Abstract:
The present invention relates to a SIMM/DIMM board handler, which enables a single test site handling machine to be integrated into an inline, multi-site test cell, and includes an angled conveyor belt, an angled fail tray for transporting and sorting tested circuit boards and an adjustable circuit probe for performing separate testing of circuit boards.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of pending provisional application Ser. No. 60/192,701 filed Mar. 28, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to parts handling equipment, and more particularly to an improved electronic circuit board handling and testing apparatus that is adapted to position each of an inventory of identical circuit boards into a test fixture and, subsequent to the completion of a testing protocol, sort each board in accordance with a test result. Multiple machines may be positioned in-line such that all sorted GOOD circuit boards are transported to a single location at the end of the line. 
     The present invention is particularly adapted for handling and testing of small printed circuit boards, which include one or more memory devices typically referred to as Memory Modules, SIMM boards, DIMM boards, and RIMM boards. 
     2. Description of Related Art 
     Single Test Site, Gravity Operation 
     Known circuit board handlers, such as U.S. Pat. No. 5,704,489 to Smith (“Smith &#39;489”), deposit sorted circuit boards by using gravity and a diverting mechanism to direct boards down one of a pair of exit chutes into a pass or fail bin or containment vessel. A GOOD collection bin and a BAD collection bin are required for each handler. However, high volume production environments may use ten to fifty single site test handlers. 
     The use of gravity and the diverting mechanism of the Smith patent cause undesired forces to be exerted on the circuit boards as they bounce down the exit chute. The undesired forces can cause damage to components mounted on the circuit boards. 
     Additionally, forces exerted on boards as they fall into a collection bin from the exit chute can also cause damage to components on the circuit board. Components on circuit boards lying in the collection bin also may be damaged as newly sorted boards are dropped onto them. 
     Magazine Sleeve, Singulator Mechanism and Adjustable Circuit Probe 
     Known circuit board handlers, such as disclosed in Smith &#39;489, typically include magazine sleeves of several sizes, each of which is adapted to accommodate a plurality of circuit boards of corresponding width. The circuit boards are stacked one on top of each other within the magazine sleeve. 
     The known circuit board handlers, such as Smith &#39;489, include a singulator mechanism having the magazine sleeves releasably attached directly above the singulator mechanism. The singulator mechanism performs a sequence of steps to drop a single circuit board from the bottom of the stack of boards held in the magazine sleeve. The separated or “singulated” circuit board is dropped from the magazine assembly onto a shelf member of a testing assembly and then pushed into the modular-testing component of the testing assembly. Such circuit board handlers can potentially cause damage to components, due to dropping the entire stack the height of one circuit board. As the entire stack is dropped within the magazine sleeve, relative motion between the circuit boards causes interference between components mounted on the bottom of one board with components mounted on the top of the circuit board stacked immediately adjacent. Additionally, such known circuit board handlers are limited in the number and/or type of tests that may be performed on each circuit board. 
     Furthermore, the known circuit board handlers can potentially cause damage to components by allowing operators to improperly load the circuit boards into the magazine sleeve. For example, circuit boards may be loaded upside down causing a misalignment of the circuit board contacts with the testing apparatus contacts. 
     Potential Component Damage, Singulation Sequence, Adjustable Circuit Probe 
     The singulation sequence, performed on known circuit board handlers, such as Smith &#39;489, can potentially damage components mounted on the circuit boards. The singulation sequence causes the lowermost circuit board to drop from the bottom of the stack onto a shelf member. The singulation sequence then causes the entire stack to drop the equivalent of the height of one circuit board. 
     Additionally, the known circuit board handlers can potentially cause damage to components, due to mechanical interference between the singulator mechanism and components mounted near the edge of the circuit board. 
     Also, the known circuit board handlers can potentially cause damage to components, due to dropping a single circuit board onto the shelf member. 
     Furthermore, the known circuit board handlers do not reliably control the extension of the singulator block. The singulator blocks in known handlers are screwed onto a cylinder shaft and retained with thread locking adhesive. Inherent problems in this design include variation in the extension of the cylinder shaft, non reusable cylinders due to the thread retaining adhesive, and cylinder bumper wear. These problems result in component damage due to varying upper and lower ledge retainers, such as Smith &#39;489. 
     Finally, the known circuit board handlers are limited in what tests they may perform, as well as where circuit boards may be tested. 
     Modular Test Assembly, Connectors, Adjustable Circuit Probe 
     The known circuit board handlers utilize a “Zero Insertion Force” (ZIF) contact mechanism. The contact fixture uses a set of gold plated, metal fingers, which must be flexed or forced into position to make electrical contact with connector pads on the circuit board under test. The gold plated, metal fingers of the ZIF contact fixture used on known circuit board handlers must be manufactured to a required length to allow for flexing of the fingers to contact the circuit board under test. The required length of the metal fingers is detrimental to higher frequency test signals. Complete testing at high frequency operation is not possible using the metal fingers used on known handlers. Additionally, no tests on the circuit board may be performed outside of the text fixture. 
     Furthermore, the gold plated, metal fingers of the ZIF contact fixture are susceptible to breaking, are expensive and are manufactured by a single source only. 
     Therefore, there exists a need in the circuit board handler art for an improved handler that overcomes the above-mentioned problems, and allows at least one additional test to be performed on circuit boards by an adjustable circuit probe. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a circuit board handling and testing apparatus (i.e., handler), which comprises a housing defining a stationary top surface. Attached to the housing of the present invention are an improved singulating mechanism, an improved magazine assembly, an improved modular test component, a new conveyor transport assembly, and an adjustable circuit probe for performing additional testing. 
     In a preferred embodiment of the present invention, the new conveyor transport mechanism is mounted directly below a pivotal shelf member, which is used to eject circuit boards from a testing assembly and/or adjustable circuit probe. The conveyor transport extends out of the sides, beyond a housing of the handler. This allows individual machines, built in accordance with the present invention, to be installed next to each other and transport sorted GOOD circuit boards from one machine through multiple machines in a line to a single destination, instead of individual bins at each machine. 
     The conveyor transport and the unique workings of a fail tray included in the present invention eliminate the use of a divert mechanism, such as disclosed in the Smith &#39;489 patent, thus eliminating risk of damage to components during the sorting process. 
     The improved magazine assembly uses precision guide rails to hold stacked circuit boards in relative position thus minimizing risk of damage to components mounted on the circuit boards. 
     The materials and design of the singulating mechanism of the present invention have been improved for increased reliability of the singulation process and minimized risk of damage to components mounted on the circuit boards. In the preferred embodiment of the present invention, the modular test assembly has been improved to accommodate a wider range of test connectors thus allowing test systems to test the circuit boards at higher frequencies. 
     The addition of an adjustable circuit probe, between a magazine and a modular test assembly, allows the present invention to perform additional testing of circuit boards. 
     The improvements regarding the magazine sleeve, the singulator mechanism, the modular test assembly and the adjustable circuit probe of the present invention are also useful on known handlers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a top plan view of a circuit board handler with a conveyor transport mechanism and adjustable circuit probe, in accordance with the present invention; 
     FIG. 2 is a side elevational view of the circuit board handler, adjustable circuit probe and conveyor transport mechanism of FIG. 1; 
     FIG. 3 is a front elevational view of multiple circuit board handlers of the present invention connected together in-line; 
     FIG. 4 is a plan view of an improved magazine assembly having precision guides of the present invention therein; 
     FIG. 4A is an enlarged partial sectional view taken along line  4 A of FIG. 4; 
     FIG. 5 is a top plan view of an improved singulator mechanism of the present invention; 
     FIG. 5A is an enlarged partial sectional view taken along line  5 A of FIG. 5; 
     FIGS. 5B and 5C illustrate operation of the singulator mechanism of FIG. 5; 
     FIG. 6 is an improved circuit board ejector assembly of the present invention; 
     FIG. 6A illustrates a prior art circuit board ejector assembly; 
     FIG. 7 is a front perspective view of a circuit board handler, adjustable circuit probe and conveyer system, having a magazine assembly thereon, in accordance with the present invention; and 
     FIGS. 8 and 9 are front elevational view of one embodiment of the adjustable circuit probe of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is an improvement to the circuit board handler disclosed in U.S. Pat. No. 5,704,489 to Smith (Smith &#39;489″). The disclosure of the Smith &#39;489 patent is incorporated herein, in its entirety, by this reference thereto. 
     Modular Handler, Conveyor Transport 
     As best shown in FIGS. 1-3 and  7 , circuit board handlers  10  constructed in accordance with the present invention include an angled conveyor transport mechanism  13 , which allows individual machines to be modularly inserted into a single multi-site, in-line test cell (see FIG.  3 ). 
     The angled conveyor transport  13  is preferably angled at between 20°-30°, with 25° being a currently preferred angle. A fail tray  15 , which eliminates the sort mechanism of the Smith &#39;489 patent, is mounted spaced from the conveyor  13 , at the same angle. As a default, the fail tray  15  interrupts the transition of a tested circuit board onto the conveyor  13 . When a board is sorted to GOOD, the fail tray  15  slides to the left, as shown in FIGS. 1 and 7, and allows the GOOD board to directly transition onto the conveyor  13 , for transport to a further machine or collection site. When a board is sorted to fail, the fail tray  15  remains in place (shown in broken line in FIG. 1) until a failed board is received. Once a failed board is received, the fail tray  15  slides to the left to sort the failed board. While inside the unit  10 , a guide (not shown) for the conveyor acts as a guide for the failed board. Once outside the handler  10 , a step in the guide allows the failed board to slide off the fail tray  15  to fall by gravity and into a fail bin (not shown), beside the handler  10 . 
     The angled conveyor  13  and angled fail tray  15  of the present invention are circuit board friendly. Their angle corresponds to the angle a pivotal shelf or tray  136  takes, when it is used to eject circuit boards from the test assembly in a known manner. The angled conveyor, which directly receives GOOD boards from the pivotal shelf  136  eliminates dropping the GOOD boards from the pivotal shelf member onto a sort tray as used in Smith &#39;489. On handlers built in accordance with Smith &#39;489, the ends of the board drop in excess of five inches, causing problems if they land improperly. The angled design of the conveyor and fail tray of the present invention provides a parallel sorting transition. The result is a safe and controlled sorting method. 
     To maintain reliability and increase cycle time, sensors monitor the entire process. The fail tray  15  has extend and retract sensors to ensure proper timing and to monitor any jams. The fail tray  15  also contains a further sensor to ensure that any board therein has exited the tray properly. 
     The modular design of the present invention allows simple line expansion or reduction of multi-site test cells. This invention also maintains left/right sortation. 
     Multiple machines built in accordance with the present invention use the same GOOD bin or circuit board loader. Space for individual GOOD bins is eliminated allowing more tabletop space in production areas. The present invention maintains standard height and tabletop mounting. This is an important ergonomic consideration for operators. 
     The present invention also maintains default to FAIL operation, and includes an improved circuit board ejector (see FIGS.  1  and  6 ). 
     Magazine Assembly Improvements 
     As shown in FIGS. 1,  3 ,  4 ,  4 A and  7 , a magazine assembly  38  mounted on the circuit board handler  10  of the present invention uses precision guide rails  41 , to position a stack of circuit boards  12 . Utilizing the standard connector notch defined in JEDEC standards for memory module circuit boards, the guide rails  41  define surfaces on both sides of the boards that positively contain the circuit boards in two degrees of freedom. 
     The precision guide rails  41  eliminate motion of any one circuit board  12 , relative to an entire stack, thus eliminating interference problems between components mounted on the bottom of one board with components mounted on the top of the circuit board stacked immediately adjacent. 
     The magazine assembly  38  on the circuit board handler  10  of the present invention uses the adjustable, locating, guide rail  41  (see FIG. 4A) to match the position of a polarizing keyway found on memory board circuit boards. This locating guide rail  41  eliminates operator error by allowing a single, unique, loading orientation. The circuit boards cannot be loaded upside down when the polarizing keyway on the circuit board is matched to the guide rail. 
     Singulator Improvements 
     A singulator mechanism  42  having two separate support blocks  44  on the circuit board handler  10  of the present invention utilizes precise extension control. The extension of a singulator block  44  is governed by a toleranced stop. The toleranced stop controls exactly how far the singulator block  44  extends under and over a circuit board. In addition, the singulator mechanism  42  is dowel pinned to a top plate of the circuit board handler  10 , therefore, precisely controlling the overall block extension relative to a circuit board. This new design also allows for the replacement of cylinders with use of lock nuts, rather than thread locking adhesive, to retain the blocks. 
     The singulator mechanism  42 , shown in FIGS. 5-5B, includes guides that are made out of aluminum. The singulator  42  include upper and lower parts  60 ,  70 , that are preferably made out of stainless steel (upper  60 ) and brass (lower  70 ). Using three different materials allows the singulator  42  to slide with little friction and it enables control over wear surfaces. 
     The upper singulator  60  made from stainless steel is extremely strong, virtually eliminating any notch from forming due to wear on aluminum singulators made in accordance with the prior art. 
     The upper singulator  60  includes a chamfer  66  that has be en shortened with respect to known devices, even more to handle present day circuit boards  12  with components mounted closer to the edges. The height of the upper singulator has been increased to hold low profile chips, such as Thin Small Outline Package (TSOP) equipped modules, by a small step  74  in the lower singulator  70 . 
     The lower singulator step  74  is approximately 0.062, and is, therefore, capable of handling the majority of memory circuit boards currently on the market when used with the new upper singulator. In addition, small radii on edges of approximately 0.30″ on the lower singulator  70  helps eliminate component damage. 
     Extension stops on upper cylinders operating the upper singulators  60 , along with flow controls, keep modules held therein from dropping and lined up straight. These modifications have proven very successful for eliminating multiple board drop problems and damage to components near, or at the edge of the module. 
     Modular Test Assembly Improvements 
     Circuit board handlers  10  constructed in accordance with the present invention include an improved modular test assembly. The improved test assembly allows the use of standard circuit board connectors on the testing apparatus. Use of standard circuit board connectors eliminates the longer circuit lengths required by the gold plated, metal fingers of the ZIF contact fixture used on circuit board handlers constructed in accordance with the Smith &#39;489 patent. Reducing the circuit lengths allows testing at much higher frequencies as required by the latest circuit board technology. Furthermore, the improved circuit board ejectors shown in FIGS. 1 and 6 more precisely control the ejection of circuit boards  12  from the test assembly and eliminates any chance of damaging the boards. 
     Adjustable Circuit Probe 
     As best shown in FIGS. 1,  2  and  7 - 9 , to enable the circuit board handler  10  of the present invention to perform at least one additional or extra test on circuit boards  12 , an adjustable circuit probe  80  is secured to the top surface of the handler. 
     The circuit probe  80  includes a frame or gantry mount  82  from which is suspended a movable element  84  having a probe  86  secured to a lower end  88  thereof. The probe  86  is electrically connected, as by means of leads or wires  90 , to a test instrument (not shown). The frame or gantry mount  82  includes a coarse adjustment knob or mechanism  92 , to allow movement in the direction of arrow  91 ,  93  (see FIG.  9 ), as well as fine or micrometer X-Y adjustment means  94 ,  96 , such as knobs. The adjusting means  92 ,  94 ,  96 , allow the movable element  84  and probe  86  to be adjusted to test various components  98 ,  100  on circuit boards  12 . 
     It, therefore, can be seen that after a circuit board  12  has been dropped from the magazine  38 , it can be selectively tested with the handler  10  of the present invention. For example, normal testing, such as performed with existing handlers, can be done with the testing fixture, as explained above. Or, one or more additional tests or programming functions may be performed on circuit boards  12  by using the adjustable circuit probe  80  of the present invention. 
     Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.