Patent Publication Number: US-2018035575-A1

Title: Slurry dispensing apparatus for emi shielding

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Korean Patent Application No. 10-2016-0098135, filed on Aug. 1, 2016, in the Korean Intellectual Property Office. The disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field 
     One or more example embodiments relate to an apparatus for dispensing a slurry for electromagnetic interference (EMI) shielding, and more particularly, to an apparatus for dispensing a slurry, in which a conductive metal powder and an adhesive are mixed, to an electronic component in order to form an electromagnetic wave shielding layer on the electronic component. 
     2. Description of the Related Art 
     Electromagnetic interference (EMI) refers to a disturbance caused by an electromagnetic wave that is directly radiated or transmitted from an electric or electronic device and hinders an electromagnetic receiving function of another device. EMI causes various problems such as degradation of functions and reliability of a device and increase in heat emitted from the devices. 
     The EMI may be resolved through three methods, which are a reflection method in which an electromagnetic wave is returned to the device that generated the electromagnetic wave, a by-pass method in which EMI is passed on to another place by using a reflection method or a grounding method, and a shielding method in which a slurry that prevents electromagnetic radiation is dispensed to a product that is likely to generate EMI. Meanwhile, a slurry refers to a mixture of a conductive metal powder having the function of forming an electronic wave shielding layer and an adhesive. Hereinafter, the shielding method which in related to the present disclosure will be described. 
     In the shielding method, a thickness of a slurry to be dispensed varies according to a frequency band of a product, from which an electromagnetic wave is radiated, and metal components of the slurry vary according to the thickness of the slurry. 
     For example, in the case of a product used in a mobile phone that forms a high-frequency band ranging from 1 GHz to 10 GHz, EMI may be prevented effectively even by dispensing a slurry of a small thickness. In this case, as the thickness of the slurry is small, the amount of the included metal powder is relatively small, and thus, silver (Ag) powder, which is relatively expensive, may be used to manufacture a slurry. 
     On the other hand, products used in a communication chip such as Bluetooth devices or an engine control unit (ECU) or a transmission control unit (TCU) used in automobiles, create a relatively low frequency band (MHz). Thus, a slurry has to be relatively thick in order to prevent radiation of low-frequency electromagnetic waves to the outside. Due to the relatively thick thickness of the slurry, if expensive silver powder is used, the manufacturing costs may be increased. Thus, in products that form a low-frequency band, a slurry including iron (Fe) powder which is less expensive than silver powder is used in consideration of the thickness of the slurry. 
     A slurry mixed with metal powder as described above has a relatively high viscosity compared to viscous liquids such as silicon or epoxy and also a low liquidity. In addition, when a slurry is disposed in order to prevent low-frequency band electromagnetic waves, an electromagnetic wave shielding layer having a relatively thick thickness has to be formed, and thus, the amount of a slurry to be dispensed is relatively large. 
     Accordingly, an apparatus for effectively supplying a slurry having a high viscosity and a lower liquidity is needed. 
     In addition, when a slurry, which is a mixture of a metal powder such as silver or iron powder and an adhesive, is on a standby state, the metal powder may precipitate and be separated from the adhesive which is liquid. In order to prevent this, an apparatus for effectively dispensing a slurry to an electronic component while maintaining a uniform mixture of a metal powder and an adhesive of the slurry is needed. 
     SUMMARY 
     One or more example embodiments include a slurry dispensing apparatus for electromagnetic interference (EMI) shielding, whereby a slurry having a high viscosity may be effectively dispensed to an electronic component while maintaining a uniform mixture state of the slurry in which a metal powder is not separated from an adhesive by precipitation. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     According to one or more example embodiments, a slurry dispensing apparatus for electromagnetic interference (EMI) shielding is included, wherein the slurry dispensing apparatus dispenses a slurry, in which a conductive metal powder and an adhesive are mixed, in order to form an electromagnetic wave shielding layer, and includes: a syringe for storing the slurry; a discharge pipe comprising an inlet connected to the syringe to receive the slurry, a nozzle, through which the slurry received through the inlet is discharged, and a connection flow path configured to connect the inlet and the nozzle; a first circulation pipe branched off from the connection flow path of the discharge pipe and connected to the syringe to transfer the slurry supplied to the connection flow path of the discharge pipe, to the syringe; a first conversion valve mounted in a connection portion between the discharge pipe and the first circulation pipe to selectively open and close a flow of the slurry of the connection flow path of the discharge pipe with respect to the nozzle and the first circulation pipe; and a discharge unit mounted on the connection flow path of the discharge pipe to pressurize the connection flow path such that the slurry flows to the first conversion valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawing in which: 
         FIG. 1  is a structural diagram of a slurry dispensing apparatus for electromagnetic interference (EMI) shielding according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A slurry dispensing apparatus for electromagnetic interference (EMI) shielding according to the present invention will now be described more fully with reference to the accompanying drawings. 
     The slurry dispensing apparatus for EMI shielding according to the present embodiment dispenses a slurry to electronic components in order to form an electromagnetic wave shielding layer. A ‘slurry’ described hereinafter refers to a mixture in which a conductive metal powder and an adhesive are mixed. 
     Referring to  FIG. 1 , the slurry dispensing apparatus for EMI shielding according to the present embodiment includes a syringe  100 , a discharge pipe  200 , a first circulation pipe  410 , a first conversion valve  510 , a discharge unit  600 , a reservoir  700 , a supply pipe  800 , a second circulation pipe  420 , a second conversion valve  520 , and a supply unit  900 . 
     The syringe  100  is filled with a slurry to be dispensed to an electronic component. The syringe  100  is in the form of a container. A first agitating member  110  is rotatably mounted in the syringe  100 . The first agitating member  110  agitates the slurry to prevent separation of a metal powder in the slurry from a liquid adhesive by precipitation. The first agitating member  110  according to the present embodiment includes a first agitating axis  112  located in internal space of the syringe  100 , a plurality of first agitation blades  111  coupled to the first agitating axis  112 , and a first rotation motor  113  rotating the first agitating axis  112 . 
     The discharge pipe  200  is connected to the syringe  100 . The discharge pipe  200  includes an inlet  201 , a nozzle  203 , and a connection flow path  202 . The inlet  201  of the discharge pipe  200  is connected to the syringe  100  to receive a slurry. The slurry supplied through the inlet  201  passes by the connection flow path  202  to be transferred to the nozzle  203 . The slurry discharged from the nozzle  203  is dispensed to an electronic component. The connection flow path  202  connects the inlet  201  and the nozzle  203 . The connection flow path  202  of the discharge pipe  200  is formed of an elastic material. According to the present embodiment, the connection flow path  202  is formed of a soft silicon-based tube or a rubber-based tube. The connection flow path  202  formed of an elastic material as described above is elastically deformed in a diameter direction so that the slurry contained in the connection flow path  202  is moved via a roller  630  which will be described later. 
     The first circulation pipe  410  is branched off from the connection flow path  202  of the discharge pipe  200  to be connected to the syringe  100 . The slurry is circulated again to the syringe  100  along the first circulation pipe  410 . 
     The first conversion valve  510  is mounted in a connection portion between the discharge pipe  200  and the first circulation pipe  410 . The first conversion valve  510  selectively opens or closes a flow of the slurry of the connection flow path  202  of the discharge pipe  200  with respect to the nozzle  203  and the first circulation pipe  410 . According to the present embodiment, as illustrated in  FIG. 1 , the first conversion valve  510  is configured, such that a first flow path  512  and a second flow path  513  in a valve body  511  cross each other in a T-shape and are fluidly connected to each other. 
     The discharge unit  600  is mounted on the connection flow path  202  of the discharge pipe  200 . The discharge unit  600  pressurizes the connection flow path  202  so that the slurry flows to the first conversion valve  510 . The discharge unit  600  includes a flow path support  610 , a discharge rotational axis  620 , and a plurality of rollers  630 . 
     As illustrated in  FIG. 1 , the flow path support  610  is mounted at a side of the connection flow path  202  to support the connection flow path  202 . The discharge rotational axis  620  is rotatably mounted at a location separated from the flow path support  610 . Three rollers  630  are mounted on the discharge rotational axis  620 . The three rollers  630  are each arranged at an identical radius from the discharge rotational axis  620  along a circumferential direction. When the discharge rotational axis  620  rotates, the three rollers  630  roll while sequentially pressurizing the connection flow path  202  with respect to the flow path support  610 . 
     The reservoir  700  stores a slurry to be used to replenish the syringe  100 . A second agitating member  120  is rotatably mounted in the reservoir  700 . The second agitating member  120  maintains a uniform mixture of the slurry in the reservoir  700  and prevents deposition of the slurry on an internal wall of the reservoir  700 . In addition, the second agitating member  120  prevents separation of the metal powder included in the slurry from the liquid adhesive by precipitation. 
     The second agitating member  120  includes a second agitating axis  122  located in an internal space of the reservoir  700 , a plurality of second agitation blades  121  coupled to the second agitating axis  122 , and a second rotation motor  123  rotating the second agitating axis  122 . 
     A supply pipe  800  is connected to the reservoir  700 . The supply pipe  800  connects the reservoir  700  and the syringe  100  to supply a slurry in the reservoir  700  to the syringe  100 . The supply pipe  800  is also formed of an elastic material like the discharge pipe  200 . According to the present embodiment, the supply pipe  800  is formed of a soft silicon-based or rubber-based tube. The supply pipe  800  formed of an elastic material is elastically deformed in a diameter direction such that the slurry may be moved via a roller  930  which will be described later. 
     The second circulation pipe  420  is branched off from the supply pipe  800  and is connected to the reservoir  700  again. The slurry moving along the supply pipe  800  is circulated to the reservoir  700  via the second circulation pipe  420 . 
     The second conversion valve  520  is mounted in a connection portion between the supply pipe  800  and the second circulation pipe  420 . The second conversion valve  520  selectively opens or closes a flow of the slurry in the supply pipe  800  with respect to the syringe  100  and the second circulation pipe  420 . Like the first conversion valve  510 , the second conversion valve  520  is rotatably mounted to the connection portion between the supply pipe  800  and the second circulation pipe  420 . According to the present embodiment, like in the first conversion valve  510 , a first flow path  522  and a second flow path  523  cross each other in a T-shape and are fluidly connected to each other inside a vale body  521  in the second conversion valve  520 . 
     The supply unit  900  is mounted to the supply pipe  800 . The supply unit  900  pressurizes the supply pipe  800  such that the slurry flows to the second conversion valve  520 . Like the discharge unit  600 , the supply unit  900  also includes a supply support  910 , a supply rotational axis  920 , and a plurality of rollers  930 . 
     As illustrated in  FIG. 1 , the supply support  910  is mounted on a side of the supply pipe  800  to support the supply pipe  800 . The supply rotational axis  920  is rotatably mounted to the supply support  910  at a distance from the supply support  910 . Three rollers  930  are arranged at an identical radius along a circumferential direction and at an identical angle distance from the supply rotational axis  920 . The three rollers  930  roll while sequentially pressurizing the first side of the supply pipe  800  with respect to the supply support  910 . 
     Meanwhile, the reservoir  700  has a concave bottom portion. The supply pipe  800  is connected to a lowest point in the concavely formed reservoir  700 . Metal powder precipitated from the slurry may precipitate in the concavely formed area in the reservoir  700 . As the supply pipe  800  is connected to the lowest point in the reservoir  700 , a portion of the slurry that is located at the lowest point in the reservoir  700  may be discharged first and supplied into the syringe  100 . 
     A supply flowmeter  400  is mounted between the syringe  100  and the second conversion valve  520 . The supply flowmeter  400  measures a supply amount of the slurry supplied to the syringe  100 . 
     Hereinafter, an operation of the slurry dispensing apparatus for EMI shielding of the embodiment configured as described above will be described. 
     First, an operation of the slurry dispensing apparatus will be described with respect to the reservoir  700 , from which a slurry is transferred to replenish the syringe  100 . 
     As the second agitating member  120  mounted in the reservoir  700  is operated, the slurry in the reservoir  700  is agitated. The plurality of second agitation blades  121  rotate via operation of the second rotation motor  123  coupled to the second agitating axis  122 , thereby agitating the slurry. According to the operation of the second agitating member  120  as described above, precipitation of metal powder of the slurry is prevented, and a mixture ratio between the metal powder and the adhesive is maintained uniform. 
     An operator may operate the second conversion valve  520  to circulate the slurry or supply the slurry to the syringe  100 . When the supply pipe  800  and the second circulation pipe  420  are connected via the second conversion valve  520 , the slurry in the lower portion of the reservoir  700  flows along the supply pipe  800  to return to the reservoir  700  through the second circulation pipe  420 . When replenishing the syringe  100  with the slurry, the valve body  521  of the second conversion valve  520  is rotated so as to connect the supply pipe  800  and the syringe  100  via the first flow path  522  and the second flow path  523  of the second conversion valve  520 . 
     The supply unit  900  pumps the slurry in the supply pipe  800  such that the slurry in the supply pipe  800  flows along the supply pipe  800 . When the supply rotational axis  920  of the supply unit  900  is rotated, the three rollers  930  sequentially pressurize the supply pipe  800  to elastically deform the supply pipe  800 , thereby pumping the slurry in the supply pipe  800  along the supply pipe  800 . The supply support  910  supports the supply pipe  800  with respect to the rollers  930  so as to facilitate elastic deformation of the supply pipe  800  by the rollers  930 . The slurry in which metal powder is mixed is frequently highly viscous, and by using the supply unit  900  having the above-described structure, the highly viscous slurry may also be effectively supplied. 
     When the slurry in the reservoir  700  is agitated and circulated to the reservoir  700  as described above, following effects may be obtained. 
     Separation of metal powder of the slurry from the adhesive by precipitation may be prevented and deposition of the slurry on an inner wall of the reservoir  700  may be prevented. In addition, by continuously circulating the slurry that is used to replenish the syringe  100 , the syringe  100  may be replenished with the slurry including uniform components. 
     As described above, the supply pipe  800  may be connected to the lowest point in the reservoir  700 . According to the structure, the slurry that is located at the lowest portion in the reservoir  700  is first discharged to replenish the syringe  100  or is circulated to the reservoir  700 . If the slurry is accumulated in the reservoir  700 , the slurry may be adhered to the inner wall of the reservoir  700  as time passes, and the inconvenience of having to clean the reservoir  700  may be aroused. However, when the slurry is replenished into the syringe  100  or circulated again to the reservoir  700  by discharging first the slurry located in the lower portion in the reservoir  700  through the supply pipe  800  connected to the lower portion of the reservoir  700  as described above, the above problem may be prevented. 
     Meanwhile, an operator may measure an amount of the slurry supplied to the syringe  100  by using the supply flowmeter  400 . If the amount of the slurry supplied to the syringe  100  is determined to be excessive, a rotational speed of the supply rotational axis  920  may be reduced to adjust the amount of the supplied slurry. In addition, by measuring the amount of the slurry supplied to the syringe  100 , by using the supply flowmeter  400 , a degree of agitation of the slurry in the syringe  100  may be predicted, and a rotational speed of the first rotational motor  113  in the syringe  100  may be adjusted such that components of the slurry are maintained uniform. 
     When the slurry in the reservoir  700  is used to replenish the syringe  100  as described above, the slurry stored in the syringe  100  may be used and dispensed to electronic components. 
     Hereinafter, an operational relationship with respect to the syringe  100  will be described. 
     First, an operation of circulating the slurry stored in the syringe  100  will be described. 
     The first agitating member  110  prevents deposition of the slurry in the syringe  100  on an inner wall of the syringe  100 , and prevents separation of the metal powder in the slurry from the adhesive by precipitation so as to maintain uniformity of the components of the slurry. The plurality of agitation blades  111  agitate the slurry by rotating via an operation of the first rotation motor  113  coupled to the first agitating axis  112 . 
     When an operator rotates a valve body  511  of the first conversion valve  510  so as to connect the connection flow path  202  of the discharge pipe  200  and the first circulation pipe  410  via the first flow path  512  and the second flow path  513 , the slurry flows from the inlet  201  of the discharge pipe  200  connected to the syringe  100  to pass through the connection flow path  202  and then flow to the first circulation pipe  410 . 
     The discharge unit  600  pumps the slurry in the connection flow path  202  such that the slurry in the connection flow path  202  of the discharge pipe  200  flows along the connection flow path  202 . When the discharge rotational axis  620  of the discharge unit  600  is rotated, the three rollers  630  sequentially pressurize the connection flow path  202  to deform the connection flow path  202 , thereby moving the slurry in the connection flow path  202  along the connection flow path  202 . Here, the flow path support  610  supports the connection flow path  202  with respect to the rollers  530  to thereby facilitate elastic deformation of the connection flow path  202  by the rollers  630 . The slurry in which metal powder is mixed is frequently highly viscous, and by using the discharge unit  600  having the above-described structure, the slurry having a high viscosity may be effectively pumped. 
     The slurry has a high viscosity as a conductive metal powder and an adhesive such as an epoxy are mixed in the slurry. The highly viscous slurry has a high possibility of deposition, and thus, it is difficult to move the slurry through flow paths by using a typical pump. By considering this, the slurry dispensing apparatus for EMI shielding according to the present embodiment includes the discharge unit  600  that operates in a peristaltic pump manner and the connection flow path  202  that is formed of an elastic material, and accordingly, the highly viscous slurry may be effectively pumped. 
     The highly viscous slurry flows smoothly and circulates while maintaining a uniform state by using the discharge unit  600  that operates in a peristaltic pump manner and through the connection flow path  202  formed of an elastic material. In addition, as the slurry is continuously circulated, pollution that may be caused by accumulation of the slurry in the syringe  100  may be prevented. 
     Hereinafter, an operation of dispensing a slurry to an electronic component will be described. 
     When an operator operates the first conversion valve  510  to connect the connection flow path  202  and the nozzle  203  of the discharge pipe  200  via the first flow path  512  of the first conversion valve  510 , the slurry of the syringe  100  is discharged through the nozzle  203  via an operation of the discharge unit  600 . The slurry discharged through the nozzle  203  is dispensed to an electronic component disposed below the nozzle  203 . The first agitating member  110  in the syringe  100  operates continuously while the slurry is dispensed to electronic components, thereby maintaining components of the slurry uniform. 
     The syringe  100 , the discharge pipe  200 , the first conversion valve  510 , and the discharge unit  600  may be mounted on a transporting member to be transported forward and backward and to the left and to the right. In this case, a slurry dispensing operation may be sequentially performed on a plurality of electronic component disposed below the above-described elements. 
     As described above, as the slurry is continuously circulated with respect to the syringe  100  before being dispensed to an electronic component, a density of the metal powder is maintained uniform. In addition, the highly viscous slurry may be stably supplied to the nozzle  203  via the discharge unit  600 , and thus, an exact amount wished by the operator may be dispensed to an electronic component. 
     While the present invention has been described with reference to preferred embodiments above, the scope of the present invention is not limited to the embodiments described above and illustrated in the drawings. 
     For example, while the embodiment has been described above, in which the syringe  100 , the discharge pipe  200 , the first circulation pipe  410 , and the first conversion valve  510  that are used to dispense a slurry, and the discharge unit  600 , the reservoir  700 , through which the slurry is supplied into the syringe  100 , and other peripheral components are included, the slurry dispensing apparatus according to the present invention may also include only a syringe and a discharge unit to dispense a slurry, and may not include a reservoir and peripheral components. In this case, a reservoir having a different structure than the above-described structure may be connected to the slurry dispensing apparatus, and the slurry dispensing apparatus having a structure not including a reservoir and peripheral components thereof may be manufactured to be produced, sold or used. 
     In addition, as illustrated in  FIG. 1  above, while the embodiment in which the slurry in the reservoir  700  is also circulated to replenish the syringe  100  with the slurry has been described above, an embodiment in which a reservoir storing a slurry is connected to a syringe to replenish the syringe with the slurry, without circulating the slurry in the reservoir, may also be implemented. 
     In addition, the first conversion valve  510  and the second conversion valve  520  may also have other various configurations such as a structure in which flow paths may be selectively opened or closed. 
     In addition, while it is described that the operator rotates the valve bodies  511  and  521  of the first conversion valve  510  and the second conversion valve  520 , the embodiments are not limited thereto. A controller that is additionally provided may be used to operate a first conversion valve and a second conversion valve via an electrical signal. 
     In this case, the controller receives an amount of a slurry measured using a supply flowmeter. The controller controls a rotational speed of a supply rotational axis such that a desired amount of a slurry by the operator is supplied to the syringe. In addition, an amount of a slurry supplied to the syringe may be transmitted to the controller to predict a present amount of the slurry in the syringe, and an operation of a first rotational motor may be controlled to adjust a degree of agitation in the syringe based on the predicted amount of the slurry. In addition, if the amount of the slurry supplied to the syringe is determined to be excessive, a rotational speed of the discharge rotational axis may be controlled. 
     A viscosity measuring sensor for measuring a viscosity of the slurry may be further mounted in the supply flowmeter. A viscosity of the slurry sensed using the viscosity measuring sensor is transmitted to the controller, and the controller may adjust rotational speeds of a first rotational motor and a second rotational motor such that a viscosity of the slurry wished by the operator is maintained. 
     According to the slurry dispensing apparatus for EMI shielding, a slurry may be dispensed while preventing separation of a metal powder included in the slurry from an adhesive by precipitation and maintaining a uniform mixture ratio in the slurry. 
     While one or more example embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.