barcode scanner programming asp.net PROPERTIES USED TO CLASSIFY BASE MATERIALS in Software

Paint QR Code in Software PROPERTIES USED TO CLASSIFY BASE MATERIALS

PROPERTIES USED TO CLASSIFY BASE MATERIALS
Scan Denso QR Bar Code In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Drawing QR Code In None
Using Barcode drawer for Software Control to generate, create Denso QR Bar Code image in Software applications.
Historically, the Tg has been the most common property used to classify FR-4 base materials, and this is one of the primary properties documented in IPC-4101. Materials with high Tg values were generally viewed as being more reliable. While this question was never as simple as specifying only the Tg, the move toward lead-free assembly has caused a fundamental redefinition of what properties are needed to ensure a given level of reliability. The reason is that the alloys used in lead-free assembly require higher peak temperatures than those used in tinlead assembly. These higher peak temperatures can approach the point where many base materials begin to decompose. For this reason, the decomposition temperature is becoming another property used to classify base materials. Other important properties include Z-axis expansion characteristics, moisture absorption, and adhesion characteristics within the material, commonly measured using time-todelamination tests such as the T260 test. The Tg and its impact on Z-axis expansion are summarized below along with the decomposition temperature. The other properties will be discussed in Chaps. 8 and 10.
QR Decoder In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Encode Denso QR Bar Code In C#
Using Barcode maker for .NET Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications.
Glass Transition Temperature, Tg The Tg of a resin system is the temperature at which the material transforms from a relatively rigid or glassy state, to a more deformable or softened state.This is a thermodynamic change in the material which is reversible as long as the resin system has not been degraded. This is to say that when a material that has been heated above its Tg is cooled back below the Tg, it returns to a more rigid state with essentially the same properties as before. However, if the material is heated to too high a temperature beyond Tg, irreversible changes in properties may result. The temperature at which this will happen varies by material type and is related to resin decomposition, discussed later.
Paint QR-Code In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
Generate QR Code JIS X 0510 In Visual Studio .NET
Using Barcode maker for VS .NET Control to generate, create QR Code image in .NET framework applications.
PRINTED CIRCUITS HANDBOOK
Generating QR Code In Visual Basic .NET
Using Barcode creator for .NET Control to generate, create QR Code JIS X 0510 image in .NET framework applications.
DataMatrix Generator In None
Using Barcode generation for Software Control to generate, create Data Matrix ECC200 image in Software applications.
A material is not in a liquid state when it is above the Tg, as some discussions of Tg imply. It is a temperature at which physical changes take place due to the weakening of molecular bonds within the material. It is important to understand Tg since the properties of base materials are different above Tg than below Tg. While the Tg is typically described as being a very precise temperature, this is somewhat misleading, because the physical properties of the material can begin to change as the Tg is approached and some of the Tg molecular bonds are affected. As the temperature increases, Temperature more of the bonds become weakened until for all practical purposes, all relevant bonds are affected. This explains the FIGURE 6.1 Glass transition temperature by TMA. curved line in Fig. 6.1, which is discussed in the following text. The Tg of a resin system has several important implications. These include:
Encode UPC - 13 In None
Using Barcode printer for Software Control to generate, create UPC - 13 image in Software applications.
Code 128A Generation In None
Using Barcode generator for Software Control to generate, create ANSI/AIM Code 128 image in Software applications.
Thickness
Printing Barcode In None
Using Barcode generator for Software Control to generate, create barcode image in Software applications.
UPCA Creation In None
Using Barcode generation for Software Control to generate, create UPC A image in Software applications.
The impact on thermal expansion. A measure of the degree of cure of the resin system.
USPS PLANET Barcode Drawer In None
Using Barcode printer for Software Control to generate, create USPS Confirm Service Barcode image in Software applications.
Print EAN13 In Java
Using Barcode encoder for BIRT reports Control to generate, create EAN13 image in BIRT reports applications.
6.3.1.1 Thermal Expansion. All materials will undergo changes in physical dimensions in response to changes in temperature. The rate at which the material expands is much lower below the Tg than above. Thermomechanical analysis (TMA) is a procedure used to measure dimensional changes versus temperature. Extrapolating the linear portions of the curve to the point at which they intersect provides a measure of the Tg (see Fig. 6.1). The slopes of the linear portions of the curve above and below the Tg represent the respective rates of thermal expansion, or as they are typically called, the coefficients of thermal expansion (CTEs). CTE values are important since they influence the reliability of the finished circuit. Other things being equal, less thermal expansion will result in greater circuit reliability as less stress is applied to plated holes. 6.3.1.2 Degree of Cure. The resin systems used in base materials begin with subcomponents that contain reactive sites on their molecular structures. The application of heat to the resin system and curing agents causes the reactive sites to cross-link or bond together. This process of curing the resin system brings about physical changes in the material in proportion to the degree to which the cross-linking occurs, including increases in the Tg.When most of the reactive sites have cross-linked, the material is said to be fully cured and its ultimate physical properties will be established. Besides TMA, two other thermal analysis techniques are also commonly used for measuring Tg and degree of cure: differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).
Scanning Code39 In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
Bar Code Maker In .NET
Using Barcode maker for Reporting Service Control to generate, create barcode image in Reporting Service applications.
DSC measures heat flow versus temperature rather than the dimensional changes measured by TMA.The heat absorbed or given off will also change as the temperature increases through the Tg of the resin system.Tg measured by DSC is often somewhat higher than measurements by TMA. DMA measures the modulus of the material versus changes in temperature, and also will give somewhat higher values for Tg.
Generating GS1-128 In Java
Using Barcode printer for Eclipse BIRT Control to generate, create EAN 128 image in BIRT applications.
Drawing ANSI/AIM Code 39 In Java
Using Barcode maker for Android Control to generate, create ANSI/AIM Code 39 image in Android applications.
Materials that are not fully cured can cause problems in circuit manufacturing processes and with finished circuit reliability. For example, an undercured multilayer circuit at the drilling process can result in excessive resin smear across the internal circuit connections in
Create ANSI/AIM Code 128 In Java
Using Barcode printer for BIRT Control to generate, create Code-128 image in BIRT applications.
DataMatrix Generation In .NET
Using Barcode creator for .NET framework Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
Copyright © OnBarcode.com . All rights reserved.