Improving Electromagnetic Compatibility Performance of Packages and SiP Modules using a Conformal Shielding Solution

High-speed digital and wireless devices radiate unintentional electromagnetic noise, which can affect the normal operation of other devices within the same system, causing intra-system electromagnetic interference (EMI) problems, or contribute to the total radiated EMI from the system, resulting in potential system-level EMI issues. PCB and system level shielding may alleviate the system-level EMI between wireless PCB board and the outside environment, but seldom prevent the intra-system EMI within the shielding enclosure. Package and System in Package (SiP) level shielding is desirable to shield the unintended radiation and protect the other circuits on board. Traditionally an external metal lid is employed to isolate the radiation from an IC, but the package cost and the size penalty due to the solder pads for shield attachment make the solution unattractive. in this paper, a new shielding technology for IC packages based on metal spray coating (conformal shielding) is presented. by spraying a conductive material on the sides of the package, a very thin metal layer is constructed around the top and four sides of a package. This very thin sprayed metal layer adds zero penalty to the package size and works similar to a solid metal shielding with very good shielding effectiveness; hence, it is suitable for wireless infrastructure, tele-communications, and high-speed digital applications. © 2010 IEEE

Extraction of SPICE-Type Equivalent Circuits of Signal Via Transitions using the PEEC Method

Digital devices and discontinuities are typically analyzed by inserting their equivalent circuits into SPICE-type simulators. The partial element equivalent circuit method has been proven to be very useful for electromagnetic modeling. It can be used in both the time and the frequency domain. In this paper, the PEEC technique is employed as an efficient full-wave modeling tool to derive SPICE-type equivalent circuits of signal via transition structures. A nodal analysis technique is utilized in conjunction with the optimization algorithm to extract the equivalent circuits, whose component values are the parameters optimized. The good agreement between different approaches demonstrates that the proposed approach can be a powerful tool for deriving the equivalent circuits of signal via transitions

Estimating DC Power Bus Noise

Simultaneous switching noise (SSN) resulting from IC devices can result in significant power bus noise, as well as radiation problems. An approach for estimating the power bus noise spectrum is presented in this paper. The power bus noise caused by digital circuits injecting high-frequency noise onto the DC buses feeding digital devices is calculated. The transient current drawn by an IC device is modeled using the load current and the shoot-through current through the power dissipation capacitance. Modeling and experimental results for several digital chips are shown. The modeling agrees well with the experimental results

An Efficient Approach for Power Delivery Network Design with Closed-Form Expressions for Parasitic Interconnect Inductances

Investigation of a dc power delivery network, consisting of a multilayer PCB using area fills for power and return, involves the distributed behavior of the power/ground planes and the parasitics associated with the lumped components mounted on it. Full-wave methods are often employed to study the power integrity problem. While full-wave methods can be accurate, they are time and memory consuming. The cavity model of a rectangular structure has previously been employed to efficiently analyze the simultaneous switching noise (SSN) in the power distribution network. However, a large number of modes in the cavity model are needed to accurately simulate the impedance associated with the vias, leading to computational inefficiency. A fast approach is detailed herein to accelerate calculation of the summation associated with the higher-order modes. Closed-form expressions for the parasitics associated with the interconnects of the decoupling capacitors are also introduced. Combining the fast calculation of the cavity models of regularly shaped planar circuits, a segmentation method, and closed-form expressions for the parasitics, an efficient approach is proposed herein to analyze an arbitrary shaped power distribution network. While it may take many hours for a full-wave method to do a single simulation, the proposed method can generally perform the simulation with good accuracy in several minutes. Another advantage of the proposed method is that a SPICE equivalent circuit of the power distribution network can be derived. This allows both frequency and transient responses to be done with SPICE simulation

Effects of Open Stubs Associated with Plated Through-Hole Vias in Backpanel Designs

Plated through-hole (PTH) vias are commonly used in printed circuit boards. They usually leave open stubs if the signal(s) does not transition the entire depth of the board. These open stubs can have a negative impact on signal transmission. This summary reports the investigation of the impact of the open via stubs in a typical backpanel design

Establishment of a chemokine-based prognostic model and identification of CXCL10+ M1 macrophages as predictors of neoadjuvant therapy efficacy in colorectal cancer

BackgroundAlthough neoadjuvant therapy has brought numerous benefits to patients, not all patients can benefit from it. Chemokines play a crucial role in the tumor microenvironment and are closely associated with the prognosis and treatment of colorectal cancer. Therefore, constructing a prognostic model based on chemokines will help risk stratification and providing a reference for the personalized treatment.MethodsEmploying LASSO-Cox predictive modeling, a chemokine-based prognostic model was formulated, harnessing the data from TCGA and GEO databases. Then, our exploration focused on the correlation between the chemokine signature and elements such as the immune landscape, somatic mutations, copy number variations, and drug sensitivity. CXCL10+M1 macrophages identified via scRNA-seq. Monocle2 showed cell pseudotime trajectories, CellChat characterized intercellular communication. CytoTRACE analyzed neoadjuvant therapy stemness, SCENIC detected cell type-specific regulation. Lastly, validation was performed through multiplex immunofluorescence experiments.ResultsA model based on 15 chemokines was constructed and validated. High-risk scores correlated with poorer prognosis and advanced TNM and clinical stages. Individuals presenting elevated risk scores demonstrated an increased propensity towards the development of chemotherapy resistance. Subsequent scRNA-seq data analysis indicated that patients with higher presence of CXCL10+ M1 macrophages in tumor tissues are more likely to benefit from neoadjuvant therapy.ConclusionWe developed a chemokine-based prognostic model by integrating both single-cell and bulk RNA-seq data. Furthermore, we revealed epithelial cell heterogeneity in neoadjuvant outcomes and identified CXCL10+ M1 macrophages as potential therapy response predictors. These findings could significantly contribute to risk stratification and serve as a key guide for the advancement of personalized therapeutic approaches

Circuit model extraction in digital and RD circuits using the partial element equivalent circuit (PEEC) method

This dissertation discusses four topics relevant to power integrity and design, numerical modeling, and characterization and modeling of MEMS switches --Abstract, page iv

Efficient Capacitance Calculations for PEEC Circuit Analysis

The partial element equivalent circuit (PEEC) method has proven to be useful for electromagnetic modeling. It can be used in both the time and the frequency domain. It is very important for the partial element equivalent circuit method to evaluate the partial inductances and the coefficients of potential rapidly and accurately. The evaluation of these parameters is much more challenging for the nonorthogonal mesh case. Based on a derivation for the potential due to a distribution of sources on a flat quadrilateral panel, this paper proposes an approach to rapidly extract the partial capacitance of generally quadrilateral PEEC elements. The proposed approach is compared to rectangular-shaped elements for which an analytical solution is known. The accuracy of the results demonstrates the effectiveness of the proposed approach

Memory DIMM DC Power Distribution Analysis and Design

DC power bus design is critical in meeting signal integrity (SI) and electromagnetic compatibility (EMC) requirements. A suitable modeling tool is beneficial to evaluate power bus design and develop design guidelines. This paper discusses difficulties met in evaluating the power distribution design on a dual inline memory module (DIMM) board, such as a power bus with arbitrary shape, parasitic inductance associated with vias, and so on. Moreover, some solutions are given in this paper. A simple cavity model with a segmentation method was employed to model a power bus with irregular shapes. The partial element equivalent circuit (PEEC) technique was applied to model the electrical properties of a high-speed via interconnect. For each proposed approach, the difference between the estimates and measurements demonstrates the application of these approaches in the DIMM DC power distribution analysis and design

Influence of interface electric field on interaction between molten iron and refractory interface

In steel processing, electric field present at the interface between molten iron and refractory materials has important influence on erosion and clogging of the submerged entry nozzle. In this study, a voltage was applied between a droplet of molten iron and several nozzle constituent materials, while measuring the liquid/solid contact angle to quantify the effect of the voltage on interfacial wetting. At 0 V the contact angles between molten iron and graphite, Al2O3-C, and ZrO2-C substrates are 130% 136 degrees, and 128% respectively. The contact angles are reduced to 85 degrees, 88 degrees, and 103 degrees when a potential of 3 V is applied. Also, it was found that silicon atoms in the molten iron diffuse and aggregate at the interface of the two phases under an external electric field, and that the electric field promotes chemical reactions between the two phases. Mass transfer, atomic diffusion, and dissolution at solid-liquid interface are promoted by interfacial electric field, which is partially responsible for the improvement in wetting. These results provide kinetic conditions related to erosion and clogging of refractory material