Incorporation of Isolation Resistor(s) into Probes using Probe Tip Spring Pins

Abstract

An isolation resistor is incorporated into the plunger of a probe tip spring pin by, for example, doping a ceramic that is used to form the plunger, or forming the plunger of first and second electrically coupled materials, at least a first of which has a resistivity sufficient to serve as an isolation resistor. Alternately, an isolation resistor is embedded in a printed circuit board trace that is used to couple either an upper or lower blind plated hole to a via. A probe tip spring pin is then inserted into the upper blind plated hole.

1 . A probe tip spring pin, comprising: 
 a conductive sleeve; and    a plunger, spring loaded within and electrically coupled to the conductive sleeve, the plunger comprising an isolation resistor.    
   
   
       2 . The probe tip spring pin of  claim 1 , wherein the plunger comprises a crowned probe tip, and wherein the isolation resistor is part of the crowned probe tip.  
   
   
       3 . The probe tip spring pin of  claim 2 , wherein the crowned probe tip is flared outward, away from a center axis of the probe tip spring pin.  
   
   
       4 . The probe tip spring pin of  claim 1 , wherein the isolation resistor has a value of at least 100 Ω.  
   
   
       5 . The probe tip spring pin of  claim 1 , wherein the isolation resistor has a value of 100-200 Ω.  
   
   
       6 . The probe tip spring pin of  claim 1 , wherein the isolation resistor comprises a doped ceramic material.  
   
   
       7 . The probe tip spring pin of  claim 6 , wherein the plunger is a doped ceramic material.  
   
   
       8 . A method for constructing a probe tip spring pin, comprising: 
 doping a ceramic material to give the ceramic material a resistivity sufficient to serve as an isolation resistor;    forming a plunger from the ceramic material; and    spring-loading the plunger in a conductive sleeve, said spring-loading electrically coupling the plunger to the conductive sleeve.    
   
   
       9 . The method of  claim 9 , wherein the ceramic material is doped to a resistivity of at least 100 Ω.  
   
   
       10 . The method of  claim 9 , wherein the ceramic material is doped to a resistivity of 100-200 Ω.  
   
   
       11 . A method for constructing a probe tip spring pin, comprising: 
 constructing a plunger from first and second electrically coupled materials, at least a first of which has a resistivity sufficient to serve as an isolation resistor; and    spring-loading the plunger in a conductive sleeve, said spring-loading electrically coupling the plunger to the conductive sleeve.    
   
   
       12 . The method of  claim 11 , wherein constructing the plunger comprises forming a crowned probe tip from one of the first and second electrically coupled materials.  
   
   
       13 . The method of  claim 12 , wherein said material from which the crowned probe tip is formed serves as said isolation resistor.  
   
   
       14 . The method of  claim 11 , wherein the first and second materials are electrically coupled using solder.  
   
   
       15 . The method of  claim 11 , wherein the first and second materials are electrically coupled using a conductive adhesive.  
   
   
       16 . The method of  claim 11 , wherein the first material is a resistive fluid into which the second material is dipped.  
   
   
       17 . The method of  claim 11 , wherein the isolation resistor has a value of at least 100 Ω.  
   
   
       18 . The method of  claim 11 , wherein the isolation resistor has a value of 100-200 Ω.  
   
   
       19 . A probe apparatus, comprising: 
 a printed circuit board having first and second traces, an isolation resistor embedded in at least one of the traces, a via that electrically couples the first and second traces, and upper and lower blind plated holes that respectively intersect the first and second traces; and    a probe tip spring pin retained within the upper blind plated hole.    
   
   
       20 . The apparatus of  claim 19 , wherein the isolation resistor has a value of at least 100 Ω.  
   
   
       21 . The apparatus of  claim 19 , wherein the isolation resistor has a value of 100-200 Ω.  
   
   
       22 . The apparatus of  claim 19 , wherein the first and second traces are inner traces of the printed circuit board, and wherein the via is a buried via in the printed circuit board.  
   
   
       23 . The apparatus of  claim 19 , wherein the isolation resistor is embedded in the trace that intersects the upper blind plated hole.  
   
   
       24 . The apparatus of  claim 19 , further comprising a fixed pin retained within the lower blind plated hole.