I do appreciate the acknowlegement of a great role PCB design plays for
the output of overall solder quality. To reinforce what is stated here;
For last 2 decades, it has been "make it believe" dreams to produce 4 /
6 sigma level quality when PCB designs only meet 2 / 3 sigma level
quality. If a design does not meet IPC Class 3, the assembly is not
expected to meet the Class 3 quality. What usually ends up doing is that
assembly processes are bastardized in the hope of meeting a desirable
sigma level or meeting on-time delivery.
On top of this, thousands of parts, materials, equipment and processes
come into play to produce a desirable sigma level quality that is
expected. From my personal thoughts & experience, 50% of PCB assembly
defects originate from design aspect, 30% from parts & process materials
and 20% from assembly processes. One key point is that understanding
manufacturing capabilities and implementing designs to meet the
manufacturing capabilities will go a long way to improve DPMO.
Thanks
Matthew S. Park,
Process Development Engineer
Vansco Electronics
email: [log in to unmask]
gtel: (309)-263-7788
dtel: (309)-266-2288
fax: (309)-266-6674
1651 N. Main Morton. IL 61550
>>> [log in to unmask] 12/7/2005 10:56:56 AM >>>
And...another aspect of the equation is that the assembly house does
not
actually have complete control over the soldering statistics... It
might not
be obvious at first glance but built into those numbers is a dependence
upon
how well the PCB Designer does their job of providing correct land
geometries, component spacing, thermal relief, and planning for copper
distribution, etc., this has a big effect on their successful
soldering
numbers. The particular design being built really plays a large roll in
the
success of the assembly house in getting all the solder joints
soldered
correctly on all the boards they build and the assembly engineers are
challenged daily to come up with ways to overcome deficiencies in
design and
'make' the assembly work. My hat is off to the folks who make their
living
overcoming difficult design driven assembly problems on a daily
basis... you
guys and gals are 'wizards' in your own right. The more training we get
as
designers on how to make their lives easier the better the statistics
will
be as well.
Best regards,
Bill Brooks - KG6VVP
PCB Design Engineer, C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
Datron World Communications, Inc.
_______________________________________
San Diego Chapter of the IPC Designers Council
Communications Officer, Web Manager
http://dcchapters.ipc.org/SanDiego/
http://pcbwizards.com
-----Original Message-----
From: Stadem, Richard [mailto:[log in to unmask]]
Sent: Wednesday, December 07, 2005 5:06 AM
To: [log in to unmask]
Subject: Re: [TN] Nonwetting Pad numbers
Both of those were excellent responses, Rainer!
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Blomberg, Rainer
(FL51)
Sent: Tuesday, December 06, 2005 8:59 AM
To: [log in to unmask]
Subject: Re: [TN] Nonwetting Pad numbers
I believe you are asking if there are written or accepted levels of
solder
touch-up. No, there is no written or accepted level of soldering
defects
prior to normal touch-up. We all have different "normal" levels of
touch-up
and all strive for six-sigma values. Differences in design, component
type
and innumerable other variables drive success. You must support your
claims
based on your own experience and product and decide what is acceptable
for
you.
> Rainer G. Blomberg
> Honeywell -Space Systems Clearwater
> Staff Production Engineer
(727) 539-5534
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Baski Devre
Sent: Tuesday, December 06, 2005 8:52 AM
To: [log in to unmask]
Subject: Re: [TN] Nonwetting Pad numbers
Dear Ramon
But most of the manufacturer can not succedd in full joint soldering ,
and
it is normal for them to touch up after assembly and they may indicate
some
ppm value according to their experience but we just want to support
our
claims based on writen or accepted criteria or standard.
We also want to reach a point where there is no nonwetting opportunity
but
sometimes some of the pads or soldering region need to be touched up
or
reworked after assembly Best Regards
Yusuf
Dehoyos, Ramon yazmis:
>
> Hi Les:
> I agree, six sigma is achievable, if you have dedicated
personnel, tech support and standardized good equipment that work in a
symbiotic relationship. It is hard but it can be done. Toyota
manufacturing
plants are doing just that even in the U.S. Ego gets in people's way
and
prevents that from happening. It is a shame. Some people are more
preoccupied in bettering themselves than moving the company forward as
a
whole. Do you know the DPMO to be six sigma?
> Regards,
> Ramon
>
>
>
> _____
>
>From: - Bogert [mailto:[log in to unmask]]
>Sent: Monday, December 05, 2005 5:34 PM
>To: TechNet E-Mail Forum; Dehoyos, Ramon
>Subject: Re: [TN] Nonwetting Pad numbers
>
>
>But it is not six sigma.
>
> ----- Original Message -----
> From: Dehoyos, Ramon <mailto:[log in to unmask]>
> To: [log in to unmask]
> Sent: Monday, December 05, 2005 1:16 PM
> Subject: Re: [TN] Nonwetting Pad numbers
>
> Less than 1000 defects per million ops is good, less
> than
500 DPMO is great.
> Regards,
> Ramon
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of
Brooks,Bill
> Sent: Monday, December 05, 2005 1:07 PM
> To: [log in to unmask]
> Subject: Re: [TN] Nonwetting Pad numbers
>
> Yusuf Gomec,
>
> This is a strange question from a designer's point of view...
> If
you send me a board with "nonwetted or insufficient soldered pads" we
will
reject them.
> 100% of all solder locations must be properly soldered, all
the
time, every day, no exceptions. There is no criteria for 'acceptable
numbers' for bad solder joints. The circuit will not work or be
reliable
unless they are all good solder joints. You cannot tolerate bad solder
or
dewetted surface finishes.
>
> Now... if you are looking for statistical figures for the
> industry
about how much scrap or rework assembly houses make, someone else will
have
to answer that one... Although it occurs to me that data might be a
point of
interest to someone trying to set up or run a board shop and figure out
the
costs of doing business...
>
> Your company BaskiDevre is in the business of making boards is
> it
not?... I would expect that your Quality Assurance people would have
collected this statistic and it would be used as a running gauge for
seeing
if they had control of their processes and were maintaining them
correctly
in order to keep those numbers as small as possible with the equipment
and
methods that they had to work with. The ideal situation would be zero
defects, like John Burke says. That would mean your process controls
were
working.
>
> Best regards,
>
> Bill Brooks - KG6VVP
> PCB Design Engineer, C.I.D.+, C.I.I.
> Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 Datron World
Communications, Inc.
> _______________________________________
> San Diego Chapter of the IPC Designers Council Communications
Officer, Web Manager http://dcchapters.ipc.org/SanDiego/
> http://pcbwizards.com
>
> -----Original Message-----
> From: Baski Devre [mailto:[log in to unmask]]
> Sent: Monday, December 05, 2005 9:05 AM
> To: [log in to unmask]
> Subject: Re: [TN] Nonwetting Pad numbers
>
> I may ask wrongly so please let me ask again. What is the ppm
> of nonwetted or insufficient soldered pads numbers which will be
> touched up after assembly of the PCBs
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