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Electronic Assemblies
Published in Michael Pecht, Handbook of Electronic Package Design, 2018
The simplest subassemblies are known as die assemblies. They consist of a bare die, such as a transistor or diode, mounted on a tab having a conductive surface. Figure 4.2 shows examples of typical die assemblies. These die assemblies are then mounted on top of a substrate which is protectively overcoated (in commercial applications) or within a hermetically sealed package or hybrid (in military applications). There are three reasons for building these assemblies: These assemblies need only be slightly bigger then the dice themselves, making them much smaller then a discretely packaged or “canned” diode or transistor. Why not just mount the dice directly on the higher assembly’s substrate to further decrease the size needed by the dice? This is, indeed, the common practice used in hybrid assemblies. However, by first mounting the dice on tabs and not directly on the substrate, it is possible to test the dice functionally prior to committing them to the more expensive higher assembly.With the ability to pretest these die assemblies, they are utilized for low-yield dice, such as application-specific integrated circuits (ASICs); high-power dice, such as field effect transistors (FETs); or when it is essential to “match” pairs of dice for functional reasons.The tab allows for easier rework. When a die is determined to be inoperative, it must be replaced. To replace the die, the substrate assembly must be heated to reflow the solder or soften the epoxy with which the die is mounted. The die is then extracted from the substrate. Since most dice are only 0.010-in.-thick silicon, they tend to come off in pieces. These pieces must be carefully pried off one at a time. Extreme care must be taken to not damage the neighboring components in the process. Die assemblies with the support of the tab lift up in one piece. This greatly eases the reworkability of the assembly.
Affective Design of Smart TV Navigation Interface Considering the Diversity of User Needs
Published in International Journal of Human–Computer Interaction, 2023
Fu Guo, Xiaohui Tian, Mingcai Hu, Zeyu Zhang
The definitions of the design attributes are then given one by one. Scrolling mode: The way of browsing more content refers to the switching method of information in the navigation interface. At present, the common ones are drop-down waterfall (up and down layout, that is, page down), one-page design, horizontal pull, and F-shaped (down and right expanded content), etc. Navigation bar structure: Refers to the design and layout of the navigation bar. At present, the common ones are top tab navigation, left tab navigation, icon style navigation, etc. Content layout: Refers to the content distribution law of the main navigation interface, which means the obvious degree of similar content divisions, including regular layout and cross layout. Module area difference: This refers to the area size distribution between the modules of the navigation interface, which is divided into three categories: uniform area (all modules have the same area), regular area (the area changes according to a certain pattern) and irregular area (the area changes are inconsistent or irregular). Navigation bar logic is defined from the perspectives of text description accuracy, navigation tab content settings, and logic hierarchy. It is divided into high, medium, and low levels. Presentation mode (graphic-to-text ratio): Refers to the way in which the main navigation interface presents content mainly with graphics or text. Module quantity level: Refers to the number of modules in the interface. Navigation label (Tab) quantity level: Refers to the number of navigation labels in the interface. Proportion of the recommended bit: Refers to the number and area ratio of recommended bits on the main navigation interface. System Function key position: The position of the function key. APP: Applications that are installed on a smart TV to provide additional functionality. Design of ad message: the way in which advertising messages are designed on the interface. Icon and text size: It refers to the overall size perception of the graphics and text in the interface. Color contrast: Refers to the contrast between the background color of the interface and the color of the foreground image and text. Detail design: Mainly defined whether the interface module has rounded corners, background gradient or pattern design, and the prompt style of the current position.