We search for industry news, so you don't need to. HOME EXPERTS NEWS PAPERS PRESS SEARCH SUBSCRIBE ARCHIVE/TRANSLATE Ask the Experts Panel   Questions Index  ■  Submit a Question  ■  Experts Panel  ■  Join the Panel Mark McMeen VP Engineering Services STI Electronics Inc. Mark T. McMeen is STI Electronics Inc.ʼs Vice President of Engineering Services. He oversees the daily operations of the Engineering Services division of STI. He has over 18 years experience in the manufacturing and engineering of PCBs. Mark McMeen has submitted responses to the following questions. Baking Concerns for Stacked Trays of Components We also bake parts out on a regular basis and I assume you are using standard trays which stack and ... Selective Solder System Purchased At Auction Very good question and you have two choices. Buy a second pot for your machine and make it the Lead ... Concerns With Silver Finish Component Leads Really good question - would have liked a little more information but here is an answer I think addresses why you ... Cleanliness Testing I would recommend using an ion chromatography approach to quantify and qualify the amount of ionic contamination present on the ... Dendritic Growth and Contamination at BGA Sites My suggestion is to remove BGA's and clean the boards in a water wash or solvent cleaner after removing the ... Type 4 Solder Ball Use There is no downside to using type 4 paste. You will get a larger metal content due to metal load ... Mixed Technology - Which First We always smt first and then thru hole for repeatability due to thru hole component size issues. SMT components are ... Organic Flux Residue Concerns The answer lies in what type of organic residue is left. My recommendation is to have an ion chromtagraghy analysis ... SMT Component Lead Oxidation The answer is to retin the leads to remove the oxidation and prepare the leads for the SMT operation. A wetting ... Delamination dilemma Please review your bake out time and temperature for your bare boards. Rule of thumb is 105C for 6 hours ... Cutting inner layer circuits Please insure all technicians are trained to the 7711 / 7721 rework standard and have proper certification training. The drills ... Reworked BGA component bridging at the corners The short answers is bga's can be reballed and replaced. We do it all the time for clients and we ... Technology to Measure Oxidation Levels The answer is the use of a Wetting Balance Tester to determine the wet ability of the surface mount leads. ... Nickel Barrier Thickness Requirement The rule of thumb is no lower than 100 microinches and the nominal should be 150 microinches. It is ok ... Wave solder process issue Dewetted / unwetted solder is a sign that the solder alloy does not like the surface of the pads in ... BGA Replacement limit There is no hard industry rule but the rule of thumb for most companies is no more than 5 to ... Pre-Bake Standard for Rework The rule of thumb used by us in our rework area for FR4 and Kapton based materials is 105 degrees ... Procedure for Baking Flexible Circuits This is a very good question and most people have different views but I am an old flexible printed circuit ... Lead frame contamination The answer is really a 2 part solution to this request. First, Lead frames need to be free from all ... Opens on BGA solder joints after reflow soldering The answer to the question is the development of an analytical test protocol. The substance needs to be identified – ... About Us | Advertising | Archives | Ask the Experts | Calendar | Contact Us | Custom Email Broadcast | Disclaimer | Exclusives | News | Press Releases | Press Release Submit | Privacy Policy | Search | Subscription | Technical Papers | Technical Paper Submit | Viewpoint Circuitnet Media, LLC 6 Liberty Square #2040, Boston MA 02109 USA Jeff Ferry, Publisher | Ken Cavallaro, Editor/Business Manager Copyright © Circuitnet Media LLC. All rights reserved. A Circuitnet Media Publication