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high-frequency electrical simulation analysis
of a spring, elastomer, coaxial spring, and
coaxial elastomer socket was conducted
in the frequency and time domains. It was
concluded that the coaxial elastomer socket
had the best signal characteristics in both
the frequency and time domains.
In conclusion, the coaxial elastomer
socket based on the elastomer socket
has the advantages of a short signal
transmission length and an excellent
manufacturing cost, as well as the
characteristics of electromagnetic wave
shielding by a metal frame. Therefore,
Table 2: Time domain analysis comparison. it was concluded that it could be another
solution that could show the best
the characteristic impedance is matched to As a result of analysis, as shown performance in the SLT environment.
nearly 50 ohms. in Table 2, the eye width and eye
Through analysis of the frequency height of the spring socket were the References
domain, the signal integrity characteristics narrowest and the jitter value was large. 1. K. Ranganathan, A. Bhalla, “Key
of the spring, elastomer, coaxial spring, Because the spring socket does not have trends driving the need for more
and coaxial elastomer socket were impedance matching and the length semiconductor system-level testing,”
revealed, and it was confirmed that the of the signal is relatively long, the eye https://www.evaluationengineering.
insertion loss, return loss, and crosstalk diagram characteristic is not the best. com/instrumentation/article/13017769,
loss characteristics of the coaxial elastomer The elastomer socket also does not Jun 22nd 2018.
socket were the best. As a result, the coaxial have impedance matching, but because 2. E. Song, J. Cho, J. Kim, Y. Shim, G.
elastomer socket has the advantage of being it is shorter than the spring socket, the Kim, J. Kim, “Modeling and design
shorter than the coaxial spring socket, eye diagram characteristics are better optimization of a wideband passive
so it has excellent signal transmission than those for the spring socket. On the equalizer on PCB based on near-end
characteristics and can achieve impedance other hand, the coaxial spring socket crosstalk and reflections for high-speed
matching. Therefore, it has excellent signal and coaxial elastomer socket, which serial data transmission,” IEEE Trans.
reflection characteristics, and has the have impedance matching through the on Electromagnetic Compatibility, V.
advantage of improving crosstalk with the coaxial structure, have better eye diagram 52, No. 2, pp. 410~420, May 2010.
metal housing. characteristics than the noncoaxial 3. J. Kim, S. Shin, D. Shin, N. Jeong,
structures. In particular, it was confirmed “Coaxial probe for RF solution,”
Time domain analysis that the eye diagram characteristics of the TestConX Session 6A Presentation 2,
Analysis of signal characteristics in short coaxial elastomer socket secured the pp. 623~640, Mar. 2019.
the time domain was conducted through best signal characteristics. 4. G. Kim, D. G. Kam, S. J. Lee, J. Kim,
use of an eye diagram, and the rise time M. Ha, K. Koo, J. S. Pak, J. Kim,
of the signal based on a 16GHz operating Summary “Modeling of eye-diagram distortion
frequency was applied as 10ps. The eye Currently, an optimal socket solution and data-dependent jitter in meander
diagram is an indicator that can check that could deliver high-quality signals by delay lines on high-speed printed
signal characteristics in the time domain, minimizing crosstalk between signals is circuit boards (PCBs) based on a time-
and it is concluded that the larger the eye needed because the sockets used in system- domain even-mode and odd-mode
width and eye height, the smaller the jitter, level tests require signal transmission analysis,” IEEE Trans. on Microwave
and the better the signal characteristics. characteristics without loss at high Theory and Techniques, V. 56, No. 8,
Figure 6 shows the eye diagram for the test frequencies. Therefore, to find the optimal pp. 1962~1972, Aug. 2008.
socket and coaxial test socket. socket solution as discussed in this article, a

Biographies
Dave Oh is President of TSE, Korea. He studied Electronic Engineering at Namseoul U., Korea, and
received an MBA from Korea U., Korea. He worked as a test hardware development engineer at Samsung’s
system LSI division (e.g., logic handlers and vision inspection equipment). He joined TSE in 1997 as a Senior
Engineer and Sales Manager focused on package and wafer test interface hardware technology and products;
email: daveoh@tse21.com

BH Kim is a Principle Engineer, Test Socket Division, at TSE, Korea. He studied Mechanical Engineering
at Korea U. of Technology and Education, Korea. He focuses primarily on the application of high-speed signal transmission
technologies to test socket and wafer test hardware and holds many patents in these fields.

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