Environmental hood for testing printed circuit cards
First Claim
1. An environmental hood for disposing over a printed circuit card under test comprising:
- (a) a transparent inner wall containing therein at least one probe hole through which a probe can be inserted;
(b) an outer wall surrounding said inner wall with a spacing therefrom;
(c) at least one mixing ring containing at least one opening in the walls thereof disposed between said inner and outer walls and bonded thereto, said ring surrounding said at least one probe hole and a hole in the outer wall;
(d) means to supply a cold gas to the inside of said inner wall; and
(e) means to supply a hot gas to the space between said inner and outer walls whereby said hot gas will exit through said hole in said ring, be mixed with the cold gas escaping from said probe hole and raise its temperature above the dew point so as to prevent frosting, thereby allowing an operator to see the printed circuit card for probing purposes.
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Accused Products
Abstract
In order to permit probing access to a printed circuit board while the printed circuit board is under test in a cold controlled environment, a doubled walled environmental hood is provided, the inner and outer walls spaced apart by rings containing orifices therein, a probe hole formed in the center of the ring and the outer wall cut away in the area of the ring, with a cold gas supplied to the inside of the inner wall and a hot gas supplied to the space between the walls, whereby the hot gas escaping through the orifices in the rings will raise the temperature of the cold gas escaping from the probe hole to prevent frosting and permit viewing of the printed circuit board under test for probing.
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Citations
12 Claims
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1. An environmental hood for disposing over a printed circuit card under test comprising:
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(a) a transparent inner wall containing therein at least one probe hole through which a probe can be inserted; (b) an outer wall surrounding said inner wall with a spacing therefrom; (c) at least one mixing ring containing at least one opening in the walls thereof disposed between said inner and outer walls and bonded thereto, said ring surrounding said at least one probe hole and a hole in the outer wall; (d) means to supply a cold gas to the inside of said inner wall; and (e) means to supply a hot gas to the space between said inner and outer walls whereby said hot gas will exit through said hole in said ring, be mixed with the cold gas escaping from said probe hole and raise its temperature above the dew point so as to prevent frosting, thereby allowing an operator to see the printed circuit card for probing purposes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method to permit probe testing of a printed circuit card under controlled cold environmental conditions comprising:
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(a) disposing, around the printed circuit card under test, a double walled hood made of a clear material; (b) forming an opening in the inner wall of said hood; (c) surrounding said opening with a mixing ring containing therein at least one opening and bonding said mixing ring to both said inner and outer walls; (d) forming an opening in said outer wall of a diameter no larger than the maximum diameter which permits bonding to said mixing ring; (e) supplying a dry cold gas to the space within said inner wall; (f) supplying a dry hot gas to the space between said inner and outer walls, whereby, frosting of said inner and outer walls will be prevented, a probe can be inserted through the openings in said outer and inner walls and frosting at the area of insertion of said probe will be prevented by the mixing of the hot dry gas escaping through the openings in said mixing ring with the cold dry gas escaping through the hole through which said probe is inserted and raising it above the dew point. - View Dependent Claims (10, 11, 12)
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Specification