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Claims  |
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I claim:
1. A method of testing a circuit board by means of a circuit board testing
machine having a test surface including a number of test points
electrically insulated relative to one another and arranged in a matrix
configuration and for testing a circuit board of an electrically
insulating material having circuit tracks of an eletrically conductive
material arranged on at least a first side surface thereof, the method
comprising:
providing a connector assembly adapted to provide electrical connection
between selected areas of said first side surface of the circuit board and
selected test points of the test surface of the testing machine, and
wherein said connector assembly comprising:
a board of an electrically insulating material having opposite first and
second side surfaces,
a first plurality of individual connector pads being arranged on the first
side surface of the connector assembly board in a configuration
corresponding to said selected areas of said first side surface of the
circuit board,
a second plurality of individual connector pads being arranged on the
second side surface of the connector assembly board in a configuration
corresponding to said selected test points of said test surface of the
testing machine,
electrical cconductor means extending through the board of the connector
assembly board and electrically connecting said individual connector pads
of said first plurality to respective individual connector pads of said
second plurality, and
connector contact means secured to each of said connector pads of said
first plurality and of said second plurality,
arranging said first side surface of the circuit board facing said test
surface of the testing machine,
arranging said connector assembly so as to have its first side surface face
said first side surface of the circuit board and so as to have its second
side surface face said test surface of said testing machine, and
sandwiching said connector assembly between said first side surface of the
circuit board and said test surface of the testing machine so as to
provide electrical connection between said selected areas of said first
side surface of the circuit board and said selected test points of the
test surface of the testing machine through said connector contact means
secured to said connector pads of said first plurality, through said
individual connector pads of said first plurality, through said electrical
conductor means, through said individual connector pads of said second
plurality, and through said second connector contact means secured to said
connector pads of said second plurality.
2. A method according to claim 1, wherein said connector contact means
comprises at least one sheet of an electrically insulating material,
arranged on one side surface of the board of the connector assembly and
having through-going, electrically conductive paths.
3. A method according to claim 2, wherein said sheet is a polymer sheet,
and wherein the through-going, electrically conductive paths are
constituted by metal fibres of high electrical conductivity, of a
thickness of 2-100 .mu.m, and of a density of 1-20 fibres per mm.sup.2.
4. A method according to claim 3, wherein the metal fibres are of a noble
metal.
5. A method according to claim 2, wherein the connector contact means
comprises a first and a second sheet of an electrically insulating
material and having through-going, electrically conductive paths, the
method further comprising arranging said first sheet on the first side
surface of the board of the connector assembly so as to establish
electrical connection between said selected areas of the circuit board and
said individual connector pads of said first plurality, and arranging said
second sheet on the second side surface of the board of the connector
assembly, so as to establish electrical connection between said selected
test points of the testing machine and said individual connector pads of
said second plurality.
6. A method according to claim 1, wherein the board of the connector
assembly is constituted by a board of a double-sided printed circuit board
having a first and a second side surface, wherein said individual
connector pads of said first plurality and of said second plurality
comprise printed circuit pads arranged on said first side surface and on
said second side surface, respectively, of the double-sided printed
circuit board, and wherein said electrical conductor means are constituted
by through-platings of said double sided printed circuit board.
7. A method according to claim 6, wherein the board of the double-sided
printed circuit board is a 1.5 mm glass fibre reinforced epoxy resin
board, and wherein the printed circuit pads are 25-100 .mu.m Cu-layer
pads, provided with gold platings.
8. A method according to claim 7, wherein the individual connector means of
said first or second plurality further comprise connector bodies of an
electrically conductive material.
9. A method according to claim 8, wherein the connector bodies are arranged
in respective bores of a supporting board of an electrically insulating
material and aligned relative to their respective printed circuit pads.
10. A method according to claim 9, wherein the connector bodies are solid
bodies of an electrically conductive elastomer.
11. A method according to claim 9, wherein the connector bodies are solid,
metallic bodies.
12. A method according to claim 1, wherein the board of the connector
assembly is constituted by a thick-film substrate, and wherein said first
and second plurality of individual connector pads comprise layers provided
in thick-film technique and arranged on a first side surface and on a
second side surface, respectively, of the substrate.
13. A method according to claim 1, wherein the board of the connector
assembly is constituted by a thin-film substrate, and wherein said first
and second plurality of individual connector pads comprise layers provided
in thin-film technique and arranged on a first side surface and on a
second side surface, respectively, of the substrate.
14. A method according to claim 1, wherein the number of individual
connector pads of said second plurality is identical to that of said first
plurality.
15. A method according to claim 1 and of testing a circuit board further
having circuit tracks arranged on a second side surface opposite to said
first side surface, the circuit board testing machine having a further
test surface opposite to said at least one test surface, said further test
surface including a number of test points electrically insulated relative
to one another and arranged in a matrix configuration, the method further
comprising:
providing a further connector assembly adapted to provide electrical
connection between selected areas of said second side surface of the
circuit board and selected test points of said further test surface of the
testing machine, and said further connector assembly comprising:
a board of an electrically insulating material having opposite first and
second side surfaces,
a first plurality of individual connector pads being arranged on the first
side surface of the connector assembly board in a configuration
corresponding to said selected areas of said second side surface of the
circuit board,
a second plurality of individual connector pads being arranged on the
second side surface of the connector assembly board in a configuration
corresponding to said selected test points of said further test surface of
the testing machine,
electrical conductor means extending through the board of the connector
assembly board and electrically connecting said individual connector pads
of said first plurality to respective individual connector pads of said
second plurality, and
connector contact means secured to each of said connector pads of said
first plurality and of said second plurality,
arranging said second side surface of the circuit board facing said further
test surface of the testing machine, arranging said further connector
assembly so as to have its first side surface face said second side
surface of the circuit board and so as to have its second side surface
face said further test surface of said testing machine, and sandwiching
said further connector assembly between said second side surface of the
circuit board and said further test surface of the testing machine so as
to provide electrical connection between said selected areas of said
second side surface of the circuit board and said selected test points of
the test surface of the testing machine through said further connector
assembly's connector contact means secured to said connector pads of said
first plurality, through said further connector assembly's individual
connector pads of said first plurality, through said further connector
assembly's electrical conductor means, through said further connector
assembly's individual connector pads of said second plurality, and through
said further connector assembly's second connector contact means secured
to said connector pads of said second plurality.
16. A method according to claim 1 and of testing a circuit board further
having circuit tracks arranged on a second side surface opposite to said
first side surface, the method further comprising:
providing a short-circuiting circuit board adapted to provide electrical
interconnection between selected areas of said second side surface of the
circuit board said short-circuiting circuit board comprising:
a board of an electrically insulating material having opposite first and
second side surfaces,
a first plurality of individual connector pads being arranged on the first
side surface of the short-circuiting circuit board in a configuration
corresponding to said selected areas of said second side surface of the
circuit board,
a second plurality of individual connector pads being arranged on the
second side surface of the short-circuiting circuit board,
electrical conductor means extending through the board on the
short-circuiting circuit board and electrically connecting said individual
connector pads of said first plurality to respective individual connector
pads of said second plurality,
short-circuiting tracks being arranged on the second side surface of the
short-circuiting circuit board interconnecting selected individual
connector pads of said second plurality corresponding to said selected
areas of said second side surface of the circuit board, and
connector contact means secured to each of said connector pads of said
first plurality and of said second plurality,
arranging said second side surface of the circuit board facing said further
test surface of the testing machine,
arranging said short-circuiting circuit board so as to have its first side
surface face said second side surface of the circuit board and so as to
have its second side surface face said further test surface of said
testing machine, and
sandwiching said short-circuiting circuit board between said second side
surface of the circuit board and said further test surface of the testing
machine so as to provide electrical interconnection between said selected
areas of said second side surface of the circuit board through said
short-circuiting circuit board's connector contact means secured to said
connector pads of said first plurality, through said short-circuiting
circuit board's individual connector pads of said first plurality, through
said short-circuiting board's electrical conductor means, through said
short-circuiting circuit board's individual connector pads of said second
plurality, through said short-circuiting circuit board's second connector
contact means secured to said connector pads of said second plurality, and
through said short-circuiting circuit board's short-circuiting tracks.
17. A method according to claim 1, wherein one of said selected areas
constitutes a selected area of the circuit tracks of the circuit board.
18. A method according to claim 1, wherein one of the said selected areas
constitutes a selected area interposed between circuit tracks of the
circuit board. |
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Claims |
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Description |
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The present invention relates to a connector assembly for a circuit board
testing machine.
Hitherto a visual inspection or examination of circuit boards, especially
printed circuit boards, has been a sufficient "testing" routine as to the
correctness of single-sided or double-sided printed circuit boards.
However, the appearance of more complex, more compact, more elaborated,
and consequently more expensive circuit boards, such as thin-film or
thick-film circuit boards, i.e. circuit boards including circuit tracks
provided in thin-film or thick-film technique, respectively, multi-layer
printed circuit boads, i.e. printed circuit boards including several
layers of boards made of an insulating material having circuit tracks of
an electrically conductive material arranged on one side surface of each
of the boards and further through-platings connecting the circuit tracks
of the individual boards to one another, and circuit boards combining the
printed circuit board technique, the multi-layer printed circuit board and
layer techniques, e.g. the so-called mixed boards or boards provided in
PTF technique (PTF: Polymer Thick-Film), requires a more accurate and
reliable testing routine, as a visual inspection or examination may not
reveal an incorrectness of the circuit board, especially an incorrectness
of a multi-layer circuit board having incorrect circuit connections
embedded within the circuit board assembly. An incorrectness of a
thin-film or thick-film circuit board may also be hard to detect by visual
inspection, even when a microscope is employed.
For providing a more reliable and economical testing routine than the
visual inspection or examination of a circuit board, i.e. a board made of
an insulating material having circuit tracks of an electrically conductive
material arranged on at least one side surface thereof, such as a
single-sided, double-sided or multi-layer printed circuit board, a ceramic
thick-film substrate or the like, circuit board testing machines have been
developed. These known testing machines are adapted to supply DC or AC
current to a selected point or area of the circuit tracks of the circuit
board and to determine the current transferred to other selected points or
areas of the circuit tracks of the circuit board. These testing machines
have been equipped or adapted to a particular circuit board layout, as
individual connector pins have been arranged in a configuration
corresponding to the selected points or areas of the circuit board layout
in question and internally connected to current generating means and
current measuring means through switching means. The testing machines have
further been programmed to the circuit board layout in question, and on
the basis of the information programmed into the testing machine, the
machines are able to determine whether a circuit board includes the
required circuit board connections and no further connections, and,
consequently, whether the tested circuit board is a correct circuit board,
or whether the circuit board includes erroneous connections or fails to
include certain connections, and, consequently, whether the test circuit
board is an incorrect circuit board. However, as the circuit board testing
machine has to be equipped or adapted to the circuit board layout in
question, the automatic circuit board testing routine is only profitable
in connection with large-scale production of circuit boards.
Furthermore, due to the individual connector pins, the prior art testing
machines are not able to test highly delicate and compact circuit boards
such as thin-film or thick-film substrates, mixed boards or boards
provided in PTF technique, and furthermore, they are not able to test
circuit boards having components mounted thereon. The connector pin
concept of the prior are testing machines also makes these machines highly
liable to mechanical failure.
Therefore, there is a need for a connector assembly for a circuit board
testing machine, rendering the circuit board testing machine more easily
adaptable to different circuit board layouts, and, consequently, rendering
it possible to perform machine tests of different circuit boards of
different layouts, even of a relatively small number, and even circuit
boards of highly complex, compact and elaborated configuration, such as
multi-layer printed circuit boards, circuit boards provided in PTF
technique, mixed boards, or highly complicated thin-film or thick-film
circuit boards and, furthermore, circuit boards having components mounted
thereon.
This need is fulfilled by means of a connector assembly according to the
invention for a circuit board testing machine having a connector assembly
for a circuit board testing machine having a test surface including a
number of test points electrically insulated relative to one another and
arranged in a matrix configuration and for testing a circuit board of an
electrically insulating material having circuit tracks of an electrically
conductive material arranged on at least one side surface thereof, the
connector assembly being adapted to provide electrical connection between
selected areas of the circuit board and selected test points of the test
surface of the testing machine, the connector assembly comprising:
a board of an electrically insulating material having opposite first and
second side surfaces,
a first plurality of individual connector means being arranged on the first
side surface of the connector assembly board in a configuration
corresponding to said selected areas of the circuit board,
a second plurality of individual connector means being arranged on the
second side surface of the connector assembly board in a configuration
corresponding to said selected test points of the testing machine, and
electrical conductor means extending through the connector assembly board
and electrically connecting said individual connector means of said first
plurality to respective individual connector means of said second
plurality.
Normally, the electrical conductor means extend through holes of the
connector assembly. However, certain insulating materials may in a
treatment be made electrically conductive, and the electrical conductor
means of the connector assembly may consequently be provided in a
selective treatment of the insulating material of the board.
The connector assembly normally serves the purpose of providing electrical
connection between selected areas of the circuit tracks of the circuit
board and selected test points of the test surface of the test machine.
However, certain circuit boards, e.g. circuit boards for HF (High
Frequency) applications or circuit boards involving certain security
requirements such as requirements as to insulation between particular
circuit tracks, may advantageously be tested by providing electrical
connection by means of the connector assembly according to the invention
between one or more test points of the test surface and selected areas
interposed the circuit tracks of the circuit board. Furthermore, the
circuit board to be tested may have components arranged thereon, e.g.
discrete components, components provided in layer technique, such as
printed resistors, printed capacitors, and printed inductors or chip
components.
The connector assembly may in a first embodiment provide direct electrical
connection between selected areas of the circuit board and the test points
of the test surface through its individual connector means of the first
and second pluralities and further through its electrical conductor means.
However, in the presently preferred embodiment of the invention, the
connector assembly further comprises at least one sheet of an electrically
insulating material, arranged on one side surface of the board of the
connector assembly and having through-going, electrically conductive
paths. The sheet consequently serves the purpose of providing electrical
connection through its through-going, electrically conductive paths
between the individual connector means of the first plurality or the
second plurality, arranged on the first side surface and on the second
side surface, respectively, of the board of the connector assembly and
selected areas of the circuit board and the selected test points of the
testing machine, respectively.
The sheet is preferably of a highly insulating material, such as a sheet of
a polymer material, and the through-going, electrically conductive paths
are preferably constituted by metal fibres of high electrical
conductivity, of a thickness of 2-100 .mu.m, preferably 5-30 .mu.m, and of
a density of 1-20 fibres per mm.sup.2. In order to reduce any corrosive
influence on the metal fibres, the metal firbres are preferably of a noble
metal such as silver, platinum or, preferably, gold.
As mentioned above the sheet may be arranged on the first side surface of
the board of the connector assembly or, alternatively, on the second side
surface of the board of the connector assembly. In the preferred
embodiment of the invention, the connector assembly comprises a first and
a second sheet of the above type, i.e. of an electrically insulating
material and having through-going, electrically conductive paths, the
first sheet being arranged on the first side surface of the board of the
connector assembly, so as to establish electrical connection between said
selected areas of the circuit board and the first plurality of individual
connector means, and the second sheet being arranged on the second side
surface of the board of the connector assembly, so as to establish
electrical connection between said selected test points of the testing
machine and the second plurality of individual connector means.
The teachings of the present invention are applicable to printed circuit
board technique including single-sided, double-sided and multi-layer
printed circuit boards, mixed boards and circuit boards provided in PTF
technique, as well as to thin-film or thick-film technique, and the
connector assembly according to the invention may be provided in
accordance with any of these techniques or any combination of these
techniques.
Consequently, the board of the connector assembly may be constituted by a
board of a double-sided printed circuit board, the first or second
plurality of individual connector means comprising printed circuit pads
being arranged on a first side surface and on a second side surface,
respectively, of the double-sided printed circuit board, and the conductor
means of the connector assembly being constituted by through-platings of
the double-sided printed circuit board, or the board of the connector
assembly may, alternatively, be constituted by a thick-film or thin-film
substrate, the first and second plurality of individual connector means
comprising layers provided in thick-film or thin-film technique arranged
on a first side surface and on a second side surface, respectively, of the
substrate. The board of the double-sided printed circuit board and the
substrate may be a solid board or substrate, respectively, or,
alternatively, be constituted by a flexible sheet or foil, e.g. a polymer
sheet.
It should be mentioned that the board of the connector assembly may be
provided in accordance with any of the above circuit board techniques and
be employed for testing a circuit board also provided in accordance with
any of these techniques.
As the circuit board to be tested is conventionally designed by employing
computer aided design technique (CAD-technique), the computer which
actually designs the circuit board layout inherently knows the layout of
the circuit board and therefore only has to be programmed as to the matrix
configuration of the test points of the circuit board testing machine in
question for designing the configuration of individual connector means of
the first and second pluralities and, consequently, for providing the
connector assembly according to the invention.
In order to make the testing machine discriminate between the different
test areas of the circuit board to be tested, the number of individual
connector means of said second plurality is preferably identical to that
of said first plurality. Therefore, the conductor means of the connector
assembly provide a one-to-one correspondence between the individual
connector means arranged on the first side surface of the connector
assembly board and the individual connector means arranged on the second
side surface of the connector assembly board.
One of the main features of the connector assembly according to the
invention is that the connector assembly, as described above, may be
provided very easily involving double-sided printed circuit board
technique and employing relatively inexpensive materials, and in the
presently preferred embodiment of the connector assembly according to the
invention the board of the double-sided printed circuit board is a
conventional 1.5 mm glass fibre reinforced epoxy resin board, and the
printed circuit pads are 25-100 .mu.m Cu-layer pads, such as 35 .mu.m or
70 .mu.m CU-layer pads, preferably provided with gold platings.
In a further embodiment of the double-sided printed circuit board
embodiment of the connector assembly according to the invention, the
individual connector means of said first or second plurality may further
comprise connector bodies of an electrically conductive material, as the
connector bodies increase the mechanical strength of the connector means.
In a further embodiment, the conductor bodies may be arranged in respective
bores of a supporting board of an electrically insulating material and
aligned relative to their respective printed circuit pads. In this
embodiment, the connector bodies may be solid bodies made of an
electrically conductive elastomer cooperating with a substantially
non-compliant or inelastic supporting board. Alternatively, the support
board may be of a compliant or elastic material, and/or the connector
bodies may be constituted by substantially inelastic bodies.
In an alternative embodiment of the double-sided printed circuit board
embodiment of the connector assembly according to the invention including
connector bodies, the connector bodies are solid, metallic bodies. The
solid metallic bodies may be pins or alternatively male or female
connectors adapted to cooperate with mating female or male connectors.
It is to be emphasized that the above described embodiments of the
connector assembly according to the invention may be combined, in that the
individual connector means of one of the pluralities may be provided in
accordance with any of the above embodiments of the connector assembly,
and the individual connector means of the other plurality may be provided
in accordance with any of the above embodiments of the connector assembly
according to the invention. Furthermore, the different embodiments of the
individual connector means may be combined within one of the pluralities
without departing from the concept of the present invention.
The present invention also relates to a testing machine for testing a
circuit board of an electrically insulating material having circuit tracks
of an electrically conductive material arranged on at least a first side
surface thereof, and comprising a test surface including a number of test
points electrically insulated relative to each other and arranged in a
matrix configuration and the connector assembly having any of the above
described characteristics of the connector assembly according to the
invention and adapted to be arranged on said first side surface of the
circuit board providing electrical connection between selected areas of
the first side surface of the circuit board and selected test points of
the test surface through the individual connector means of the connector
assembly.
The circuit board testing machine is adapted to test the circuit board from
the first side surface thereof. The circuit board testing machine
according to the invention may alternatively or further be adapted to test
a circuit board further having circuit tracks arranged on the second side
surface opposite to said first side surface, i.e. to test a double-sided
printed circuit board, a multi-layer printed circuit board, a circuit
board provided in thin-film or thick-film technique having thin-film or
thick-film layers, respectively, arranged on both side surfaces of the
substrate of the circuit board, or a circuit board provided in PTF
technique, or a mixed board having circuit tracks arranged on both side
surfaces, and in its presently preferred embodiment the circuit board
testing machine comprises two opposite test surfaces for receiving the
circuit board therebetween and two connector assemblies having any of the
above characteristics of the connector assembly according to the invention
and adapted to be arranged on opposite side surfaces of the circuit board.
For testing a circuit board further having circuit tracks arranged on a
second side surface opposite to said first side surface, the circuit board
testing machine according to the invention may alternatively further
comprise a short-circuiting board and a further connector assembly having
any of the above characteristics of the connector assembly according to
the invention and adapted to be arranged on said second side surface of
the circuit board for providing electrical connection between selected
areas of the second side surface of the circuit board and selected areas
of the short-circuiting board.
The circuit board testing machine according to the invention may be adapted
to test the circuit board by manual connection of a generator means to one
or more test points of the testing machine and by detection or measurement
of the signal transmission to other test points of the testing machine.
Thus, the signal generator means are external means and an external signal
measuring means is further employed. In an automatic circuit board testing
machine according to the invention, the machine further comprises first
means for generating a test signal, second means for supplying a test
signal to the test points individually, third means for addressing the
test points individually and for receiving a signal therefrom, and fourth
means for measuring the signal received from the third means. Furthermore
the circuit board testing machine may comprise control means for
controlling the overall operation of the machine, such as a microprocessor
controller means, and may further or alternatively be connected to
external control or processing means such as an external computer which
may further control an automatic production of circuit boards involving
testing of the individual circuit boards by means of the circuit board
testing machine according to the invention.
The present invention further relates to a method of testing a circuit
board by means of a circuit board testing machine having a test surface
including a number of test points electrically insulated relative to each
other and arranged in a matrix configuration and for testing a circuit
board of an electrically insulated material having circuit tracks of an
electrically conducting material arranged on at least a first side surface
thereof, the method comprising:
arranging said first side surface of the circuit board facing the test
surface of the testing machine and sandwiching a connector assembly having
any of the characteristics of the above described connector assembly
according to the invention therebetween for providing electrical
connection between selected areas of the first side surface of the circuit
board and selected test points of the test surface of the testing machine
through the individual connector means of the connector assembly.
If the circuit board further has circuit tracks arranged on a second side
surface opposite to said first side surface, the method according to the
invention may in a first embodiment further comprise employing a circuit
board testing machine having a further test surface opposite to said at
least one test surface and arranging the second side surface of the
circuit board facing the further test surface of the testing machine and
sandwiching a further connector assembly having any of the characteristics
of the above described connector assembly according to the invention
therebetween for providing electrical connection between selected areas of
the second side surface of the circuit board and selected test points of
the further test surface of the testing machine through the individual
connector means of the further connector assembly, or, alternatively, in a
second embodiment further comprises arranging a short-circuiting circuit
board facing the second side surface of the circuit board sandwiching a
further connector assembly having any of the characteristics of the above
described connector assembly according to the invention therebetween for
electrically interconnecting selected areas of the second side surface of
the circuit board.
Normally, the selected areas of the circuit board constitute selected areas
of the circuit tracks of the circuit board in order to positively test the
electrical conductive circuit track or circuit pattern of the circuit
board. Consequently, in accordance with a further embodiment of the method
according to the invention at least one of the said selected areas may
constitute a selected area of the circuit tracks of the circuit board.
However, as mentioned above, certain circuit boards, e.g. circuit boards
for HF (High Frequency) applications or circuit boards involving certain
security requirements such as requirements as to insulation between
particular circuit tracks may advantageously be tested by providing
electrical connection to a selected area interposed the circuit tracks of
the circuit board in order to render possible the test or measurement of
the insulation between the circuit tracks in question or the capacitive or
inductive coupling therebetween. Consequently, in accordance with a
further or alternative embodiment of the method according to the invention
at least one of the said selected areas may constitute a selected area
interposed selected circuit tracks of the circuit board.
The invention will now be further described with reference to the drawings,
wherein
FIG. 1 is a vertical, sectional view through a top surface of a circuit
board testing machine, a connector assembly according to the invention and
a circuit board to be tested,
FIG. 2 is a vertical, sectional view through a second embodiment of a
connector assembly according to the invention,
FIG. 3 is a vertical, sectional view through a third embodiment of a
connector assembly according to the invention,
FIG. 4 is a vertical, sectional view through a fourth embodiment of a
connector assembly according to the invention,
FIG. 5 is a vertical, sectional view through a fifth embodiment of a
connector assembly according to the invention,
FIG. 6 is a vertical, sectional view through a sixth embodiment of a
connector assembly according to the invention,
FIG. 7 is an overall perspective view of a circuit board testing machine
according to the invention,
FIG. 8 is a perspective and partially broken away view of a test head
constituting a component of the circuit board testing machine shown in
FIG. 7 and including a test surface of the circuit board testing machine,
FIG. 9 is an exploded and perspective view of two test heads including two
test surfaces and constituting two individual components of the circuit
board testing machine shown in FIG. 7, and illustrating the concept of
sandwiching a circuit board to be tested between two connector assemblies
according to the invention which are further sandwiched between the test
heads of the circuit board testing machine,
FIG. 10 a vertical sectional view basically through the test head,
connector assembly and circuit board set up of FIG. 9, in which one of the
test heads is replaced by a short-circuiting or dummy circuit board,
FIG. 11 is a diagram illustrating the matrix addressing of the test points
of the test surface of the test head shown in FIGS. 8 and 9, and
FIG. 12 is an overall schematical view of the circuit board testing machine
shown in FIG. 7 connected to an external control computer and further
illustrating the internal microprocessor of the testing machine.
In FIG. 1, a schematical, vertical, sectional view through a first
embodiment of a connector assembly 10 according to the invention is shown.
The connector assembly 10 comprises an assembly board 12 of an insulating
material, such as a 1.5 mm glass fibre reinforced epoxy resin board,
having printed circuit pads 14 and 16 arranged on the top surface and on
the bottom surface, respectively, of the assembly board 12. The printed
circuit pads 14 and 16 are made of 35 .mu.m or 70 .mu.m Cu-layers provided
with gold platings, and each of the top surface printed circuit pads, such
as the pad designated 14, is connected to a respective bottom surface,
printed circuit pad, such as the pad designated 16 through a metallic
conductor 18 constituted by a through-plating of the double-sided printed
circuit board or connector assembly 10. The top surface printed circuit
pads and the bottom surface printed circuit pads, such as the pads 14 and
16, respectively, are each provided with an electrically conductive
connector body, such as the bodies designated 20 and 22, respectively,
constituted by electrically conductive elastomeric bodies.
The connector assembly 10 is adapted to cooperate with a circuit board
testing machine such as a manual testing machine or an automatic testing
machine, a modified, conventional circuit board testing machine or,
preferably, a circuit board testing machine according to the invention to
be described below. The upper side surface part of the circuit board
testing machine shown in FIG. 1 and designated the reference numeral 24 is
provided with a number of test point pads, one of which is designated the
reference numeral 26, and which are arranged in spaced apart, insulated
relationship in a matrix configuration together constituting a test
surface. Thus, the distance between two adjacent test point pads is e.g.
1/10" (2,54 mm) or 2.5 mm. The test point pads are internally connected to
switching means of the circuit board testing machine for connecting a test
point pad to a current generator means or to a current detector means in
order to carry out a circuit board testing routine as will be described
below.
The connector assembly 10 is further adapted to cooperate with a circuit
board to be tested and comprising a circuit board 28 of an insulating
material, such as a conventional, printed circuit board having printed
circuit tracks arranged on at least one side surface thereof, such as the
printed circuit tracks or pads arranged on the lower side surface of the
printed circuit board 28, one of which is designated the reference numeral
30. The printed circuit board 28 is a bare board, i.e. a board without any
components mounted thereon, however, the circuit board may alternatively
be provided with electronic components. Furthermore, the connector
assembly 10 according to the invention may alternatively be employed for
testing other circuit boards, such as thick-film or thin-film substrates
having conductive layers applied on a single or both side surfaces of the
substrate, multi-layer printed circuit boards, mixed boards, circuit
boards provided in PTF technique or any combination of these circuit
boards further provided with components if desired.
The layout of the circuit board to be tested, i.e. the layout of the
printed circuit board 28, is determined solely by the layout of the
electronic circuitry to be provided by the electronic component to be
mounted on the circuit board. Therefore, the arrangement of the printed
circuit pads 14 arranged on the top surface of the connector assembly 10
is determined by the arrangement of the printed circuit tracks or printed
circuit pads arranged on the lower side surface of the printed circuit
board 28. Normally, the printed circuit pads 14 are arranged aligned in
relation to a printed circuit track or printed circuit pad of the printed
circuit board 28 so as to establish electrical contact to the printed
circuit track or the printed circuit pad in question.
However, certain circuit boards, such as circuit boards for HF (High
Frequency) applications and circuit boards involving security
requirements, e.g. requirements as to insulation between circuit tracks or
circuit pads, are preferably tested by providing a printed circuit pad 14
at a position interposed in relation to the printed circuit tracks or
printed circuit pads of the circuit board so as to render possible the
detection of irregularities of the insulating area between the printed
circuit pads or printed circuit tracks in question. Such irregularities
may originate from insufficient etsing of the printed circuit board. In
connection with substrates having layers applied on a single or both side
surfaces of the substrate, there is a pronounced risk that the layers
constituting the conductive circuit tracks or circuit pads of the circuit
board become mashed or smeared due to deficiencies in the production
process. Obviously, deficiencies of the insulation between circuit tracks
or circuit pads of the circuit board may have different origin in
thin-film or thick-film, multi-layer, printed circuit, etc. techniques.
Contrary to the printed circuit pads 14, the arrangement of the printed
circuit pads 16 arranged on the lower side surface of the connector
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