Patent Publication Number: US-10319519-B2

Title: Method for producing an induction component

Description:
The invention relates to a method of producing an induction component and to an induction component produced by this method. 
     A method of producing an inductor is already known (KR 10-1044607). A coil core, a coil casing and a cover made of a metallic magnetic powder are produced here and pressed in a mould with the previously wound coil. The winding ends are located in the region of the end side of the inductor thus produced. 
     In the case of a further known method (KR 10-1044608), a multiplicity of connection terminals are incorporated in a first mould and a multiplicity of individual coils are incorporated in a second mould. The two moulds are positioned one upon the other and the coil connections are soldered to the connection terminals. 
     In the case of yet a further known method (KR 10-2011-0100096), a coil core, coil casing and coil cover are pressed in a mould together with the coil. Electrical contact is made at the winding ends, which are located in the end surface of the resulting inductor, by sputtering. 
     It is an object of the invention to provide a method of producing induction components which is easy to carry out and with the aid of which a multiplicity of induction components can be produced at the same time. 
     In order to achieve this object, the invention proposes a method having the features mentioned in Claim  1 . Developments of the invention form the subject matter of dependent claims. 
     In accordance with the method, therefore, a multiplicity of coils are arranged one beside the other and embedded in a block, common to all the coils, made of pressed ferromagnetic substrate. The interior of the coils arranged in the block is filled with for example ferromagnetic substrate, which is present in powder form, and the substrate powder is then pressed. This results in a block with a multiplicity of coils. The wires leading to the windings of each coil are exposed and provided with connection contacts. Only then is the block divided up into the individual induction components, which then contain normally just a single coil. In some cases, it is also possible to divide up the block to produce induction components which contain more than one coil. 
     The individual coils of the multiplicity of coils may be identical to one another. However, it is likewise possible for the coils to differ from one another, both in the number of windings and in shape. 
     According to the invention, provision can be made, in a development of the invention, for the block to be formed only once the coils have been arranged in position, for example by the substrate powder being applied around the coils and then pressed. 
     However, it is likewise possible, and falls within the context of the invention, for the block to be produced, by virtue of the substrate powder being pressed, in a first instance with a cavity for each coil, said cavity corresponding in shape and size to a respective coil, and for the coils then to be inserted into the cavity. 
     In a development of the invention, provision can be made, in order to produce the coils, for a template which has a multiplicity of stubs arranged one beside the other and running parallel to one another. A winding wire can then produce the coils, with the aid of a suitable device, by winding around the individual stubs. Provision can be made here for use to be made of a continuous wire for a multiplicity of coils, possibly even for all the coils. 
     Once winding has taken place around the stubs on the template, this template can serve, at the same time, for arranging the coils in position during production of the block from ferromagnetic material. For this purpose, provision can be made for the template with the coils wound on its stubs to be incorporated in a moulding press. The substrate powder is then introduced into the moulding press until the stubs are completely covered with powder. This is followed by the substrate powder being pressed, which results in the block provided with the coils embedded therein being produced. 
     In a development of the invention, provision can be made for the template with the stubs to be removed from the block, the block with the hollow-interior coils then remaining. The block can then be turned round, and therefore the opening which leads into the interior of the coils is directed upwards. In this orientation, the block is incorporated in a moulding press and further substrate powder is introduced, this further substrate powder then filling the interior of the coils. A subsequent pressing operation results in the coil core being formed and being connected to the block. As an alternative, it is also possible to insert a prefabricated coil core. 
     In a development of the invention, provision can be made, prior to the connection contacts being applied, for the upper side of the block, that is to say the side on which the wires run between the coils, to be provided with incisions between the coils. Continuous wires can be severed during production of these incisions, and therefore the winding ends of the coils are defined, at the same time, in this way. The operation of applying the connection contacts, for example by sputtering, then takes place into the incisions, and therefore the walls of the incisions are metallized. 
     In a development of the invention, provision can be made for the incisions to be made between the coil regions, at the location where the block is later divided up to form the individual induction components. 
     It has proven to be particularly expedient for the coils to be arranged in a matrix-like arrangement, in rows and columns, in the block. The incisions are then arranged only between the rows of the coils, to be precise in the direction transverse to the course taken by the wires. 
     It is also possible, prior to the connection contacts being applied, for masking then to take place in rows. 
    
    
     
       Further features, details and advantage of the invention can be gathered from the claims and the abstract, which are both worded with reference to the contents of the description, from the following description of preferred embodiments of the invention and with reference to the drawing. Individual features of the different embodiments can be combined with one another in any desired manner here without departing from the framework of the invention. In the drawing: 
         FIG. 1  shows a plan view of a template for winding a multiplicity of coils; 
         FIG. 2  shows a side view of the template from  FIG. 1 ; 
         FIG. 3  shows, schematically, the plan view of the template from  FIG. 1  once winding has taken place around the individual stubs; 
         FIG. 4  shows the lateral view, corresponding to  FIG. 2 , of the template once the coils have been produced; 
         FIG. 5  shows, schematically, the arrangement of the wound template in a moulding press; 
         FIG. 6  shows, schematically, the block produced in the moulding press, once the template has been removed; 
         FIG. 7  shows the arrangement of the turned-around block in a moulding press; 
         FIG. 8  shows the block with coils, removed from the moulding press from  FIG. 7 ; 
         FIG. 9  shows the block once incisions have been made; 
         FIG. 10  shows the block once the connection contacts have been applied; 
         FIG. 11  shows, on an enlarged scale, a side view of an induction component produced; 
         FIG. 12  shows a perspective view, in simplified form, of a block with, in this example, eight cavities of different shapes; 
         FIG. 13  shows a perspective view of a coil; 
         FIG. 14  shows the side view of the coil from  FIG. 13 ; 
         FIG. 15  shows a section through the block with coils incorporated therein; 
         FIG. 16  shows the isostatic pressing operation; 
         FIG. 17  shows the method step of exposing the winding ends of the coils; 
         FIG. 18  shows the result of the operation of exposing the winding ends; 
         FIG. 19  shows the induction components produced by the block being divided up; 
         FIG. 20  shows the perspective view of an induction component according to the invention; and 
         FIG. 21  shows the induction component from  FIG. 20  in a partially opened state. 
     
    
    
     The method proposed by the invention of producing a number of induction components at the same time will be explained hereinbelow with reference to a possible embodiment. 
     In the first instance, use is made of a template  1 , which can be used a number of times. This template  1  is illustrated in  FIGS. 1 and 2 . It contains a wire-winding plate  2  which, in the example illustrated, is of right-angled design. Three rows of stubs  3 , which are aligned in four columns, are arranged on the upper side of the wire-winding plate  2 . In the example illustrated, all the circular-cylindrical stubs  3  have the same diameter and, as can be gathered from  FIG. 2 , the same length. All the stubs  3  on the upper side of wire-winding plate  2  run perpendicularly to the wire-winding plate and are thus oriented parallel to one another. There is an identical distance between the individual stubs  3  in the direction of the rows, and the same goes in the direction of the columns. The stubs  3  merge into the plate  2  by way of a radius, which ensures that the coil, see  FIG. 14 , has a conical recess on the side on which the start of the winding and winding end are located. This gives rise to the winding end and start of the winding being guided out of the coil over a radius. This prevents damage to the insulation of the winding wire and also prevents the winding wire from being bent and damaged when it is being embedded in the substrate and when the substrate is being pressed. 
     A wire-winding machine is then used to wind, around the stubs, a wire  4  which, in the example illustrated schematically in  FIG. 3 , is continuous for a respective row of stubs  3 . One coil  5  is thus produced for each stub  3 . It is possible, for example, that they have an identical number of windings for each coil  5 . 
     Instead of the arrangement illustrated in  FIG. 3 , in which use is made of a dedicated wire  4  for each row of stubs  3 , it is also possible to have an arrangement in which use is made of a continuous wire  4  for all the stubs  3 . 
       FIG. 4  shows, schematically, the wound template from  FIG. 3  as seen from the side, that is to say from the same direction as the view of  FIG. 2 . 
     That part of the wire  4  which projects beyond the side edges of the wire-winding plate  2  is cut off, and the template  1  is then incorporated in a schematically illustrated moulding press  6 , see  FIG. 5 . The template  1  is oriented such that the wire-winding plate  2  is located at the bottom and the stubs  3  with the coils  5  project into the interior of the moulding press  8 . A first substrate powder  7  is then introduced into the interior of the moulding press  6  until the stubs  3  are completely concealed in the substrate powder  7 . The substrate powder  7  is then pressed to form a solid block, this not being illustrated specifically. It is possible, for example, for a pressure of 250 kg/cm 2  to be applied during this pressing operation of the first substrate powder  7 . 
     The block  8  pressed to this extent is then removed, with the template  1 , from the moulding press  6  and turned round. Thereafter, the template  1  is removed from the block, the coils  5  now being embedded there, see  FIG. 6 . A cavity  9 , which projects into the block  8 , is now located where the stubs  3  were located beforehand. 
     The block  8 , according to  FIG. 7 , is then incorporated, in its turned-round state, in a moulding press  10  once again, and a second substrate powder  11  is introduced into the openings until the interiors of the coils  5  are completely filled with substrate powder  11 . The second substrate powder  11  may differ from the first substrate powder  7 . It is also possible for the cavity  9  to be filled with a pre-pressed coil core, wherein interspaces are filled, in addition, with substrate powder. Then, once again, pressing takes place until the coil cores thus formed are connected to the block  8 . It is possible, for example, for a pressure of 200 kg/cm 2  to be applied during this second pressing operation. 
     The result is a block  8  with coils  5  embedded therein, said coils each also having a coil core, and with continuous wires  4  between all the coils  5  of one row. The result is illustrated in the schematic lateral view, or in section, in  FIG. 8 . 
     If necessary, in order to achieve desired dimensions of the block  8  or of the induction components produced therefrom in the mould  10 , it is possible for said block  8  to be provided with a further layer of substrate powder, said layer then being pressed. The substrate powder here may be the same as, or different from, the first substrate powder  7  or second substrate powder  11 . Using different substrate powders, with differently magnetic properties, for the individual pressing operations makes it possible to set a desired level of inductance for induction components produced. It is possible, for example, for a pressure of 220 kg/cm 2  to be applied during this third pressing operation. The pressing operations for producing or pressing the block  8  are carried out, for example, at a pressure between 200 kg/cm 2  and 300 kg/cm 2 . 
     The block  8  can then be pressed isostatically, the pressure here being significantly higher, for example at least ten times the pressure, in particular 4500 kg/cm 2 , than during the preceding pressing operations. The isostatic pressing operation advantageously follows a temperature and pressure profile over time. 
     The next step is for all the coils of a column to be provided with a masking  12 . Incisions  13  are then made in the block  8 , between the columns of the coils  5 , the depth of said incisions being less than that of the coils  5 , see  FIG. 9 . The incisions  13  thus run transversely to the course taken by the wires  4 , see  FIG. 3 . 
     Electrical connection is then made by known methods, for example by sputtering. The metal here is applied to the surface of the block  8  and to the side walls of the incisions  13 . The result is illustrated in  FIG. 10 , where the contacts  14  rest both on the wire structure  4  and in the incisions  13 . 
     Thereafter, the block  8  is divided up, to be precise by way of cuts which are guided both between the rows, and between the columns, of the coils  5 . The cuts here run centrally in the incisions  13 . 
     This gives rise to a multiplicity of induction components  15 , see  FIG. 11 , which have the respective connection contact  14  both on their underside  16  and on the two adjacent sides  17 . In the event of soldering to a printed circuit board  18 , the solder  19  also adheres to the sides  17  of the induction component  15 . The presence of the solder  19  can therefore be detected optically from a direction perpendicular to the printed circuit board. This allows automatic fault detection. 
     The method proposed by the invention will now be explained with reference to a further exemplary embodiment.  FIG. 12  here shows a perspective view of a block  101  which has been produced, under high pressure, in the form of a pressed substrate from an in particular ferromagnetic powder mixture at the beginning of the method process. The block  101  is in the form of a flat rectangular plate with a planar upper side  102  and a likewise planar underside  103 , which runs parallel to the upper side  102 . Proceeding from the upper side  102 , the block has formed in it, in the example illustrated, eight cavities  104 , which are designed in the form of blind holes, that is to say each with a base  105 . The example illustrated has two rectangular cavities  104 , two square cavities  104 , two round cavities  104  and two elliptical cavities  104 . This is intended to illustrate that the block  101  can be designed for induction components of a wide variety of different shapes and sizes. 
       FIG. 13 , then, shows the perspective view of a coil  108 , which has the winding ends  106 ,  107  at its one axial end, illustrated at the top in  FIG. 13 . The two winding ends  106 ,  107  are bent such that they run transversally to the axis of the coil  108  and project outward beyond the outer contour of the coil  108 . The two winding ends  106 ,  107  also run along a diameter of the coil. As can be seen, the winding ends  106 ,  107  are guided out of the winding over a radius. 
       FIG. 14  shows the coil  106  from  FIG. 13  from the side. It can also be seen here that the winding ends  106 ,  107  of the coil-forming winding project beyond the outer contour of the coil and are located in a common plane. The winding end  106  forms the start of the winding. 
     The block  1  from  FIG. 12  is intended, as already mentioned, for accommodating a multiplicity of coils. Continuing the method, then, all the coils  108  are inserted into the associated cavities  104 . In the case of a coil  108 , as shown in  FIGS. 13 and 14 , the cavities  104  are adapted to the coil  108  such that the winding ends  106 ,  107 , rather than fitting into the cavity, end up in abutment against the upper side  102  of the block  101 . The winding ends  106 ,  107  then rest in planar fashion on the upper side  102 . 
       FIG. 15 , then, shows the arrangement of a block  101  in a moulding press  109 . In the first instance, the coils  108  are inserted into the respective cavity  104 , wherein the winding ends  106 ,  107  end up in abutment against the upper side  102  of the block  101 . When the coils  108  are inserted into the respective cavity, it is ensured that the winding ends assume a certain orientation in relation to the cavities. The free space within each cavity is then filled up with a pulverulent substrate, in particular a ferromagnetic powder, or with a pre-pressed core and additional powder, which is filled to the extent where a layer  110  of this powder covers the upper side  102  of the block  101  throughout. The winding ends  106 ,  107  are located in said layer  110 . The block  101  is located on a support plate  111  in the moulding press. The upper part  112  of the moulding press  109  is pressure-activated in the direction of the arrows  113 , wherein the course taken by the pressure corresponds to a time/pressure profile. This profile is selected such that the energy absorbed cannot result in damage to the wire insulation or to the pre-pressed structure. It is additionally possible to have temperature activation taking place in accordance with a predetermined time/temperature profile. Once the amount of time corresponding to the profile has elapsed, the operation of pre-pressing the block  101  with the coils  108  has thus been completed. For example a first pressure ranging between 200 kg/cm 2  and 300 kg/cm 2  is applied during a pre-pressing operation. 
     The block  101  is then removed from the moulding press  109  and introduced into a pressure vessel  114 , which is illustrated schematically in  FIG. 1 . The pressure vessel  114  contains a bearing plate  115  with an upper side  116  which is directed towards the block  101  and of which the surface quality does not exceed a roughness of 0.1 μm, it therefore being possible for said bearing plate also to be referred to as a polished plate. Said upper side  116  contains, for each cavity, a protrusion  117  which is in the form of a small cone and forms a marking. Each of said cones  117  is associated with the orientation of the winding ends  106 ,  107  of the respective coil  108 , in particular with the start of the winding. In other words, the start of the winding  106  of each coil  108  is located opposite a respective cone  117 . The block  101  is oriented on the bearing plate  115 . A silicon layer  118  is then positioned on the layer  110 , which has been applied to the upper side  102  of the block  101 . The unit made up of block  101 , bearing plate  115  and silicon layer  118  is then expediently packed in a liquid-tight manner and, if appropriate, evacuated. Thereafter, the pressure vessel  114  is completely filled with liquid, for example with water, and is subjected to pressure on all sides, as is indicated by the arrows  119 . The silicon layer  118  should prevent damage to the winding ends  106 ,  107 , which are contained in the layer  110 , during pressure activation. The pressure activation causes the cones  117  to generate a complementary depression  21  in the underside  103  of the block  101 . 
     During the pressure-activation operation, temperature activation also takes place. The pressure activation advantageously takes place in accordance with a predetermined time/pressure profile. The temperature activation can also follow a predetermined time/temperature profile. The pressure applied during the isostatic pressing operation is significantly higher than during the pre-pressing operation. For example, the isostatic pressing operation takes place at a maximum pressure of 4500 kg/cm 2  over a temperature range of 20° C. to 100° C., preferably at 80° C. The isostatic pressing operation follows a predetermined temperature profile and pressure profile over time, a so-called temperature/pressure/time profile. 
     Following completion of the isostatic pressing operation, the resulting block provided with the layer  110  is removed from the pressure vessel  114 . The result is then illustrated on the left in  FIG. 17 . The underside  103  of the block  101  has formed in it the depressions  121  which are produced by the cones  117 , each constitute a marking and are located opposite the respective start  108  of the winding of the coils  108 . 
     Next, the upper side of the layer  110 , which can still be seen at the left-hand end of  FIG. 17  is removed with the aid of a grinding or milling device  122  to the extent where the winding ends  106 ,  107  of each coil  108  are freed of their insulation and in particular up to half the cross section thereof is exposed. This is illustrated in the right-hand part of  FIG. 17 . 
     The result is a block  101  in which the winding ends  106 ,  107  of all the coils  108  have been exposed. These winding ends  106 ,  107  can then be provided, by way of a known method, with connection contacts. 
     Thereafter, the induction components, which are the desired end products, are produced by virtue of the block  101  being divided up, see  FIG. 19 . Proceeding from  FIG. 18 ,  FIG. 19  shows how individual inductors  124  are produced from the continuous block  101  by virtue of the latter being sawn up. 
     The following figure,  FIG. 20 , shows a perspective view of an inductor  124 . The former underside  103  of the block  101  now forms the upper side of the inductor  124 . This upper side can be seen to contain a hole  121 , which has been generated by the cone  117  of the support plate  115 . Two connection-contact elements  126 ,  127  are applied to the former upper side of the block  101 , said former upper side forming the Underside of the inductor  124 , and are connected electrically and mechanically to a respective winding end  106 ,  107 . This connection between the contact elements  126 ,  127  and the winding ends  106 ,  107  is indicated in  FIG. 21 , which does not illustrate the ferromagnetic material, which actually tightly encloses the coils  108 . Since it has been pressed by means of the polished bearing plate  115 , the upper side of the inductor  124  has a very low level of surface roughness and can therefore be gripped reliably for pick-and-place purposes by extremely small suction grippers. Typically, the inductor  124  has an edge length between approximately 1 mm and 5 mm. The hole  121 , which is designed in the form of a conical blind hole, is an indication of the orientation of the start  106  of the winding, and therefore the induction component  124  can be positioned automatically with desired orientation of the start  106  of the winding.