First of all, you need to clearly define whether you have resin smear causing what appears to be post-separation, or if you have true post-separation. You need to carefully prepare a microsection and LIGHTLY microetch the section using a solution of 10 mls ammonium hydroxide, 10 mls of DI/distilled water, and 10 DROPS of 35% hydrogen peroxide (or 10 mls of 3% hydrogen peroxide from the pharmacy). If you have polished the section correctly and do not overetch the section, you should be able to clearly see your electroless copper deposit (assuming that you are using electroless copper and not a DM system). If there is smeared resin, you should be able to see it using a backfield setting on your microscope; if there is separation rather that smear you should be able to see if it is between the electroless copper and the post (innerlayer) or between the plated copper and the electroless. 1. In the case of resin smear: consult with vendors and verify that the desmear chemistry and cycle is working properly. When using permanganate desmear, solvent/sweller life is a very important part of making this process work properly, as is by-product/residue levels in the permanganate bath itself. I would recommend requesting SEM work to verify proper resin attack and topography. 2. In the case of electroless to post separation: in a somewhat decreasing order of likelihood: a) excessive catalyst concentration or dwell time; b) excessive rinse time following microetch, catalyst, or accelerator; c) poor microetch quality or quantity (I would recommend 30-70 microinches weight loss, depending on the weight of the innerlayer copper foil - the heavier the innerlayer foil, the more the weight loss should be); d) incorrect conditioner (some conditioners use polyelectrolytes that are very large and rinse very poorly, leaving deposits on the innerconnect; and e) permanganate residues (only in the case of using a persulfate microetch). 3) When the plated copper separates from the electroless deposit, if there is a severe photoresist developing problem you should see problems with peeling circuits, etc. Generally this problem is caused by poor pre-electrolytic copper plating cleaning - I have had much better success when using a two-step cleaning process; an acid cleaner (non-hydrochloric acid-based) followed by a light microetch (generally a non-proprietary peroxide/sulfuric at 5-8 microinches). There are other causes of this problem, but they are generally rare. I would expect a wide variety of quality within the same date code, due to process variables in drilling, desmear, and pre-plate cleaning. You can expect to always have some resin smear when drilling FR-4 type materials; if you have resin smear as well as nailheading, glass pulls or other roughness in the hole, etc. then you need to look at your drilling process. In my experience, even the very worst resin smear can be cleaned up with only a few minutes in the permanganate - the additional dwell time is there to provide either etchback or topography. One last thing - if you're that worried about your suppliers cheating you, you need to seriously re-evaluate both yourself and your suppliers. As a chemical field service person for eight years, I can assure you that most people are out only to do their job, and not screw everyone in sight - the supplier can't be successful if the customer is not successful first - otherwise how can the customer purchase the suppliers stuff? It is of course possible that you need some new suppliers, as there are some jeks around, but you need to realize that some of the fabricators aren't necessarily straight shooters, either. regards, Fred J. >>> Ken Patel <[log in to unmask]> 10/14/97 06:14pm >>> Fab Gurus, I have seen post separation on my assembled board and also resin smear. I have few question in that regards. (1)Can any one provide me the possible causes for the defects? (2)How much is a variation for this kind of defects within a same date code? (3)What about the reliability of my assembled boards? Also being new in fab business, can any one suggest books that talk about the fab processes and also that talk about possible causes. I am of the opinion that I should know more about the fab than the fab supplier so that no one can try to cheat you!!! I would really appreciate anyone's help. Regards, Ken Patel ______________________________________________________ Ken Patel Phone: (408) 490-6804 575 Cottonwood Dr. Fax: (408) 490-6859 Milpitas, CA 95035 Beeper: (888) 769-1808 ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ############################################################## ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################