Abstract:
In order to properly hold a number of miniaturized electronic component chips so that processing such as formation of external electrodes can be efficiently performed, a holder having an adhesive face to be stuck to first end surfaces of a number of electronic component chips for holding the electronic component chips is employed. The number of electronic component chips being held by the holder are dipped in electrode paste, so that external electrodes are formed on second end surfaces thereof. Then, an adhesive face of another holder having stronger adhesion than the adhesive face of the first holder is stuck to the electronic component chips, whereby the number of electronic component chips are simultaneously transferred to this holder. The first end surfaces are then also dipped in electrode paste to form external electrodes thereon.

Description:
This is a continuation of application Ser. No. 07/855,202 filed on Mar. 20, 1992, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of handling electronic component chips and a combination of electronic component chip holders which are advantageously employed for carrying out the method. 
     2. Description of the Background Art 
     FIG. 10 is a perspective view showing an exemplary electronic component chip 1, to which the present invention can be applied. The electronic component chip 1 may be a capacitor chip such as a multilayer ceramic capacitor, a resistor chip, or an inductor chip, for example. 
     The electronic component chip 1 has first and second end surfaces 2 and 3, which are opposite to each other. A first end portion of the electronic component chip 1 including the first end surface 2 is provided with an external electrode 4, while a second end portion including the second end surface 3 is provided with another external electrode 5. Throughout the specification, the term &#34;electronic component chip&#34; includes a finished electronic component chip which is already provided with the external electrodes 4 and 5, as well as a semifinished electronic component chip which is not yet provided with the external electrode 4 and/or 5. 
     FIG. 11 shows an electronic component chip holder 6, which has generally been employed for forming external electrodes 4 and 5 on such electronic component chips 1. Such a holder 6 is disclosed in U.S. Pat. Nos. 4,395,184 and 4,381,321. 
     The holder 6 is in the form of a plate as a whole, and provided with a number of receiving portions 7, which are defined by through holes, for receiving the electronic component chips 1, in order to efficiently carry out a step of forming external electrodes. 
     FIG. 12 shows a section of the holder 6. This holder 6 comprises cores 8 which are covered with an elastic member 9, and the aforementioned receiving portions 7 are defined by through holes which are formed to pass through the elastic member 9. Thus, the electronic component chips 1 inserted in the receiving portions 7 are held by elasticity of the elastic member 9. 
     In order to form the external electrodes 4 and 5 on the electronic component chips 1, the following operation is carried out: 
     First, the electronic component chips 1 are inserted in the receiving portions 7 of the holder 6, so that a plurality of electronic component chips 1 are held by the holder 6 as shown in FIG. 12. An orientation device and pushers, which are not shown in the figure, can be employed for inserting the electronic component chips 1 in the receiving portions 7. 
     On the other hand, electrode paste 11 is applied onto a surface plate 10 in a prescribed thickness. 
     Then, the holder 6 is moved toward the surface plate 10 as shown by arrow 12, to dip the electronic component chips 1 in the electrode paste 11. Thus, the external electrodes 4 are formed on first end portions of the electronic component chips 1 including the first end surfaces 2, for example. 
     The external electrodes 4 formed by the electrode paste 11 are dried. 
     The electronic component chips 1 are extruded by pushers toward an opposite surface of the holder 6 through the through holes defining the receiving portions 7, and held in a state exposing the second end portions including the second end surfaces 3. 
     A step substantially similar to that shown in FIG. 12 is carried out to form the other external electrodes 5. 
     While such a holder 6 is adapted to handle a number of miniature electronic component chips, recent development of miniaturization of electronic component chips sometimes leads to difficulty in employment of such a holder 6. Since the receiving portions 7 of the holder 6 must be reduced in inner diameter following reduction in size of the electronic component chips, it is difficult to manufacture the holder 6 itself. Further, pushers for inserting and transferring the electronic component chips in and from the receiving portions 7 of the holder 6 must have operating portions which are smaller in diameter than the receiving portions 7. Thus, the operating portions of the pushers are made so insufficient in strength that it is difficult to properly use the same. In addition, parts of the electronic component chips inserted in the receiving portions 7 are reduced in length, and hence it is difficult to hold the electronic component chips by the holder 6. 
     While the above description is made in relation to the step of forming external electrodes on the electronic component chips, a similar problem may also be caused in a step of performing processing other than formation of external electrodes on the electronic component chips. 
     On the other hand, Japanese Utility Model Laying-Open No. 62-140720 (1987) describes a holder for holding electronic component chips with adhesion, for measuring characteristics of the electronic component chips. This holder comprises an elastic member of silicone rubber, for example, having viscosity at least on its surface, to hold electronic component chips on the surface of the elastic member with adhesion. Terminals for measurement are brought into contact with the electronic component chips held in such a manner, to measure prescribed electric characteristics of the electronic component chips. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a combination of electronic component chip holders, which can properly hold and transfer electronic component chips even if the same are miniaturized. 
     Another object of the present invention is to provide a method of handling electronic component chips using the aforementioned combination of electronic component chip holders. 
     Provided according to the present invention is a combination of a first electronic component chip holder having a first adhesive face which is stuck to electronic component chips for holding the electronic component chips and a second electronic component chip holder having a second adhesive face which provides adhesion being stronger than that provided by the first adhesive force. 
     The inventive handling method is applied to electronic component chips having first and second end surfaces which are opposite to each other for performing prescribed processing on respective ones of first end portions including the first end surfaces and second end portions including the second end surfaces, and in order to solve the aforementioned technical problems, this method comprises the steps of: 
     (1) preparing a first electronic component chip holder having a first adhesive face which is stuck to prescribed surfaces of electronic component chips for holding the electronic component chips and a second electronic component chip holder having a second adhesive face which provides adhesion stronger than that provided by the first adhesive face, 
     (2) sticking the first adhesive face of the first electronic component chip holder to the first end surfaces of the electronic component chips for holding the electronic component chips by the first electronic component chip holder, 
     (3) performing prescribed processing on the second end portions of the electronic component chips which are held by the first electronic component chip holder, 
     (4) moving the first electronic component chip holder holding the electronic component chips toward the second electronic component chip holder for sticking the second adhesive face to the second end surfaces of the electronic component chips, 
     (5) separating the first and second electronic component chip holders from each other for holding the electronic component chips by the second electronic component chip holder, and 
     (6) performing prescribed processing on the first end portions of the electronic component chips which are held by the second electronic component chip holder. 
     Throughout the specification, the &#34;end surfaces&#34; and &#34;end portions&#34; of the electronic component chips are not restricted to the end surfaces 2 and 3 which are located on longitudinal ends of the electronic component chip 1 and the end portions including the end surfaces 2 and 3 as shown in FIG. 10, but also include &#34;end surfaces&#34; and &#34;end portions&#34; which are located on cross-directional and perpendicular ends. 
     Each of the electronic component chip holders according to the present invention holds the electronic component chips with adhesion provided by its adhesive face. Thus, each electronic component chip holder need only be provided with such an adhesive face, whereby its structure is remarkably simplified. 
     Further, each electronic component chip holder can hold the electronic component chips with no regard for the sizes thereof. Further, each electronic component chip holder can hold the electronic component chips by merely sticking the adhesive face to the electronic component chips, whereby the operation for holding the electronic component chips is extremely simplified. 
     In addition, each electronic component chip is held by each electronic component chip holder, whose adhesive face is stuck to either end surface thereof. Thus, the other end surface of each electronic component chip is open so that it is possible to perform prescribed processing such as formation of an external electrode on the end portion including the other end surface with no trouble. 
     Further, each electronic component chip holder according to the present invention requires no specific structure such as through holes for receiving electronic component chips, but the overall adhesive face can be used for holding the electronic component chips. Thus, a single electronic component chip holder can be applied to various sizes of electronic component chips. When a plurality of electronic component chips are held, for example, it is possible to arbitrarily select the state of distribution of the electronic component chips held by the electronic component chip holder. 
     In the inventive method of handling electronic component chips, the aforementioned combination of electronic component chip holders is employed. Therefore, the inventive handling method also has the function/effect of each electronic component chip holder. 
     In the inventive handling method, first and second electronic component chip holders are employed. The first electronic component chip holder has a first adhesive face, while the second electronic component chip holder has a second adhesive face. The second adhesive face is so set as to provide adhesion which is stronger than that provided by the first adhesive face. Therefore, electronic component chips are first held by the first electronic component chip holder, so that respective end portions thereof are successively processed in a prescribed manner. In this state, prescribed processing is performed on end portions of the electronic component chips, which are then held by the second electronic component chip holder so that the other end portions are subjected to prescribed processing. The electronic component chips can be efficiently transferred from the first electronic component chip holder to the second electronic component chip holder on the basis of the aforementioned difference in adhesion. Namely, the second adhesive face of the second electronic component chip holder is stuck to the electronic component chips which are held by the first electronic component chip holder, and thereafter the second electronic component chip holder is separated from the first electronic component chip holder, so that the electronic component chips can be held by the second electronic component chip holder. Therefore, when a plurality of electronic component chips are handled, for example, it is possible to simultaneously transfer such electronic component chips to the second electronic component chip holder while maintaining the state of arrangement on the first electronic component chip holder. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an electronic component chip holder which is employed in an embodiment of the present invention; 
     FIG. 2 is an illustrative sectional view showing a first step included in an external electrode forming method which is carried out using the holder shown in FIG. 1; 
     FIG. 3 is an illustrative sectional view showing a second step included in the external electrode forming method; 
     FIG. 4 is an illustrative sectional view showing a third step included in the external electrode forming method; 
     FIG. 5 is an illustrative sectional view showing a fourth step included in the external electrode forming method; 
     FIG. 6 is an illustrative sectional view showing a fifth step included in the external electrode forming method; 
     FIG. 7 is an illustrative sectional view showing a sixth step included in the external electrode forming method; 
     FIG. 8 is a sectional view of an orientation device 33 which is employed in another embodiment of the inventive method of handling electronic component chips, showing a step corresponding to that shown in FIG. 3; 
     FIG. 9 is a sectional view showing an electronic component chip holder which is employed in still another embodiment of the present invention; 
     FIG. 10 is a perspective view showing an electronic component chip 1 to which the present invention is applied; 
     FIG. 11 is a perspective view showing a conventional electronic component chip holder 6; and 
     FIG. 12 is an illustrative sectional view for illustrating a conventional external electrode forming method for electronic component chips. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view showing an electronic component chip holder 21 which is employed in an embodiment of the present invention. The holder 21 comprises a plate-type body 22 which is made of a material such as a metal or resin, for example. An adhesive film 23 is formed on the body 22, thereby defining an adhesive face 24 on the surface of the adhesive film 23. 
     According to this embodiment, the adhesive film 23 is formed on an elastic body such as rubber, for example. In this case, the adhesive face 24 may be provided from the stickiness of the itself, such as rubber. Alternatively, the elastic body, such as rubber, may be coated with another adhesive to provide the adhesive face 24. 
     The adhesive film 23 may be independently formed in another place, and then pasted on the body 22. Alternatively, the adhesive film 23 may be formed on the body 22. 
     When the adhesive film 23 is formed by an elastic body as described above, the adhesive film 23 is deformed against its own elasticity when electronic component chips are pressed against the adhesive face 24 to be held by the same, so that the adhesive face 24 can be reliably brought into contact with the electronic component chips while advantageously absorbing dimensional errors between the electronic component chips, as described later. Thus, the adhesive face 24 has improved reliability for adhesively holding the electronic component chips. When such an advantage is not desired, however, the adhesive face 24 may be formed by coating the surface of a rigid body with an adhesive, or pasting a pressure sensitive adhesive double coated tape onto such a surface, for example. 
     With reference to FIGS. 2 to 7, a method of forming external electrodes 4 and 5, for example, on electronic component chips 1 such as that shown in FIG. 10, is now described. In this method, two types of electronic component chip holders are prepared, each having the structure shown in FIG. 1. Namely, a first electronic component chip holder 21a shown in FIG. 2, for example, and a second electronic component chip holder 21b shown in FIG. 6, for example, are prepared. The first and second holders 21a and 21b comprise bodies 22a and 22b and adhesive films 23a and 23b of elastic bodies, such as rubber, respectively. A first adhesive face 24a is defined on the adhesive film 23a of the first holder 21, while a second adhesive face 24b is defined on the adhesive film 23b of the second holder 21b. The second adhesive face 24b is so set as to provide adhesion which is stronger than that provided by the first adhesive face 24a. 
     As shown in FIG. 2, an orientation device 25 is overlapped on the first holder 21a, and a plurality of electronic component chips 1 are placed in the orientation device 25 and vibrated to be directed in a prescribed direction in orienting portions 26 which are provided in the orientation device 25. Inlets of the orienting portions 26 are preferably tapered. 
     Then, a flat pressing plate 27 is employed as shown in FIG. 3, to press the respective electronic component chips 1 against the first holder 21a as shown by arrow 28. Thus, the first adhesive face 24a of the first holder 21a is stuck to first end surfaces 2 of the respective electronic component chips 1. Therefore, the electronic component chips 1 are held by the first holder 21a. 
     When the adhesive face 24a is defined on the surface of the adhesive film 23a which is formed by an elastic body such as rubber as shown in this embodiment, it is possible to advantageously absorb longitudinal dimensional errors, which may be caused between the plurality of electronic component chips 1, when the step shown in FIG. 3 is carried Out. Thus, no specific electronic component chip 1 is damaged or separated from the adhesive face 24a. 
     Then, electrode paste 30 is applied to a surface plate 29 in a prescribed thickness, as shown in FIG. 4. On the other hand, the holder 21a is orientated to downwardly direct the electronic component chips 1 which are held by the same. In this state, the holder 21a is moved toward to the surface plate 29 as shown by arrow 31, whereby second end portions of the electronic component chips 1 including second end surfaces 3 are dipped in the electrode paste 30. 
     Then, the electronic component chips 1 are raised up from the electrode paste 30. Thus, external electrodes 5 are formed on the second end portions of the respective electronic component chips 1, as shown in FIG. 5. The external electrodes 5 thus formed by the electrode paste 30 are then dried. 
     The first holder 21a holding the electronic component chips 1 is then moved towards the second holder 21b as shown by arrow 32 in FIG. 6, so that the second adhesive face 24b is stuck to the second end surfaces 3 of the electronic component chips 1. In this step, the electronic component chips 1 are pressed against the second holder 21b through the first holder 21a, similarly to the step shown in FIG. 3. 
     As described above, the adhesion provided by the second adhesive face 24b of the second holder 21b is selected to be stronger than that provided by the first adhesive face 24a of the first holder 21a. When the first and second holders 21a and 21b are separated from each other after the step shown in FIG. 6, therefore, the electronic component chips 1 are held by the second holder 21b, as shown in FIG. 7. 
     Then, steps substantially similar to those shown in FIGS. 4 and 5 are carried out in order to form external electrodes 4 on first end portions of the electronic component chips 1, which are held by the second holder 21b, including the first end surfaces 2. 
     Thus, the external electrodes 4 and 5 are formed on the first and second end portions of each electronic component chip 1, as shown in FIG. 10. 
     While the electronic component chips 1 are dipped in the electrode paste 30 to be provided with the external electrodes 4 and 5 in the aforementioned embodiment, such electrodes may alternatively be formed by another method such as plating, for example. 
     While the electronic component chips 1 are handled to be provided with the external electrodes 4 and 5 in the aforementioned embodiment, the electronic component chip holders and the method of handling electronic component chips according to the present invention are also applicable to processing other than external electrodes 4 and 5. 
     Although the pressing plate 27, which is independent of the orientation device 25, is employed as shown in FIG. 3 in the aforementioned embodiment, an orientation device 33 having a configuration which is integrated with such a pressing plate 27 may alternatively be employed as shown in FIG. 8, to carry out the steps shown in FIGS. 2 and 3. Orientation device 33 has orienting portions 34 which are provided with bottoms. Referring to FIG. 8, elements corresponding to those shown in FIG. 3 are indicated by similar reference numerals, to omit redundant description. 
     Referring to FIG. 8, a plurality of electronic component chips 1 are placed on the orientation device 33 and vibrated to be inserted in a prescribed direction into the orienting portions 34. Electronic component chips 1 which are left on the top surface of the orientation device 33 are removed. Then, a holder 21a is arranged opposite to the orientation device 33. In this state, the holder 21a is moved towards the orientation device 33, whereby the adhesive film 23a is stuck to the electronic component chips 1. According to the embodiment shown in FIG. 8, since the step of inserting the electronic component chips 1 into the orienting portions 26, as shown in FIG. 2, and the step of pressing the electronic component chips 1 against the holder 21a, as shown in FIG. 3 can be continuously carried out, the production facilities can be simplified, and the productivity can be increased. 
     FIG. 9 shows another exemplary electronic component chip holder 21. The feature of this electronic component chip holder 35 resides in the configuration of an adhesive face 38 defined by an adhesive film 37 which is formed on its body 36. The adhesive face 38 is provided with a plurality of cavities 39. Dimensions of these cavities 39, which are adapted to enable correct location and further reliable fixation of electronic component chips, are preferably in conformity to those of the electronic component chips. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention being limited only by the terms of the appended claims.