Hi, Ni is around 3.9~5 microns & Au is around 0.07 to 0.10microns. Thanks! U.Nagaraj > How thick is the ENIG? > > Victor, > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M. > Sent: Wednesday, March 16, 2011 10:43 PM > To: [log in to unmask] > Subject: Re: [TN] Query on failure of assembled PCB > > U.Nagaraj > > Chris and Joyce have suggested good possibilities. The intermittent > failures could be brittle solder joint fractures at BGA ball / PCB pad > interface or they could be HOP failures. If the boards really do work > immediately after they are built but are intermittent a couple of weeks > later and they have not been under any mechanical stress then HOP might be > the cause. With HOP you might get enough contact immediately after > soldering to pass test but as the solder surfaces oxidize the contact > resistance could increase causing intermittent failures. > > Regards, > George > George M. Wenger > Senior Principal Reliability / FMA Engineer > Andrew Corporation - Wireless Network Solutions > 40 Technology Drive, Warren, NJ 07059 > (908) 546-4531 Office (732) 309-8964 Mobile > E-mail: [log in to unmask] > > > -----Original Message----- > From: Joyce Koo [mailto:[log in to unmask]] > Sent: Wednesday, March 16, 2011 11:20 PM > To: [log in to unmask]; Wenger, George M. > Subject: Re: [TN] Query on failure of assembled PCB > > One major difference: the exit test is possibly connectivity test: open or > short, not function. The BGA intermittent is a functional test. You > could pass open or short, but still got intermittent fault. HOP may pass > open short test if it got some contact, sounds like either bga cracked, or > hOP,or microvia cracked. All of them will exhibit intermittent but > partially show connectivity when apply pressure. Are those parts > underfilled? > -------------------------- > Sent using BlackBerry > > > ----- Original Message ----- > From: Wenger, George M. [mailto:[log in to unmask]] > Sent: Wednesday, March 16, 2011 10:42 PM > To: [log in to unmask] <[log in to unmask]> > Subject: Re: [TN] Query on failure of assembled PCB > > U.Nagaraj > > What was the PCB surface finish? > > Regards, > George > George M. Wenger > Senior Principal Reliability / FMA Engineer > Andrew Corporation - Wireless Network Solutions > 40 Technology Drive, Warren, NJ 07059 > (908) 546-4531 Office (732) 309-8964 Mobile > E-mail: [log in to unmask] > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Uppina Nagaraj > Sent: Wednesday, March 16, 2011 10:28 PM > To: [log in to unmask] > Subject: [TN] Query on failure of assembled PCB > > Dear All, > > 1. We are manufacturers of PCBs. One of our customer has reported > failure in assembled boards. The main observation is that after > assembly, the assembled units were functioning normally > and had passed all the stipulated electrical tests. These parts > were kept at the assembly house for around over 3-4 months. Later > when the assembled units were scheduled to be integrated into > the system, the assembled units were tested again, but now they > see failure. > > These are the inputs given to us.......... > a) Failures are intermittent in nature. > b) Failures are concentrated in and around the area where > BGA is mounted. > c) Some failures are recovered by applying mechanical stress on > the PCB. > d) Some are recovered by subjecting to reflow. > e) There are no component failures. > > 2. Our customer's assembly process flow is… > a) 100Deg C, 16 hours baking > b) Assembly done within 24 hours after baking > c) Pb-free reflow conducted with a peak temperature of 262Deg C > d) Reflow is done 2 times (once for each side of components) > e) Visual and physical inspection done > f) Cycling done at -20~+70Deg C for 10 cycles. First 9 cycles > are 30minutes per cycle and the last cycle is 1 hour cycle > g) Electrical testing > > 3. We had retrieved a blank PCB from the same batch and conducted > the following trial...... > > a) A standard step of baking prior to assembly (100Deg C, > 16 hours baking) was skipped due to time constraint. > b) 2x reflow done at customer's place using standard profile > used for assembly of this part. > > Electrical Testing (BBT) on bare PCB passed . > > c) 10 cycles of temp. cycling done at customer's place using the > standard cycling profile used for assembled unit. > > Electrical Testing (BBT) on bare PCB passed . > > d) Repeated 2x reflow (2nd time) at customer's place using > standard profile used for assembly of this part. > > Electrical Testing (BBT) on bare PCB passed . > > Based on the above trial, we feel that the failure seen is > not due to PCB failure. > > > 4. This particular PCB is a 8 layer PCB, built using ISOLA FR370HR > material. > ----------------------------------------------------------------- > > > Please share your inputs and thoughts on the failure phenomenon and > how to ascertain if the failure is due to PCB or assembly. > > Thanks in advance! > > Best Regards, > U.Nagaraj > > > > > ______________________________________________________________________ > 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 15.0 > 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 > Please visit IPC web site > http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums 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] > ______________________________________________________________________ > > --------------------------------------------------------------------- > This transmission (including any attachments) may contain confidential > information, privileged material (including material protected by the > solicitor-client or other applicable privileges), or constitute non-public > information. 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