Received: |
by ipc.org (Smail3.1.28.1 #2)
id m0wKWru-000BjhC; Thu, 24 Apr 97 17:19 CDT |
Old-Return-Path: |
|
Date: |
24 Apr 1997 14:54:05 -0700 |
Precedence: |
list |
Resent-From: |
|
Resent-Sender: |
|
X-Status: |
|
Status: |
O |
X-Mailing-List: |
|
TO: |
|
Return-Path: |
<TechNet-request> |
From [log in to unmask] Tue Apr 29 09: |
53:01 1997 |
Resent-Message-ID: |
<"pqhjD3.0.vsJ.EozNp"@ipc> |
Subject: |
|
From: |
|
X-Loop: |
|
X-Mailer: |
Mail*Link SMTP-QM 4.0.0 |
Message-ID: |
|
Parts/Attachments: |
|
|
Subject: Time:10:02 AM
OFFICE MEMO ASSY: Non-wetting Date:4/23/97
Hello everybody:
I have the following case study that I would like to share and get your comments before arriving to a conclusion.
Problem: Non-wetting on 90% (RM0705) chip resistors (different values), 100% grainy solder joints on chip components (RM0705), ceramic flat packs show shiny and smooth solder joints on the same assembly. Non-wetting accentuated after second reflow.
Process:
-Vapor Phase (216oC) with infrared preheat system, Solder Paste Sn63/Pb37 RMA
-Profile: shows that some Temp across the PWB were between 180oC to 187oC before entering to the vapor (reflow)
Background & Tests:
- Chip components belong to different lots (different values) but same part type
- Lots are 2 year old!!
-Termination: Metallization: fired platinum-gold, vacuum deposited nickel chrome, electrodeposited nickel, electrolytically deposited gold, and then coated with Sn60/Pb40 (QQ-S-571)
-SEM/EDX results show oxidized termination (lead oxide) and traces of Phosphorus
-Solderability test "Dip & Look" per ANSI/J-STD-002 using:
R Flux: did not pass
RMA Flux: pass
Thank you in advance for any inputs,
Gino Cochella
(310) 814-3955
e-mail: [log in to unmask]
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************
|
|
|