Received: |
by ipc.org (Smail3.1.28.1 #2)
id m0tXDGq-0000NUC; Tue, 2 Jan 96 14:25 CST |
Lines: |
47 |
Old-Return-Path: |
|
Date: |
Tue, 2 Jan 1996 19:47:24 GMT |
Precedence: |
list |
Reply-To: |
|
Resent-Sender: |
|
X-Status: |
|
Status: |
RO |
X-Mailing-List: |
|
TO: |
|
Return-Path: |
|
From [log in to unmask] Tue Jan 2 16: |
26:02 1996 |
Resent-Message-ID: |
<"eaEro3.0.3A6.lIPwm"@ipc> |
Subject: |
|
From: |
|
X-Loop: |
|
Resent-From: |
|
X-Mailer: |
FIMail V0.9d |
Message-Id: |
|
Parts/Attachments: |
|
|
> > All,
> > Does anyone have any data on the relationship between solder balls (no
> > clean flux w/ N2) and various solder masks?
> > Some of our lines run OK and some do not for the same mask. The hard
> > part to understand is that a mask will run poorly on one line and OK on
> > another. My feeling is that the mask is statistically significant, but
> > not necessarily the major contributor. All DOE have shown no sweet spot,
> > but of course going to aqueous or eliminating N2 have shown positive
> > results.
> > The other variable that has completely eliminated solder balls is to
> > shorten leads to ~.080". This went over poorly with the connector
> > people.
> > Any help would be appreciated.
> > Steve Joy
> > [log in to unmask]
> >
> >
Steve,
We use no clean technology and had problems early on with solder balls adhering
to the solder mask. The company that supplied our soldering equipment did do a
lot of work evaluating different fluxes and solder mask finishes. They are
Blundell Production Equipment Ltd at Coventry in England; Paul Blundell is the
MD and their telephone number is UK 1203 473003.
The solder mask surface is important and a smooth high gloss finish will enable
solder balls to attach more readily than a micro matt surface. Unfortunately
most solder masks today are applied by curtain coat and have a very smooth
surface. The solder ball is stuck to the surface of the mask by a small residue
of flux.
The main emphasis is therefore in finding a flux which will give the least
solder balling. The soldering parameters such as pre-heat temperature, solder
temperature, and speed through the wave are also important.
We use Apple House NC213 no clean flux on a Coates Imagecure XV501TSM solder
mask applied by curtain coat and have no problems.
Hope this assists you,
Paul Gould
Teknacron Circuits Ltd
---------------------------------------------------------------------------
| EMail [log in to unmask]
---------------------------------------------------------------------------
|
|
|