection terminals  22  from being optionally interconnected during connection of the circuit board. Therefore, the second connection terminals  22  may be spaced from one another at a certain interval. In example embodiments, the certain interval may or may not be predetermined. When a large number of second connection terminals  22  are used, that is, when a pitch spacing between adjacent second connection terminals  22  is relatively small, aligning the second connection terminals  22  in a zig-zag form as shown in  FIG. 1  may prevent them from being interconnected or reduce an interconnection that may form between the second connection terminals  22 . Also, a second solder mask  24  may be formed on the second circuit board  20  in order to enclose the plurality of second connection terminals  22  so that interconnection of the second connection terminals  22  optionally caused by impurities may be prevented or retarded. In example embodiments, it may be required that the second connecting part  23  of each of the second connection terminals  22  be connected with a first connecting part  12  of each of the first connection terminals  11  and, therefore, the second solder mask  24  may not cover the second connecting part  23  of the second connection terminal  22  and surroundings thereof. 
       FIG. 4  is a plan view illustrating the first circuit board  10  and the second circuit board  20  connected to each other in the circuit board connection structure according to example embodiments.  FIG. 5  is a cross-sectional view taken along line C-C as shown in  FIG. 4 .  FIG. 6  is a cross-sectional view taken along line D-D as shown in  FIG. 4 . 
     As shown in  FIGS. 4 to 6 , the connection structure for a circuit board according to example embodiments may be employed to arrange the first circuit board  10  and the second circuit board  20  using the solder bump  30 . In example embodiments, the first circuit board  10  may be placed under a bottom surface of the second circuit board  20 . In example embodiments, the solder bump  30  formed on the first circuit board  10  is inserted into the perforated part  26  of the second circuit board  20 . If a plurality of solder bumps  30  are inserted into a plurality of perforated parts  26 , the plurality of first connection terminals  11  may correspond to a plurality of second connection terminals  22 , respectively, so that arrangement of the first circuit board  10  and the second circuit board  22  may be easily embodied. 
     In example embodiments, the second circuit board  20  may be fixed to the solder bump  30 . Accordingly, the solder bump  30  may restrict movement of the second circuit board  20  relative to the first circuit board  10 . Therefore, the solder bump  30  may continuously maintain an arrangement of the first circuit board  10  and the second circuit board  20 . As shown in  FIG. 5 , the first circuit board  10  may be connected with the second circuit board  20  by sliding soldering. Therefore, the second circuit board  20  may be fixed to the solder bump  30  and movement thereof may be restricted even if a soldering iron tip  40  slides over or contacts the second circuit board  20 . Accordingly, an arrangement of the first circuit board  10  and the second circuit board  20  may be maintained. In this regard, the soldering iron tip  40  may stably supply fused solder  41  between the first connection terminal  11  and the second connection terminal  22 , thereby solving a problem of increased transfer resistance caused by lack of solder between both connection terminals  11  and  22 . 
     In example embodiments it is not necessary to entirely insert the solder bump into the perforated part  26 . In example embodiments, the solder bump  30  may not be entirely inserted into the perforated part  26 , instead only a portion of the solder bump  30  may be inserted into the perforated part  26 . By inserting only a portion of the solder bump  30  into the perforated part  26  arrangement of the first circuit board  10  and the second circuit board  20  may be easily performed. That is, if the solder bump  30  has a part inserted into the perforated part  26 , the first circuit board  10  and the second circuit board  20  may be easily arranged even though the formed solder bump  30  is larger than the perforated part  26 . 
     Hereinafter, a process for connecting circuit boards using the connection structure for a circuit board according to example embodiments will be described in greater detail. 
     Referring to  FIGS. 1 to 6 , the solder bump  30  is placed on the first circuit board  10 . More particularly, the solder bump  30  is positioned to fix the same to the first connecting part  12  of the first connection terminal  11 . 
     According to example embodiments, the perforated part  26  is formed on the second circuit board  20 . The perforated part  26  may be larger than the solder bump  30  in order to receive the solder bump  30 . However, even if the formed perforated part  26  is smaller than the solder bump  30 , example embodiments may be favorably employed when the perforated part  26  is formed to receive at least a part of the solder bump  30 . 
     The first circuit board  10  is connected with the second circuit board  20  using the solder bump  30 . The solder bump  30  formed on the first circuit board  10  is inserted into the perforated part  26  formed on the second circuit board  20 . While maintaining arrangement of the first circuit board  10  and the second circuit board  20 , the solder iron tip  40  slides over the second circuit board  20  and supplies fused solder  41  between the first connection terminal  11  and the second connection terminal  22 . As a result, the solder bump  30  is fused and connects the first connection terminal  11  and the second connection terminal  22 . 
     In example embodiments, the solder iron tip  40  may heat and melt the solder bump  30 , thus, the melted solder from the solder bump  30  may spread and flow to connect the first connecting part  12  to the first connection terminal  11 . Additionally, fused solder  41  may be supplied to the connection part, that is, in the perforated part  26  occupied by the solder bump  30 , to connect the solder bump  30  to the second connection terminal  22 . As another alternative, the iron tip  40  may be configured to melt the solder bump  30  and provide solder in the perforated part  26  to connect the first connecting part  12  to the second connection terminal  11 . 
       FIG. 7  illustrates a second connection terminal according to example embodiments. 
     As shown in  FIG. 7 , a second connection terminal  22   a  may be integrated into a second circuit board  20   a . A second connecting part  23   a  of the second connection terminal  22   a  may be placed in the perforated part  26   a , which may be the same as illustrated in  FIG. 2  except that a second connecting part  23   a  of the second connection terminal  22   a  may be not positioned at an inner side  27   a  of the perforated part  26   a . That is, the second connecting part  23   a  of the second connection terminal  22   a  may be formed along an external periphery of the perforated part  26   a  at a top side of the perforated part  26   a . In example embodiments, a process for fabrication of the second circuit board  20   a  may be relatively easy and simple. 
     The solder bump  30   a  may be inserted into the perforated part  26   a  to supply fused solder to the first and second connection terminals  11   a  and  22   a  while maintaining arrangement of the first circuit board  10   a  and the second circuit board  20   a , so that the first connection terminal  11   a  may be connected with the second connection terminal  22   a  via the solder bump  30   a . Like example embodiments according to  FIG. 1 , the first connection terminal  11   a  may include a first connecting part  12   a  and a first solder mask  13   a  may be formed on a surface of the first circuit board  10   a.    
       FIG. 8  shows a first circuit board according to example embodiments. 
     As shown in  FIG. 8 , a solder mask  13   b  may be placed on a first circuit board  10   b  to enclose a first connection terminal  11   b . However, the solder mask  13   b  may not be present in a region S including a first connecting part  12   b  of the first connection terminal  11   b  and surroundings thereof. Referring to  FIG. 1 , the first solder mask  13  may be placed between plural first connecting parts  12  of first connection terminals  11 . However, in  FIG. 8 , if an amount of supplied fused solder is accurately controlled during fabrication of a circuit board, interconnection of the plural first connection parts  12   b  of the first connection terminals  11   b  may be prevented or reduced even though the solder mask  13   b  is not present in the region S including the first connecting part  12   b  of the first connection terminal  11   b  and surroundings thereof as shown in  FIG. 8 . In  FIG. 8 ,  30   b  represents a solder bump accurately formed in the region S. 
       FIG. 9  shows alignment of a first connection terminal and a second connection terminal according to example embodiments. 
     As shown in  FIG. 9 , a first connection terminal  11   c  may be integrated into a first circuit board  10   c  while a second connection terminal  22   c  may be integrated into a second circuit board  20   c . Each of the first connection terminal  11   c  and the second connection terminal  22   c  may comprise a plurality of connection terminals.  FIG. 9  illustrates a plurality of first connecting parts  12   c  of the plural first connection terminals  11   c  and a plurality of second connecting parts  23   c  of the plural second connection terminals  22   c  aligned in respective rows. If a small number of first connection terminals  11   c  and second connection terminals  22   c  are used, that is, if a pitch spacing between adjacent first connecting parts  12   c  of the first connection terminals  11   c  or between adjacent second connecting parts  23   c  of the second connection terminals  22   c  is relatively large, decreasing possibility of connection by fused solder during fabrication of a circuit board, it may be possible to align a plurality of first connecting parts  12   c  of first connection terminals  11   c  and a plurality of second connecting parts  23   c  of second connection terminals  22   c  in respective rows. In addition, a plurality of solder bumps  30   c  may also be aligned in a row to correspond to a plurality of first connecting parts  12   c  of first connection terminals  11   c.    
     Although example embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in example embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.