agree. it could be improper de-smear as well that could cause poor
wetting. If I were OP,I'll start looking for alternative board house
- 4 layer capability should not be that hard to find in TX. IMHO.
jk
On May 9, 2019, at 5:51 AM, Gerry Gagnon wrote:
> Dwight,
>
> Sorry to hijack your response but I had an elderly moment with this
> keyboard on my phone. 😬😬
>
> My first vote is for poor electroless copper coverage. Could be due
> to air bubbles as electroless does use air. Could also be that
> electroless did not “take” due to poor hole clean and pre-
> electroless hole prep.
>
> No electroless, no electroplating.
>
> Another possibility could be HASL which typically uses HBR as a
> flux or pre-flux prep before the solder application. A few extra
> “shots” through HASL process in order to meet solder thickness
> specs could take out thin-to-no copper.
>
> Thanks and Best regards,
>
> Gerry Gagnon
>
>> On May 8, 2019, at 8:39 PM, Dwight Mattix
>> <[log in to unmask]> wrote:
>>
>> <<The manager says "in the pattern
>> plating tank we have no air. >>
>>
>> /facepalm/
>>
>> I'd have asked him "Do you even lift, errr... plate bro?"
>>
>> Dielectric reacts with plating solution and outgasses. So it's not
>> just a matter of wetting the hole. It's a matter of continuously
>> egressing the gas out of the hole.
>>
>> -----Original Message-----
>> From: TechNet <[log in to unmask]> On Behalf Of Robert Kondner
>> Sent: Wednesday, May 8, 2019 5:12 PM
>> To: [log in to unmask]
>> Subject: [EXT] Re: [TN] Bad Vias - Need help determining the root
>> cause
>>
>> Be sure to let us know what you find. Enquiring Minds want to Know.
>>
>> Thanks,
>> Bob K.
>>
>> -----Original Message-----
>> From: TechNet <[log in to unmask]> On Behalf Of Christopher Brand
>> Sent: Wednesday, May 8, 2019 7:45 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Bad Vias - Need help determining the root cause
>>
>> Hi Richard, Victor, Dennis and All,
>>
>> I greatly appreciate all the help and insight so far on this.
>>
>> The boards don't have any selective or wave soldering, just reflow
>> and hand soldering for a few thru-hole connectors. The boards are
>> HASL. The sample of boards in the photos are mostly 2 sided and
>> one that is 4 layer. These are small production runs usually.
>>
>> In talking with the manager of the board shop, he's sending out
>> samples of their plating tanks to be tested. I've asked him the
>> following questions from input from you folks:
>>
>> * Air bubbles in the plating tank? The manager says "in the pattern
>> plating tank we have no air. solution was eductors moving the
>> solution and swishing of the panels during plating".
>> * Is their plating current is sufficient? The manager says that they
>> are "plating the top of the cu scale to be sure". Is there a
>> method
>> I can tell them to check if their plating current is good?
>> * They do have a copy of IPC-9121
>>
>> I am going to look into sending out to get some of the vias
>> microsectioned to get a better look inside them.
>>
>> Is there anything else I need/should be asking them to check?
>>
>> Thank you kindly,
>>
>> Christopher Brand
>> Ludlum Measurements, Inc.
>> 501 Oak Street
>> Sweetwater, TX 79556 USA
>> (325) 235-5494 Phone, ext:3318
>>
>>> On 5/8/2019 9:07 AM, Stadem, Richard D wrote:
>>> Christopher,
>>> Having a little more time to look at your pictures this morning,
>>> I noticed several pics such as 006 and 010 that show gross open
>>> breakout between the via PAD (foil copper) and via BARREL (plated-
>>> up copper). There is no evidence of selective or wave soldering
>>> on many of these. The breakout is on the TOP side with no
>>> evidence of additional solder applied, therefore my only
>>> conclusion is that the root cause was purely the plating issues
>>> from the fabricator.
>>> dean
>>>
>>> -----Original Message-----
>>> From: TechNet <[log in to unmask]> On Behalf Of Dennis Fritz
>>> Sent: Monday, May 6, 2019 2:38 PM
>>> To: [log in to unmask]
>>> Subject: Re: [TN] Bad Vias - Need help determining the root cause
>>>
>>> Do you have a copy of IPC 9121 - troubleshooting guide? That has
>>> a large number of pictures of failed via holes, causes, and
>>> remedies.
>>>
>>>> On Mon, May 6, 2019 at 3:12 PM Christopher Brand
>>>> <[log in to unmask]> wrote:
>>>>
>>>> Greetings,
>>>>
>>>> I'm having issues with open vias on a couple of runs of PCBAs
>>>> and was
>>>> hoping to get some help on finding a root cause or at least
>>>> point me
>>>> in the right direction. I know that there is lots of knowledge and
>>>> experience on this forum and I'm hoping someone will say they've
>>>> seen
>>>> this before, as my knowledge is rather limited on this.
>>>>
>>>> Here are a few photos of the vias in question.
>>>>
>>>> https://ludlums.com/software/BadVias/badvia_01.jpg
>>>> https://ludlums.com/software/BadVias/badvia_02.jpg
>>>> https://ludlums.com/software/BadVias/badvia_03.jpg
>>>> https://ludlums.com/software/BadVias/badvia_04.jpg
>>>> https://ludlums.com/software/BadVias/badvia_05.jpg
>>>> https://ludlums.com/software/BadVias/badvia_06.jpg
>>>> https://ludlums.com/software/BadVias/badvia_07.jpg
>>>> https://ludlums.com/software/BadVias/badvia_08.jpg
>>>> https://ludlums.com/software/BadVias/badvia_09.jpg
>>>> https://ludlums.com/software/BadVias/badvia_10.jpg
>>>> https://ludlums.com/software/BadVias/badvia_11.jpg
>>>> https://ludlums.com/software/BadVias/badvia_12.jpg
>>>>
>>>> On some, the via barrel has a void in the center and on others the
>>>> edge of the barrel doesn't connect with the pad, Both issues are
>>>> causing an open via as you can see in the photos.
>>>>
>>>> I know that the board shop recently changed up their plating tanks
>>>> (new chemical and power supply). Could these bad vias be the
>>>> result
>>>> of insufficient current in the plating process or some other
>>>> process?
>>>>
>>>> I'd be much appreciative of any insight this forum could give.
>>>>
>>>> --
>>>> Thank you kindly,
>>>>
>>>> Christopher Brand
>>>> Ludlum Measurements, Inc.
>>>> 501 Oak Street
>>>> Sweetwater, TX 79556 USA
>>>> (325) 235-5494 Phone, ext:3318
>>>>
>>>
>>> --
>>> Denny Fritz
>>> Consultant
>>> 812 584 2687
|
