Manon, There are several questions to ask first when establishing retention times for your in-house material controls. 1. Do you properly maintain the environment, where the component will be retained, 70F 5F 50RH? 2. If not, then do you use desiccants and/or Oxidation Arrest Paper in each ESD bag to minimize die moisture absorption and free oxides? 3. When determining retention times, do you base it on the suppliers date code or on your internal retention times. There are some hard to come by components that are sold by Brokers. These parts may have sat at an un-disclosed site with poor retention procedures and with a 1195 (wwyy) date code. 4. Because of oxides, do you establish guidelines for your purchasing department to only buy certain devices with x date code. (i.e, Actives with at least 12 months remaining from the date they were manufacturing, assuming a 24 month retention time. Less than this will require engineering review to see if there where problems in assembly associated to this part. Passives, same way). 5. DO NOT over look PCBs that should follow the same criteria. Evaluate your PCB supplier to insure they retain overage material properly. You never know when you have to go back and request the overage, you'll get a big surprise if the material was not stored properly. 6. Most importantly, what type of Solderpaste and Flux are you using. You allow yourself a wider process window when using OA fluxes versus no-clean. Your process window narrows greatly when using no-cleans. You must pay particular attention to all variables introduced to the assembly set-up. 7. Re-consider baking PCBs and Components! I am against the practice. Proper retention should be established first, versus trying to fix a problem that could only get worst. Think IMC when baking PCBs and Components. Intermetallic Compounds only worsen as temperature and humidity increase, thus the solderability is substantially reduced. Hope this helps, John Gulley Director of Technology and Marketing -----Original Message----- From: Manon Dutil [mailto:[log in to unmask]] Sent: Tuesday, August 24, 1999 6:23 AM To: [log in to unmask] Subject: [TN] old date codes Hi technetters, What is an acceptable date code on a resistor or cap for commercial use, 3 years old or 5 years old ? Manon Dutil Product Manager [log in to unmask] 819-569-9561 tel 819-569-8222 fax ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################