Ryan- Picture http://stevezeva.homestead.com/files/Via_Barrel_2.jpg shows walls that appear to thin considerably wherever the solder mask is not. Is this true, or is it just a trick of the lighting? Wayne Thayer -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dwight Mattix Sent: Tuesday, April 22, 2008 7:08 PM To: [log in to unmask] Subject: Re: [TN] Via barrel cracks gee, was that hole drilled or punched? ;^) At 03:53 PM 4/22/2008, stephengregory5849 wrote: >Hi Ryan! > >Have your pics up! They're at: > >http://stevezeva.homestead.com/files/Via_Barrel.jpg > >http://stevezeva.homestead.com/files/Via_Barrel_2.jpg > >http://stevezeva.homestead.com/files/Via_Barrel_3.jpg > >Steve > >----- Original Message ----- >From: "Ryan Grant" <[log in to unmask]> >To: <[log in to unmask]> >Sent: Tuesday, April 22, 2008 5:08 PM >Subject: Re: [TN] Via barrel cracks > > >Steve, > >I would much appreciate your help with posting these pictures. > >Thanks, >Ryan > >-----Original Message----- >From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell >Sent: Tuesday, April 22, 2008 3:55 PM >To: [log in to unmask] >Subject: Re: [TN] Via barrel cracks > >Would you have an image for posting? > > >=================== >Hi Technetters, > >I have a case of via barrel cracks (E crack) and I would like to know >possible causes. > >The crack is circumferential and occurs at the center of the via. The >hole appears smooth, i.e., no glass nodules or tearout and there is >neither positive nor negative etchback. Of course there is some >wicking, but only about 25um max. The copper thickness is 20um at the >crack and roughly 35-40um at the knee. Although, at the initiation >point of the crack, the copper thickness is only 10um, but that could >be due to stretching and subsequent thinning of the copper. Around the >periphery of the crack are micro-voids in the resin about 30um. It is >triangular shaped, so I can't tell if it is resin recession or a >laminate crack. > >In other words, this via pretty much looks normal, except for one >thing, which might be an artifact of stretching and cracking of the >via. For a span of about 60um on the vertical of the via, at the >crack, there is a roughness that slightly reduces the copper thickness. >The surface of the copper at this point appears both rough and black in color. > >This board has seen two reflows and a hot functional test before final >failure. > >The board shop's initial response was speculation of the OSP soft etch >attacking the copper, but this particular via has solder mask plugging >both sides of the via; therefore chemicals after solder mask cure can >not get into the via. > >In case it matters, at one time, we have had occurrences of this board >shop "re-working" panels after copper plating by placing the panel in a >tank of etchant, then re-running the board through copper plating. >(They do panel plating). > >I'm a little suspicious of their FA, so I would like some independent >opinions and places for me to dig into. > >Thanks for any help, >Ryan > >--------------------------------------------------- >Technet Mail List 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