Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1998-09-03
2001-03-27
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S765010
Reexamination Certificate
active
06208156
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the manufacture and testing of semiconductor components. More particularly, this invention relates to systems and carriers for testing bumped semiconductor components such as bare semiconductor dice, chip scale packages, BGA devices, and semiconductor wafers, having contact balls.
BACKGROUND OF THE INVENTION
Semiconductor components, such as bare dice, chip scale packages, BGA devices and wafers can include terminal contacts in the form of contact balls. This type of component is sometimes referred to as a “bumped” component (e.g., bumped die, bumped wafer).
The contact balls provide a high input/output capability for a component, and permit the component to be surface mounted, or alternately flip chip mounted, to a mating substrate, such as a printed circuit board (PCB). Typically, the contact balls comprise solder, which permits bonding to the mating substrate using a solder reflow process. For some components, such as chip scale packages and BGA devices, the contact balls can be arranged in a dense array, such as a ball grid array (BGA), or a fine ball grid array (FBGA).
One problem with solder contact balls is that solder is a relatively soft material, and the balls deform easily during handling and testing of the components. During testing, the component is typically inserted into a test socket having electrical connectors, such as spring loaded pins (e.g., “POGO PINS”), that electrically engage the contact balls. Because solder is a soft material, the electrical connectors on the test socket can deform the contact balls on the components. This problem is compounded during testing at elevated temperatures, such as burn-in testing, as heating further softens the solder.
For performing subsequent test procedures, it may be difficult to make low resistance electrical connections with deformed contact balls. In particular, the electrical connectors on the test apparatus may not adequately engage the surfaces of the contact balls. Also, for subsequent bonding procedures, deformed balls can make alignment and bonding of the component with a mating substrate more difficult to perform. In addition, deformed contact balls are a cosmetic problem that can affect a users perception of a semiconductor component.
In addition to making electrical connections for test procedures more difficult, deformed contact balls can alter test results by affecting electrical characteristics, such as contact resistance, inductance, and signal speed during the test procedure. Further, solder readily oxidizes, which adds resistance to the electrical connections with the contact balls.
Another problem with solder contact balls is the adverse affect that solder can have on a semiconductor test system. For example, solder flakes can break loose from the balls, contaminating test sockets, and other electrical components associated with the test system. This can change the calibration of the test system and affect test results on all of the components being tested. In addition, solder is a contaminant to other semiconductor fabrication processes, and its presence requires special handling and segregation of the components. For some components, technicians may be required to wear gloves, and other protective clothing, to prevent lead from being deposited on their skin.
In view of the foregoing, it would be advantageous to provide a test carrier for temporarily packaging bumped semiconductor components in which contact balls on the components are protected during test procedures. In addition, it would be advantageous to provide a calibration carrier for calibrating, and a cleaning carrier for cleaning, test systems for bumped semiconductor components.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved test carrier for temporarily packaging bumped semiconductor components having contact balls is provided. Also provided are an improved method for testing semiconductor components using the test carrier, and an improved test system which incorporates the test carrier. In an alternate embodiment of the invention a calibration carrier for calibrating test systems for bumped semiconductor components is provided. In another alternate embodiment of the invention, a cleaning carrier for removing solder contaminants from test systems for bumped semiconductor components is provided.
The test carrier, simply stated, comprises: a base for retaining one or more components for testing; an alignment member for aligning the components on the base; and a force applying mechanism for biasing the components against the base. The base includes contact members configured for electrical communication with contact balls on the components. The contact members on the base comprise recesses covered with a conductive layer having either sharp edges or blades, for penetrating the contact balls.
The base also includes terminal contacts and conductive vias in electrical communication with the contact members. The terminal contacts are configured for electrical communication with a test socket of a test system. The terminal contacts can comprise hard metal balls, hard metal balls covered with non-oxidizing metal layers, or glass, ceramic or plastic members covered with a conductive material.
The test carrier can be configured for testing bare ice, chip scale packages, BGA devices, or wafers. During test procedures using the test carrier, the contact members on the base make low resistance electrical connections with the contact balls on the components, and protect the contact balls from deformation. In addition, the terminal contacts on the base make low resistance electrical connections with electrical connectors of a test socket, and resist wear, deformation, and oxide build up even with continued usage in a production environment.
The calibration carrier comprises a base having terminal contacts, and a semiconductor die mounted to the base in electrical communication with the terminal contacts. As with the test carrier, the terminal contacts can comprise hard metal balls, hard metal balls covered with non-oxidizing metal layers, or glass, ceramic or plastic balls covered with a conductive material. The calibration carrier is configured for placement in a test socket of a test system to simulate a conventional semiconductor component having solder contact balls. The calibration carrier can be used to calibrate the test system, and to locate defective electrical connectors on the test socket. The calibration carrier can also include on board circuitry for evaluating electrical characteristics of the test system, such as contact resistance between the terminal contacts on the carrier, and the electrical connectors on the test socket.
The cleaning carrier comprises a base having terminal contacts formed of a solder wettable metal such as pressed and sintered metal balls, braided metal wires, or metal bristles. The cleaning carrier can be heated and placed into a socket of a test system, with the terminal contacts on the carrier in physical contact with electrical connectors on the test socket. Solder contaminants within the socket are attracted to the terminal contacts, and can be removed with the cleaning carrier. The cleaning carrier can also include an on board heating element for heating the terminal contacts.
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Brown Glenn W.
Gratton Stephen A.
Micro)n Technology, Inc.
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