Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-05-28
2001-04-24
Karlsen, Ernest (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S072500
Reexamination Certificate
active
06222378
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to electrical probing of integrated circuit packages and more specifically to a probe adapter for acquiring signals from solder ball connections of a Ball-Grid-Array package.
Surface mounted (SMT) integrated circuit devices have become the dominant type of IC packaging in the electronics industry. These device come in a wide variety of package configurations and lead pitch geometries. For example, IC packages may be square or rectangular with electrical contact or lead counts from 44 to 232 or higher. A variety of electrical contact or lead types are also being used. Quad flat pack IC's use Gull wing leads or J-leads. Both type of leads extend from the perimeter of the IC package with the former type of leads bending down and outward from the package while the later bend down and fold under the package in a J-shape. The leads are soldered to electrical contact pads formed on a circuit board. Pin-Grid-Array (PGA) and Ball-Grid-Array (BGA) devices have electrical contacts formed in a matrix on the bottom surface of the IC package. The PGA devices have lead wires extending downward that engage a corresponding matrix of through holes in the circuit board. The leads are soldered in the through holes to make the electrical connections. BGA devices have a matrix of electrical contacts formed on the bottom surface of the IC with solder balls formed on each contact, which allow soldering of the contacts to a corresponding matrix of electrical contact pads on the circuit board.
Probing PGA devices with standard measurement instrument electrical probes, such as passive and active oscilloscope probes or the like, requires access to the reverse side of the circuit board on which the PGA device is soldered. For BGA devices, additional contact pads have to be formed on the circuit board and electrically connected to the matrix of contact pads underneath the BGA device to allow probing of the device.
Another solution for probing electrical contacts of a BGA device is a probe adapter as described in U.S. Pat. No. 5,548,223 and assigned to Tektronix, Inc., assignee of instant invention. The probe adapter is made of a flexible dielectric material having electrical contacts formed in a central region that correspond to the electrical contacts on the BGA device. Extending outward from the central region of the adapter are wings on which are formed conductive runs that extend from each of the electrical contacts in the central region to electrical contacts formed at the periphery of the wings. The central region of the adapter is positioned between the BGA device and the substrate or circuit board and soldered in place using the solder balls of the BGA device. Such an adapter is intended for use in troubleshooting and debugging prototype circuit designs but not intended for troubleshooting circuits in production circuit boards or failed circuits boards in products.
What is needed is a probe adapter that allows electrical probing of individual solder ball connections of a mounted Ball-Grid-Array device.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a probing adapter for a Ball-Grid-Array package. The probing adapter has an elongate body with a centrally disposed slotted region formed therein with an aperture formed in one end of the body that extends to the slotted region. The slotted region contains a slider that is movable from a first position to a second position. The slider has an electrically conductive plunger attached to it. An electrical contact is electrically coupled to the plunger with a portion of the electrical contact exposed outside of the elongate body. An electrode extends from the plunger and through the aperture in the elongate body to expose the electrode outside of the body for making electrical contact with a solder ball contact of the Ball-Grid-Array package. The adapter may include a flexible member attached to the one end of the elongate body with an aperture formed in it through which the electrode extends. The slider has detents formed in it for engaging corresponding detents formed in the slot. A spring-loaded push-button is mounted on the slider that engage and disengage the slider detents from the slot detents. A scale pointing element can be affixed to the slider that points to an adjacent scale positioned on the elongate body. Preferably the scale is disposed in the slot adjacent to the slider. In the preferred embodiment of the invention, the scale is adjustable using a scale adjustment member that is disposed in a second aperture formed in the elongate body that is opposite from the first aperture. A substantial portion of the electrode is covered with an insulating material with the ends of the electrode being exposed for making electrical connections with the plunger and the solder balls of the Ball-Grid-Array package. The exposed end of the electrode may be hooked-shaped for engaging the solder balls of the Ball-Grid-Array device.
The objects, advantages and novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawings.
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Campbell Julie A.
Zandonatti Raymond A.
Bucher William K.
Karlsen Ernest
Tektronix Inc.
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