Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1998-08-07
2001-04-17
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090
Reexamination Certificate
active
06218851
ABSTRACT:
TECHNICAL FIELD
This invention has as object a machine for the opposite control of printed circuits.
The invention finds particular even if not exclusive application in the sector of the control of the printed circuit cards.
BACKGROUND ART
In prior art machines for the control of the printed circuits are known.
These machines generally consist of a board or bed bearing a plurality of electrically conductive needles, on which must be disposed the card with the printed circuit and by activating properly the electric conductivity among the different needles and by making the respective measurings it is possible to check whether the printed circuit has defects.
Obviously for such control it is necessary for the needles to contact the printed circuit in the proper position.
As the printed circuits are very different, it results necessary to apply over the needle base board, an adaptation board that comprises the same needles but displaced in a different way in conformity with the printed circuit to be controlled.
The drawback of this solution is the limitation of the machine and the possibility to control only the printed circuits that have at disposal corresponding adapters or adaptation boards.
Needing as many adaptation boards as are the cards with different printed circuits to be controlled.
Furthermore it is known that the layers of the circuits are not always coplanar, wherefore a suitable electric conduction for an effective contact is not always ensured.
EP,A,0 164 722 (Black) Dec. 18, 1985 discloses: an automatic test system for testing printed circuit boards (cards) in which:
In this document prior art is cited:
use of a “bed of nails” (bed or plate or board of needles), in which each nail or needle is fixedly placed in said bed or plate or board.
In this solution the “bed of nails” has the nail position absolutely fixed and corresponding to the specific pattern of the printed card to be tested.
Drawback of this solution is the requirement of as many “beds of nails” as the different printed circuit cards to be tested. use of a universal grid matrix having a maximum possibility of positionally fixed needles (nails) and a computer program to activate only the required needles (nails) at a time. The programming being dependant on the pattern of the printed card to be tested.
This solution has the drawback of continuously reprogramming the machine. Furthermore, because the contact nails or needles are bulky, it is impossible to cover all kinds of patterns.
This problem is avoided rendering displaceable along the coordinate axis said contact needles or nails.
Nevertheless this solution requires a very complicated and expensive construction of the testing machine and in this case the needles or nails cannot be placed closely one next to the other. Furthermore a continuous reprogramming is required to move one needle or nail in respect to the other.
Finally, EP,A,0 164 722 discloses its claimed solution, in which there is a magazine for temporarily storing a plurality of probes (nails or needles) and a base receiver member positioned adjacent to the test head (bed or plate) on one side thereof and in a position to contact the base of each probe. The test head (bed or plate) is adapted to receive the probes and position the probes in a pattern matching test points on the printed circuit board. Means are provided for supporting the test head adjacent to the magazine and in a position to receive probes (nails or needles) from the magazine. Means are also provided for transferring selected ones of the probes from the magazine to the test head.
The probes (nails or needles) are for this purpose, movable axially from inside the said test head to the outside or vice versa and some of these further axially moved in order to allow contact with the printed circuit of the card to be tested.
This solution is extremely complex because of the mechanisms to move the probes (nails or needles) and the program to operate. Furthermore this solution does not allow a complete universal testing of all kinds of printed circuit cards because of the limitation of the pattern of the test head.
EP,A,0 468 153 (ATG ELECTRONIC) Jan. 29, 1992, discloses a system in which the respective contact needles are not fixed in position on the respective needle bearing board, but are movable both axially and from their position along the coordinate axis.
In this way it is possible to make the testing machine universal. Nevertheless, this solution is complex and requires a continuous reprogramming. Furthermore this solution is lengthy because the movable needles are obliged to move for a long way to reach the exact coordinates, and this has to be done continuously during the testing of each single card for the respective interested points to be tested in the circuit.
EP-A-0 547 251 discloses a method for testing a micro circuit, where a “wafer holder” and a “test head . . . incorporating a matrix of probes” is provided and wherein said wafer holder is movable on its (X-Y) plane whereas the test head is movable along the orthogonal (Z) direction.
This solution is able to test printed circuit cards because it is conceived for testing on one side only.
DISCLOSURE OF THE INVENTION
The purpose of the present invention is that to obviate the abovementioned drawbacks, and in particular to allow the making of a universal machine able to control the printed circuits, that is having a system of conductive detection needles that can be adapted to any type of circuit.
This and other purposes as claimed are obtained by means of a machine for the control of printed circuits, comprising a board bearing a plurality of conductive needles connectable on their reverse side to analysis means of electric parameters between one and the other needle: wherein
two needle bearing boards are used, one opposing the other and between them is placed for the analysis the respective printed circuit card to be controlled, said printed circuit card being movably supported on its plane,
characterized in that:
each needle bearing board supports a plurality of conductive needles said needles being axially movable only in the respective needle bearing board;
at least one of said needle bearing boards is movable on its plane, in order that the positioning of the needle concerned to put in contact with the point concerned of the printed circuit of the card to be tested, is obtained.
In this way it is obtained the immediate advantage of simplifying all the system by making universal the application of the machine on different printed circuits without needing adapters. In fact by this it is possible to activate a board needle in any leading end circuit position and to activate an opposite needle of the opposite board, which thanks to the movability of the same board will be able to reach any definite circuit end point to be tested independently from its position, place and shape.
In this way the universalization of the testing system for any card is ensured.
Advantageously the machine has also the characteristic that the detection needles are axially movable.
In this way, among a plurality of needles it is possible to make interact only some of them, centering more easily the desired positions of the printed circuit.
Further advantage derives from that with the axial movability of the needles it is possible to contact better the respective desired points of the circuit even when the card or the layer of the circuit is not perfectly on the same plane in all its points.
Advantageously the needles are made axially movable by electromagnetic means.
In this way the desired needle is operated in a simple and safe way.
REFERENCES:
patent: 4841241 (1989-06-01), Hilz et al.
patent: 5068600 (1991-11-01), Hilz et al.
patent: 5818246 (1998-10-01), Zhong
patent: 6124722 (2000-09-01), Vodopivec et al.
Fumo Cesare
Vodopivec Jozef
Brown Glenn W.
Kobert Russell M.
New System S.R.L.
Wenderoth Lind & Ponack LLP
LandOfFree
Method and apparatus for testing a printed circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for testing a printed circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for testing a printed circuit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2456921