Surface-mounted power resistors

Abstract

A surface-mount power resistor may be fabricated using a power resistor of conventional design as its core. A conventional resistor is reworked so as to flatten its leads from a point near their emergence from the generally tubular body of the resistor to the ends of the leads. The reworked resistor is then encapsulated from a point of the flattened portion of one lead to a corresponding point on the other lead, with the resulting mold being shaped as to have at least two opposing flat surfaces. The ribbon-shaped portions of the leads which exit from the molded body are then shaped as desired to afford the finished product. Similar surface-mount electrical components may be fabricated for any component with axial leads.

What is claimed is: 
     
       1. A surface-mount power electrical resistor comprising: a power resistor of conventional design having a first body with opposite ends;   a pair of electrical leads exiting from the opposite ends of the first body and extending axially outwardly therefrom;   each of said leads having a circular cross section along its length from its point of exit from the body to a transition point, and having a ribbon shape along its length thereafter, with the ribbon portion of each lead being approximately coplanar; and,   a hardened molding compound of electrically insulating and thermally conducting material surrounding and completely embedding the resistor of conventional design from a point on the ribbon shaped portion of one lead to a corresponding point on the other lead to form a second body with opposite ends and having at least two opposing flat and coparallel surfaces other than the ends, a portion of the ribbon shaped lead exiting from each of the ends of the second body and protruding approximately coplanarly therefrom, said molding compound encasing and providing rigid structural support for the transition points of said leads.   
     
     
       2. The resistor of claim 1 where the second body is a generally rectangular block with a top surface, a bottom surface, two opposite side surfaces, and two opposing end surfaces. 
     
     
       3. The resistor of claim 2 where the lower surface has two outer recesses for receiving the leads. 
     
     
       4. The resistor of claim 3 where each of said recesses in generally inclined toward the upper surface. 
     
     
       5. The resistor of claim 3 where the leads exiting from the ends of the second body are shaped into a J-bend design with the terminal portion of the leads fit into the recesses. 
     
     
       6. The resistor of claim 3 where the lower surface has a central channel. 
     
     
       7. A surface-mount electrical device with axial leads comprising: a device with axial leads of conventional design a first body with opposite ends;   a pair of electrical leads exiting from the opposite ends of the first body and extending axially outwardly therefrom;   each of said leads having a circular cross section along its length from its point of exit from the body to a transition point, and having a ribbon shape along its length thereafter, with the ribbon portion of each lead being approximately coplanar; and,   a hardened molding compound of electrically insulating and thermally conducting material surrounding and completely embedding the device with axial leads of conventional design from a point on the ribbon shaped portion of one lead to a corresponding point on the other lead to form a second body with opposite ends and having at least two opposing flat and coparallel surfaces other than the ends, a portion of the ribbon shaped lead exiting from each of the ends of the second body and protruding approximately coplanarly therefrom, said molding compound encasing and providing rigid structural support for the transition points of said leads.   
     
     
       8. A surface-mount electrical device of claim 7 where the device is an inductor, a diode, or a capacitor. 
     
     
       9. The device of claim 7 where the second body is a generally rectangular block with a top surface, a bottom surface, two opposite side surfaces, and two opposing end surfaces. 
     
     
       10. The device of claim 9 where the lower surface has two outer recesses for receiving the leads. 
     
     
       11. The device of claim 10 where each of said recesses in generally inclined toward the upper surface. 
     
     
       12. The resistor of claim 10 where the leads exiting from the ends of the second body are shaped into a J-bend design with the terminal portion of the leads fit into the recesses. 
     
     
       13. The device of claim 10 where the lower surface has a central channel. .Iadd. 
     
     
       14.  An improved method of manufacturing a surface-mounted electrical device which is intended for use on printed circuit boards and the like, which has a conventional design, and which includes a first body having opposite ends and having a pair of electrical leads that exit axially from the opposite ends of the first body and that have a generally circular cross-section along their lengths from the opposite ends of the first body to their free ends, the improved method comprising the steps of: flattening a portion of each of the electrical leads, this portion extending form the free end of the electrical lead to a predetermined transition point that is spaced from but is adjacent to the opposite ends of the first body; and   embedding the first body in a second body of moldable, hardenable, electrically insulative and heat conductive material, with the second body encapsulating the first body and each of the axial leads from the first body beyond the transition points so that the second body, when the material hardens, provides a rigid structural support for the transition points of the electrical leads. .Iaddend. .Iadd.15. The improved method of claim 14 which further comprises the steps of cutting at least one of the electrical leads at a point between its transition point and its free end and shaping the remaining flattened portion of the electrical lead to facilitate mounting the device on a surface of printed circuit board. .Iaddend. .Iadd.16. The improved method of claim 14 wherein the electrical device is a power resistor; and which further comprises the step of flattening the electrical leads between their transition points and free ends so that the flatten portions of the electrical leads are coplanar at least adjacent to the transition points. .Iaddend. .Iadd.17. The improved method of claim 14 wherein the electrical device is a power resistor; and which further comprises the steps of shaping the second body so that it is a generally rectangular block or box-like in shape, with all of its surfaces, including the opposite ends, being generally flat. .Iaddend. .Iadd.18. The improved method of claim 17 which further comprises the step of forming the second body so that all of its opposing surfaces are approximately parallel. .Iaddend. .Iadd.19. The improved method of claim 16 which further comprises the steps of cutting at least one of the electrical leads at a point between its transition point and its free end and shaping the remaining flattened portion of the electrical lead to facilitate mounting the device on a surface of printed circuit board. .Iaddend. .Iadd.20. The improved method of claim 19 which further comprises the steps of shaping the second body so that it is a generally rectangular block or box-like in shape, with all of its surfaces, including the opposite ends, being generally flat and with all of its opposing surfaces being approximately parallel. .Iaddend.