IC device under test temperature control fixture

Details IC device under test temperature control fixture IC device under test temperature control fixture

1998-10-09

2001-02-20

Metjahic, Safet (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

06191599

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a temperature control fixture for an integrated circuit (IC) Device Under Test (DUT), and more particularly pertains to a temperature control fixture which provides for cooling or heating of one side of an integrated circuit which is being tested by contacts and electrical leads applied to the opposite side thereof.
2. Discussion of the Prior Art
Prior art test fixtures for integrated circuits have not provided for suitable testing of an integrated circuit which must be cooled or heated from the same side as it is being viewed during testing.
Moreover, such prior art test fixtures have not adequately controlled thermal expansion gradients which can cause fracturing of thinned, active integrated circuits. This problem arises when active, power dissipating devices are nonuniformly distributed on the integrated circuit and the structural strength of the integrated circuit is reduced due to thinning.
Other problems arise from heating of the viewing optics and camera by thermal infrared (IR) radiation, which can cause camera noise and possible damage to the integrated circuit.
The present invention provides a solution to a problem which arises when an integrated circuit must be heated or cooled from the same side as it is being viewed during testing.
The problem confronting the present invention is that for testing purposes, one would like to apply test signals to an integrated circuit silicon chip from the electrical lead side thereof while observing the opposite side of the silicon chip. During such testing; any defects in the integrated circuit silicon chip, such as shorts in the silicon gate areas, are likely to emit radiation in the near infrared portion of the spectrum (generally from 0.7 to 0.5 microns). The defects provide mechanisms similar to those in an LED (Light Emitting Diode) to generate and emit such radiation in the near infrared portion of the spectrum.
This testing requires the application of test signals to the electrical leads in the lead side of the integrated circuit silicon ship under normal application, heat stabilized conditions. However, under normal heat stabilized conditions the opposite side of the integrated circuit silicon chip is in contact with a heat sink to enable the chip to function in a normal thermally stabilized manner.
To observe the opposite side of the integrated circuit silicon chip requires removal of the normal heat sink applied thereto.
SUMMARY OF THE INVENTION
The present invention compensates for removal of the normal heat sink by immersing the side of the chip which is opposite the electrical lead side thereof in a coolant heat transfer medium to cool the chip in a manner to enable normal thermally stabilized operation thereof. An observation window in the test chamber allows the opposite surf side of the chip to be observed through the coolant heat transfer medium during testing of the chip. The observation window is designed to pass radiation in the near infrared portion of the spectrum while blocking radiation (heat) in the far infrared portion of the spectrum (above 2 microns), which would merely add noise to the portions of the spectrum desired to be observed.
It is a primary object of the present invention to provide a temperature control fixture for an integrated circuit under test which provides for heating or cooling of one side of the integrated circuit while it is being tested by contacts and electrical leads applied to the opposite side of the integrated circuit.
The subject invention also solves a problem with thermal expansion gradients which can cause fracturing of thinned, active integrated circuits which have active, power dissipating devices nonuniformly distributed thereon.
Other problems arise from heating of the camera and viewing optics by thermal infrared (IR) radiation, which can cause camera noise and possible damage to the integrated circuit. A heat blocking observation window is provided to control these problems. The observation window is designed as a radiation filter to pass radiation above a given wavelength and block infrared radiation below that wavelength (i.e. far infrared radiation at wavelengths above 2 microns).
The present invention:
provides a controllable temperature environment for a device under test (DUT);
reduces the chances of fracture of a thinned device under test (DUT) caused by thermal gradients;
fills possible normal operational requirements for a heat sink for a device under test (DUT);
increases the accuracy of measurement of the environment temperature of the device under test (DUT);
increases the light transmission through the back surface of the device under test (by approximately 30%). The present invention accomplishes this by matching the index of refraction of the heat transfer medium to the indices of refraction of the integrated circuit silicon chip and the observation window.
The design benefits of the disclosed testing apparatus include:
a low profile; economic usage of materials, e.g. the infrared blocking window also functions to contain the heat transfer medium in the test chamber;
reduces or eliminates thermal effects on the optics and the camera, reducing noise from those components;
reduces thermal air turbulence effects on image quality, resulting in more accurate testing;
removes air bubbles in the heat transfer medium which can obstruct vision through the observation window.
In accordance with the teachings herein, the present invention provides a test apparatus for testing a device under test which comprises a test housing defining a sealed test chamber therein. A test mounting is provided for mounting the device under test within the test chamber, and is connected to a plurality of test lines for conducting test signals between a lead side of the device under test and a test instrument external to the test apparatus. The device under test is mounted on the test mounting to expose the opposite side thereof to a flow of coolant in the sealed test chamber to provide for cooling or heating of the opposite side thereof. An observation window in the test housing enables observation of the opposite side of the device during testing. A flow of a temperature-controlled heat transfer medium is introduced into and through the sealed test chamber to immerse the device under test in the flow of the heat transfer medium to control the temperature thereof.
In greater detail, the test control fixture provides for heating or cooling of one side of the device under test which is being tested by contacts and electrical leads applied to an opposite side of the device under test. The device under test comprises an integrated circuit, and the test mounting mounts the integrated circuit with a side thereof immersed in and exposed to the flow of the heat transfer medium, and with conductive leads extending to an opposite electrical lead side thereof which are plugged into female electrical contacts of the test mounting. The test mounting comprises a test socket attached to electrical cables having a plurality of wires to conduct input and output test signals between the device under test and an external test instrument or instruments. Moreover, a far infrared blocking window is provided on one side of the sealed test cavity to enable observation of the surf side of the integrated circuit.
The test control fixture can comprise an upper housing positioned on top of a lower housing, wherein the upper housing is sealed relative to the lower housing by a seal positioned therebetween and around the sealed test chamber. The lower housing defines a lower rectangular shaped recess and an upper slightly larger, rectangular shaped recess. The test mounting is fixedly mounted within the lower recess such that the device under test is mounted on the test mounting and extends into the upper recess through which the heat transfer medium flows.
The temperature of the heat transfer medium is maintained relatively constant by feedback control of a heating/cooling unit by a thermocouple positioned in the

Affiliated with

Also associated with

Rating

IC device under test temperature control fixture does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with IC device under test temperature control fixture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and IC device under test temperature control fixture will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2609960