The status of lead-free standards: lead-free standards are difficult to develop without a consensus.IPC (1) (InterProcess Communication) The exchange of data between one program and another either within the same computer or over a network. It implies a protocol that guarantees a response to a request. has many standards either under development or under revision to support the electronics manufacturing This article presents a typical manufacturing process of an electronic assembly. Component manufacturing Components such as resistors, capacitors and integrated circuits are generally made by specialized contractors. and interconnect manufacturing service (EMS/IMS) industries and has recently released a white paper (IPC-SPVC-WP-006), "Round Robin Testing and Analysis, Lead-Free Alloys--Tin, Silver and Copper." The first standard published specifically to support lead-free assembly was J-STD-006A, Requirements for Electronic Grade Solder Alloys and Fluxed and Non-Fluxed Solid Solders, in May 2001. The standard separated alloys into tables for traditional tin-lead alloys, lead-flee alloys and specialty alloys and also established an impurity im·pu·ri·ty n. pl. im·pu·ri·ties 1. The quality or condition of being impure, especially: a. Contamination or pollution. b. Lack of consistency or homogeneity; adulteration. c. threshold of 0.2% for the maximum lead content in lead-free alloys. The committee is monitoring European discussions that could drive that impurity level as low as 0.1% but has not yet been able to justify that lower level. J-STD-004A, Requirements for Soldering Fluxes, is being reballoted after solving some technical issues. The standard provides the test methods and acceptance criteria for various types of fluxes, including those that need to support the higher lead free processing temperatures. J-STD-002B and J-STD-003A, the solderability test methods and acceptability criteria for component leads and printed circuit boards (PCBs), respectively, were published earlier this year. They both include a significant change in the type of flux used for testing but remain focused on traditional tin-lead finishes. Many comments regarding lead-flee issues were brought up during the development of the last version of I-STD-002C. J-STD-003B has already started to include lead-flee finishes. A test plan will validate some of the needed requirements. The joint IPC/JEDEC group responsible for maintaining J-STD-020B, Moisture/Reflow Sensitivity Classification for Non-Hermetic Solid State Surface-Mount Devices, expects to publish an amendment by the end of the year to modify the high-end test temperatures to 260[degrees]C for some package sizes. Revisions specific to lead free have been started for J-STD-020C and J-STD-033B, Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface-Mount Devices. Moisture-sensitive components require special handling and process control to protect them from cracking and de-lamination during reflow (1) The process of heating and melting the solder that has been screen printed onto a printed circuit board in order to bond chips and other components to the board. Surface mount chips (SMT) use the reflow method. Contrast with wave soldering. See also reflowable text. . The basic platform for assemblies, the PCB PCB: see polychlorinated biphenyl. PCB in full polychlorinated biphenyl Any of a class of highly stable organic compounds prepared by the reaction of chlorine with biphenyl, a two-ring compound. , as built under the standards IPC-6012A and IPC-A-600F, must also withstand the higher processing temperatures encountered with lead-free alloys. The polymeric materials used to fabricate a typical PCB will commonly be exposed to reflow and wave soldering Applying liquid solder to the underside of printed circuit boards in order to bond the chips and discrete components that are placed on top of the board and whose metal leads (pins) extend through the board. temperatures up to 30[degrees]C higher than when lead-based eutectic alloys were the norm. The laminate laminate, n a thin slice of porcelain or plastic fabricated in a dental lab, which is cemented to the front of the teeth to cover gaps, whiten stained teeth, or reshape chipped or broken teeth. materials, as specified in IPC-4101A, IPC-4103 or IPC/JPCA-4104, must tolerate these increases with alternate material specification sheets for higher glass transition temperatures. Solder resists, as addressed in IPC-SM-840C, are also being severely stressed. Delamination delamination /de·lam·i·na·tion/ (de-lam?i-na´shun) separation into layers, as of the blastoderm. de·lam·i·na·tion n. 1. A splitting or separation into layers. 2. , blistering, bow and twist and hole barrel cracking are typical defects prompted by- the increased thermal excursions seen with lead-flee alloys. Additionally, PCB manufacturers are being asked to use appropriate surface finishes to allow the final assembly to be truly lead free. Such alternate surface finishes, which were initiated to more easily facilitate surface mount assembly, are now recognized as lead-free contributors to the final assembly. Finally, the committees developing updates for the soldering standards IPC-A-610D, Acceptability of Electronic Assemblies, and J-STD-001D, Requirements for Soldered Electrical and Electronic Assemblies, have struggled for several years to determine if special acceptance criteria are needed for lead-free assembly. Several industry groups and companies conduct environmental stress screening Environmental stress screening (ESS) refers to the process of exposing a newly manufactured product or component (typically electronic) to stresses such as thermal cycling and vibration in order to force latent defects to manifest themselves by failure during the screening process. and other tests on assemblies manufactured with lead-free processes. Unfortunately, the data have been slow to develop and have hampered development. In this area, IPC's Solder Product Value Council (SPVC SPVC Soft Permanent Virtual Connection SPVC Switched Permanent Virtual Circuit SPVC Security Policy Verification Committee SPVC Soft Permanent Virtual Circuit ) has taken the lead. In its efforts to achieve a worldwide consensus on a standard alloy for the electronics industry, the SPVC Lead Free Technical Committee completed analysis of round robin testing of three tin-silver-copper alloys, in the following percentages respectively: 96.5/ 3.0/ 0.5; 95.5/ 3.8/ 0.7; and 95.5/ 4.0/ 0.5. The results of these tests were published in the report: IPC SPVC-WP-006. "The tests were designed to determine if there are any significant differences in performance between the three lead-flee alloys," said Dr. Greg Munie, Kester Solder, the editor of the white paper. "Based on the statistical analysis of the data gathered from the tests, the difference between alloys is not statistically significant." The next phase of the SPVC's lead-free lest program will be long-term interconnection reliability testing, including thermal shock Thermal shock in mechanical models Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high and thermal cycling of the three lead-flee alloys. The council recently completed the down-select testing of solder manufacturers. Quantity samples of the lead-flee candidates were given to Engent AAT Alpha-1-antitrypsin (AAT) A blood component that breaks down infection-fighting enzymes such as elastase. Mentioned in: Chronic Obstructive Lung Disease , an independent process development, technology commercialization and test laboratory, for evaluation of the paste based on the recommendation of Solectron and Flextronics. The alloys will now be sent to the electronics manufacturing services Electronic manufacturing services (EMS) is term used for companies that design, test, manufacture, distribute and provide return/repair services for electronic component and assemblies for original equipment manufacturers (OEMs). (EMS) companies for assembly, with reliability testing by the U.S. Naval Surface Warfare That portion of maritime warfare in which operations are conducted to destroy or neutralize enemy naval surface forces and merchant vessels. Also called SUW. Center-Crane Division expected to begin this month. The next opportunity to participate in IPC standard development committees is at the co-located APEX and IPC Printed Circuits Expo meetings. Copies of committee minutes, drafts and comments can be downloaded at www.ipc.org/Committeepage.asp. A free copy of the IPC-SPVC-WP-006 report is available at www.ipc.org/leadfree. Assembly Standards Update The following industry consensus standards have been published recently: * IPC Roadmap 2003, National Technology Roadmap The context of product management The existence of product managers in the product software industry indicates that software is becoming more and more commercialized as a standard product. for Electronic Interconnections * IPC-0040, Optoelectronic Assembly and Packaging Technology * IPC-WP/TR-584, IPC White Paper and Technical Report on Halogen-Free Materials Used for PCBs and Assemblies * IPC-SPVC-WP-006, Round Robin Testing and Analysis, Lead Free Alloys--Tin, Silver and Copper * IPC-2221A, Generic Standard on Printed Board Design * IPC-2226, Sectional Design Standard for High Density Interconnect (HDI HDI Human Development Index (UNDP yardstick of human welfare) HDI Help Desk Institute HDI Humpty Dumpty Institute (New York, New York) HDI High Density Interconnect ) Printed Boards * IPC-2501 Definition for Web-Based Exchange of XML XML in full Extensible Markup Language. Markup language developed to be a simplified and more structural version of SGML. It incorporates features of HTML (e.g., hypertext linking), but is designed to overcome some of HTML's limitations. Data * IPC-8413-1, Specification for Process Carriers Used to Handle Optical Fibers in Manufacturing * IPC-9151, Printed Board Process Capability and Relative Reliability (PCQR2) Benchmark Test Standard and Database The following standards are being balloted for industry acceptance: * J-STD-001CS, Addendum Specific to Electronic Hardware Used in Space * J-STD-004A, Requirements for Soldering Fluxes * IPC-HDBK-O05, Soldering Paste Handbook to Support J-STD-O05 Requirements for Soldering Pastes * PC-T-50G, Terms and Definitions for Interconnecting and Packaging Electronic Circuits * IPC-CM-770E, Guidelines for Printed Board Component Mounting * IPC-2251, Design Guidelines for Electronic Packaging Utilizing High Speed Techniques * IPC-2581. Generic Requirements for Printed Board Assembly Products Manufacturing Description Data and Transfer Methodology * IPC-6013A, Qualification and Performance Specification for Flexible Printed Boards * IPC-7095A, Design and Assembly Process Implementation for Ball Grid Arrays (BGAs) * IPC-7351 Generic Requirements for surface-Mount Design and Land Pattern Standard * IPC-7912A, Calculation of DPMO DPMO Defects Per Million Opportunities (Six Sigma) DPMO Deployment Process Modernization Office DPMO Defense Prisoner of War (POW)/Missing Personnel (MP) Office and Manufacturing Indices for Printed Board Assemblies * IPC/SMEMA-9851, Equipment Interface Specification Jack Crawford Jack Crawford may refer to:
|
|
||||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion