Low-cost high-density gang-punch

Abstract

A gang-punch pin apparatus for punching selected hole patterns in thin sheet materials such as greensheets is provided. The gang-punch pin apparatus uses program plates in the punch apparatus which plates are positioned intermediate the non-punching end of the punch pins and a clearance plate wherein punch pins not used for punching a particular layer of the MLC are retracted into during punching. At the other punch pin locations, the punch pins, upon activation of the punch apparatus by compressing an expandable chamber, usually by application of a force on the punch apparatus, are extended through the lower portion of the punch apparatus to form vias in a greensheet. A die apparatus is also provided for use with the punch assembly to form the vias and to remove the punched material (slugs) from the die apparatus. The gang punch-pin may be shorter than conventional pins and be made at a low cost because of the thin sheet metal plates preferably used to make the component parts of the punch and die apparatus.

1 . A programmable gang-punch apparatus using punch pins for punching selected hole patterns in thin sheet material wherein, depending on the hole pattern to be punched, some of the punch pins are used for punching and the remaining punch pins are non-punching, the apparatus comprising a pair of opposed plates containing vertical through-holes which are separated by a pressure chamber and in which punch pins having an enlarged upper end are positioned, a program plate overlying the upper opposed plated containing a plurality of vertical through-holes for punch pins where punching is not desired, a clearance plate overlying the program plate having vertical through-holes in all punch pin locations and into which holes non-punching punch pins are retracted during punching of the thin sheet material.  
     
     
         2 . A gang-punch apparatus for punching selected hole patterns in thin sheet material comprises: 
 a lower stripper plate formed with a plurality of vertical through-holes;    a guide plate formed with a plurality of corresponding vertical through-holes wherein the through-holes;    a pressure chamber or other expandable/contracting means between the guide and lower stripper plates, the plates when the chamber is not compressed being in an extended non-punching position and, when compressed, the plates being in a contracted punching position;    a plurality of elongated punch pins axially slideably disposed in the vertical through-holes of the guide and stripper plates with the upper ends of the pins being larger so that the pins rest on the guide plate shoulder, the pins being of a length when the guide and stripper plates are in a contracted punching position, the lower ends of the pins extend below the lower surface of the stripper plate and through a thin sheet material and die;    a program plate disposed on the upper surface of the guide plate formed with a plurality of vertical through-holes overlying non-punching punch pins;    a clearance plate disposed on the surface of the program plate formed with a plurality of vertical through-holes corresponding to the vertical through-holes of the guide and stripper plates, the clearance plate being of a thickness sufficient to contain in the through-holes the non-punching punch pins when the guide and stripper plates are in a contracted punching position; and    means to exert a force on the clearance plate to force the guide and stripper plates closer together thereby extending the punching punch pins below the lower surface of the stripper plate and forming a hole pattern in the thin sheet material with the non-punching punch pins extending into the vertical through-holes of the clearance plate so that there is no punching of the thin sheet material at the non-punching punch pin locations.    
     
     
         3 . The gang-punch apparatus of  claim 2  wherein the expandable contacting means is a pressure chamber.  
     
     
         4 . The gang-punch apparatus of  claim 3  wherein a head plate having corresponding vertical through-holes is disposed intermediate the guide plate and the program plate to form a shoulder on the guide plate to secure the punch pins in the guide and stripper plates.  
     
     
         5 . The gang-punch apparatus of  claim 4  wherein at least one of the plates is made of a thin material fabricated by laser, photoetching, mechanical drilling or electro-discharge machining.  
     
     
         6 . The gang punch apparatus of  claim 2  wherein the guide plate, stripper plate, program plate or clearance plate comprise a composite of multiple plates with the outer plates having uniform, accurately placed holes and the inner plate or plates having larger holes.  
     
     
         7 . The gang punch apparatus of  claim 6  wherein the outer holes are formed by laser or photoetching.  
     
     
         8 . The gang punch apparatus of  claim 7  wherein the outer holes are tapered.  
     
     
         9 . The gang punch apparatus of  claim 2  wherein all the possible punch locations are incorporated on a closely spaced grid.  
     
     
         10 . A die apparatus for use with a punch apparatus for punching hole patterns in thin sheet material comprising: 
 a die plate formed with vertical through-holes corresponding to the punch pins of the punch apparatus;    a window plate on which the die plate is disposed, the window plate comprising a plurality of vertical through-holes each through-hole corresponding to at least one of the vertical through-holes of the die plate and larger than the vertical through-holes of the die plate to support the die plate and to facilitate punched material removal after punching; and    a groove plate on which the window plate is disposed, the groove plate having a plurality of channels preferably less than the number of vertical through-holes in the window plate, each channel corresponding to at least one of the vertical through holes in the window plate and connected to a vacuum and/or pressure source to remove punched material from the die apparatus.    
     
     
         11 . The die apparatus of  claim 10  wherein the window plate comprises a plurality of interconnecting webs which support the die plate and which provides an open area for the removal of punched material.  
     
     
         12 . A method of gang-punching selective hole patterns in thin sheet material comprises the steps of: 
 providing a gang-punch pin apparatus of claim  2 ;    positioning the punch apparatus on top of a greensheet which is disposed on top of a die apparatus;    exerting a force on the punch apparatus collapsing the pressure chamber and moving the desired punch pins through the greensheet and into the die apparatus with the non-punching pins retracting into the clearance plate; and    removing the force on the punch assembly and expanding the pressure chamber to retract the punch pins from the die plate and greensheet into the guide and stripper plates.    
     
     
         13 . The method of  claim 12  wherein the gang-punch pin apparatus is the apparatus of  claim 4 .  
     
     
         14 . The method of  claim 12  wherein the gang-punch pin apparatus is the apparatus of  claim 5 .  
     
     
         15 . A thin sheet material having hole patterns therein made by the method of  claim 12 .  
     
     
         16 . A thin sheet material having hole patterns therein made by the method of  claim 13 .  
     
     
         17 . A thin sheet material having hole patterns therein made by the method of  claim 14 .  
     
     
         18 . The thin sheet material of  claim 15  wherein the thin sheet material is a greensheet.