High frequency function test socket
What is the high frequency function test socket?
With fast growing in semiconductor technology, the IC packages are continually changing from inside to outside. The inside of the package is updating more cell with square millimeter. The package size is going to smaller and smaller.
So,The new big challenges are placed on those who must test these ICs. The frequency and functions are required highest, at the same time, the package pads and pitches are becoming smaller and closer. IC frequency, in general-purpose computers, have increased a thousand-times in past twenty years. Data frequency transmission of 10GB/s are becoming the popular. Besides, the higher response, Now the test socket engineer teams and manufacturer companies need to face a important challenge: higher frequencies. Wireless communications is going to the Micro-wave field extreme (up to 35GHz or more).
How to test the IC chip package?
One of the key “IC production backend” tests is the testing of the IC package function, life and so on. In this test work, the IC is tested after it has been finished all process production. The IC packaging elements are estimated and confirm the IC work well when it is soldered on the test PCB in their final application. IC Package testing is usually the final test before those are sent to their buyer, that is the one of the important test in the Chips life.
Maybe in the final testing ,the most key fact is testing the IC test sockets.this way has been used over 30 years.In test sockets that have already appeared,most of test sockets frequency is usually lower than 50 MHz,reliable performance is lower than 10 GHz.The design can’t be used for today’s Micro-wave equipment(Microwave refers to electromagnetic waves with frequencies from 300MHz to 300GHz),but not for future. Current socket designs that attempt to solve the problem tend to be large,the life time is relatively short.Need to maintain timely, It is high self-inductance and mutual capacitance,This may lead to an unexpected problem in the overall performance of the circuit.
Any physical side effects that are generally considered too small to affect design performance,and it becomes a major factor in fast pulse edges or high clock frequencies.These features convert the socket from a passive carrier to an active component.The high-speed and clean signals requirements led to the needs for custom designed test sockets.There have been few attempts at high-end radio frequency requirements. The few available sockets that are executed at high RF levels with expensive price.
New advances in socket technology
However, in recent years ,it has developed a test socket that can handle UHF test socket.It is suitable for manual testing, processor and dynamic burn in test, this simple surface mount socket with a wide range of operating temperatures. surface mounting is necessary : Through-hole sockets bring the unpredictable impedance mismatches, stray capacitance, and inductance.The new RF socket line uses a press fit between the socket contacts and the PCB board pads to ensure reliable performance through simple contact replacement. The contacts are fixed to the contact blocks aligned with the PCB pads by fixed alignment pins. Screw the top half of the socket to the DUT (Device Under Test) board and compress half the length of the contacts to the PCB pads. If you need to replace the contact pins, simply unscrew the top plate, remove the contact block, align a new block, and screw the top plate. All this was completed in less than five minutes.
An important element of the advanced RF test socket design is the ANDK patented socket, About the Contact technology,many high frequency socket designs use the same contact design for all package leads. In contrast, the body contact design matches the contact width to the package lead width, which provides the maximum surface area wipe action contact for all package leads. These features combine to provide the lowest contact resistance.
Realize the reliability and performance of the test socket
Meeting high-frequency test requirements is critical for device manufacturers developing wireless and related application ICs. For this reason, the test socket must not only be able to adapt to high frequency parameters but must also provide reliability and high performance. For test sockets, high performance means two things: 1) substantial device insertion before the socket needs to be replaced; and 2) excellent electrical performance.
Sockets are the most important thing for each IC manufacturer to achieve the lowest overall cost. Ideally, the outlet does not need to be repaired, and it can work completely reliably throughout the entire life cycle. In fact, at some time,it will need to be cleaned, repaired or replaced.
Cleaning may require to remove the socket from the PCB board. Repairing a socket almost requires the test board to break down,then making another setup. Socket adjustments can waste valuable testing time. As a result, the test throughput dropped and the cost per device test increased.Temperature will affect the life and reliability of the outlet.
Each device must be tested under the same
conditions as its conditions of use. Test temperature limits can range from
-55°C to +150°C. Of course, sockets that can withstand these temperatures
through hundreds of thousands of cycles are more expensive than traditional
test sockets or Burn-in sockets, but they will pay more for their greatly
improved service life.
Thermal considerations relate to continuous use of temperature and coefficient of thermal expansion (CTE). Different materials expand at different rates under the same temperature conditions, so the shell material must be flexible enough to accommodate these changes, and tough enough to withstand them.
Occasionally, the socket contacts or the socket body must be replaced. Because the normal work abrasion or bad usage. In both cases, this situation can lead to maintenance costs and the cost of replacing parts.
One of the major problems in the production and application of high
frequency test sockets is performance. The ideal test socket should be
electrically "transparent", ie its presence has no effect on the test
results. This feature can be achieved by the low self-inductance and
capacitance between the contacts and the ability of the contacts to maintain a
The high frequency capability of the socket is inversely proportional to its contact inductance. High lead inductance values can cause unwanted oscillations and signal attenuation. This is why package engineers are focused on developing packages with low lead inductance.
Both inductance and capacitance affect the overall impedance of the socket contacts. Therefore, the contact resistance of the test socket should closely match the contact impedance of the device package. Impedance mismatch can cause signal reflections that can result in signal loss and oscillation.
Impedance is a complex property term that defines the resistance and reactance components of an electrical signal medium, whether it be a wire or a printed circuit board (PCB) microstrip line. The resistive element is determined by the resistance of the wire (ohms, Ω), and the reactive element is determined by the inductance of the PCB microstrip trace (Henry, H) and the capacitance (Fara, F). When the electrical signal propagates through the trace, its basic characteristics change as the impedance changes. As the frequency of the signal increases, its response to changes in impedance also increases.
Although board designers can easily match the pin impedance, it is often difficult for socket manufacturers to do this. Most sockets do not have any impedance control at all.
The mutual inductance and capacitance characteristics introduce other problems. As the frequency of the signal increases, its electromagnetic field also increases. If the design and construction materials of the socket contribute to the coupling characteristics, unwanted electrical "crosstalk" between these fields will promote the development of oscillations, reduce the gain level and increase the signal attenuation, and then adversely affect the performance.
Testing today's high-frequency IC devices requires new RF test sockets. These outlets need to meet performance and reliability standards, which are often as complex as the devices they are required to help with testing.
Key components in an RF test socket that successfully meets current requirements include: Electrical response parameters that can adapt to higher speeds and higher frequencies of today's RF devices; performance is inherently transparent to the device because it has no impact on the device or test And reliability, because the socket minimizes the need for repair or replacement, thereby reducing the overall cost of the device under test.
Fortunately, ANDK socket' latest RF test socket products do contain products that meet all of these standards.