Shielded electrical contact spring probe assembly

• US 5,175,493 A
• Filed: 10/11/1991
• Issued: 12/29/1992
• Est. Priority Date: 10/11/1991
• Status: Expired due to Term

• Current Assignee: Interconnect Devices Incorporated (Smiths Group International Holdings Ltd.)
• Original Assignee: Interconnect Devices Incorporated (Smiths Group International Holdings Ltd.)
• Inventors: Langgard, Ulf R.
• Primary Examiner(s): Karlsen, Ernest F.
• Assistant Examiner(s): BURNS, WILLIAM
• Application Number:
  US07/775,714
• Time in Patent Office: 445 Days
• Field of Search: 324/158 P, 324/158 F, 324/72.5, 439/482
• US Class Current: 324/750.27
• CPC Class Codes: G01R 1/067 Measuring probes
• CPC Class Codes: G01R 1/06772 High frequency probes

Abstract

A shielded electrical contact spring probe assembly for testing electrical printed circuit boards includes an outer barrel having an open end and a remote end, an inner core of dielectric material coaxially mounted within the barrel, and an electrical contact spring probe reciprocally seated within an axial bore in the core. A shield surrounds the core between the barrel inner wall and the core and extends the full length of the barrel. A shielding plunger is located in a cylindrical space between the barrel and the shield. The probe assembly remote end is for connection of an electrical transmission line, or in an alternative embodiment, inserting a second electrical contact spring probe within the core. The configuration and material of the core and the shield enable the entire probe assembly to maintain a selected impedance. The electrical contact spring probe seated within the core axial bore includes a separate barrel having a spring seating end and an open end, a compression spring seated in the closed end of the barrel, and a plunger inserted into the barrel. The plunger includes a tail section, connected to a shaft or probe section that protrudes from the barrel and includes the probe tip. The shielding plunger of the assembly is spring loaded to extend outwardly surrounding the probe tip when the probe tip is also in an outwardly extended position. The plunger fits snugly against portions of a circuit board surrounding test site and shields the probe tip against emission of RF energy.

Claims

1. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having an open end and a remote end, said remote end providing means for an electrical path through said barrel;

b) a core of dielectric material coaxially mounted within said barrel and having an open end coincident with said barrel open end, said core having an axial bore therein;

c) an electrical contact spring probe reciprocally seated within said core bore and having a tip end axially extensible beyond said core open end, said probe having means biasing said probe to an outwardly extended position, said probe tip end having means for electrical contact with a target;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open end, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) a shielding plunger, formed of electrically conductive material, located in said space and having a seating end having a biasing means in said seating end, said plunger having means biasing said plunger to a outwardly extended position terminating coincidentally and surrounding said probe tip when said probe tip is in an outwardly extended position for fitting snugly against a target and shielding said probe tip against emission of RF energy.

18. The coaxial electric connector probe assembly of claim 1 wherein the dielectric insulating material is mad preferably of foamed "Teflon".

19. The coaxial electric connector probe assembly of claim 1 wherein the outer conductive circular barrel is made of beryllium copper.

20. The coaxial electric connector probe assembly of claim 1 wherein the grounding shield concentric plunger made of beryllium copper.

21. The coaxial electric connector probe assembly of claim 1 wherein the barrel enclosed grounding shield is made of a very thin layer of non-magnetic stainless steel.

22. The coaxial electric connector probe assembly of claim 1 wherein all parts are gold-plated.

2. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having an open end and a remote end, said remote end providing means for an electrical path through said barrel;

b) a core of dielectric material coaxially mounted within said barrel and having an open end coincident with said barrel open end, said core having an axial bore therein;

c) an electrical contact spring probe reciprocally seated within said core bore and having a tip end axially extensible beyond said core open end, said probe having means biasing said probe to an outwardly extended position, said probe tip end having means for electrical contact with a target, said probe having means for easy removal and replacement of said probe from said core bore;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open end, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) a shielding plunger, formed of electrically conductive material, located in said space and having a seating end having a biasing means in said seating end, said plunger having means biasing said plunger to an outwardly extended position terminating coincidentally and surrounding said probe tip when said probe tip is in an outwardly extended position for fitting snugly against a target and shielding said probe tip against emission of RF energy and electrically connected to said shield.

3. A shielded electrical contact spring probe assembly as claimed in claim 2 wherein said probe is unitary structure including a receptacle, a plunger and a plunger tip, said plunger having means biasing said plunger and plunger tip to an outwardly extended position, said tip end having means for electrical contact with a target, said unitary structure having means for easy removal and replacement of said structure from said core bore.

4. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having an open end and a remote end, said remote end providing means for an electrical path through said barrel;

b) a core of dielectric material coaxially mounted within said barrel and having an open end coincident with said barrel open end, said core having an axial bore therein;

c) an electrical contact spring probe reciprocally seated within said core bore and having a substantially cylindrical barrel with a spring seating end and an open end, four spaced crimps spaced about the circumference of said barrel at a location between said spring seating end an said open end, a compression spring seated in said spring seating end of said barrel, said compression spring providing means biasing said probe to an outwardly extended position, a plunger seated within said barrel and retained within said barrel by said crimps, said plunger further having a tail section, a shank section, and a tip section, said tip section axially extensible beyond said core open end, means for alternatively admitting and expelling air from said cylinder as said plunger reciprocates in said barrel, said tip end having means for making electrical contact with a target;

d) a shield formed of electrically conductive material surrounding said core and extending full length thereof, and coincidentally terminating with said core at said open end, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) a shielding plunger, formed of electrically conductive material, located in said space and having a seating end having a biasing means in said seating end, said plunger having means biasing said plunger to an outwardly extended position terminating coincidentally and surrounding said probe tip when said probe tip is in an outwardly extended position for fitting snugly against a target and shielding said probe tip against emission of RF energy and electrically connected to said shield.

5. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having an open end and a remote end, said remote end providing means for an electrical path through said barrel;

b) a core of dielectric material coaxially mounted within said barrel and having an open end coincident with said barrel open end, said core having an axial bore therein;

c) an electrical contact spring probe having a substantially cylindrical barrel with a spring end and an open end and four equally spaced V-shaped crimps about the circumference of said barrel at a location between said spring seating end and said open end, a compression spring seated in said spring seating end of said barrel, a plunger seated within said barrel and retained within said barrel by said crimps, said plunger further including a tail section having a cross-section larger than the cross section of said probe at said crimps, said tail section having a contact stem, said compression spring being pressed onto said contact stem, said compression spring providing means biasing said probe to an outwardly extended position, said tail section being disposed between said spring seating end of said barrel and said crimps, a probe tip section with a probe tip, said tip section axially extensible beyond said core open end, said probe tip end making electrical contact with a target;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open end, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) a shielding plunger, formed of electrically conductive material, located in said space and having a seating end having a biasing means in said seating end, said plunger having means biasing said plunger to a outwardly extended position terminating coincidentally and surrounding said probe tip when said probe tip is in an outwardly extended position for fitting snugly against target and shielding said probe tip against emission of RF energy.

6. A shielded electrical contact spring probe assembly as claimed in claim 5 wherein said electrical contact spring probe plunger is made from a single piece of metal.

7. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having an open end and a remote end, a crimp about the circumference of said barrel located between said open end and said remote end, said remote end providing means for an electrical path through said barrel;

b) a core of dielectric material coaxially mounted within said barrel and having an open end coincident with said barrel open end, said core having an axial bore therein;

c) an electrical contact spring probe reciprocally seated within said core bore and having a tip end axially extensible beyond said core open end, and a spring compression seating end having a compression spring seated in said seating end of said probe, said probe having means biasing said probe to an outwardly extended position, said probe having means for alternatively admitting and expelling air from said probe as said probe extends outwardly from said core bore, said probe tip end having means for electrical contact with a target, said probe having means for easy removal and replacement of said probe form said core bore;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open end, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being concentrically separated to form a space;

f) a shielding plunger located in said space, having a substantially cylindrical barrel having a spring seating end, an open end, a crimp about the circumference of said barrel at a location between said open end and said spring seating end, a compression spring seated in said spring seating end, said spring seating end having a tail section having a cross section larger than the cross section of said barrel at said crimp, said tail section having a contact stem, said compression spring being pressed onto said contact stem, said tail section being disposed between said spring seating end and said crimp, said crimp of said barrel of said electrical contact spring probe assembly retaining said shielding plunger in said space, said shielding plunger having means for alternatively admitting and expelling air from said space as plunger extends outwardly from said barrel of said probe assembly, said compression spring providing means biasing said plunger to an outwardly extended position terminating coincidentally and surrounding said electrical contact spring probe tip when said probe tip is in an outwardly extended position for fitting snugly against a target and shielding said probe tip against emission of RF energy.

8. A shielded electrical contact spring probe assembly as claimed in claim 7 wherein said barrel of said shielding plunger is made from a single piece of metal.

9. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having an open end and a remote end, a crimp about the circumference of said barrel located between said open end and said remote end, said remote end providing means for an electrical path through said barrel;

b) a core of dielectric material coaxially mounted within said barrel and having an open end coincident with said barrel open end and a sealed end, said core having an axial bore therein, said sealed end terminating coincidentally with remote end, said core extending beyond barrel providing means for connecting an electrical transmission line to said remote end;

c) an electrical contact spring probe reciprocally seated within said core bore and having a tip end axially extensible beyond said core open end, said probe having means biasing said probe to an outwardly extended position, said probe tip end having means for electrical contact with a target, said probe having means for easy removal and replacement of said probe from said core bore;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open end, said shield having means for an electrical conductive path through said shield and said barrel, said shield and said core providing means for said probe to have a selected impedance;

f) said shield and said barrel being separated to form a space;

g) a shielding plunger, formed of electrically conductive material, located in said space and having a seating end having a compression spring seated in said seating end, said plunger having means for alternatively admitting and expelling air from said annular channel as plunger extends outwardly from said barrel, said crimp of said barrel of said electrical contact spring probe assembly retaining said shielding plunger in said space, said compression spring providing means biasing said plunger to a outwardly extended position terminating coincidentally and surrounding said probe tip when said probe tip is in an outwardly extended position for fitting snugly against a target and shielding said probe tip against emission of RF energy.

10. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having two open ends;

b) a core of dielectric material coaxially mounted within said barrel and having open ends coincident with said barrel open ends, said core having an axial bore therein;

c) two electrical contact spring probes reciprocally seated and diametrically positioned within said core bore, each said probe having a tip end axially extensible beyond said core open ends and barrel open ends, each said probe having means biasing said probes to an outwardly extended position, each said probe tips being diametrically positioned providing means for simultaneous electrical contacts with two targets, said targets being parallel to each other, each said probe having means for easy removal and replacement of said probes from said core bore,

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open ends, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) two shielding plungers, formed of electrically conductive material, located in said space and each said plunger having a seating end having a means biasing seated in said seating end, each said plunger having means biasing said plungers to an outwardly extended position terminating coincidentally and surrounding said probe tips when said probe tips are in an outwardly extended position for fitting snugly against a target and shielding said probe tips against emission of R energy.

11. A shielded electrical contact spring probe assembly as claimed in claim 10 wherein each said probe is a unitary structure including a receptacle, a plunger and a plunger tip, each said plunger having means biasing said plunger and plunger tip to an outwardly extended position, each said tip end having means for electrical contact with a target, each said unitary structure having means for easy removal and replacement of said structure from said core bore.

12. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having two open ends;

b) a core of dielectric material coaxially mounted within said barrel and having open ends coincident with said barrel open ends, said core having an axial bore therein;

c) two electrical contact spring probes reciprocally seated and diametrically positioned within said core bore and each probe including a substantially cylindrical barrel with a spring seating end and an open end, four spaced crimps equally spaced about the circumference of each said barrel at a location between said spring seating end and said open end, a compression spring seated in said spring seating end of each said barrel, said compression spring providing means biasing each said probe to an outwardly extended position, a plunger seated within each said barrel and retained within each said barrel by said crimps, said plungers having a tail section, a shank section, and a tip section, each said tip section axially extensible beyond each said core open end, means for alternatively admitting and expelling air from each said cylinder as each said plunger reciprocates in each said barrel, said probe tips being diametrically positioned providing mean for simultaneous electrical contacts with two targets, said targets being parallel to each other;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open ends, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) two shielding plungers, formed of electrically conductive material, located in said space and each said plunger having a seating end having a means biasing seated in said seating end, each said plunger having means biasing said plungers to an outwardly extended position terminating coincidentally and surrounding said probe tips when said probe tips are in an outwardly extended position for fitting snugly against a target and shielding said probe tips against emission of RF energy.

13. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having two open ends;

b) a core of dielectric material coaxially mounted within said barrel and having open ends coincident with said barrel open ends, said core having an axial bore therein;

c) two electrical contact spring probes, each said probe including a substantially cylindrical barrel with a spring end and an open end and four equally spaced V-shaped crimps about the circumference of said barrel at a location between said spring seating end and said open end, a compression spring seated in said spring seating end of said barrel, a plunger seated within said barrel and retained within said barrel by said crimps, said plungers having a tail section having a cross-section larger than the cross section of said probes at said crimps, said tail section having a contact stem, said compression spring being pressed onto said contact stem, said compression spring providing means biasing each said probe to an outwardly extended position, said tail section being disposed between said spring seating end of said barrel and said crimps, a probe tip section with a probe tip, said tip section axially extensible beyond said core open end, said probe tips being diametrically positioned providing means for simultaneous electrical contacts with two targets said targets being parallel to each other;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open ends, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) two shielding plungers, formed of electrically conductive material, located in said space and each said plunger having a seating end having a means biasing seated in said seating end, each said plunger having means biasing said plungers to an outwardly extended position terminating coincidentally and surrounding said probe tips when said probe tips are in an outwardly extended position for fitting snugly against target and shielding said probe tips against emission of R energy.

14. A shielded electrical contact spring probe assembly as claimed in claim 14 wherein each said electrical contact spring probe plunger is made from a single piece of metal.

15. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having two open ends, two crimps about the circumference of said barrel located between said open end and said remote end;

b) a core of dielectric material coaxially mounted within said barrel and having open ends coincident with said barrel open ends, said core having an axial bore therein;

c) two electrical contact spring probes reciprocally seated and diametrically positioned within said core bore, each said probe having a tip end axially extensible beyond said core open ends and barrel open ends, each said probe having means biasing said probes to an outwardly extended position, each said probe tips being diametrically positioned providing means for simultaneous electrical contacts with two targets, said targets being parallel to each other, each said probe having means for easy removal and replacement of said probes from said core bore;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open ends, and said shield having means for an electrical conductive path through said shield and said barrel;

e) said shield and said barrel being separated to form a space;

f) two shielding plungers located in said space, each comprising a substantially cylindrical barrel having a spring seating end, an open end, a crimp about the circumference of said barrel at a location between said open end and said spring seating end, a compression spring seated in said spring seating end, said spring seating end having a tail section having a cross section larger than the cross section of said barrel at said crimp, said tail section having a contact stem, said compression spring being pressed onto said contact stem, said tail section being disposed between said spring seating end and said crimp, each said crimp of said barrel of said electrical contact spring probe assembly retain said shielding plungers in said space, each said plunger having means for alternatively admitting and expelling air from said space as each plunger extends outwardly from said barrel of said probe assembly, each said compression spring providing means biasing each said plunger to an outwardly extended position terminating coincidentally and surrounding said probe tips when each said probe tip is in an outwardly extended position for fitting snugly against a target and shielding each said probe tip against emission of RF energy.

16. A shielded electrical contact spring probe assembly as claimed in claim 15 wherein each said shielding plunge is made from a single piece of metal.

17. A shielded electrical contact spring probe assembly comprising:

a) a barrel formed of conductive material and having two open ends, two crimps about the circumference of said barrel located between said open end and said remote end;

b) a core of dielectric material coaxially mounted within said barrel and having open ends coincident with said barrel open ends, said core having an axial bore therein;

c) two electrical contact spring probes reciprocally seated and diametrically positioned within said core bore, each said probe having a tip end axially extensible beyond said core open ends and barrel open ends, each said probe having means biasing said probes to an outwardly extended position, each said probe tips being diametrically positioned providing means for simultaneous electrical contacts with two targets, said targets being parallel to each other, each said probe having means for easy removal and replacement of said probes from said core bore;

d) a shield formed of electrically conductive material surrounding said core and extending the full length thereof, and coincidentally terminating with said core at said open ends, and said shield having means for an electrical conductive path through said shield and said barrel, said shield and said core providing means for each said probe to have a selected impedance;

e) said shield and said barrel being separated to form a space;

f) two shielding plungers, formed of electrically conductive material, located in said space and each said plunger having a seating end having a means biasing seated in said seating end, each said crimp of said barrel of said electrical contact spring probe assembly retain said shielding plungers in said space, each said plunger having means biasing said plungers to an outwardly extended position terminating coincidentally and surrounding said probe tips when said probe tips are in an outwardly extended position for fitting snugly against a target and shielding said probe tips against emission of RF energy.