Patent Application
20110128988
Temperature can be an important factor in the operation of electronic devices. At too high a temperature, circuits may fail. The practical upper temperature limit of an electronic device may be determined by many factors, such as the limit of the semiconductor material, interconnections, and packaging.
A designer of an electronic device may be given a specification that describes the maximum upper temperature limit at which the device is required to reliably operate. The designer may wish or be required to test the device at the maximum upper temperature limit.
Because electronic devices generate heat when operating, it may be necessary to cool the electronic device in order to keep the temperature of the device below the upper temperature. One technique for cooling an electronic device may rely on conduction cooling in which a thermally conductive solid is used to conduct heat away from the electronic device. One advantage of conduction cooling is that forced air (which can contain contaminates) is not required to cool the electronics. The heat is transported (conducted) away and eventually dissipated to the surrounding atmosphere.
When temperature testing an electronic device that is designed to be implemented in a conduction-cooled system, it may be desirable to test the operation of the electronic device at the upper temperature limit in a test environment that simulates the final deployed system for the electronic device as closely as possible.
One implementation is directed to a system for testing an electronic device. The system may include a air mover unit, a testing apparatus, and a testing chamber. The air mover unit may include a fan; logic to control operation of the fan based on a temperature signal received by the air mover unit, the temperature signal indicating a temperature associated with the testing apparatus or the electronic device; and an outlet hose connected to an output of the fan to carry air blown by the fan. The testing apparatus may include an inlet hose connected to receive the air blown through the outlet hose; a heat exchanger connected to the inlet hose such that the blown air is passed over the heat exchanger to cool the heat exchanger, the heat exchanger additionally configured to hold the electronic device that is being tested; and a temperature sensor attached to the heat exchanger, the temperature sensor generating the temperature signal that is received by the air mover unit. The testing chamber may include a chamber to hold the testing apparatus and a heater to heat the testing chamber to a user designated temperature during testing of the electronic device.
Another implementation is directed to a method for testing an electronic device. The method may include maintaining a first air temperature, within a testing chamber that includes the electronic device, the electronic device including a heat exchanger to dissipate heat generated by the electronic device. The method may further include setting, in a control unit, a desired surface temperature of the electronic device and controlling, by the control unit, cooling of the heat exchanger to maintain the electronic device at the desired temperature of the electronic device, the cooling including blowing room temperature air from outside of the testing chamber over the heat exchanger, where the temperature of the room temperature air is less than the first air temperature. The method may further include testing operation of the electronic device while the electronic device is within the testing chamber and transmitting results of the testing of the electronic device to a computing device located externally to the testing chamber.
In another implementation, a device may include a baseplate; a rail attached to the baseplate, the rail being formed of thermally conductive material, the rail being formed to secure a printed circuit board (PCB) case; a heat exchanger connected to the rail and the baseplate, the heat exchanger being formed of thermally conductive material; a backplane connected to the baseplate, the backplane include an electrical connection to form an electrical interface with the PCB case when the PCB case is inserted into the rail; an inlet hose connected to deliver air blown from an external source to the heat exchanger; and a temperature sensor attached to the heat exchanger, the temperature sensor generating a temperature signal that is used to control an amount of air delivered via the inlet hose.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments described here and, together with the description, explain these embodiments. In the drawings:
The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. Also, the following detailed description does not limit the invention.
As described herein, a testing platform for a conductive-cooled electronic device may include a testing chamber in which the temperature of the ambient air in the testing chamber may be maintained at a desired testing temperature. The device to be tested may be placed inside the testing chamber. A heat exchanger may be attached to the device to assist in keeping the device at the desired temperature. A temperature control mechanism, such as variable speed fans that blows external air over the heat exchanger, may be used to keep the heat exchanger at the testing temperature.
Control equipment 150 may also be used to monitor information relating to the testing. In alternative implementations, control equipment 150, or portions of control equipment 150, may be located inside testing chamber 110, such as control equipment integrated with testing apparatus 130.
An electronic device that is to be tested, such as a printed circuit board (PCB), may be inserted into testing apparatus 130 and then both testing apparatus 130 and the PCB may be placed in chamber 120. Testing apparatus 130 may include electronic circuitry for interfacing with and testing the PCB. Testing apparatus 130 may include mechanical and electrical connections that may be connected, through testing chamber 110, to control equipment 150. In this manner, testing apparatus 130 may be externally controlled and tested at a user-specified temperature inside of testing chamber 110.
When testing the device, the operating temperature limits may be defined by a surface temperature as well as surrounding ambient air temperature. In some cases, these temperature values can be the same which can present a problem: when an electronic device is powered on, it begins to produce heat, its temperature begins to rise and since the electronic device is already at equilibrium with the ambient air it will get hotter than the ambient air and exceed the surface temperature limit. Therefore, during testing, a measure of control over the surface temperature should be implemented to keep the electronic device at the same value as the ambient air temperature. System 100 may be used to test the device while keeping the device at the same temperature as the ambient air temperature.
Computing device 230 may include, for example, a laptop or personal computer.
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Testing apparatus 130 may include inlet hoses 315 and 320, rail/heat exchanger 330 and 335, backplane 350, and base plate 360. Additionally, temperature sensors 332 and 337 may be located on rails/heat exchanger 330 and 335. Inlet hoses 315 and 320 may connect to air ducts 215 and 220, respectively, of fan unit 210 and may carry a coolant, such as fan blown air, into testing chamber 110. Inlet hose 315 may be particularly configured to blow air over rail/heat exchanger 335. Rail/heat exchanger 335 may include a rail into which PCB package 340 may be slideably inserted and a heat exchanger that may be attached to or integrated as part of the rail. Rail/heat exchanger 335 may be formed from a metal, such as copper or aluminum, that is a relatively good thermal conductor. Rail/heat exchanger 335 may thus tend to transfer heat away from PCB package 340 and air blown from inlet hose 315 may be blow over rail/heat exchanger 335 to thus remove the heat from rail/heat exchanger 335. Inlet hose 320 and rail/heat exchanger 335 may be configured similarly to inlet hose 315 and rail/heat exchanger 330. That is, rail/heat exchanger 330 may hold PCB package 340 and act as a heat conductor that transfers heat from PCB package 340 to rail/heat exchanger 330, where the heat may be dissipated by the air blown through inlet hose 320.
Temperature sensors 332 and 337 may be positioned to measure the temperature of PCB package 340. The temperature sensors may be located, for example, on rails/heat exchanger 330 and 335. Temperature sensors 332 and 337 may include thermistors or other types of sensors.
Backplane 350 of testing apparatus 130 may include an electrical interface to PCB package 340. Control and power signals may be transferred through backplane 350 to circuitry external to testing chamber 110, such as fan unit 210 and/or computing device 230. For instance, temperature values measured by temperature sensors 332 and 337 may be transmitted through backplane 350 to air mover unit 210. Alternatively, the temperature values measured by temperature sensors 332 and 337 may be independently transmitted to air mover unit 210, such as by separate sets of wires. Baseplate 360 may include a substantially flat base that supports testing apparatus 130. Rails/heat exchangers 330 and 335, and backplane 350, may be attached to baseplate 360. As illustrated, baseplate 360 may include holes through which base plate may be fixedly attached to testing chamber 110.
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In one possible implementation, PCB 410 may be a network device, such as a router that is to be employed in a conduction cooled closed-system environment, in which the system may be sealed to prevent contamination with external dust, etc.
Fan control logic 210 may additionally include interface logic 530, which may act as an interface for signals communicated with computing device 230. Through interface logic 530, a user of computing device 230 may, for example, receive the temperatures received by fan control logic 520, directly control fan control logic 520, or generate other signals for transmission to test chamber 110, such as signals used to interact with PCB 410.
In some implementations, fan unit 210 may not connect to computing device 230. In this case, fan unit 210 may include, for instance, an input mechanism, such as a keypad through which the user may input the desired control temperature.
A user may set the desired temperature for testing chamber 110 (block 610). Testing chamber 110 may include, for example, an integrated control panel through which the desired temperature may be set. Alternatively, the temperature of testing chamber 110 may be remotely set by the user, such as through computing device 230. Generally, the desired temperature may be set to a temperature at which stress testing of the electronic device is to be performed. For example, if the specification for an electronic device calls for the device to reliably function up to a maximum ambient air temperature of 85° C., the desired temperature for testing chamber 110 may be set at 85° C.
The desired temperature for the heat exchangers connected to PCB package 340 (e.g., rails/heat exchangers 330 and 335) may also be set (block 620). This temperature may be set, for example, in air mover unit 210. Air mover unit 210 may generally operate to vary the speed of fans 510 and 515 to keep the rails/heat exchangers 330/335 at the desired temperature. In a typical operation, the desired temperature for the heat exchangers may be set to be equal to the desired temperature of testing chamber 110.
When the desired temperatures for testing chamber 110 and rails/exchangers 330 and 335 are set, high temperature stress testing of PCB 410 may begin. During testing, air mover unit 210 may continually monitor temperature sensors 332 and 337 (block 630) and adjust the operation of fans 510 and 515 based on the current temperature readings (block 640). More specifically, fan control logic 520 may adjust fans 510 and 515 based on the difference between the measured temperatures and the desired temperatures of rails/heat exchangers 330 and 335. In general, as the temperatures of rails/heat exchangers 330 and 335 increase above the desired temperature, fan control logic 520 may increase the speed of fans 510 and/or 515 to blow an increasing volume of cooler (e.g., room temperature) air over rails/heat exchangers 330/335. Techniques for implementing feedback control loops to minimize an error signal (e.g., the difference between the desired and measured temperature) are generally known and will not be described in additional detail herein.
During the high temperature stress testing, PCB 410 may be operated. In one implementation, test functions or a test suite may be run on PCB 410 (block 650). The test functions may include functions designed to simulate the use of PCB 410 when deployed in the final system. For example, in some designs of PCB 410, this may involve simply turning on PCB 410. In other situations, PCB 410 may be loaded with software designed to test the elements of PCB 410 or computing device 230 may provide control signals to PCB 410 in order to test various elements of PCB 410.
The results of the test functions may be monitored or recorded (block 660). In some implementations, the output of PCB 410 may be received by computing device 230 and compared to an expected output to determine if PCB 410 continues to operate correctly under temperature stress. In other implementations, additional sensors may be installed on PCB 410, such as sensors monitoring individual components 420, and monitored to ensure the values measured by the sensors are within acceptable ranges. In some implementations, the results may be monitored in real-time by computing device 230 during the course of the test. In other possible implementations, testing apparatus 130 may record results relating to the test, which may then be analyzed after the test.
In
In
Air mover unit 840 may include an air mover control board, such as fan control unit 520, that controls, based on signals from the temperature sensors, air movers 1 and 2. Each of the air movers may be, for example, fans.
As is also shown in
With the system shown in
As described above, a high temperature testing system for an electronic device may include a testing chamber in which the temperature of the ambient air in the testing chamber may be maintained at a desired testing temperature. The device to be tested may be tested inside the chamber while external air, such as room temperature air, may be blown over a heat exchanger associated with the device to thereby keep the device at the set desired surface temperature.
The foregoing description of implementations provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention.
For example, while series of acts have been described with regard to
It will also be apparent that aspects described herein may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement aspects described herein is not intended to limit the scope of the invention. Thus, the operation and behavior of the aspects were described without reference to the specific software code—it being understood that software and control hardware can be designed to implement the aspects based on the description herein.
Further, certain aspects described herein may be implemented as “logic” or as a “component” that performs one or more functions. This logic or component may include hardware, such as an application specific integrated circuit or a field programmable gate array, or a combination of hardware and software.
No element, act, or instruction used in the description of the invention should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
