Thermal conductivity of soft solder from 90 K to 300 K

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O~ood, E. B. Ph D thesis, University of California (unpublished) Supplied by G. Barmaper Ltd, New Barnet, Herts, UK The valve used is a Mullard EI80F or E810F which has a shot noise resistance of 110 12 equivalent to voltage noise of ~1.4 nV Hz"1/2. The solid state device is two Texas Instruments E 1570 transistors, used in cascode Adler, M. S., Senturia, S. D., Hewes, C. R. Rev Sci Instr 42 (1971) 704 Bloembergen, N. JApp Phys 23 (1952) 1383 Anderson, A. C., Connolly, J. L., Wheatley, J.C. PhysRev 135 (1964) A910 Smythe, W. R. Static and Dynamic Electricity (McGraw Hill, 1968) p 411

A SPECIAL SURPLUS DISPOSAL OFFER One used T B T h e l i u m / h y d r o g e n l i q u e f a c t i o n p l a n t c a p a c i t y 8 litres l i q u i d h e l i u m per hour. T w o unused BOC 150 litres l i q u i d h y d r o g e n vessels. L o w prices S.E.E.C., 21 H a m p s o n St., S a l f o r d 5, Manchester

Walstedt, R. E., Dowley, M. W., Hahn, E. L., Froideaux, C.

Phys Rev Lett 8 (1962) 406; Butterworth, J. Phys Rev Lett 8 (1962) 423

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LETTER TO THE EDITORS Thermal conductivity of soft solder from 90 K to 3 0 0 K The thermal conductivity o f soft solder has been measured from 4 K to 90 K by Berman et al 1 and they have extrapolated the values from 100 K to 300 K based on the characteristics o f the thermal conductivity curves of metals in the same series classification. 2

From information 5 gathered from the National Bureau of Standards, Washington, there seem to be no measurements on the thermal conductivity of soft solder in the temperature range 90 K to 300 K and it is hoped that these measurements will help to fill this gap in the experimental data.

In the course of measuring the thermal and electrical conductivities o f the heavy rare earth specimens in the temperature range 90 K to 300 K, preliminary measurements were carried out on the thermal conductivity of soft solder. The soft solder with an activated core was in the form of a wire o f diameter 1 mm and when analysed 3 was shown to have the following composition: Sn 59.80%, Pb 40.18%, Sb 0.019%, Cu 0.001%, and traces (<0.0005%) o f As, Bi, Cd, Ni, Co, and Ag. The correction for radiation losses and electrical lead conduction losses were made using the method described by Noren and Beckman. 4

School of Physics and Mathematics, University o f Science, Malaysia, Penang, Malaysia

D. G. S. CHUAH and R. R A T N A L I N G A M

References 1 Berman, R., Foster, E. L., Rosenberg, H. M. A Compendium of the Properties of Materials at Low Temperature (phase I) 3.291 (Pergamon Press, 1961) 2 Berman, R., Foster, E. L., Rosenberg, H. M. A Compendium of the Properties of Materials at Low Temperatures (phase II) 13.291 Wadd Technical report 60-56 Part IV (1961) 3 The analysis was carried out by M/S Eastern Smelting Co Ltd, Penang, Malaysia 4 Noren, B., Beckman, O. Arkiv Fysik 25 (1964) 567 5 Private communication. W. L. Carrol, NBS Washington (June 1972)

The results of these measurements are shown by curve I in Fig.1. For comparison curve II shows both the experimental and extrapolated values of Berman et al. 1-2 The measured results compare well with the extrapolated values within the estimated maximum uncertainty for the extrapolated values. T. ¢

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Berrnon ¢t al experimental values

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Berman et el e x t r a p o l a t e d values •

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Plot of thermal conductivity of soft solder from 90 K to 300 K

CRYOGENICS.

MARCH

1973

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Temperoture T,K

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