It is now well known that testing for CDM Electrostatic Discharge [ESD]
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
" href="https://incompliancemag.com/terms/electrostatic-discharge/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">ESD evaluation is becoming a bigger challenge. Previously (In Compliance Magazine, March 2021), capacitively coupled TLP (CCTLP) was described as an alternate approach. It offers many advantages compared to the standardized field-induced CDM setup according to the JS002 standard [1]. Testing of a package, bare die, or wafer is enabled with high reproducibility. The failure correlation between CDM and CCTLP has been investigated based on peak current stress levels and not by a charging voltage level [2]. If testing with an alternative CDM method as CCTLP is done to reproduce JS002, the CDM charging voltage must be transferred into peak current levels.
A measure for the severity of the CDM stress is the effective Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance Ceff of a device [3]. Ceff characterizes the amount of exchanged charge between DUT and test setup at a specific stress level (e.g., VCDM) in a specific testing environment.
Products can be categorized with respect to Ceff in an FICDM setup because of the direct relation to the peak current for a given test voltage, as described in [4].
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance values play a role according to the three-capacitances model, as shown in Figure 1.
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance CDUT is defined as the Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance from the device to the field plane. The static Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance value for CDUT is extracted from a Finite Element Method [FEM]
A technique for finding approximate solutions to boundary value problems for differential equations.
" href="https://incompliancemag.com/terms/finite-element-method/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">Finite Element Method (Finite Element Method [FEM]
A technique for finding approximate solutions to boundary value problems for differential equations.
" href="https://incompliancemag.com/terms/finite-element-method/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">FEM) simulation according to the three-capacitances model shown in Figure 1. Differences between Ceff and CDUT capacitances either extracted from FEM-simulation or calculated as parallel plate Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance Cplate (A is the area of the DUT, and d is the thickness of the FR4 dielectric layer) are demonstrated based on the metallic circular coin modules (height 1.27 mm, diameters see Table 1).
A technique for finding approximate solutions to boundary value problems for differential equations.
" href="https://incompliancemag.com/terms/finite-element-method/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">FEM simulation of CDUT does not coincide with the simple plate Capacitor
A passive electronic component that consists of two conductive plates separated by an insulating dielectric.
" href="https://incompliancemag.com/terms/capacitor/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitor formula since fringing effects are also considered, especially for small devices. CDUT also shows a linear dependency on the area-capacitance relation. In contrast, Ceff values show saturation with increasing area or volume of a DUT. As a result, not only the area of the bottom surface contributes to the Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance but also the sidewalls and, therefore, the volume.
To calculate the CDM discharge current from the volume, the device area is considered as the maximum edge length a x b, including the pins and mold compound (Figure 3). For a bare die product that does not go into a final package, the area is calculated from the edge length of the silicon accordingly.
裝置尺寸的影響為了根據體積計算 CDM 放電電流，裝置面積被視為最大邊緣長度 a x b，包括接腳和模塑膠（圖 3）。對於不進入最終封裝的裸晶片產品，面積是根據矽的邊緣長度相應計算的。
- From Our Sponsors -
Statistical analysis of CDM testing data shows the relevance of device area and volume for predicting stress current levels in a CDM test since the height h of the device has a non-neglectable influence on the discharge current. A database with over 15 million CDM waveforms has been used to evaluate the relation between area, volume, peak current, and the effective Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance Ceff. The area and volume of about 10000 different device types can be derived from the package dimensions included in the database. For each device type, only the waveforms are evaluated, showing the maximum positive peak current Ipeak out of several CDM discharges for a positive charging voltage level of 500 V. According to the measurement results, the peak current reduces with the increasing height of the device.
- 來自我們的贊助商- 圖3：設備面積A=a x b 和體積V=A x h 的定義CDM 測試數據的統計分析顯示了設備面積和體積對於預測自高度h 以來CDM 測試中的應力電流水平的相關性元件的性能對放電電流有著不可忽視的影響。擁有超過 1500 萬個 CDM 波形的資料庫已用於評估面積、體積、峰值電流和有效電容 Ceff 之間的關係。大約 10000 種不同設備類型的面積和體積可以從資料庫中包含的封裝尺寸得出。對於每種裝置類型，僅評估波形，顯示在 500 V 正充電電壓等級下多次 CDM 放電的最大正峰值電流 Ipeak。
This can be shown using the set of nine cylindrical solid metal coins P1 to P8 with different diameters and volumes (see Table 1)[5]. The coin reference for the peak current still gives a reasonable orientation for the maximum peak current. Figure 4 shows the dependency of the effective Capacitance
The ability of a a component or circuit to store an electric charge.
" href="https://incompliancemag.com/terms/capacitance/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">capacitance Ceff on the volume. For very flat packages, the limit of the coins is exceeded but still givesa meaningful value. The coin with the smallest volume and, therefore, lowest Ceff reaches the lowest peak current and vice versa. For devices, this means that their Ceff with the according current can be related to the current of the coins. As shown, the device height is becoming relevant for the estimation of the stress current level, therefore, the volume is introduced as the preferred parameter. Thus, the volume value can be used to estimate the expectable peak current with respect to the coin values as shown in Figure 5.
A practical solution is presented for the problem, how CDM targets can be translated to current test levels. CDM current test levels are important as they allow using alternative CDM testing methods, such as CCTLP. The first testing proposal is a simple approach, representing the worst case: Increase the CCTLP testing voltage until the peak current value is reached at the product pin given in Figure 5.
To avoid over-testing, these levels can be lowered based on the second proposal if details of the electrical properties on-package and on-chip are known. Ceff values can be predicted by Finite Element Method [FEM]
A technique for finding approximate solutions to boundary value problems for differential equations.
" href="https://incompliancemag.com/terms/finite-element-method/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">FEM simulation even before devices are available.
為了避免過度測試，如果封裝上和晶片上的電氣特性的詳細資訊已知，則可以根據第二個建議降低這些水平。即使在設備可用之前，也可以透過 FEM 模擬來預測 Ceff 值。
The full paper was published in [6].
論文全文發表於[6]。
References
American National Standards Institute [ANSI]
A private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.
" href="https://incompliancemag.com/terms/american-national-standards-institute/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">ANSI/JEDEC/ESDA, “Joint Standard for Electrostatic Discharge [ESD]
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
K. Esmark, R. Gaertner, S. Seidl, F. zur Nieden, H. Wolf and H. Gieser, “Using CC-TLP to get a CDM robustness value,” 2015 37th Electrical Overstress/Electrostatic Discharge [ESD]
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
" href="https://incompliancemag.com/terms/electrostatic-discharge/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">ESD), Anaheim, CA, USA, 2007, pp. 5A.1‑1‑5A.1-10.
N. Jack, B. Carn and J. Morris, “Toward Standardization of Low Impedance Contact CDM,” 2019 41st Annual EOS/Electrostatic Discharge [ESD]
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
" href="https://incompliancemag.com/terms/electrostatic-discharge/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">ESD), Riverside, CA, USA, 2019, pp. 1-7.
T. J. Maloney and N. Jack, “CDM Tester Properties as Deduced From Waveforms,” in Institute of Electrical and Electronics Engineers [IEEE]
A professional association that is dedicated to advancing technological innovation and excellence.
" href="https://incompliancemag.com/terms/institute-of-electrical-and-electronics-engineers/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">IEEE Transactions on Device and Materials Reliability, vol. 14, no. 3, pp. 792-800, Sept. 2014, doi: 10.1109/TDMR.2014.2316177
L. Zeitlhoefler, T. Lutz, F. Zur Nieden, K. Esmark and R. Gaertner, “Voltage to Current Correlation for CDM Testing,” 2023 45th Annual EOS/Electrostatic Discharge [ESD]
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
Sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
" href="https://incompliancemag.com/terms/electrostatic-discharge/" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex="0" role="link">ESD), Riverside, CA, USA, 2023, pp. 1-11, doi: 10.23919/EOS/ESD58195.2023.10287735
