Mounting apparatus for vectorless testing

A mounting device (10) is shown particularly adapted for adjustably mounting vectorless test heads for circuit board components and the like to be tested for processing faults of component pin connections with traces of a circuit board in which the components are mounted. A U-shaped bracket (18) is lockably received on a rail (2) and has first and second projections (18d,18e) slidably received through a respective slot (16c,16d) of a leg (16) of a T-shaped member (12). The base leg (14) of the T-shaped member (12) is connected to one end of a pin member (24) which slides through a bore (18p) in one arm (18b) of U-shaped bracket (18) and is threadingly received in a threaded bore (18n) of the other arm (18a) of the U-shaped bracket (18). Rotational movement of the pin member (24) causes T-shaped member (12) to move in a Z direction to permit precise locating of a test head (30) mounted on the base leg (14). The mounting device (10) is also shown mounted on a resinous mounting plate (40) having a plurality of sets (40a) of mounting apertures.

FIELD OF THE INVENTION 
This invention relates generally to the testing of integrated circuit (IC) 
components, circuit boards, connectors and the like for pin processing 
faults and more particularly to an improved mechanism for mounting test 
heads employed in conducting such tests. 
BACKGROUND OF THE INVENTION 
It is conventional to test the integrity of soldered pin connections of IC 
components with traces on a circuit board and the like by mounting such 
boards in a test fixture and positioning test heads of various types in 
overlying, closely adjacent relationship to the components to be tested. A 
typical circuit board to be tested has anywhere from 20 to 40 or more test 
heads which must be mounted in very precise locations relative to the 
components to be tested in the X, Y and Z axes, i.e., in three directions 
perpendicular to one another. For example, when using vectorless testing 
techniques, such as a magnetic inductive test or capacitive coupling test, 
the test head, comprising a magnetic inducer or a capacitive probe 
respectively, is placed directly over the component under test and 
positioned no more than a selected distance, such as 0.010-0.020 inches 
from the component. As seen in FIG. 1, each test head (1) is mounted on a 
bracket 4 which is suspended from any one of a plurality of rails 2 
movably mounted in an X direction (slots 6) over the mounting surface and 
circuit board CB mounting the component. The bracket typically is 
adjustably attached to the rail in the Y and Z directions by using one or 
more screw members 5. Due to the precise locating requirements of the test 
head, it is not unusual for a skilled technician to take the better part 
of a man-day to complete a typical set-up. A common time consuming problem 
occurs when an adjustment to the position of one of the heads must be made 
after a test set up has been largely completed. In order to get at the 
screws of the test head to be adjusted, an adjacent rail may have to be 
moved due to spatial limitations causing the heads on that rail to move 
out of position thereby adding to the already long set up-time to 
thereafter reposition the test heads. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide mounting apparatus 
particularly adapted for vectorless testing of solder connections of IC 
components and the like on circuit boards which overcomes the prior art 
limitations noted above. Another object of the invention is the provision 
of a vectorless test head and improved mounting apparatus which is 
relatively inexpensive yet reliable and accurate, in which the Y and Z 
positions of the test head can be easily and precisely adjusted, and 
particularly without interference from the mounting mechanisms of 
neighboring test heads. Yet another object is the provision of an improved 
mounting device for mounting sensors, transducers, tools or other small 
objects which can be easily adjusted in a vertical, or Z, direction. 
Briefly, in accordance with a preferred embodiment of the invention, a 
generally T-shaped member, preferably formed of suitable moldable plastic 
material such as polyvinylchloride, has a first laterally extending base 
leg and a second slide leg extending therefrom intermediate the ends of 
the first leg. Suitable apertures, such as slots, are formed at opposed 
ends of the first leg for mounting a pin member and the test head 
respectively. The second slide leg is formed with first and second 
elongated slots extending along the length of the second leg. A generally 
U-shaped bracket of suitable material, such as aluminum, has first and 
second arms extending from a bight portion with the bight portion disposed 
on one face surface of the second leg and with a pair of slide projections 
on the bight portion received through respective slots in the second slide 
leg of the T-shaped member. The slide projections are provided with heads 
which extend over a portion of the opposed face surface of the second 
slide leg to slidingly couple the T-shaped member and the U-shaped bracket 
together. Preferably, a tongue and groove arrangement is formed between 
the T-shaped member and the bracket as by forming a tongue along the 
length of the bight portion which is slidingly received in a groove formed 
in the said one face surface of the second leg and extends along the 
length of the second leg. A pin member is attached to the first leg of the 
T-shaped member as by forming the pin member with an annular groove 
adjacent one end of the pin member with the groove received in the slot at 
one end of the first leg of the T-shaped member. The pin member is 
slidingly received through a bore formed at the distal end of the lower 
arm of the U-shaped bracket and a threaded portion extending from the pin 
member along the longitudinal axis thereof is threadingly received in a 
first threaded bore formed in the distal end of the upper arm of the 
bracket. A knob is preferably provided at the free end of the threaded 
portion to facilitate adjusting rotation of the pin member. Preferably, a 
lock nut is disposed on the threaded portion between the knob and the 
U-shaped bracket. Rotational movement of the pin member will cause 
relative movement of the bracket and the T-shaped member. Preferably a 
compression spring is disposed about the threaded portion between the body 
of the pin member and the bracket to place a force on the pin member so 
that the threaded portion is always biased against the thread in the 
bracket arm in the same direction to provide consistent positioning of the 
first leg of the T-shaped member relative to the rotational angle of the 
pin member regardless of the direction of rotation. 
According to a feature of the invention, a rail seat is formed between the 
first and second arms of the bracket and a second threaded bore is formed 
through the upper arm of the bracket aligned with the seat. A set screw is 
received in the second threaded bore to lock the bracket in any selected x 
position along a rail received in the seat. A suitable test head, for 
example a magnetic inducer or a capacitive probe, is disposed on the lower 
surface of the first leg of the T-shaped member and attached thereto by 
suitable means such as screws received through a slot in the first leg. 
According to another feature of the invention, instead of mounting the 
devices on rails, a sheet of resinous material such as Lexan or Plexiglass 
may be provided with a plurality of sets of apertures which can be used to 
mount devices in various X-Y locations. 
Additional objects and features of the invention will be set forth in part 
in the description which follows and in part will be obvious from the 
description. The objects and advantages of the invention may be realized 
and attained by means of the instrumentalities, combinations and methods 
particularly pointed out in the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Mounting device 10, made in accordance with a preferred embodiment of the 
invention and shown in FIGS. 2, 3, comprises a generally T-shaped member 
12 preferably formed of a moldable plastic material such as 
polyvinylchloride. Member 12, shown also in FIGS. 4-6, has a first base 
leg 14 with slots 14a,14b, formed in opposite ends of the leg and an 
integrally formed second leg 16 extending away from leg 14 intermediate 
the ends thereof. Leg 16 is preferably formed with centrally disposed, 
elongated groove 16a on one face surface 16b extending essentially the 
entire length of leg 16. First and second elongated slots 16c and 16d 
extend through leg 16 from groove 16a to face surface 16e for a purpose to 
be described below. 
A generally U-shaped mounting bracket 18 (see FIGS. 7-9) having a first 
upper arm 18a and a second lower arm 18b joined by a bight portion 18c has 
first and second slide projections 18d,18e extending outwardly from the 
bight portion which are slidingly received in respective slots 16c,16d. A 
tongue 18f is formed on bight portion 18c extending essentially along its 
entire length and is slidingly received in groove 16a of second leg 16 of 
T-shaped member 12. Threaded bores 18g are formed through projections 
18d,18e for reception of screws 20 having heads with a diameter greater 
than the width of slots 16c,16d and with the heads received over face 
surface 16e to slidingly and lockingly couple the U-shaped bracket to the 
T-shaped member. A rail seat 18k is formed in arms 18a,18b for sliding 
reception of a suitable rail 2 of the type shown in FIG. 1. A threaded 
bore 18m in arm 18a is aligned with seat 18k and receives a set screw 22 
to lock bracket 18 to the rail at a selected location in the X direction. 
A pin member 24 has an annular groove 24a formed adjacent one end 24b 
thereof and a cylindrical slide portion 24c extending from groove 24a 
toward the opposite end 24d of the pin member. Slide portion 24c is 
slidingly received through a bore 18p formed in arm 18b with annular 
groove 24a received in slot 14a of leg 14 of T-shaped member 12. An 
elongated threaded member 24e is fixedly attached to pin member 24 and 
extends along the longitudinal axis of the pin member from end 24d of the 
pin member. Threaded member 24e is threadingly received in threaded bore 
18n formed in arm 18a of U-shaped bracket 18 so that rotational movement 
of threaded member 24e, with annular groove 24a locked in slot 14a will 
cause T-shaped member 12 to move in the Z direction, i.e., vertically as 
seen in FIGS. 2, 3 between an upper extremity shown in FIG. 2 and a lower 
extremity shown in FIG. 3. A knob 24f is preferably provided at the free 
distal end of threaded member 24e to facilitate rotational movement so 
that the T-shaped member can be readily adjusted to any selected position 
in the Z direction between the FIGS. 2 and 3 extremities. A lock nut 26 is 
preferably received on threaded member 24e between knob 24f and arm 18a of 
bracket 18. Preferably, a compression spring 26 is placed about threaded 
member 24e between end 24d which serves as a spring seat and arm 18a to 
maintain a bias on threaded member 24e in the same direction, e.g., 
downwardly as seen in FIGS. 2, 3. This takes up any slack or looseness 
between the male thread of member 24e and the female thread of T-shaped 
member 12. 
As shown in FIGS. 2, 3, a selected test head 30 is mounted by any suitable 
means on a seat on the lower surface of first base leg 14, as seen in 
FIGS. 2, 3, as by use of screw members 32 received through slot 14b and 
into a respective bore (not shown) in a base 30a of the test head. A 
conventional two wire insulated lead 34 is received through slot 14b and a 
suitable aperture in base 30a so that the leads can be suitably attached 
to circuit board or ground plane 30b depending on the type of test head 
employed. It will be understood that various types of test heads can be 
mounted on T-shaped member 12 such as the magnetic inducer or capacitive 
probe referenced above. 
Thus it will be seen that the invention provides apparatus which can be 
accurately positioned in the x direction on a rail, as seen in FIG. 11, 
and precisely adjusted in the z direction without any interference from 
similar neighboring mounting devices. By means of the invention, set-up 
time for a given board is greatly reduced compared to prior art 
techniques. 
FIG. 12 shows a resinous mounting plate 40 which can be used to mount 
devices 10 made in accordance with the invention to obtain the desired Z 
direction adjustment instead of using conventional rails 2. Plate 40 is 
attached to the test fixture using appropriate hardware 42 and is provided 
with a plurality of aperture sets 40a for mounting devices 10. Although 
only three sets of apertures 40a are shown it will be understood that any 
desired number can be provided in both the X and the Y directions. Each 
set includes a first bore 40b for reception of elongated member 24e, a 
second bore 40c for reception of a screw (not shown) which is received in 
bore 18m used to affix device 10 to plate 40, a slot 40d for reception of 
the upper portion of leg 16 in the upper position of T-shaped member 12, 
and bore 40e to provide access to screws 32 (not shown in FIG. 12) to 
allow adjustment of a head in slot 14b. 
Although the invention has been described with regard to a specific 
preferred embodiment thereof, variations and modifications will become 
apparent to those skilled in the art. For example, the tongue and groove 
arrangement of the bight portion 18c and leg 16 can be reversed with the 
tongue formed on leg 16 and the groove formed in bight portion 18c, if 
desired. Further, although two slots 16c,16d are shown in leg 16 it will 
be understood that a single elongated slot could be used with both slide 
projections received therethrough, if desired. The use of material such as 
PVC for T-shaped member 12 and aluminum for bracket 18 is particularly 
advantageous in providing smooth, low friction movement, however, the use 
of other materials is within the purview of the invention. Although pin 
member 24 is shown with groove 24a for reception in slot 14a, the pin 
could be attached to base leg 14 by other means, such as by a screw 
received through a bore in base leg 14 and into an axially extending bore 
formed in pin member 24 or a reduced diameter portion of the pin member 
could be received in a bore in base leg 14 and locked there by means of a 
washer and a screw in an axially extending bore formed in pin member 24. 
It will also be understood that T-shaped member 12 could, if desired, be 
formed as an L-shaped member with both the pin member and the test head 
mounted on the base leg thereof. The mounting device, although 
particularly adapted to mount test heads of the type described supra, can 
be employed to mount various devices, such as sensors, transducers and 
even tools. It is, therefore, the intention that the appended claims be 
interpreted as broadly as possible in view of the prior art to include all 
such variations and modifications.