September 2025
www.us -
tech.com
Open Circuit Voltage Test Batteries are typically graded in A-B-C
categories (A for mission-critical batteries, B for higher quality consumer grade appli- cations, C for easier, cost-effective appli- cations). This is done in a sorting station in the production line and unlike the for- mation process this involves a test. The demands here for the test probe
are not as critical as for the formation stage as the currents are much lower. Here, the main purpose is to check the voltage. No charging or discharging occurs in that test. However, compared to formation, the probe itself is cycled more often (mechanical touchdowns), and the test is very fast as it only takes seconds to acquire all data and to sort the batteries. Here, one needs to ensure to select a
test probe that has a long cycle life, but with regards to the tip style the demands are less challenging compared to formation probes. Thread-mount probes are pre- ferred. This prevents the “snap- effect.” Friction-fit probes could walk out of the receptacle if the probes are cycled fast, e.g. due to a pneumatic actuator with high acceleration. This would not only annoy
the technicians who then fre- quently need to push the probe back in, but this could also cost a lot of money due to this mainte- nance effort. The simple solution is to change to such thread- mount options, which are in - stalled with special insertion tool bits and a torque driver.
ACIR and EIS EIS stands for “electrochem-
range, typically in the < 100 mW range. This means that test probes also should have low resistance itself, or else those may interfere with the test. Also, it is advisable to use four-wire tech- niques, to eliminate errors. For that one can either use additional spring-probes (four probes needed if anode and cathode are contact- ed) or one can use a coaxial probe, which is basically a probe-in-a- probe (with outer and center con- ductor) — two probes needed.
Current Rating It is important to note that
ical impedance spectroscopy,” which offers a holistic view of the health of a battery cell. ACIR is similar, but not the same. The internal resistance of the battery, both the electrolyte resistance, reaction resistance and diffusion resistance give an indication about the cell’s performance. A Nyquist (Cole-Cole) plot shows resistance on the X-axis and reactance on the Y-axis. Lower frequencies from 1 Hz to 1 kHz are used in the test. Narrow resistance changes would indi- cate a pristine battery, whereas wide resistance swings would indicate a degraded battery. Resistances are in the mW
most test probes are rated at continuous cur- rent. The probe diameter, along with the internal design of the probe (with regards to mechanical biasing techniques, spring mate- rial etc.) determines the current rating.
Page 57
Touch-and-Go: Test Probes for Battery Cell Manufacturing Continued from previous page
It is typically suggested to use high-tem-
perature springs. Most manufacturers offer probes with either “standard” temperature range, typically from –40 to +176°F (–40 to +80°C) or extended temperature range, which typically goes from –148 to +392°F (–100 to +200°C), which are better suited for battery test applications. If in doubt, reach out to an application engineer. To improve the current rating, some test probes have options for additional cool- ing. Low-pressure 15 psi air can work like magic to cool down the surface. Especially for densely packed fixture
Four-probe vs two-probe setup for Kelvin/Four-wire measurements for ACIR/EIS.
trays, this is an easy way to reduce tem- perature by forced-cooling. Also, since some testing does not require a full 100% duty cycle, the probe may not heat up as much as when driven with its rated cur- rent for continuous operation. However, “one second on and one second off” gives Continued on next page
See at SEMICON West, Booth 5578
Headquarters, Vista, California, USA. +1 (760) 438-1138 -
sales@visionpro.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96
