Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2001-08-10
2003-09-30
Karlsen, Ernest (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S1540PB
Reexamination Certificate
active
06628132
ABSTRACT:
BACKGROUND OF THE INVENTION
Semiconductor manufacturers typically test their semiconductor devices prior to shipping. Such tests may involve electrically probing and exercising the semiconductor devices under a variety of thermal conditions (e.g., over a wide temperature range) to identify faulty devices, to find out-of-tolerance devices and to categorize the devices into various grades (e.g., according to maximum operating speed, according to the amount of usable memory, etc.).
Such testing is useful for a variety of reasons. For example, in some situations, a manufacturer may be able to detect and repair faulty or out-of-tolerance devices (e.g., cure minor defects using a laser at a repair station) thus improving manufacturing yields. Additionally, the manufacturer may be able to charge a premium for devices having exceptionally high maximum operating speeds and/or exceptional amounts of usable memory.
Some manufacturers employ an automated test equipment (ATE) handling system (or simply “handler”) to test semiconductor devices. Some handlers are capable of testing an assemblage having multiple semiconductor devices attached thereto, e.g., lead frames that support multiple electrically-isolated and packaged integrated circuit (IC) devices, strips of devices having Ball Grid Array (BGA) packages, configurations of other chip scale packaging (CSP) devices, and the like. A well-known general term for such an assemblage is “a panel”.
A typical handler includes a temperature soak assembly, a test assembly, a temperature desoak assembly, and robotic equipment which moves panels from one assembly to another in a pipelined manner. In general, the temperature soak assembly is configurable to raise or lower the temperature of the panels to a predetermined temperature (a process commonly known as “temperature soaking”) prior to testing. The test assembly is typically capable of testing the semiconductor devices of the panels while maintaining the panels at the predetermined temperature (e.g., by lowering a bed of nails onto particular locations of the panels to test the devices individually). The temperature desoak assembly is typically an area of the handler where the temperature soaked and tested panels reside while returning back to a temperature which is suitable for further processing and handling (a process commonly known as “temperature desoaking”). For example, the temperature soaked and tested panels can be moved to a location where they are simply allowed to idly sit and move to a near-ambient temperature (e.g., near room temperature) in an inactive manner.
Typically, at any one particular time, a manufacturer configures a handler to exclusively perform either a low temperature test or a high (or elevated) temperature test. In the low temperature test, the manufacturer configures the temperature soak assembly of a handler to lower the temperature of the panels to a predetermined low temperature (e.g., −55 degrees Celsius). For example, the manufacturer can connect cooling members of the temperature soak assembly to a cooling source (e.g., to a cryogenic source such as liquid nitrogen, to a refrigerant or cold oil circulator, etc.). Accordingly, panels sitting on the cooling members of the temperature soak assembly move to the predetermined low temperature from their initial temperature (e.g., room temperature, ambient factory temperature, etc.). During low temperature testing, the robotic equipment moves a temperature soaked panel (i.e., cooled panels) from the temperature soak assembly to the test assembly, and lowers a bed of nails onto the panel to individually test the devices of the panel. The robotic equipment then moves the cooled and tested panel from the test assembly to the temperature desoak assembly. A typical approach to heating up the cooled and tested panel in the temperature desoak assembly is to let the panel simply absorb heat from the surroundings (i.e., to idly sit at room temperature in an inactive manner). After the panel moves to a safe handling temperature, the panel is ready for further processing, e.g., the manufacturer can then reconfigure the handler to perform high temperature testing, or move the panels to a similar handler that is already configured for high temperature testing.
In the high temperature test, the manufacturer configures a temperature soak assembly of a handler to raise the temperature of the panels to a predetermined high temperature (e.g., 155 degrees Celsius). For example, the manufacturer can power heating elements within the temperature soak assembly to raise the temperature of the panels to the predetermined high temperature. During high temperature testing, the robotic equipment moves a heated panel from the temperature soak assembly to the test assembly, and lowers a bed of nails onto the panel for electrical testing. The robotic equipment then moves the heated and tested panel from the test assembly to the temperature desoak assembly so that the panel can cool down for further processing (e.g., labeling and storage in gravity feed handlers or other device-carriers, etc.). A typical approach to cooling down the heated and tested panel is to let them simply dissipate heat into the surroundings (i.e., placing the panel in a room temperature environment to idly cool down close to room temperature in an inactive manner).
If the manufacturer attempts to handle the heated and tested panels before the panels have significantly cooled, the manufacturer runs the risk of damaging the panels and/or the handling and processing equipment.
One conventional handler does not wait for panels to move back to a suitable handling temperature by simply exposing the panels back to a room temperature environment in an idle manner. Rather, the temperature desoak assembly of that handler includes a set of thermo-electric elements (i.e., ceramic or plastic electronic components) that actively heat or cool the panels. Each thermo-electric element has a first side and a second side, and receives direct current. When the direct current flows in a first direction through the thermo-electric elements, the first sides of the elements become hot and the second sides become cold. However, when the direct current flows in a second direction through the thermo-electric elements (i.e., the direction opposite the first direction), the first sides of the elements become cold and the second sides become hot.
The operation of the above-described conventional handler with thermo-electric elements will now be described. During a low temperature test, the thermo-electric elements of the temperature desoak assembly receive current in the first direction so that the first sides of the elements become hot. The robotic equipment of the handler moves cooled and tested panels from the test assembly of the handler onto the first sides of the thermo-electric elements to heat them up to a suitable handling temperature. Since the first sides of the thermo-electric elements are hot, the panels reach a suitable handling temperature more quickly than they would if simply exposed to a room temperature environment to idly warm up in an inactive manner, i.e., to simply absorb heat from the surrounding room temperature environment.
Similarly, during a high temperature test, the thermo-electric elements receive current in the second direction so that the first sides of the elements become cold. Accordingly, the robotic equipment of the handler moves heated and tested panels from the test assembly onto the first sides of the thermo-electric elements to cool them down to a suitable handling temperature. Since the first sides of the thermo-electric elements are cold, the panels reach a suitable handling temperature more quickly than they would if simply exposed to a room temperature environment to idly cool off in an inactive manner, i.e., to simply dissipate heat to the surrounding room temperature environment.
Recall that the second sides of the thermo-electric elements become hot in order for the first sides to become cold. To facilitate heat dissipation from the second sides
Dunn, Jr. John J.
Pfahnl Andreas C.
Chapin & Huang , L.L.C.
Huang, Esq. David E.
Karlsen Ernest
Teradyne, Inc.
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