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

Generation QR Code ISO/IEC18004 in Software PRINTED CIRCUITS HANDBOOK

PRINTED CIRCUITS HANDBOOK
Reading QR Code ISO/IEC18004 In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
QR Creator In None
Using Barcode maker for Software Control to generate, create QR Code image in Software applications.
ORGANIC SOLDERABILITY PRESERVATIVE (OSP)
Denso QR Bar Code Scanner In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
Quick Response Code Drawer In C#.NET
Using Barcode maker for VS .NET Control to generate, create QR Code image in .NET framework applications.
As the name connotes, OSPs are very thin organic coatings used to preserve the solderability of PCB surface copper. Differing from alternative surface finishes that attempt to serve other PCB functions, OSPs are generally limited to solderability preservation only. The most widely used OSPs, benzimidazoles and phenylimidazoles, have evolved from earlier antitarnish coatings and can endure multiple soldering operations. OSP is the least expensive and simplest of all major surface finish options, so it enjoys wide use throughout the world. OSP use is limited, however, due to poor contact functionality for ICT and electrical test. Also, it suffers from degradation after multiple thermal operations, so solder wetting on Pb-free assemblies can pose problems.
Painting Quick Response Code In Visual Studio .NET
Using Barcode generator for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
Make QR-Code In .NET
Using Barcode printer for .NET framework Control to generate, create Quick Response Code image in .NET applications.
Chemistry OSP is the simplest chemical process of the surface finishes, but the chemical itself is actually quite complicated. In brief, a large organic molecule (see Fig. 32.3) is dissolved into a solution of water and organic acid. The circuit board is exposed to the solution, and the OSP molecule attaches to the PCB s exposed copper surfaces. A chemical bond is formed between copper and a nitrogen group in the OSP. Copper is present in the chemical bath, so multiple layers of an OSP-copper complex can deposit on the surface, reaching a thickness of 0.10 to 0.60 mm.
QR Code 2d Barcode Maker In VB.NET
Using Barcode printer for VS .NET Control to generate, create QR-Code image in VS .NET applications.
Make EAN / UCC - 14 In None
Using Barcode printer for Software Control to generate, create UCC-128 image in Software applications.
N R2
Printing Barcode In None
Using Barcode printer for Software Control to generate, create bar code image in Software applications.
Create EAN-13 Supplement 5 In None
Using Barcode printer for Software Control to generate, create European Article Number 13 image in Software applications.
N N N H Imidazole
Barcode Generation In None
Using Barcode creator for Software Control to generate, create barcode image in Software applications.
Code 3 Of 9 Drawer In None
Using Barcode generation for Software Control to generate, create Code-39 image in Software applications.
FIGURE 32.3
Paint DUN - 14 In None
Using Barcode generator for Software Control to generate, create GTIN - 14 image in Software applications.
Paint GTIN - 13 In Objective-C
Using Barcode drawer for iPhone Control to generate, create EAN-13 Supplement 5 image in iPhone applications.
NH N
Making EAN128 In None
Using Barcode maker for Online Control to generate, create UCC-128 image in Online applications.
Generate UPC-A Supplement 2 In None
Using Barcode creator for Office Word Control to generate, create GS1 - 12 image in Office Word applications.
Benzotriazole
Data Matrix ECC200 Encoder In VB.NET
Using Barcode generator for Visual Studio .NET Control to generate, create Data Matrix ECC200 image in .NET framework applications.
Bar Code Printer In Java
Using Barcode drawer for Android Control to generate, create bar code image in Android applications.
OSP molecule types.
Reading GTIN - 12 In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Read ANSI/AIM Code 128 In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Substituted benzimidazole R is proprietary substitution group
Another generation of OSPs is designed to survive exposure to multiple high-temperature soldering operations. These chemicals are normally based on benzimidazole with attached functional groups to add molecular weight and thermal resistance. Substituted phenylimidazole and OSP systems with metal codeposits have been used as well. The intent of the new generation of OSP is to withstand Pb-free soldering temperatures. These high-temperature OSP coatings, made for use with Pb-free alloys and the associated fluxes, can be deposited at higher thicknesses and may be measured as high as 1.0 micron.
Fabrication Process Table 32.5 show the fabrication process for OSP, including chemicals and dwell times. Almost universally, OSP is applied in conveyorized equipment. The cleaner and microetch may use flood or spray application, but OSP is applied using flood. Because the OSP process is very mild to the PCB materials, rinsing is very important to ensure that contamination from all prior fabrication steps is removed. Often, OSP is applied when the PCB is in part form after the PCB has been electrical tested, routed, and depanelized. This is to preserve the
PRINTED CIRCUIT BOARD SURFACE FINISHES
TABLE 32.5 Process Flow for Organic Solderability Preservative Process Cleaner Microetch Pre-Dip OSP Chemicals Aqueous solvents, detergents, and emulsifiers. Acid can help undercut residues and remove thick copper oxides. 1 2 m of Cu is oxidized to Cu++ and dissolved. Normally, the predip employs ingredients of the OSP bath without the OSP chemical itself. OSP, acetic or formic acid, source of copper or other metals. Time (min/) 1 4
0.5 0.5 1.0
fragile OSP surface, which is sensitive to handling, contamination, and fingerprints. The OSP parts should stabilize at room temperature and controlled humidity before packaging, as any moisture in the package can turn the OSP surface black. OSP thickness is normally determined by indirect sampling. No method exists for determining the OSP thickness during production on the actual PCB. Instead, a sample coupon is processed along with the production parts.The coupon is immersed in an acid/solvent solution that dissolves the coating. The solution is transferred to a UV-VIS cell, where the absorbance of light allows the estimation of the thickness of OSP on the coupon. That measurement is used as a quality control for the production boards. The lack of a true thickness measurement control is a key issue to OEMs that require control metrics. If the OSP coating is too thin, the PCBs will have inadequate protection. If the coating is too thick, there is a possibility for poor solder wetting and poor PTH filling. The OSP coating is invisible to the eye, so there is no way to inspect for unprotected copper if the OSP coating was not applied correctly.
Advantages and Disadvantages Table 32.6 compares the advantages and disadvantages of using OSP as a surface finish.
TABLE 32.6 Comparing the Advantages and Disadvantages of OSP OSP Advantages Flat; fine-pitch assembly Least expensive finish Simple process Widely available Cu/Sn solderjoint No Pb Reworkable High productivity at fabrication OSP disadvantages No direct thickness measurement High surface contact resistance Poor PTH soldering Shorter shelf-life Exposed copper on final assembly Not inspectable before assembly Degrades with multiple reflow Handling-sensitive Problems with paste misprint cleaning
Failure Modes The OSP process is simple, so few failure modes exist at fabrication due to chemical stability. Aggressive microetch and poor rinsing can result in attack at the junction of solder mask and exposed PCB metal, especially if nickel-gold has been selectively deposited on edge fingers. Galvanic attack at this interface can cause electrical opens. PCBs using selective nickel-gold can also suffer from deposition of OSP on the gold surface. OSP on copper prevents good
Copyright © OnBarcode.com . All rights reserved.