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Evaluating hot-dipped solder plating with corrosion testing
Report
Evaluating hot-dipped solder plating with corrosion testing
Hirokazu Tanaka Technical Center, Technical Development Headquarters
T
o evaluate solder plating materials for corrosion resistance, we coated copper
materials with several types of hot-dipped solder plating, and then we performed
the following tests on these specimens: the salt mist cyclic test, the gas corrosion
test, and the weathering test. Following these tests, we analyzed both surfaces
and cross sections to investigate the causes of corrosion of the solder plating
materials and the effects of corrosion on the copper substrate.
Our results indicate that the primary factors causing corrosion of the solder
plating materials are corrosive factors in the environment (such as sulfur and
chlorine) selectively reacting with components in the solder materials, causing
the formation of corrosion products. The components that react with the corrosive
factors in the environment are: (1) for tin-lead solder (Sn-37Pb), the components
Pb (lead) and Sn (tin); (2) for tin-silver-copper solder (Sn-3Ag-0.5Cu), the
component Sn; (3) for tin-zinc solder (Sn-9Zn), the component zinc. With tin-zinc
solder in particular, the component zinc exhibited a sacrificial protection effect by
forming a corrosion product that showed a much stronger resistance to corrosion
of the copper substrate than conventional tin-lead eutectic solder.
This technology report has previously been published as a research paper in the
journal of the JIEP (Japan Institute of Electronics Packaging) as Evaluating
low-temperature lead-free solder with corrosion testing, in Vol.6, No.5,
August 2003.
1
Introduction
Miniaturized electronic products are now being used under a variety of environmental
conditions, causing the internal electronics and the PCBs to be inundated with corrosive factors.
Investigation needs to be carried out on environmental factors such as the effects of the various
gas components in environmental pollution, and the ocean salt particles in proximity to the sea
coast.
The corrosion of metallic materials is a phenomenon that occurs when these metallic materials
react with the environmental conditions that envelop them. Electronic parts involved in
high-density mounting in particular are susceptible to corrosion-induced mechanical and
electrical changes leading to failure.
When corrosiveness is examined from the aspect of the surface of the corroded material, Sn
(tin), the main component of solder plating materials, is found to form a passive film that is highly
resistant to metallic corrosion. 1) However, the addition of various alloys can change the level of
resistance to corrosion.
- 1 -
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
The passive region of the Pb (lead) component of conventional eutectic lead solder is
much narrower than that of Sn, and the Pb element may be dissolved by moderate
acidity. 2) Also, to consider lead-free solder from the electrochemical standpoint, the
metals Ag (silver), Cu (copper), and Bi (bismuth) are more noble metals than Sn. Among
the lead-free solder materials, the sole base metal used in forming alloys is Zn (zinc), and
so the corrosion resistance of the Sn-Zn solder alloy Sn-Zn needs to be examined.
For these reasons, we ran the salt mist cyclic test, the gas corrosion test, and the
weathering test to evaluate the corrosion resistance of several types of hot-dipped solder
plating materials for this report. We also investigated the corrosion factors and their
affects on the copper substrate. 3),4)
2
Experimental method
Table 1 shows the solder plating materials, the test preparation conditions, and the
various test conditions used to evaluate corrosion resistance. Fig.1 shows the method
used to prepare the specimens. The solder plating materials included conventional
tin-lead (Sn-37Pb) eutectic solder as a benchmark, and tin-silver-copper
(Sn-3Ag-0.5Cu), in which silver and copper are both more noble than Sn, and tin-zinc
(Sn-9Zn), in which zinc is more base than Sn.
The preparation of the test materials consisted of applying a hot-dipped solder plating
to copper substrate at 260°C for five seconds using rosin flux. Next, the materials were
given an isopropyl alcohol (IPA) bath, followed by a methylene chloride bath, and finally
another IPA bath to completely remove any contaminants that might be adhering to the
surface.
The salt mist cyclic test was performed in accordance with IEC 60068-2-52, using a salt
solution concentration of five percent and a neutral solution of saltwater with a
temperature of 35°C. Following the test, the specimen surfaces were rinsed with
deionized water to remove the salt content.
The gas corrosion test was run with a low gas concentration (NO2 at 1 ppm) and a high
gas concentration (NO2 at 50 ppm) using a single gas. To simulate the actual field
environment, a test combining four types of gases was also run. That test conformed to
IEC 60068-2-60 method 4 and consisted of H2S at 0.01 ppm, SO2 at 0.2 ppm, NO2 at 0.2
ppm, and Cl2 at 0.01 ppm. The weathering test was performed on the roof of a typical
residence in the vicinity of a bypass to the Tomei Highway in Hiratsuka City of Kanagawa
Prefecture. The specimens were exposed to the weather for 18 months (one year and six
months).
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Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
Following the tests, the surfaces of the specimens were analyzed using an EPMA (electron probe
micro analyzer, model JXA-8100 of JEOL). Cross sections were observed, and elemental analysis
was performed.
Table 1 Materials and conditions for testing
Solder plating
composition (%)
Specimen
preparation
conditions
Salt mist cyclic
test (IEC
60068-2-52)
Corrosive gas
test (single gas
test)
Flowing mixed
gas corrosion test
(IEC
60068-2-60)
Weathering test
Sn-37Pb
Sn-3Ag-0.5Cu
Sn-9Zn
Substrate: copper plate
(0.3 x 10 x 30 mm)
Hot-dipped solder plating
temperature: +260°C
Bath time: 5 sec.
Salt solution concentration: 5%
Salt solution temperature: +35°C
Test time: 336 h
Gas type: NO2
Gas concentration (2 conditions):
1 ppm, 50 ppm
Temperature and humidity:
+25°C, 75%rh
Test time: 300 h
Gas type/concentration (4 gases):
H2S, 0.01 ppm; SO2, 0.2 ppm; NO2,
0.2 ppm; Cl2, 0.01 ppm
Temperature and humidity:
+25°C, 75%rh
Test time: 300 h
Site: Tomei Highway bypass,
Hiratsuka City, Kanagawa Pref,
Japan.
Test time: approx. one year and six
months
- 3 -
(a) Specimen preparation
conditions
(b) Plated specimen
Fig.1 Test preparation method
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
3
Test results and considerations
3-1 Salt mist cyclic test
After running the salt mist cyclic test for 336 hours, the surfaces of the various types of
solder plating were covered with a white corrosion product. Both Sn-37Pb and
Sn-3Ag-0.5Cu were confirmed to exhibit a gradual build-up of the white corrosion product
throughout the duration of the test. Sn-9Zn, however, was observed to exhibit complete
surface covering of the white corrosion product 96 hours from the start of the test. (Fig.2)
Table 2 presents the results of quantitative analysis of the elements detected using EPMA
on the surface of the various types of solder plating following the full 336 hours of the salt
mist cyclic test. The post-test analysis detected more of the following elements: both the
Sn and Pb components from the Sn-37Pb solder, the Sn component from the
Sn-3Ag-0.5Cu solder, and the Zn component from the Sn-Zn solder. In addition, the
detection of the corrosive substances Cl (chlorine) and O (oxygen) from the salt solution
can be assumed to indicate that these corrosive substances formed chloride compounds
by selectively reacting with the metallic components during the process of the corrosion.
The cross-sectional observation following the 336 hours of testing was able to confirm
neither the composition of the solder alloy layer formed during the process of corrosion,
nor the effects on the copper substrate.
Fig.2 Changes in appearance of plating after the salt mist cyclic test
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Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
Table 2 Results of surface quantitative analysis after the salt mist cyclic test
Solder type
Fig.3 shows SE (Secondary Electron) images of the surfaces of the solder plating
following the gas corrosion test. The surfaces of the specimens showed much more
severe progression of corrosion for all types of solder plating materials following the 50
ppm NO2 test than after either the 1 ppm NO2 test or the flowing mixed gas test.
Fig.3 SE images of solder plating surface after gas corrosion testing
- 5 -
Elements detected (%)
Sn Zn Ag Cu Pb O Cl
Sn-37Pb 47.5 - - - 45.0 7.3 0.2
Sn-3Ag-0.5Cu 55.5 - 0.4 2.0 - 41.4 0.6
Sn-9Zn 13.7 47.4 - - - 38.7 0.3
3-2 Gas corrosion test
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
Fig.4 shows BE (Backscattered Electron) images of the surfaces of Sn-37Pb and
Sn-9Zn following the NO2 gas test at 1 ppm. Observation of these images found that Pb
was selectively corroded from the Sn-37Pb solder, while Zn was selectively corroded
from the Sn-9Zn solder.
With Sn-3Ag-0.5Cu, however, corrosion was not observed at any specific site. Also,
no major progression of corrosion was found with any type of solder plating specimen
following the combined gas test.
Fig.4 Corroded portions following the gas corrosion test (NO2 gas, 1 ppm)
Fig.5 shows the results of cross-sectional observation for Sn-37Pb and Sn-9Zn following
the corrosive gas test with an NO2 gas concentration of 50 ppm. Cracking was observed
in the internal portion of the solder alloy in each type of solder plating specimen, and
solder-substrate peeling was also observed for each type of plating specimen.
Examination of the copper substrate revealed that Sn-37Pb plating suffered progressive
corrosion to the substrate, but the Sn-Zn plating exhibited no substrate corrosion. The
Sn-9Zn plating was thought to have escaped corrosion to the copper substrate because
the Zn component exhibited a sacrificial protection effect, after which an anti-corrosive
coating was formed by the Sn component5) . This sacrificial protection effect may be
effectively inhibiting corrosion. However, it has been reported that the formation of
corrosion products in the high-concentration gas test (NO2 at 50 ppm) run for this
evaluation are not always the same as found in actual usage conditions6) , and so the
high-concentration test may be too severe for use in evaluation testing.
Fig.5 Cross-sectional SE images of solder plating following
gas corrosion testing (NO2, 50 ppm)
- 6 -
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
3-3 Weathering test
Fig.6 shows SE images of the solder plating surfaces during the course of the
weathering test. All of the solder plating specimens exhibited corrosion products after
one month of the weathering test. After eight months of weathering, the solder plating
surfaces were found to be completely covered with large corrosion products.
Elemental analysis of the corrosion products detected S (sulfur) and Cl (chlorine). The
S component is thought to come from the SO2 (sulfur dioxide) and H2S (hydrogen sulfide)
produced by automotive exhaust gas and volcanic eruptions. The Cl component is
thought to be an effect of the ocean salt particles, since the test site is located near the
sea coast.
Fig.6 SE images of plating surfaces after the weathering test
- 7 -
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
Fig.7 shows cross-sectional SE images of Sn-37Pb and Sn-9Zn plating after 18 months
of weathering. The Sn-9Zn exhibits longitudinal cracks in the inner portion of the solder,
and the progressive condition of the corrosion is confirmed. The Sn-37Pb did not exhibit
systematic corrosion. Peeling was observed at the interface between the Sn-37Pb solder
and the substrate.
Examining the effects on the substrate, the Sn-3Ag-0.5Cu and the Sn-37Pb solder
showed progression of corrosion and local corrosion of the substrate. However, the Sn-Zn
solder did not exhibit substrate corrosion.
Fig.7 Cross-sectional SE images of solder plating following
the weathering test (Exposed for one year and six months)
Fig.8 shows elemental mapping images of solder plating cross sections for Sn-37Pb and
Sn-9Zn solder plating after 18 months of the weathering test. The Sn-37Pb solder
exhibited internal permeation of Cl and S, and these corrosive substances had reached
the substrate. However, with Sn-9Zn solder, the Cl and S remained in the internal portion
of the solder and did not reach the substrate. This inhibition of Cl and S is thought to
result from the formation of the Cu-Zn intermetallic compound (Cu-Zn layer) at the
interface between the solder and the copper substrate. The intermetallic compound is
thought to form a barrier that prevents the corrosion from progressing to the copper
substrate. The formation of this alloy layer is hypothesized to suppress the progress of
corrosion to the copper substrate better than Sn-37Pb.
Next, we compared the oxygen concentration distribution of the Sn-37Pb and the
Sn-9Zn solder. While the Sn-37Pb solder was oxidized throughout the solder portion, the
Sn-9Zn solder was oxidized only in the vicinity of the surface. The lower penetration of
oxidation is thought to result from differences in the speed of the corrosion reaction. The
Sn-37Pb corrosion reaction spreads more rapidly to the internal section of the solder than
does the corrosion reaction of Sn-9Zn, thus forming oxidation substances throughout the
solder. In the Sn-9Zn, however, the reaction progresses more slowly, and so oxidation
substances only form in the vicinity of the surface layer.
- 8 -
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
Fig.8 Elemental mapping of plating cross sections after
the weathering test (exposed for one year and six months)
- 9 -
Espec Technology Report No21

Evaluating hot-dipped solder plating with corrosion testing
4
We performed corrosion tests to evaluate the corrosion resistance of various types of
hot-dipped solder plating. The conclusions we arrived at from the results of our
investigations into the factors causing corrosion and its affects on the copper substrate
are as follows.
(1)The corrosion of hot-dipped solder plating materials occurs as a result of corrosive
factors (such as S and Cl) in the environment reacting with the Pb and Sn components
of Sn-37Pb, the Sn component of Sn-3Ag-0.5Cu, and the Zn component of Sn-9Zn to
form corrosion products.
(2)Sn-9Zn exhibits a sacrificial protection effect created when its zinc component forms a
corrosive substance. In addition, the formation of an intermetallic alloy layer (Cu-Zn
layer) at the interface between the solder and the copper substrate inhibits the
progress of corrosion products, and thus provides corrosion resistance superior to that
found in conventional Sn-37Pb solder.
(3)However, since the Sn-Zn family of solder contains zinc, which is a reactive material,
this type of solder material tends to be affected by corrosion factors. As a result, in
severely corrosive environments such as the gas corrosion test with NO2 at 50 ppm run
for this evaluation, the solder alloy layer may deteriorate and result in a loss of
bonding strength. Because of this possibility, careful consideration must be given to
the type of environment in which the product will be used when using this type of
solder material.
5
Conclusion
Acknowledgments
This report is the republication of a report based on joint research with the Japan
Institute of Electronic Packaging, "JIEP Project for Low-Temperature Lead-Free Solders
and its Report on Questionnaire Survey." We would like to express our sincere
appreciation to everyone involved. We would also like to take this occasion to express our
deep gratitude to project members including Professor Tsutomu Tsukui of Tokai
University, Mr. Kishichi Sasaki of the Reliability Center for Electronic Components of
Japan, and Mr. Yoshihisa Kato, formerly of the Oki Engineering Co. Ltd. We would also like
to express our sincere gratitude to Mr. Yoshitaka Toyoda of the Technical Center of the
Senju Metal Industry Co., Ltd. for his cooperation in supplying us with specimens and
products.
[Bibliography]
1) H. H. Uhlig and R Winston Revie; "Corrosion and Corrosion Control: An Introduction to
Corrosion Science and Engineering - 3rd edition", Wiley-Inter science, 1985
2) G. Ito; "Corrosion Science and Engineering", Corona-sha, 1979 (Japanese)
3) H. Tanaka, K, Sasaki, Y. Kato, T. Tsukui; "Evaluating low-temperature lead-free solder
with corrosion testing, the journal of the JIEP (Japan Institute of Electronics
Packaging), Vol.6, No.5, August 2003.
4) H. Tanaka; "Corrosion Factor and Effects of Tin-Zinc Lead-Free Solder on Copper
Substrate in Environmental Tests", IPC/ECWC10, S 38-3, 2005
5) J. Maki, T. Izaki, M. Fuda, T. Ohmori, K. Takikawa and M. Narita; "Development of
Tin-Zinc Hot-Dip Coated Steel Sheet", the Journal of the Surface Finishing Society of
Japan", Vol.51, No.6, 653, 2000 (Japanese)
6) K. Nakamura; "Corrosion tests for electronic products", the Journal of the JIEP (Japan
Institute of Electronics Packaging), Vol.4, No.4, P.272-275, 2001 (Japanese)
- 10 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
Topics 1
New Product: Thermal Shock Chamber TSD-100
Toshifumi Nakasuji Environmental Test Business Headquarters, Business Control Department
Yoshihiro Fujita Environmental Test Business Headquarters, Development & Design Department
1
Introduction
The current trend toward an expanding role for electronics in automobiles as well as the
increasing popularity of portable information technology has led to an ever more crucial
role for thermal shock testing. As the importance of thermal shock testing has increased,
many new challenges for testing have arisen. The use of electronics in automobiles has
expanded rapidly, with electronics installed not only in the passenger cabin, but also in the
more severe environment of the engine compartment. Automotive electronics demand
more rigorous reliability than do other consumer goods, and so testing can extend over
long periods of time. However, the development time to market is increasingly rushed,
leading to a major problem in effectively testing reliability in this foreshortened time frame.
The Thermal Shock Chamber TSD-100 was developed to solve these problems. With
faster temperature recovery time, improved temperature uniformity, and the new
“Specimen Temperature Trigger,” this model is able to apply uniform stress to the largest
possible number of specimens and complete testing within a markedly reduced time frame.
We at Espec are pleased to be able to offer our customers this model to enable them to
perform faster and more accurate testing.
Photo 1 Thermal Shock Chamber TSD-100
- 11 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
2
New product features
2-1 Faster temperature recovery
This model has a much smaller load inside the chamber than damper type thermal shock
chambers, greatly reducing the time required for temperature recovery.
Fig.1 Faster temperature recovery
- 12 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
2-1-1 How faster temperature recovery is achieved
Thermal shock chambers utilizing the three-zone system (low-temperature chamber,
test area, high-temperature chamber) have a much greater thermal mass from equipment
such as the damper and separator plates and insulation separating the test area from the
low- and high-temperature chambers, and this thermal mass creates a temperature
recovery load.
The TSD-100 utilizes a two-zone system (low-temperature chamber and hightemperature
chamber) with a mobile test area that requires neither damper nor separator
plates nor insulation to separate the test area from the low- and high-temperature
chambers, thus providing a structure with a much smaller temperature recovery load.
To ensure that the heat from the thermal cycles is directed as much as possible only to the
specimens, the temperature recovery time has been reduced.
Fig.2 Differences in methods of moving temperature
2-1-2 Reduced energy consumption
Shorter test times achieved by faster temperature recovery provide even lower energy
costs than previous Espec models. Under identical test conditions, this model is able to
reduce power consumption by about thirty percent over prior models (produced by Espec).
This achievement is environment friendly.
- 13 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
2-2 Improved temperature uniformity
This model exhibits improved temperature uniformity not only during stable exposure
time, but also during temperature change as well. Temperature uniformity minimizes
differences in stress to specimens placed at different locations inside the chamber.
Fig.3 Temperature uniformity data
2-2-1 How better temperature uniformity is achieved
The high-and low-temperature chambers each have two air circulators. Vertical and
horizontal registers are placed over the air blowout ports. Using this system, circulation can
be dispersed evenly throughout the chamber even at high wind speeds. (Refer to Fig.4.)
Fig.4 Chamber construction
- 14 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
2-3 STT function (Specimen Temperature Trigger)
The STT function monitors specimen temperature and begins counting exposure time
when the temperature of the specimen reaches the temperature setting. Conventional test
equipment does not monitor specimen temperature, and so is unable to determine whether
the specimens have reached the temperature setting and are unable to determine if the
exposure time is accurate. In the past, preliminary testing has been required to confirm
that the specimens have reached the temperature setting in order to determine the length
of the test. This new STT function has eliminated the requirement for preliminary testing,
and the specimens reliably reach the temperature setting. In addition, excess exposure
time can be eliminated, further reducing test time. (Refer to Fig.5, Fig.6, and Fig.7.)
Fig.5 STT function
Fig.6 Effectiveness of STT function (1): Accurate testing
Fig.7 Effectiveness of STT function (2): Reduced testing time
- 15 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
2-3-1 Thermocouples for measuring test temperatures
The specifications for this model offer thermocouples that are easily attached, even with
small specimens and specimens with small attachment sites, and the recovery load (small
thermal mass) of the thermocouple itself is minimal.
Photo 2 Specimen (IC) with thermocouple attached
2-4 Ambient temperature return
To enable prompt removal of test specimens upon completion or during a test pause, the
model is equipped with an ambient temperature return function inside the chamber. During
ambient temperature return, the intake and exhaust air ducts installed in the ceiling of the
high-temperature chamber remain open, allowing the ventilation to lower the temperature
inside the chamber.
While conventional chambers required at least 10 hours to lower the test area
temperature from 150°C to 55°C (natural cooling), the TSD model can achieve return to
ambient temperature within one hour for 10 kilograms of specimens.
2-5 Viewing window
The TSD is the first Thermal Shock Chamber produced by Espec to offer an optional
viewing window with lighting inside the chamber.
•Viewing window specifications: effective viewing area 340 (W) x 190 (H) mm
•Chamber lighting specifications: 25 W halogen lamp; 45 lux at center of test area; 1,000
hour minimum life
Photo 3 Viewing window (option)
- 16 -
Photo 4 Chamber lighting
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
3
The TSD-100 conforms to MIL standards and IEC standards as well as to a number of other
test standards.
Table 1 Major applicable standards
Test standard
Temperature setting
High temp.°C Low temp.°C
Recovery
time
Soak time
Number
of
cycles
A
+85
(+10, -0)
-55
(+0, -10)
5 to 14 min
(specimen
temp.)
IEC 60749-
25
(JESD22-
A104B)
B
C
H
+125
(+15, -0)
+150
(+15, -0)
+150
(+15, -0)
-55
(+0, -10)
-65
(+0, -10)
-55
(+0, -10)
5 to 14 min
(specimen
temp.)
5 to 29 min
(specimen
temp.)
5 to 14 min
(specimen
temp.)
1/ 5/ 10/ 15 min.
Not
specified
M
+150
(+15, -0)
-40
(+0, -10)
5 to 15 min
(specimen
temp.)
IEC-60068-2-14 +200±2
3 hours
Na
+175±2
-65±3
2 hours
(JIS C 0025 Na
DIN EN
60068-2-14 Na
+155±2
+125±2
+100±2
-55±3
-40±3
-25±3
10% of soak
time
1 hour
30 min.
10 min.
5
BS EN
+85±2
-5±3
3 hours if not specified
60068-2-14 Na) +70±2
in the relevant specifications
MIL-202G
Method
107G
MIL-883F
Method
1010.8
IPC-TM-650
2.6.6
A
B
C
A
B
C
D
F
A
B
+85
(+3, -0)
+125
(+3, -0)
+200
(+3, -0)
+85
(+10, -0)
+125
(+15, -0)
+150
(+15, -0)
+200
(+15, -0)
+175
(+10, -0)
+125
(+3, -0)
+85
(+3, -0)
EIAJ ED-4701 Max. storage temp.
EIAJ
ED-7407
Conformity to test standards
-55
(+0, -3)
-65
(+0, -3)
-65
(+0, -3)
-55
(+0, -10)
-55
(+0, -10)
-65
(+0, -10)
-65
(+0, -10)
-65
(+0, -10)
-65
(+0, -5)
-55
(+0, -5)
Min. storage
temp.
A +125±5 -25±5
B +125±5 -40±5
C +80±5 -30±5
D
Max. operating
temp. ±5°C
Min. operating
temp. ±5°C
5 min.
(air temp.)
Less than
15min.
(specimen
temp.)
Not
specified
5 min.
(air temp.)
or 10%
of soak
time,
whichever is
longer
Not
specified
- 17 -
28g and below : 15 min.
28g to 136g : 30min.
136g to 1.36kg : 1 hour
1.36kg to 13.6kg : 2 hours
13.6kg to 136kg : 4 hours
Above 136kg : 8 hours
10 min. or longer
after transition start
1000
At least
10
30 min. 5
15g and below : at least 10 min.
15g to 150g : 30min.
150g to 1,500g : 60min
Above 1,500g : individually specified
7min.
after specimen temp.
attainment
10
Not
specified
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
4
Specifications
Table 2 shows the main specifications for the new model.
Table 2 Main specifications
Model TSD-100
Exposure method
2-zone testing by elevating specimens between
conditioned chambers
Operating temperature +5 to 40°C
Performance *1
Test area
High temperature exposure range
Low temperature exposure range
Temperature fluctuation
High temperature chamber
Pre-heat upper limit
Temperature heat-up time
Low temperature chamber
Pre-cool lower limit
Temperature pull-down time
Temperature recovery performance
Conditions
Temperature recovery time
+60°C to +200°C
-65 to 0°C
±0.5°C
+205°C
Within 90 min from ambient temperature to +200°C
-77°C
Within 90 min from ambient temperature to –77°C
2-zone
High temperature exposure +150°C 30 min
Low temperature exposure -65°C 30 min
Specimen Plastic molded IC, 10 kg
Specimen (IC) temperature Within 15 min
Test area withstand load 30kg *2
Specimen basket dimensions W700 x H40 x D410mm
Test area dimensions W710 x H345 x D410mm
Test area capacity 100L
Outer dimensions W1100 x H1885 x D1965mm
Weight Approx. 1100 kg
200V AC 3 phase 3W 50/60Hz
208V AC 3 phase 3W 60Hz, NEC spec.
Power supply
*3
220V AC 3 phase 3W 60Hz
380V AC 3 phase 4W 50Hz
400/415V AC 3 phase 4W 50Hz, CE spec. *4
*1: Performance figures are in accordance with IEC 60068-3-5:2001.
*2: When using two optional heavy-duty shelves (15.0kg of load capacity).
*3: This equipment is in compliance with the requirements of the National Electric Code (NFPA 70)
for the United States of America.
*4: This equipment is in compliance with the requirements of the European Community Directives.
- 18 -
Espec Technology Report No21

New Product: Thermal Shock Chamber TSD-100
5
Conclusion
The new Espec TSD-100 Thermal Shock Chamber has been developed to meet a wide
range of global needs.
As the demand for thermal shock testing continues to expand, we at Espec will continue to
support our valued customers with fast and accurate reliability testing.
Contact information
For a catalog or more information on the TSD-100 Thermal Shock Chamber, please
contact the Espec International Business Headquarters or your nearest local Espec dealer.
- 19 -
Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
Topic 2
New product: Rapid-rate Thermal Cycle Chamber TCC-150W
Toshifumi Nakasuji Environmental Test Business Headquarters, Business Control Department
Norihiro Kajiguchi Technical Development Headquarters, Technical Center
1
Introduction
The current trend in electronics toward higher performance products that are smaller and
lighter than ever before goes hand-in-hand with higher density mounting of increasingly
miniaturized semiconductor devices that contain more and more terminals. In addition, the
environmental restrictions on the use of hazardous substances in electric and electronic
equipment as mandated by the “RoHS Directive” in the E.U. have eliminated the use of
leaded solder. These societal changes are bringing about a stronger demand for more
precision and accuracy in reliability testing.
In response to this need for better reliability testing, we at Espec have developed the
TCC-150W Rapid-rate Thermal Cycle Chamber. This model exhibits rapid temperature
change of at least 20°C per minute (average chamber temperature change with no
specimens), and offers high-performance temperature cycles with linear control capacity at
a maximum 15°C per minute with specimens.
Photo 1 The Rapid-rate Thermal Cycle Chamber TCC-150W
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
2
Device and mounting changes
We previously noted that products now are higher performance as well as smaller and
lighter than ever before, and contain higher density mounting of increasingly miniaturized
semiconductor devices with more terminals. This situation creates new problems.
2-1 Effects of the temperature cycle
Higher density mounting of semiconductor devices has led to extremely high operating
temperatures. Turning a device on or off creates a temperature cycle inside the equipment.
This in turn creates repeated thermal expansion/contraction between the device and the
PCB, causing the differences in the coefficient of thermal expansion of each material to
produce thermal distortion, which creates stress on the solder joints. This process is a
major cause of failure. (Refer to Fig.1.)
Fig.1 Stress on solder joints caused by temperature cycles
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
2-2 Device structural changes
The miniaturization of semiconductor devices and their increased number of terminals has
led to the change from QFP (Quad Flat Packages) to BGA (Ball Grid Arrays) and CSP (Chip
Scale Packages). (Refer to Fig.2.)
3
New test standards
Fig.2 Device structural changes
New JEDEC standards (JESD22-A104B) have been issued for evaluating solder joints.
When using these standards to evaluate solder joints in such applications as flip chips, BGA,
and laminated packages, mild temperature changes are crucial to successful testing. These
standards specifically mandate a specimen ramp rate of a maximum 15°C per minute.
These standards have been incorporated into the IEC standards as of July 2003, and
constitute a significant new method of evaluation.
Summary of standards
Number of standard : IEC 60749-25 (JESD22-A104B)
Name of standard : Temperature cycling
Range of application : Solder joints of semiconductors and assembly PCBs
Temperature range : -40/125°C, 0/100°C, -25/125°C, etc.
Temperature ramp rate : Specimen temperature max. 15°C/min.
(10 to 14°C/min. recommended)
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
4
New product features
4-1 Specimen temperature ramp control
The new model TCC-150W incorporates a specimen temperature ramp control function.
Thermocouples are attached to the specimens, and the specimen temperature may be
controlled linearly at a selected ramp rate. (Refer to Fig.3.)
Fig.3 Specimen temperature in ramp control
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
4-1-1 Optimal air volume for specimen temperature in ramp control
To keep the specimen temperature changes at the targeted ramp rate during the
specimen temperature ramp control, specimen temperature changes are simulated and
optimal air volume is determined. The heat transfer rate is crucial when using air as a
medium for transferring temperature to the specimens. If the air volume is insufficient, the
heat transfer rate will be too small to affect the specimens even if the chamber temperature
is changed. When test conditions call for a short soak time, the test may move on to the
next cycle before the specimens have reached the targeted temperature. With optimal air
volume, specimen temperatures change in response to changes in the chamber
temperature, the targeted ramp rate is quickly reached, and the targeted temperature is
reliably attained. (Refer to Fig.4.)
Fig.4 Specimen temperature change at different air volumes
4-1-2 Effectiveness of specimen temperature ramp control (1): Test adaptation to
IEC/JEDEC standards
The IEC/JEDEC test standards prescribe the specimen temperature ramp rate at a
maximum of 15°C per minute (10 to 14°C per minute recommended). Since conventional
chambers lack the capacity to control specimen temperature, performing tests in
compliance with test standards required preliminary testing to monitor specimen
temperatures. Also, careful adjustments were required to the test conditions and the
quantity and placement of the specimens to insure that the specified temperature ramp rate
for the specimens would be attained. Now, using its specimen temperature ramp control,
the TCC-150W has the capacity to simply and accurately perform the tests according to
IEC/JEDEC standards by merely attaching thermocouples to the specimens.
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
4-1-3 Effectiveness of specimen temperature ramp control (2): Accurate specimen life
evaluation capability
One crucial aspect of evaluating specimen life with temperature cycling is to attain uniform
conditions of specimen distortion. Differences in the thermal coefficients of the different
materials cause distortion in the specimens. Attaining a uniform speed at which this
distortion occurs and attaining symmetry between the distortion waveform and the rise and
fall in temperature are crucial to this test. Test dispersion is created when these factors
differ with each test, and such tests exhibit poor standardization and reproducibility. When
tests exhibit dispersion, specimen life cannot be accurately determined. The TCC-150W
allows the operator to set the ramp rate control for the specimen temperature, creating the
ability to attain uniform distortion speed and a symmetrical distortion waveform, providing
accurate specimen life evaluation. (Refer to Fig.5.)
Fig.5 Comparison of temperature waveform
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
4-2 Improved temperature uniformity
The TCC-150W has achieved dramatic improvement in temperature uniformity during
temperature change. The model identifies optimum air volume and velocity uniformity
through simulation and then attains those targets. Stress on the specimens can vary widely
during temperature change due to differences in uniformity. Differences in stress due to
specimen placement positions inside the chamber have been reduced to a minimum. (Refer
to Fig.6.)
Fig.6 Temperature uniformity data
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
4-3 Fast temperature change capability
The TCC-150W attains a temperature change rate of 20°C per minute (average chamber
temperature with no specimens). This model is very useful for tests requiring fast
temperature change, as well as for dramatically reducing test times. (Refer to Fig.7.)
Fig.7 Test time reduction
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
5
Compliance with test standards
The TCC-150W complies with both JEDEC and IEC standards as well as a number of other
test standards.
Table 1 Major applicable standards
Temperature setting
Temperature
Number
Test standard Soak time
High temp.°C Low temp.°C change rate
of cycles
IEC 60749-25
(JESD22-A104B)
JESD22-A105B
G +125 (+15, -0) -40 (+0, -10)
I +115 (+15, -0) -40 (+0, -10)
J +100 (+15, -0) 0 (+0, -10)
K +125 (+15, -0) 0 (+0, -10)
L +110 (+15, -0) -55 (+0, -10)
N +80 (+15, -0) -30 (+0, -10)
O +125 (+15, -0) -25 (+0, -10)
A +85 (+10, -0) -40 (+0, -10)
B +125 (+10, -0) -40 (+0, -10)
TC1 100 0
TC2 100 -25
IPC-9701 TC3 125 -40
TC4 125 -55
TC5 100 -55
IPC-TM-650 2.6.6
A
B
+125 (+3, -0)
+85 (+3, -0)
-65 (+0, -5)
-55 (+0, -5)
IEC-60068-2-14 Nb
(JIS C 0025 Nb)
IEC-61747-5
(EIAJ ED-2531A)
+175±2
+155±2
+125±2
+100±2
+85±2
+70±2
+55±2
+40±2
+30±2
+100±2
+95±2
+90±2
+85±2
+80±2
+75±2
+70±2
+65±2
+60±2
+55±2
+50±2
+45±2
+40±2
+35±2
+30±2
-65±3
-55±3
-40±3
-25±3
-5±3
+5±3
-50±3
-45±3
-40±3
-35±3
-30±3
-25±3
-20±3
-15±3
-10±3
-5±3
-0±3
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15 °C /min.
or less
(specimen temp.)
6.25 °C /min.
(specimen temp.)
5.5 °C /min.
(specimen temp.)
20 °C /min.
or less
(specimen temp.)
1, 5, 10, 15min.
after
specimen temp.
attainment
10 min.
after
specimen temp.
attainment
10 min.
after
specimen temp.
attainment
Not
specified
1000
200
500
1000
3000
6000
Not specified 30 min. 5
1±0.2 °C /min.
3±0.6 °C /min.
5±1 °C /min.
(Averaged over
a period of not
more than 5 min.)
1 ±0.2 °C /min.
3 ±0.6 °C /min.
5 ±1 °C /min.
(Averaged over
a period of not
more than 5 min.)
3 hours
2 hours
1 hour
30 min.
10 min.
(3 hours unless
otherwise specified
in the relevant
specifications)
3 hours
2 hours
1 hour
30 min.
10 min.
(3 hours unless
otherwise specified
in the relevant
specifications)
2
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Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
6
Specifications
Table 2 shows the main specifications for the new model.
Model
Table 2 Main specifications
TCC-150W
Temperature control system Balanced temperature control (BTC) system
Working temperature range +5 to +35°C
Performance
*1
Temperature
range
Temperature
fluctuation
Chamber
Temperature
change
Specimen
Temperature
change
Load capacity of
specimen basket
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-70 to +180°C
±0.5°C (-70°C to +180°C) when temperature is stable
- 70 ←→ +180°C
No specimens (average chamber temperature change)
At temperature rise :22°C /min.
At temperature fall :18°C /min.
- 40 ←→ +125°C
Specimens :total 9 kg
Glass epoxy PCB + jigs (Espec standard product)
At ramp control : 5 to 15°C /min.
- 40 ←→ +125°C
Specimens :total 9 kg
Glass epoxy PCB + jigs (Espec standard product)
At ramp control : 5 to 15°C /min.
5 kg per basket (evenly distributed)
7 shelves can be mounted
Test area dimensions W800 × H500 × D400 mm (effective test area)
Loading capacity 160 L
Outer dimensions W1000 × H1808 × D1915 mm
Weight Approx. 950 kg
200V AC 3 phase 3W 50/60Hz
208V AC 3 phase 3W 60Hz, NEC spec.
Power supply
*2
220V AC 3 phase 3W 60Hz
380V AC 3 phase 4W 50Hz
400V AC 3 phase 4W 50Hz, CE spec. *3
*1: Performances are based on IEC 60068-3-5: 2001.
*2: This equipment is in compliance with the requirements of the National Electric Code (NFPA 70)
for the United States of America.
*3: This equipment is in compliance with the requirements of the European Community Directives.
Espec Technology Report No21

New product: Rapid-rate Thermal Cycle Chamber TCC-150W
7
Conclusion
Our new product, the “Rapid-rate Thermal Cycle Chamber TCC-150W”, embodies a new
product concept with its specimen temperature ramp control function. Temperature cycle
tests now have the capability of meeting previously unattainable temperature test
standards. We at Espec are offering a new test method with this model, which will serve as
our new standard model. We believe that our customers will find that this model can play a
major role in improving product reliability and in improving productivity by reducing testing
time.
•Contact information
For a catalog or more information on the TCC-150W Rapid-rate Thermal Cycle Chamber,
please contact the Espec International Business Headquarters or your nearest local Espec
dealer.
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Espec Technology Report No21