I agree. This looks like one of those Chinese PWB fabricators your Uncle Dean warned you about. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ian Hanna Sent: Tuesday, October 25, 2011 11:53 AM To: [log in to unmask] Subject: Re: [TN] How do we determine the Maximum Acceptable Moisture Content (MAMC) for a board? looks like it`s a pcb for a `waterproof mp3`not a waterproof pcb -- in usa they make pcbs for space application - but these also are sub-assemblies and do not fly on their own... From: Inge Hernefjord <[log in to unmask]> To: <[log in to unmask]> Date: 25/10/2011 11:42 AM Subject: Re: [TN] How do we determine the Maximum Acceptable Moisture Content (MAMC) for a board? Sent by: TechNet <[log in to unmask]> Richard, if you want waterproof boards, buy from.....China...I hesitated to use the name..was afraid you would throw up..( chuckle) http://www.alibaba.com/product-gs/423958616/waterproof_mp3_bare_pcb.html If this was true, we would have seen a veritable success. I think it's about misusing the word 'waterproof' , or at least different opinions about what waterproof means. Inge On 25 October 2011 15:08, Stadem, Richard D. <[log in to unmask]> wrote: > Hi, Inge. > Delamination and measling still occur, but much more infrequently. I > believe this is simply due to a much more robust pre-preg quality in the > market. However, delamination does occur more frequently with polyimide > slash types. You just gotta pre-bake or you will eventually have issues. > > And don't try to save money by buying PWBs from China. You will get burned- > big time. I have been getting calls quite frequently in the past year to > look at various lots of PWBs manufactured in China with all kinds of quality > issues. Problem is, some of the more reliable PWB companies have attempted > to form offshore partnerships in an effort to reduce costs and become more > competitive, but did not do their homework when selecting an offshore > supplier, and did not place a company rep at the site. PWB suppliers never > voluntarily reveal to their customer that they are buying offshore. > Invariably, poor workmanship and/or poor materials slip through and are not > detected until during manufacturing or after. > > I am not saying all Chinese or all offshore PWB fabricators are of poor > quality, I am simply stating that there are a lot of companies out there > that make crap, and you have to be very careful of your PWB's pedigree. > > Waterproof PWBs? I would need a lot of data to believe that claim. > > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord > Sent: Monday, October 24, 2011 4:43 PM > To: [log in to unmask] > Subject: Re: [TN] How do we determine the Maximum Acceptable Moisture > Content (MAMC) for a board? > > I forgot a question I had to you all: how frequent is delamination (caused > by water vapour) nowadays. It's a long time since I heard of serious > problems. Perhaps one or two cases with a single board or two, but in a > mass > production that would not be count as an issue. > > IF delamination is much lower today, what is then the reason, and is the > improvement global or significant for a limited number of suppliers? And > also this (perhaps stupid) question: Has anyone seen boards marked > 'waterproof' . I read somewhere about such boards and my guess is that the > boards were coated. But waterproof? Hmmm.. > > Inge > > > > ------------------------- > > Hi all, > > I think many industries make their decisions based on empirical data and > own > experience. > My own opinion is, and few will agree, that the whole idea of a > standardized > humidity level is disputable, because the humdity is not constant from x to > y, nor from Z 1 to Z2. Furthermore, the humidity is varying with time and > temperature, sometimes within seconds. Moreover we have the board's surface > condition, percentage of copper, access to mobile ions and a lot more. > Which was pointed at by Dave > Hillman. > > It all starts with the ability of water condensation on the surface > followed > by the rate of penetration of gas and water vapor into the board structure. > The water content on the very surface is not included in the discussion, > because it's not relevant for the soldering process. It's the inside > accumulation of water that is the input for the standard. > > To get knowledge of the water content, you 'simply' perform a weight > control > of the board, starting with boards that have been in a humid atmosphere, > e.g. from stock or from a humidity test. Then you bake out the water and do > a weight control again. The diff is the water content. > > Here starts the questions and the aquestionings. The bakeout is the first > problem, because you don't know how effective this process is. The actual > standard says, that we hope that at least 90 % of the water will find its > way out and disappear. But who knows. It's a question of the leakage of > water molecules through millions of micron sized pores in the epoxy > structure. And the one who has learned about the percolation of molecules > know that this is very complicated a thing. furthermore we have the > diffusion of water vapor through the same micron sized 'orifices', also a > far from easy to understand process. Depending on the charachter of these > labyrints, we have a variation of water escaping rate. Compare with the > water on the surface. Water molecules can stick to the outermost crystals > as > billions of droplets, or cover the entire surface as one and a single one > water layer. The evaporation of water can vary a lot. Imagine what happens > when you clean your glasses. You breathe on them, water condensates in less > than seconds, and you have some more seconds to rapidly wipe the glass > with > a tissue. If you are late, you'll see how the water leaves rapidly. If you > do the same on a sheet of plastic, the water film can stay for minutes. > Likewise, the transportation of water from the inner regions of a PWB can > vary a lot, depending on what base material is used, number of copper > layers, reinforcement materials etc. Some water can be so bound to the > structure by the capillary force, that it's nearly impossible to get rid of > it. There is a lot more to say, but I stop here (to the relief of many). > > > > Now, what about the small activity with small resources for analysis and > advanced incoming inspection? They have no idea about the water content > Perhaps a passus in the purchase handling. Yes, it's one way. Another way > is to look back and see how their products behave in a long term. A further > way is to avoid long storage before soldering. Perhaps they have someone > who > knows a little about nature's behaviour, i.e. the ambition to get a state > of > equilibrium. If you have 50% RH in a room and put a PWB on the desk, > humidity will increase in the board until there is an equality on inside > vs. > outside. How fast? It depends on how many PTHs you have, o how many vias > and how the edges of the board are humidity inlets. One way to get an > idea > is to create buried capacitors in the PWB, expose the board to humidity and > measure the capacitance change vs. time. You'd be surprised how fast > humitity gets on inside of a board. Halfways to quilibrium can occur from > 10 > hs to 100 hs. So, a board that has been lying for weeks in a humid store, > may hold such a lot of water, that you are far from 0.1 wt% after bakeout. > You may have 0.5 wt%, 1 wt% or more. Without knowing. Tests on a variety of > boards gives that equilibrium is obtain after as short a time as a few > hours > to as long long a time as one year! > > > So, that's why I wonder with what confidence we follow the 0.2 % rule. With > all respect to those who work with the IPC norms. Am not against, nor pro. > > End of old man's gagging > > Inge > > PS, If you don't have Chris Hunt's splendid report (he is a TN member), I > got it. Title: Moisture Measurements in PCBs and Impact of Design on > Desorption Behaviour. Not a paper with pages and pages with maths that you > don't understand, but a language and with illustrations that explains > complicated things so even a gaga like me can melt. > > Inge > > > - Show quoted text - > On 23 October 2011 00:03, David D. Hillman <[log in to unmask]> > wrote: > > Hi Rigo - yes, Doug would give you the standard " it depends" response > because as you detailed,there are too many inputs to your question. The > reason that the IPC-1601 committee only put suggested values in the > standard is that clear, data determined, industry wide applicable values > for requirements could not be established. The committee is continuing to > investigate, research and gather published data on that task. Establishing > industry wide applicable values is a difficult task as the committee does > not want to impose any requirements that are not based on data and are not > value added for the industry. > > Dave Hillman > Rockwell Collins > [log in to unmask] > > > > > > "Garcia, Rigo (GSFC-300.0)[MANTECH SRS TECHNOLOGIES]" > > <[log in to unmask]> > Sent by: TechNet <[log in to unmask]> > 10/21/2011 01:31 PM > Please respond to > TechNet E-Mail Forum <[log in to unmask]>; Please respond to > > "Garcia, Rigo (GSFC-300.0)[MANTECH SRS TECHNOLOGIES]" > > <[log in to unmask]> > > > To > <[log in to unmask]> > cc > > Subject > [TN] How do we determine the Maximum Acceptable Moisture Content (MAMC) > > for a board? > > > > > > > Hi everybody, > > Does anybody know how do we determine the Maximum Acceptable Moisture > Content (MAMC) for a board? > > I understand that IPC-1601 states that for most designs a MAMC between > 0.1% and 0.5% of moisture weight to resin weight is adequate. However, it > does not describe the basis to establish the range. I can think of many > variables that can affect this number like minimum pitch, voltage across, > component clearance, whether the board gets conformal coating or not, etc. > I would like to know if anybody knows of a safe method to determine the > MAMC for a given board. > > Paul... I can already see your "it depends" coming... :)! > > Thanks for the help! > > Rigo Garcia > > Sr. Quality Assurance Engineer > Workmanship Standards, Code 300 > NASA, Goddard Space Flight Center > Greenbelt, MD 20771 > Phone. (301) 286-6129 > Fax. (301) 286-6576 > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > For additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- > > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > For additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- > > On 23 October 2011 07:31, Reuven Rokah <[log in to unmask]> wrote: > > > Hi Bev, > > You can check the graph for vapor pressure (psi) vs temp. of Werner's > white > > paper for PCBs. > > I believe this graph is based on experimental measurements. I assume that > > there are more factors (than the PV formula) influencing the vapor > pressure > > inside the PCB layers during reflow. > > Reuven > > > > On Sun, Oct 23, 2011 at 3:48 PM, Bev Christian > > <[log in to unmask]>wrote: > > > > > Reuven, > > > I respectfully disagree. Even if we assume a peak reflow temperature > for > > > eutectic tin/lead solder of only 205C and a high 260C for SAC305 the > > vapor > > > pressure due to trapped air and/or moisture is still not going to > double. > > > > > > P1V1=n1RT1 > > > P2V2=n2RT2 > > > > > > R = a constant > > > n1 = n2 > > > V1 = V2 > > > > > > Leaving > > > P1/P2 = T1/T2 > > > > > > 300/P2 = (205+273)/260+273) > > > > > > P2 = 300*533/478 > > > > > > P2 = 334 That is only an 11% increase. > > > > > > Not sure where the 300 came from in the first place, but no matter what > > > number you start with, it does not double. > > > > > > Bev > > > -----Original Message----- > > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven Rokah > > > Sent: Sunday, October 23, 2011 5:03 AM > > > To: [log in to unmask] > > > Subject: Re: [TN] How do we determine the Maximum Acceptable Moisture > > > Content (MAMC) for a board? > > > > > > Hi Garcia, > > > You didn't mention the most important variable: the process technology, > > the > > > vapor pressure (300 to 650 psi) of Lead free is more than double than > > > Leaded > > > process at the reflow peak temp. > > > the MAMC for Leaded process should be 0.20% and for Lead Free 0.17%. > > (ref. > > > Werner Engelmaier PCB FAB Notes). > > > Reuven > > > > > > On Fri, Oct 21, 2011 at 8:31 PM, Garcia, Rigo (GSFC-300.0)[MANTECH SRS > > > TECHNOLOGIES] <[log in to unmask]> wrote: > > > > > > > Hi everybody, > > > > > > > > Does anybody know how do we determine the Maximum Acceptable Moisture > > > > Content (MAMC) for a board? > > > > > > > > I understand that IPC-1601 states that for most designs a MAMC > between > > > 0.1% > > > > and 0.5% of moisture weight to resin weight is adequate. However, it > > does > > > > not describe the basis to establish the range. I can think of many > > > variables > > > > that can affect this number like minimum pitch, voltage across, > > component > > > > clearance, whether the board gets conformal coating or not, etc. I > > would > > > > like to know if anybody knows of a safe method to determine the MAMC > > for > > > a > > > > given board. > > > > > > > > Paul... I can already see your "it depends" coming... :)! > > > > > > > > Thanks for the help! > > > > > > > > Rigo Garcia > > > > > > > > Sr. Quality Assurance Engineer > > > > Workmanship Standards, Code 300 > > > > NASA, Goddard Space Flight Center > > > > Greenbelt, MD 20771 > > > > Phone. (301) 286-6129 > > > > Fax. (301) 286-6576 > > > > > > > > > > > > > ______________________________________________________________________ > > > > This email has been scanned by the MessageLabs Email Security System. > > > > For more information please contact helpdesk at x2960 or > > > [log in to unmask] > > > > > ______________________________________________________________________ > > > > > > > > --------------------------------------------------- > > > > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > > > > To unsubscribe, send a message to [log in to unmask] with following > text > > > in > > > > the BODY (NOT the subject field): SIGNOFF Technet > > > > To temporarily halt or (re-start) delivery of Technet send e-mail to > > > > [log in to unmask]: SET Technet NOMAIL or (MAIL) > > > > To receive ONE mailing per day of all the posts: send e-mail to > > > > [log in to unmask]: SET Technet Digest > > > > Search the archives of previous posts at: > > > http://listserv.ipc.org/archives > > > > For additional information, or contact Keach Sasamori at > > [log in to unmask] > > > > 847-615-7100 ext.2815 > > > > ----------------------------------------------------- > > > > > > > > > > > > > > > > -- > > > > > > Best Regards, > > > > > > *Reuven Rokah* > > > > > > Mobile: 972-52-60-120-18 > > > Tele-fax: 97239360688 > > > <http://www.rokah-technologies.com/>[log in to unmask] > > > [log in to unmask] > > > www.rokah-technologies.com > > > > > > ** > > > This e-mail message is intended for the recipient only and contains > > > information which is CONFIDENTIAL and which may be proprietary of Rokah > > > Technologies. If you have received this transmission in error, please > > > inform > > > me by e-mail, phone or fax, and then please delete all of the original > > > files > > > and all other copies exist. > > > > > > > > > ______________________________________________________________________ > > > This email has been scanned by the MessageLabs Email Security System. > > > For more information please contact helpdesk at x2960 or > > [log in to unmask] > > > ______________________________________________________________________ > > > > > > --------------------------------------------------- > > > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > > > To unsubscribe, send a message to [log in to unmask] with following text > > in > > > the BODY (NOT the subject field): SIGNOFF Technet > > > To temporarily halt or (re-start) delivery of Technet send e-mail to > > > [log in to unmask]: SET Technet NOMAIL or (MAIL) > > > To receive ONE mailing per day of all the posts: send e-mail to > > > [log in to unmask]: SET Technet Digest > > > Search the archives of previous posts at: > > http://listserv.ipc.org/archives > > > For additional information, or contact Keach Sasamori at > [log in to unmask] > > > 847-615-7100 ext.2815 > > > ----------------------------------------------------- > > > > > > > > > > > > -- > > > > Best Regards, > > > > *Reuven Rokah* > > > > Mobile: 972-52-60-120-18 > > Tele-fax: 97239360688 > > <http://www.rokah-technologies.com/>[log in to unmask] > > [log in to unmask] > > www.rokah-technologies.com > > > > ** > > This e-mail message is intended for the recipient only and contains > > information which is CONFIDENTIAL and which may be proprietary of Rokah > > Technologies. If you have received this transmission in error, please > > inform > > me by e-mail, phone or fax, and then please delete all of the original > > files > > and all other copies exist. > > > > > > ______________________________________________________________________ > > This email has been scanned by the MessageLabs Email Security System. > > For more information please contact helpdesk at x2960 or > [log in to unmask] > > ______________________________________________________________________ > > > > --------------------------------------------------- > > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > > To unsubscribe, send a message to [log in to unmask] with following text > in > > the BODY (NOT the subject field): SIGNOFF Technet > > To temporarily halt or (re-start) delivery of Technet send e-mail to > > [log in to unmask]: SET Technet NOMAIL or (MAIL) > > To receive ONE mailing per day of all the posts: send e-mail to > > [log in to unmask]: SET Technet Digest > > Search the archives of previous posts at: > http://listserv.ipc.org/archives > > For additional information, or contact Keach Sasamori at [log in to unmask] > > 847-615-7100 ext.2815 > > ----------------------------------------------------- > > > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > For additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- > ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------