 
| Received: |
by ipchq.com (Smail3.1.28.1 #2)
id m0sqodE-0000HMC; Thu, 7 Sep 95 16:37 CDT |
| Content-Type: |
TEXT/PLAIN; charset=US-ASCII |
| Old-Return-Path: |
<miso!cnct.com!twc> |
| Date: |
Thu, 7 Sep 1995 17:14:39 -0400 (EDT) |
| Precedence: |
list |
| From [log in to unmask] Sat Apr 27 14: |
44:12 1996 |
| Message-ID: |
|
| MIME-Version: |
1.0 |
| Status: |
O |
| X-Mailing-List: |
|
| TO: |
|
| Return-Path: |
|
| X-Status: |
|
| Resent-Sender: |
|
| Resent-Message-ID: |
<"8aOtG2.0.S2B.2OsJm"@ipc> |
| Subject: |
|
| From: |
|
| X-Loop: |
|
| In-Reply-To: |
|
| Resent-From: |
|
| cc: |
|
| Parts/Attachments: |
|
|
On 7 Sep 1995, Smith, Joshua wrote:
>
> We have observed corrosion caused by ionic impurities in adhesives we are
> using for an application. We have looked at total content (burn off) and
> extractable ionics (90 deg C, 40 hrs).
> 1)What standards/ procedures are accepted for measuring Ionic impurities :
> On or in flex circuits?
> on/in PCBs?
> in adhesives for PCBs?
> In adhesives for chip attach?
>
> 2)What are acceptable levels of contamination in each of these applications?
>
> 3)We have been told that 200 ppm is acceptable for PCB applications while IC
> people require 20ppm. Is this true?
>
> 4) What are the primary ions that cause trouble. Cl, Br, F others?
>
> Josh Smith
> Information, Imaging and Electronics Sector Research Laboratory
> 3M co
> 612-736-1101
>
>
>
>
Josh,
Most companies go by MIL SPEC 883D Method 5011.2 "Evaluation and
Procedures For Polymeric Adhesives." The maximum level of contamination for
Na+, K+, and F- are 50 ppm. The level for Cl- is much higher at 300
ppm. However, most companies prefer levels below 20 ppm for all four ions.
Tom Cinque
Alphametals
(201) 434-6778 x2259
[log in to unmask]
|
|
|
