barcode scanner code in asp.net PRINTED CIRCUITS HANDBOOK in Software

Make Denso QR Bar Code in Software PRINTED CIRCUITS HANDBOOK

PRINTED CIRCUITS HANDBOOK
QR Code Decoder In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Printing QR Code In None
Using Barcode creation for Software Control to generate, create QR Code ISO/IEC18004 image in Software applications.
FIGURE 40.1 (a) Photograph of a through-hole printed circuit board. (b) Optical micrograph of the component lead as it is soldered into the circuit board hole. (Courtesy of Sandia National Laboratories.)
Scanning Quick Response Code In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
QR Code 2d Barcode Generator In C#
Using Barcode drawer for .NET Control to generate, create QR Code ISO/IEC18004 image in Visual Studio .NET applications.
Impact of Pb-Free Soldering on Through-Hole Technology The change to Pb-free solders affects through-hole assembly technology. First, there is equipment selection. Manual assembly operations may require purchasing higher-temperature soldering irons. At the other end of the cost spectrum, there are the expenses to replace several hundreds of pounds of Sn-Pb solder with a Pb-free alternative in the pot of a wave-soldering machine. Alternatively, it may be advantageous simply to purchase an entirely new machine to avoid cross-contamination with legacy Sn-Pb operations and/or to have the latest technology that mitigates the higher erosion activity of Pb-free solders on machine components. The use of Pb-free solders also requires a review of the process parameters. The specific aspects are the higher processing temperature required to use Pb-free alloys and the reduced solderability of these alloys. It has been fortuitous that Pb-free solders, when used in manual (soldering iron) and wave processes, have not required a very significant increase in soldering iron temperature as was first anticipated in the early stages of Pb-free technology development. The added temperature margin was of least concern with manual soldering processes because the localized heating limits thermal degradation to either the component or substrate. Some concern arose in the wave-soldering process because the substrate is exposed to the molten solder bath. On the other hand, paste-in-hole technology that uses a Pb-free reflow process subjects through-hole components and substrates to temperatures higher than those to which they are normally accustomed, thereby possibly degrading them. The soldering of a through-hole interconnection is also susceptible to the intrinsically poorer solderability of Pb-free alloys. The higher surface tension of these solders results in a slower flow of molten alloy between the pin and barrel, thereby potentially requiring a longer soldering time. Also, the poorer solderability can result in reduced wetting of the pad and limited fillet formation, particularly on the opposite side of the circuit board to which the joint is being soldered. Some of these solderability issues can be mitigated by changing flux and/or the use of alternative surface finishes (e.g., Au solderable finishes). Both options can reduce the solder surface tension as well as enhance the base material metallurgical reaction, thereby improving solderability.
QR-Code Drawer In Visual Studio .NET
Using Barcode encoder for ASP.NET Control to generate, create QR Code 2d barcode image in ASP.NET applications.
Printing QR In Visual Studio .NET
Using Barcode printer for .NET Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications.
Design Considerations The design of a through-hole printed circuit board must necessarily consider currently available equipment and assembly practices as well as the potential for advances in future machines and processes. It is important that circuit board designs comply, as much as possible, with recommendations provided by industry standards, such as those of the IPC Association
QR Code Creation In Visual Basic .NET
Using Barcode maker for .NET framework Control to generate, create QR Code image in VS .NET applications.
EAN 128 Printer In None
Using Barcode maker for Software Control to generate, create UCC - 12 image in Software applications.
ASSEMBLY PROCESSES
Code 39 Full ASCII Printer In None
Using Barcode maker for Software Control to generate, create ANSI/AIM Code 39 image in Software applications.
Bar Code Generation In None
Using Barcode creator for Software Control to generate, create bar code image in Software applications.
Connecting Electronics Industries (IPC) and the Joint Electron Device Engineering Council (JEDEC).These recommendations include hole diameters, trace dimensions, and feature spacing. The overriding document is the specific product drawing. Any design deviations from industry standards must be fully considered with regard to how such changes will affect the assembly (process). The following are important design considerations regarding the assembly process for a through-hole printed circuit board products:
Draw Code-128 In None
Using Barcode creation for Software Control to generate, create Code128 image in Software applications.
GS1 - 12 Creator In None
Using Barcode drawer for Software Control to generate, create UPC-A Supplement 2 image in Software applications.
Tooling requirements (holes, edge clearances, etc.) Registration holes (manual alignments or vision systems) Component lead-hole sizes Circuit board dimensions (length, width, and thickness) Size and density of components Pb-free solders
British Royal Mail 4-State Customer Barcode Printer In None
Using Barcode drawer for Software Control to generate, create British Royal Mail 4-State Customer Barcode image in Software applications.
Code 128A Generation In Visual C#
Using Barcode maker for VS .NET Control to generate, create ANSI/AIM Code 128 image in .NET applications.
Three of these factors are discussed below because of their general role on all assembly processes. 40.2.2.1 Component Lead and Circuit Board Hole Sizes. Designing the correct component lead hole diameters begins by referring to the appropriated industry standard(s) (e.g., IPC, Electronic Industry Association [EIA], etc.). Hole tolerances must take into account runout by the drill, etch-back, barrel-plating thicknesses, and the need for a nominal gap of 0.07 to 0.15 mm between the pin and hole to support the capillary flow of the molten solder. In addition, there are added tolerance considerations due to the variation in component lead diameters as well as the positioning accuracy of the equipment. 40.2.2.2 Circuit Board Dimensions (Thickness). The thickness of the circuit board is typically governed by the product design and the number of layers required for signal routing. Thickness has minimal direct impact on the ability of automated machines to accept a circuit board physically. (The same is true of hand soldering.) However, the board thickness affects the soldering process. As thickness increases, it becomes more difficult to supply a sufficient amount of heat to the joint area that allows the molten solder to fill the through-hole completely prior to solidification. Copper layers contained within the laminate, which are used for signal transmission, ground planes, radio frequency (RF) shielding, and power sources as well as layers for thermal management, act as additional heat sinks that can impede the flow of molten solder into the hole. 40.2.2.3 Pb-Free Solders. Design rules and industry standards that have been established are based primarily on experiences with eutectic Sn-Pb solder. Studies are investigating through-hole processes for Pb-free solders. Part insertion, equipment tooling considerations, even paste placement for paste-in-hole technology will be largely unaffected by the change of solder alloy. As noted previously, in spite of the higher liquidus temperature, hand-soldering iron tips and wave-soldering pots will use similar temperatures. The design engineer will have to address the generally poorer solderability of Pb-free alloys, which arises from the higher surface tension of the solder. Flux selection and alternative surface finishes can mitigate this discrepancy to some degree. Other measures may be necessary. For example, the designer may be required to increase the spacing between components in order to avoid solder bridges that cause short circuits during wave and selective soldering. The high Sn content of Pb-free solders results in a greater degree of erosion of the Cu features on the circuit board. This phenomenon is particularly severe at the knee of the through hole when the molten solder is highly agitated such as in a wave-soldering or selective soldering machine. Therefore, it may be necessary to reduce the time that the joint is exposed to the molten solder or to select an alternative Pb-free alloy (Sn-Ag-Ni or Sn-Ag-Ni-Ge) that is less prone to Cu erosion.
Reading Code128 In C#
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Code 39 Creator In Java
Using Barcode generator for Java Control to generate, create Code 39 image in Java applications.
Print EAN13 In Java
Using Barcode creation for Android Control to generate, create GTIN - 13 image in Android applications.
Generate Code 3 Of 9 In Java
Using Barcode printer for Java Control to generate, create Code39 image in Java applications.
Barcode Generator In None
Using Barcode encoder for Font Control to generate, create barcode image in Font applications.
Generating UPC A In .NET
Using Barcode printer for .NET framework Control to generate, create UPC Code image in Visual Studio .NET applications.
Copyright © OnBarcode.com . All rights reserved.