Abstract:
A circuit component comprising a circuit board and a terminal for mounting the circuit board on a second circuit board. A length of the circuit board is 10 mm-80 mm, a difference in a coefficient of thermal expansion between the circuit board and the second circuit board is or 0.2×10 −5 /° C. greater. The terminal is made of an elastic material, and comprised of a first connection section, a second connection section and an elastic section disposed between the first and second connection sections. and the terminal separates the circuit board from the second circuit board by 0.3 mm-5 mm. In the circuit components of the present invention, deterioration in the conduction between the circuit board and the second circuit board due to heat cycles can be prevented. Thus, a circuit component having stable operating characteristics for a long period of time is obtained.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a circuit component and a terminal structure thereof, for use in a wireless communication equipment and the like communication apparatus.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    A conventional circuit component and its terminal structure is described in the following using a dielectric filter as an example. FIG. 22 and FIG. 23 show perspective views of a conventional dielectric filter.  
           [0003]    Referring to FIG. 23 and FIG. 24, a conventional dielectric filter comprises a coupling board  3  having electrodes formed thereon, a plurality of resonators  5 , center conductors  6  and shield covers  7 . A circuit board  1  is provided with a grounding pattern and other electrode patterns, which are not shown in the drawing. Also, chip components  2  are mounted on the circuit board  1 .  
           [0004]    The coupling board  3  is mounted on the circuit board  1  via a spacer  4 . The coupling board  3  is provided on the upper and the bottom surfaces with independent electrodes.  
           [0005]    A generally-used resonator  5  comprises a dielectric substance provided with a through hole, the surface, including that of the through hole, of the dielectric substance is covered with a conductive layer. Each of the plurality of resonators  5  has a center conductor  6  provided in the through hole, and being coupled with the conductive layer, and the center conductor  6  is connected to respective independent electrodes provided on the coupling board  3 . The plurality of resonators  5  are capacity-coupled. The shield cover  7  is attached on the circuit board  1  covering the resonators  5  in the transmittance side and the receiving side, respectively.  
           [0006]    The dielectric filter structured as described above is mounted on a circuit board  1  via a spacer  4 , and an air gap is provided between the coupling board  3  and the circuit board  1 . The air gap reduces a stray capacitance between the coupling board  3  and the circuit board  1 . In this way, a change or a dispersion in the characteristics due to a substantial stray capacitance, that could be generated when the coupling board  3  is mounted directly on the circuit board  1 , can be suppressed.  
           [0007]    In the above-described conventional structure, however, there exists a substantial difference in a coefficient of thermal expansion between the circuit board  1 , which is generally made mainly of an epoxy-glass substrate, and the coupling board  3 , which is generally made mainly of alumina or the like ceramic material. The difference in the coefficients of thermal expansion creates a substantial stress in a material (a solder, for example) coupling the spacer  4  and the electrode, resulting in micro-cracks or the like problems in the coupling material and causes an electrical connection trouble between the coupling board  3  and the circuit board  1 . This is a deteriorating factor in the characteristics.  
           [0008]    The spacers  4  of high rigidity were conventionally used, which include a square metal column, a ceramic material covered with a conductive layer, as illustrated in FIG. 25.  
         SUMMARY OF THE INVENTION  
         [0009]    A circuit component of the present invention comprises a circuit board (joint circuit board) provided with circuit patterns and terminals for mounting the circuit board on a second circuit board, length of the circuit board being 10 mm-80 mm long. Difference in coefficient of thermal expansion between the circuit board and the second circuit board is 0.2×10 −5 /° C. or more. The terminal is made of an elastic material, and separates the circuit board from the second circuit board for 0.3 mm-5 mm. The terminal comprises a first connection section, a second connection section, and an elastic section disposed between the first and the second connection sections.  
           [0010]    At least one of the connection sections of the terminal in an exemplary embodiment of the present invention is provided with a plurality of connection sections, or a connection section is branching out to form a plurality of connection sections. The plurality of branched connection sections is provided at the end with a bent section, or a protrusion.  
           [0011]    A structure in accordance with the present invention is advantageous in preventing a possible deterioration in the electrical conduction between the second circuit board and the joint circuit board which would be caused by repeated heat cycles. Thus the present invention offers a circuit component that provides stable operating characteristics for a long operating period.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0013]    [0013]FIG. 2 is a perspective view of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0014]    [0014]FIG. 3 is a perspective view of a terminal of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0015]    [0015]FIG. 4 is a side view of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0016]    [0016]FIG. 5 is a partial side view of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0017]    [0017]FIG. 6 is a perspective view of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0018]    [0018]FIG. 7 is a partial side view of a dielectric filter in accordance with an exemplary embodiment of the present invention.  
         [0019]    [0019]FIG. 8 is a perspective view of a terminal of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0020]    [0020]FIG. 9 is a perspective view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0021]    [0021]FIG. 10 is a perspective view of a terminal of a dielectric filter in accordance with yet another exemplary embodiment of the present invention.  
         [0022]    [0022]FIG. 11 is a perspective view of a dielectric filter in accordance with yet another exemplary embodiment of the present invention.  
         [0023]    [0023]FIG. 12( a ) is a perspective view of a terminal of a dielectric filter in accordance with still another exemplary embodiment of the present invention.  
         [0024]    [0024]FIG. 12( b ) is a perspective view of a dielectric filter in accordance with still another exemplary embodiment of the present invention.  
         [0025]    [0025]FIG. 13 is a perspective view of a terminal of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0026]    [0026]FIG. 14 is a perspective view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0027]    [0027]FIG. 15 is a side view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0028]    [0028]FIG. 16 is a perspective view of a terminal of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0029]    [0029]FIG. 17 is a perspective view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0030]    [0030]FIG. 18 is a side view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0031]    [0031]FIG. 19 is a perspective view of a terminal of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0032]    [0032]FIG. 20 is a perspective view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0033]    [0033]FIG. 21 is a side view of a dielectric filter in accordance with another exemplary embodiment of the present invention.  
         [0034]    [0034]FIG. 22 is a perspective view of a conventional dielectric filter.  
         [0035]    [0035]FIG. 23 is a perspective view of a conventional dielectric filter.  
         [0036]    [0036]FIG. 24 is a side view of a conventional dielectric filter mounted on a circuit board.  
         [0037]    [0037]FIG. 25 is a perspective view showing a spacer for a conventional dielectric filter. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Embodiment  
       [0038]    Description is made in the following using a dielectric filter as an example for the circuit component of the present invention.  
         [0039]    [0039]FIGS. 1 and 2 show perspective views, respectively, of a dielectric filter in accordance with a first exemplary embodiment of the present invention.  
         [0040]    Referring to FIGS. 1 and 2, a dielectric filter of the present invention comprises a circuit board  1 , a chip component  2 , a coupling board  3 , a resonator  5 , a center conductor  6  and a shield case  7 . These items have similar structures as those in the conventional dielectric filter.  
         [0041]    The dielectric filter of the present invention is provided with terminals  8  for mounting the coupling board  3  on the circuit board  1 . The conventional spacers  4  are replaced with terminals  8 .  
         [0042]    The terminal  8  is made of a plate-form material, such as phosphor bronze, brass, beryllium copper, stainless steel, nickel-plated steel or aluminum or the like, by machining it through a bending or punching process. Thus, the terminal  8  is rich in the elastic property. It is preferred that, in view of great advantages in the manufacturing process and other factors, the terminal  8  is made by bending a sheet of one of the above-described metals. Preferred thickness of the metal sheet is 0.1 mm-0.5 mm (more preferably 0.1 mm -0.3 mm). The metal sheets thinner than 0.1 mm are poor in the mechanical strength; as a result, even a small external force can make a terminal  8  deformed, or machining difficulties would arise. On the other hand, the metal sheets thicker than 0.5 mm will have too much rigidity, which would have the same problem as observed in the conventional dielectric filters.  
         [0043]    The terminal  8  should preferably be provided on the surface with an under-layer and a junction layer formed on the under-layer. A preferred material for the under-layer is copper, copper alloy, nickel or nickel alloy, and thickness of the layer is 1-5 μm, to prevent the solder leaching (or similar problems). The under-layers thinner than 1 μm are not effective to prevent the solder leaching, while the layers thicker than 5 μm are too thick to make a terminal  8  compact-shaped.  
         [0044]    A preferred material for the junction layer, which is intended to work when a terminal  8  is mounted on a circuit board  1 , is solder, lead-free solder (a bonding material of, for example, Sn, or Sn containing at least one element among the group of Ag, Cu, Zn, Bi and In), gold, or an alloy containing gold. The junction layer should preferably has a thickness 2-12 μm. The junction layers thinner than 2 μm are insufficient to be a junction layer, while the layers thicker than 12 μm are too thick to make a terminal  8  compact-shaped.  
         [0045]    Although the terminal  8  in the present embodiment is provided with both the under-layer and the junction layer, either one of the layers, the under-layer or the junction layer, may be provided on the surface, depending on the situation. Or, depending on product specifications or the like, both of the layers may be eliminated.  
         [0046]    The terminal  8  is shaped in the form of a letter S, as shown in FIGS. 3, 4 and  5 . It comprises a connection section  8   a  which makes electrical or mechanical contact with a surface electrode  3   a  of the coupling board  3 , a connection section  8   b  which makes electrical or mechanical contact with an electrode  1   a  of the circuit board  1 , and an elastic section  8   c  locating between the connection section  8   a  and the connection section  8   b.    
         [0047]    The terminal  8  is further provided with an opposing section  8   d  opposing to the connection section  8   a,  and a joint section  8   e  joining the connection section  8   a  and the opposing section  8   d.  The connection section  8   a,  the joint section  8   e  and the opposing section  8   d  constitute a holding section, which is formed in the shape of a letter C for elastically holding the coupling board  3 . Although the terminal in the present embodiment is designed so that the holding section holds the coupling board  3  elastically, it may be designed instead that a gap between the opposing section  8   d  and the connection section  8   a  is greater than the thickness of the coupling board  3  so that a coupling board  3  can be simply inserted in between.  
         [0048]    As shown in FIG. 5, the connection section  8   a  and the connection section  8   b  are making contact, respectively, with a surface electrode  3   a  of the coupling board  3  and an electrode  1   a  of the circuit board directly or an indirectly. And they are connected mechanically and electrically by a solder, a lead-free solder or the like bonding material  9 . The elastic section  8   c  is disposed to be locating between the circuit board  1  and the coupling board  3 , as shown in FIG. 4 and FIG. 5. In the above-described structure, even if a stress is applied on the terminal  8  due to difference in the coefficient of the thermal expansion between the circuit board  1  and the coupling board  3 , most of the stress is absorbed by the elastic section  8   c . As the result, the stress does not concentrate to the bonding material  9 , and generation of micro-cracks in the bonding material  9  can be reduced.  
         [0049]    A circuit component of the present invention is assembled in a procedure as shown in FIG. 6. In the first place, two pieces of terminals  8  are attached to one side edge of the coupling board  3 , by inserting the side edge to the holding section of the terminal  8 . Since the holding section of the terminal  8  elastically holds the coupling board  3 , as described earlier, the terminals  8  can be fixed provisionally to the coupling board  3 .  
         [0050]    Then, by providing a bonding material  9  bridging the terminal  8  and the surface electrode  3   a,  and heating them together, the coupling board  3  and the terminal  8  can be fixed together, both electrically and mechanically. For the sake of operational efficiency, the bonding material  9  may be applied on a predetermined portion of the surface electrode  3   a  before the terminal  8  is attached thereto, and then the terminal  8  is attached and heated for the electrical and mechanical connection on the coupling board  3 .  
         [0051]    Next, the coupling board  3  having the terminals  8  are placed on the circuit board  1 , with the connection section  8   b  of terminal  8  making a direct or an indirect contact to the electrode  1   a  of the circuit board  1 . And then the coupling board  3  is mounted and fixed to the circuit board  1  electrically and mechanically using a bonding material  9 .  
         [0052]    Another exemplary means for reducing a stress to be effected on the bonding material  9  is shown in FIG. 5. The connection section  8   a  is provided with a protruding section  8   h  protruding towards the opposing section  8   d.  In this way, the holding section can easily have a holding force for holding a coupling board  3 . By limiting the application of a bonding material  9  only to the protruding section  8   h  and the vicinity, another stress-reducing corner  8   f  can be formed between the joint section  8   e  and the connection section  8   a.    
         [0053]    The protruding section  8   h  contributes also to ensure the contact between a surface electrode  3   a  and the connection section  8   a,  preventing a possible contact trouble.  
         [0054]    Also at the connection section  8   b,  further stress-reducing means can be implemented. Namely, by connecting the connection section  8   b  with an electrode  1   a  of circuit board  1  only at the end part of the connection section  8   b  by applying a bonding material  9  only at the end part of the connection section  8   b,  a flat flexion section  8   g  is provided in the connection section  8   b.  A stress can be reduced further by the flexion section  8   g.    
         [0055]    Still another structural example of the present embodiment is shown in FIG. 7. There is no electrical contact between the connection section  8   a  and a surface electrode  3   a,  while the opposing section  8   d  is connected both electrically and mechanically to a reverse-surface electrode  3   b  with a bonding material  9 .  
         [0056]    The structure of FIG. 7 may be considered as an inverse version of the roles performed by the connection section  8   a  and the opposing section  8   d  shown in FIG. 5.  
         [0057]    Although in the examples in the present embodiment either one among the connection section  8   a  and the opposing section  8   d  is making contact with a surface electrode  3   a  or a reverse-surface electrode  3   b  of the coupling board  3 , both of the connection section  8   a  and the opposing section  8   d  may be connected to a surface electrode  3   a  and a reverse-surface electrode  3   b.    
         [0058]    Besides the above-described ways of connection illustrated in the drawings, there can be another way of connection. Namely, an end face electrode is provided on the end face  3   c  of coupling board  3  by extending a surface electrode  3   a,  or a reverse-surface electrode  3   b,  and then the end face electrode may be connected to the joint section  8   e  using a bonding material  9 . In other words, depending on the layout pattern of electrodes, there can be another way of connection, where at least one of the connection section  8   a,  the opposing section  8   d  and the joint section  8   e  makes contact with the coupling board  3 .  
         [0059]    Although in the examples shown in FIG. 1-FIG. 7 one side edge of the coupling board  3  has been provided with a couple of terminals  8 , or a coupling board  3  has been mounted on a circuit board  1  using four terminals  8 , one, three or more terminals  8  may be attached to the coupling board  3  at one side edge. However, the number of terminals  8  should preferably be five or less. A high count of terminals  8  means an increased number of process steps in assembly operation, which impairs the manufacturing productivity. It is preferable that a coupling board  3  is attached with a plurality of terminals  8  for one side edge when it is mounted on a circuit board  1 . By so doing, a coupling board  3  is supported on a circuit board  1  at a plurality of points; thus an electronic component can be mounted stable on a circuit board, and the manufacturing productivity is improved.  
         [0060]    In view of downsizing of an electronic apparatus and assurance of the physical strength, it is preferable to maintain the dimensions of the terminal  8  to satisfy the following requirements: where, L 1  represents a length, L 2  a height and L 3  a width of a terminal  8  as is shown in FIG. 3. 
         3 mm≧L 1 ≧1 mm 
         6 mm≧L 2 ≧1 mm 
         3 mm≧L 3 ≧0.4 mm 
         [0061]    It is preferred to keep a gap H between a circuit board  1  and a coupling board  3  shown in FIG. 5 within a range of 0.3 mm-5 mm (more preferably, 0.5 mm-2 mm). If the gap H is narrower than 0. 3 mm, the stray capacitance of the coupling board  3  relative to the circuit board  1  becomes large and characteristics of an electronic circuit tend to change easily. On the other hand, the gap H greater than 5 mm makes height of a dielectric filter itself great, that does not fit to the downsizing objective for an electronic apparatus.  
         [0062]    A terminal  8  in accordance with the present embodiment is especially advantageous in a case where difference in the coefficient of thermal expansion between the circuit board  1  and the coupling board  3  is 0.2×10 −5 /° C., or more. Furthermore, the length M of a coupling board  3  shown in FIG. 4 is quite relevant to its thermal expansion. The longer the length M of coupling board  3 , the greater the change in length caused by thermal expansion. It is especially preferable to use a terminal  8  of the above-described configuration in a case where length M of the coupling board  3  is within a range of 10 mm-80 mm. When the length M is shorter than 10 mm, change in the length caused by thermal expansion of joint circuit board would be so small, staying within a nominal value, and there would be only a small stress generated between the coupling board  3  and the circuit board  1 . On the other hand, a length M greater than 80 mm leads to a bulky-sized dielectric filter, which is not suitable to the downsizing objective for an electronic apparatus.  
         [0063]    The above-described examples have been put into heat cycle tests to have the advantages confirmed. Practical test results are described below.  
         [0064]    For the comparison, dielectric filter samples of conventional technology were manufactured using a spacer  4  shown in FIG. 25 for coupling a circuit board and a joint circuit board. Example 1 is dielectric filters having the connecting structure shown in FIG. 5. Example 2 is dielectric filters having the connecting structure shown in FIG. 7.  
         [0065]    The coupling board  3  of each of the samples is made of a 96% alumina, and the circuit board  1  is made of an epoxy-glass substrate.  
         [0066]    In the heat cycle test, the samples are kept at 85° C. for 30 minutes and then the temperature is lowered to −40° C. and kept at the temperature for 30 minutes, viz. one heat cycle takes 1 hour. 20 samples were provided for each category. As shown in FIG. 2 and other figures, there are two joint circuit boards in a dielectric filter (antenna duplexer). In the conventional technology, one joint circuit board employs two spacers  4 ; hence, number of spacers  4  are 80 among the 20 dielectric filter samples. In the dielectric filters of examples 1 and 2, one joint circuit board employs four terminals  8 . Or, there are eight terminals  8  in each of the dielectric filter samples; hence, number of the terminals  8  are 160 among the 20 dielectric filter samples.  
         [0067]    After conducting the heat cycle test for a certain predetermined cycles, the dielectric filter samples were visually inspected using an optical microscope of 100 magnification, for counting number of the spacers  4 , or the terminals  8 , having a crack in the bonding material. The results are shown in Table 1.  
                                                                                                   TABLE 1                                       numbers of heat cycles                20   50   100   300   500   800   1000   1200                    Comparative Ex.   0   0   0   1   4   9   20   30       Example 1   0   0   0   0   0   0   0   1       Example 2   0   0   0   0   0   1   2   4                  
 
         [0068]    Table 1 shows that, the conventional dielectric filter starts cracking at 300 cycles. Whereas, no crack is observed among Example 1 and Example 2.  
         [0069]    After 1200 cycles, the conventional dielectric filter shows crack at the bonding material of the spacer for as many as 30 pieces, while the crack is observed in 1 piece and 4 pieces, respectively, among the Example 1 and the Example 2. Thus it has been confirmed that use of the terminal  8  of the present invention provides superior results. Furthermore, it has to be noted that number of terminals  8  among each of the Example 1 and the Example 2 is twice as much as the comparative example. Despite double number of the terminals existing in each of the Example 1 and the Example 2, number of the cracks observed are significantly small. Thus, it has become obvious that a structure employing the terminal  8  of the present invention is advantageous in the heat cycle test.  
       Second Embodiment  
       [0070]    A second exemplary embodiment of the present invention is described with reference to FIG. 8 and FIG. 9.  
         [0071]    The difference with the structure of FIG. 3 is that a terminal  8  in the present embodiment has a T-shaped form at the connection section  8   b.  Or, the end of connection section  8   b  is branched towards opposite directions, and each end part of the branch makes contact with electrode  1   a  of the circuit board  1 .  
         [0072]    It is preferred that respective ends of the branched connection section  8   b  are provided with a bent section  8   i,  as shown in FIG. 8. When a terminal  8  is connected to an electrode  1   a  using a bonding material  9 , the bent section  8   i  helps the bonding material  9  form a fillet along the side face of bent section, preventing it from spreading over the electrode  1   a.  As a result, the area of bonding material  9  can be limited to be small.  
         [0073]    In place of the above-described bent section, a protrusion may be provided at the end of the branched connection section  8   b.    
         [0074]    Advantage of a terminal of the present embodiment, whose end at the connection section  8   b  is divided into two, is that, for example, in a case where an electrode  1   a  of circuit board is split into two as shown in FIG. 9 and a terminal  8  is to be connected to each of the split electrodes  1   a,  the terminal  8  can be easily connected to the electrodes  1   a.  As a result, the number of terminals  8  to be connected can be reduced, which results in a smaller number of constituent components. Another advantage with the terminal in the present embodiment is that area of connection formed between a terminal  8  and a circuit board  1  is increased, and the mounting stability of components is improved, which leads to an improved manufacturing productivity.  
         [0075]    Although the connection section  8   b  has been split into the form of a letter T in the present embodiment, it may be split into other shapes, into the form of a letter Y, for example. The connection section  8   b  may be split into two or more branches for the same effect.  
       Third Embodiment  
       [0076]    A third exemplary embodiment of the present invention is described with reference to the drawings FIG. 10 and FIG. 11.  
         [0077]    Referring to FIG. 10 and FIG. 11, a terminal  8  is provided with one connection section  8   a,  which is stretching from the joint section  8   e,  and a pair of opposing sections  8   d  stretching from the joint section  8   e  to oppose the connection section  8   a.  Namely, the terminal  8  in the present embodiment is based on the structure of FIG. 3, and is provided with an increased number of opposing sections  8 d, the connection section  8   a  is being disposed to be locating above the clearance formed by the pair of the opposing sections  8   d.    
         [0078]    In the configuration of FIG. 3, part of the elastic section  8   c  is utilized to work also as the opposing section  8   d.  So, the elastic section  8   c  has a curved form. On the other hand, the elastic section  8   c  in the present embodiment is straight-formed, as shown in FIG. 10 and FIG. 11, and the elastic section  8   c  and the connection section  8   b  form the approximate shape of a letter L.  
         [0079]    The elastic section  8   c  of terminal  8  of FIG. 3 comes underneath a coupling board  3  as shown in FIG. 5 and other drawings. However, the elastic section  8   c  of a terminal  8  configured as shown in FIG. 10 comes at a side of the coupling board  3 . Thus the terminal  8  in the present embodiment as illustrated in FIG. 10 and FIG. 11 reveals its advantage in a case where a space between a circuit board  1  and a coupling board  3  is unable to accept the elastic section  8   c  by some reason.  
         [0080]    Furthermore, the terminal  8  of the present configuration can support or hold a coupling board  3  in a more reliable manner, as compared with the case of FIG. 3, in which there is only one opposing section  8   d.  Thus, the coupling board  3  and the terminal  8  are more easily attached.  
         [0081]    Although the terminal of the present embodiment has two opposing sections  8   d  and one connection section  8   a,  the terminal may have three or more opposing sections  8 d, and two or more connection sections  8   a.  Furthermore, it may have two or more connection sections  8   a,  while number of the opposing section  8   d  is remained to be one. Still another example of the terminal may be configured in a structure as illustrated in FIGS.  12 ( a ) and  12 ( b ), where a terminal  8  of FIG. 10 is provided at the connection section  8   b  with a branch configuration like that shown in FIG. 8.  
       Fourth Embodiment  
       [0082]    A fourth exemplary embodiment of the present invention is described referring to FIG. 13 through FIG. 15.  
         [0083]    The terminal  8  in the present embodiment comprises an elastic section  8   c  disposed between the connection section  8   a  and the connection section  8   b.  The present terminal  8  is not designed to hold a coupling board  3 . The end portion of the connection section  8   a  is bent inward towards the connection section  8   b  so that it does not damage the electrodes and other elements.  
         [0084]    In a terminal  8  of the present embodiment, the connection section  8   a  and the connection section  8   b  are disposed substantially in parallel to each other, and the elastic section  8   c  is disposed slant to the connection sections  8   a  and  8   b.    
         [0085]    The connection section  8   a  is attached to an electrode disposed on the reverse-surface of the coupling board  3 , while the connection section  8   b  is attached to the electrode la disposed on the circuit board  1 . The terminals  8  provides an effective elastic property when they are disposed in an arrangement as illustrated in FIG. 15, where the slant elastic sections  8   c  oppose to each other (the connection sections  8   a,    8   b  of both terminals facing outward with respect to a coupling board  3 ).  
       Fifth Embodiment  
       [0086]    A fifth exemplary embodiment of the present invention is described with reference to FIG. 16 through FIG. 18.  
         [0087]    Also in the present embodiment, a terminal  8  is not designed to hold a joint circuit board. The terminal  8  in the present embodiment is provided at both ends of the connection section  8   a  with a bent section  8   j  which is bent towards the connection section  8   b , and the connection section  8   b  is branched. The ends of the branched connection section  8   b  are bent towards the connection section  8   a  to form a bent section  8   i.  An elastic section  8   c  joints the connection sections  8   a  and  8   b,  and is disposed at substantially right angles to either of the connection sections  8   a  and  8   b.    
         [0088]    The bent sections  8   i  and  8   j  work to prevent a bonding material  9  from spreading wide on an electrode  1   a  of circuit board  1  and an electrode  3   b  of coupling board  3 , respectively.  
       Sixth Embodiment  
       [0089]    A sixth exemplary embodiment of the present invention is described referring to FIG. 19 through FIG. 21.  
         [0090]    Also in the present embodiment, a terminal  8  is not designed to hold a joint circuit board. The shape of the whole terminal  8  represents a letter Z (or a letter S); the connection section  8   a  and the connection section  8   b  are disposed in substantially parallel to each other. The connection sections  8   a  and  8   b  are jointed by a slant elastic section  8   c.  Thus the terminal  8  is structured simple and easy to manufacture, so it is advantageous in improving the manufacturing productivity.  
         [0091]    As described in the earlier exemplary embodiments, a terminal of the present invention comprises an elastic section  8   c  disposed between the connection sections  8   a  and  8   b.  The elastic section  8   c  can provide an elastic property (spring property) in itself, or at both ends of it; therefore, it is quite advantageous in the heat cycles or other environments.  
         [0092]    Although a dielectric filter has been used as an example of circuit component to which the terminal  8  of the present invention is applicable, use of the terminal  8  is not limited to the dielectric filters. The terminal may be applied also to other electronic components, besides the dielectric filters. Among the dielectric filters, there are other types of filters, for example, a multiplexer, a band pass filter, a band elimination filter, besides the antenna duplexer as illustrated in FIGS. 1, 2 and other drawings.  
         [0093]    Although the terminals  8  in the present embodiments have been provided by machining a material of sheet form, they can of course be provided instead by, for example, press-forming a metal bar, bending an elastic metal bar, or by attaching rod form pieces there to.  
         [0094]    The examples of the present embodiments reveal their significant advantages when they are applied to the circuit components having large outer dimensions, among other circuit components. Namely, the quantity of shift due to difference in the coefficient of thermal expansion goes larger along with the increasing size of a circuit board  1  and a coupling board  3 . The advantage of the present invention becomes significant with such a circuit component which is larger than 60 mm in length L 1 , larger than 5 mm in height L 2  and larger than 15 mm in width L 3 .