Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2002-05-09
2004-09-07
Pert, Evan (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
Reexamination Certificate
active
06788083
ABSTRACT:
FIELD
Embodiments of the present invention relate to high and low temperature testing of integrated circuits. More particularly, embodiments relate to increasing the number of devices to be tested with monitoring on standard size burn-in boards a limited number of available I/O channels.
BACKGROUND
Integrated circuit (IC) devices are typically tested after manufacture by sending electrical signals to the devices while the devices are in an elevated temperature for a period of time. Devices that fail to operate normally during such electrical stressing can be discarded, and it can be determined under what temperatures a device of a certain type be expected to reliably operate. This process is referred to as burn-in. Multiple integrated circuit chips are placed on a burn-in board (“BIB”) that is similar to a computer add-on card, but typically larger. The BIB is a printed circuit board with receptacles for the IC devices. The BIB also includes printed circuit connections between pins of the IC chips and connectors of the BIB.
FIG. 1
is a block diagram of a typical prior art burn-in system. System
100
includes BIB
105
. BIB
105
includes a number of devices under test (DUTs)
110
. In typical testing applications, the BIB is placed in a burn-in oven chamber to subject the DUTs
110
to high temperature cycles. BIB
105
is electrically connected to responsive driver board
115
. Driver board
115
contains electronics
120
including traces for power, ground, and control signals to be propagated to BIB
105
. Driver board
115
has a fixed number of channels (trace that carries an electrical signal)
125
. Some of the channels
125
are used for ground channels, supply voltage, and high frequency clocks. The remaining channels are used to transmit data between the driver board
115
and the DUTS
110
on BIB
105
. The driver board
115
uses some channels to drive control signals to the DUTs
110
and uses others to monitor (read) the response of each DUT (test data output (“TDO”) signal) to determine if the DUT is failing or passing. Electronics
120
also contain firmware that controls the routing of each channel to determine if the channel is used for driving or monitoring. The driver board typically also contains firmware with the expected response values and can compare these values to the actual received TDO signal for each DUT. The driver board may then forward the failing/passing data to a processing system (not shown) that contains user interface software.
FIG. 2
is a perspective view of a prior art burn-in system
100
. Backplane board
130
provides thermal insulation between the BIB
105
that goes into the hot chamber and the driver board
115
that does not. Backplane board
130
contains connector sets
135
and
140
. Connector set
135
connects to connector set
136
of BIB
105
and connector set
140
connects to connector set
141
of driver board
115
. In backplane board
130
, connector set
135
directly connects to connector set
140
providing electrical channels
125
(not shown). Backplane board
130
may also contain additional connector sets such as connector sets
150
and
151
for interfacing additional BIB/driver board pairs.
The number of channels
125
limits the number of DUTs
110
that may be tested with monitoring on BIB
105
at a time. This limitation is not apparent when the control signals are being written to the DUTs
110
because when the DUTs
110
are receiving data it is practical to make their input channels common (i.e., the input pins are connected in parallel). Monitoring the output, however, requires each DUT to be on its own channel. For example, a number of channels may be needed to drive the control signals from the driver board
115
to the DUTs
110
. This number is a fixed value regardless of how many DUTs are on the BIB
105
. Each of the remaining channels may used to monitor a DUT—i.e., receive the TDO signal from a DUT. For example, a system having 72 channels, 21 channels may be used as ground channels, supply voltage, and high frequency clocks, leaving 51 channels available. Of these, 30 channels, for example, may be used to drive the control signals (of course the number of channels required to drive the control signals depends on the device to be tested and the test to be conducted). With 21 monitoring channels available to receive the TDO signal, the maximum number of DUTs that can be tested at a time is 21. This does not present a problem for larger, more expensive, IC devices (e.g., some microprocessors) because their size may limit the number that can be tested at one time in any case. For example, BIBs are typically of a standard size and the number of a certain type of IC device that can fit on the BIB may be less than the number of available channels for receiving the TDO signal. Moreover, relatively expensive devices may more easily absorb the costs of testing. The problem is evident for smaller, less expensive IC devices (e.g., ASICs and custom ICs) where more devices could fit on the BIB and the limited throughput adds significantly to the unit cost.
SUMMARY
An embodiment of the present invention provides a burn-in board coupled to a plurality of integrated circuit devices. Each integrated circuit device has a test data output signal associated with it. The burn-in board has a plurality of monitoring channels to transmit the test data output signals. A set of group of switches is implemented on the burn-in board. Each group of switches is coupled to a corresponding portion of the plurality of integrated circuit devices. Each group of switches receives test data output signals associated with the portion of the plurality of integrated circuit devices corresponding to that multiplexor. A programmable logic device is coupled to the set of multiplexors such that a specific multiplexor may be selected to transmit the test data output signals associated with the portion of the plurality of integrated circuit devices corresponding to the selected multiplexor. The test data output signals are transmitted via the plurality of monitoring channels.
Other features and advantages of the present invention will be apparent from the accompanying drawings, and from the detailed description, that follows below.
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Siddiqui Shakeel M.
Tymofyeyev Vadim
Nguyen Tung X.
Pert Evan
Pycon, Inc.
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