Transfer molding usually involve two steps; mold and cure at long time in an oven. There are "improved" process to eliminate cure step, that resulted rapid cure in mold with high stress (higher than 2 step process). Such device some time exhibit premature aging upon reflow, due to insufficient cure (not necessary pop corn). In theory, all device should pass jedec tests (all of them, not just selected few), in reality, watch out when you got some new plant products that may have something that lost in "translation". Well, my old 1.7 cents. It may be an old story, but a hard lesson.
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----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Fri May 08 21:20:38 2009
Subject: Re: [TN] Design considerations for MCM packages
Well. Can you explain, please what you meant by "residual stress within the package"?
Also an overmoldng material usually pops mainly due to moisture, but not to "aging due to multiple reflow".
Vladimir
SENTEC
SENTEC
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca
-----Original Message-----
From: Joyce Koo <[log in to unmask]>
Date: Fri, 8 May 2009 20:30:16
To: <[log in to unmask]>
Subject: Re: [TN] Design considerations for MCM packages
Polymeric material pass Tg multiple times. Aging of adhesives used for die attach. Molding compound aging due to multiple reflow (pop). Excessive intermetallic growth at wirebond interface due to multiple reflow.
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----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Fri May 08 11:08:09 2009
Subject: Re: [TN] Design considerations for MCM packages
what residual stress?
----- Original Message -----
From: "Joyce Koo" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, May 08, 2009 4:22 PM
Subject: Re: [TN] Design considerations for MCM packages
Warpage, residual stress within the package.
--------------------------
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----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Fri May 08 07:56:04 2009
Subject: [TN] Design considerations for MCM packages
Hi TechNetters and Dewey,
I have to write, rather quickly, kind of design rules or a little handbook.
I will use own material as well as others.
Question: do you miss something in the below list (borrowed from
Garrou&Turlic):
7.1 INTRODUCTION
7.2 MECHANICAL DESIGN CONSIDERATIONS MCM PACKAGES
7.2.1 Package size
7.2.2 Package I/O
7.2.3 Expansion matching
7.2.4 Compliant Leads
7.2.5 Vibration and Shock Considerations
7.3 ELECTRICAL DESIGN CONSIDERATIONS MCM PACKAGES
7.3.1 Package Leads Characteristics
7.3.2 Package Body Electrical Characteristics
7.4 THERMAL DESIGN CONSIDERATIONS MCM PACKAGES
7.4.1 Temperature Extreme Considerations
7.4.2 Temperature Rise Inside MCM Packages
7.5 ENVIRONMENTAL DESIGN CONSIDERATIONS MCM PACKAGES
7.5.1 Thermal Cycling
7.5.2 Hermeticity Considerations
7.5.3 Pressure Cycling
7.5.4 Hermetic-Equivalent Packaging, Moisture and Corrosion Resistance,
Reliability without Hermeticity.
7.6 EXAMPLES OF MCM PACKAGE DESIGN APPROACHES
7.6.1 Premolded Plastic MCM Packages
7.6.2 Postmolded Plastic MCM Packages
7.6.3 Encapsulated Chip-on-Board MCM Packages
7.6.4 Metal Hermetic MCM Packages
7.6.5 Ceramic Hermetic MCM Packages
7.7 Cost Considerations for MCM Packages
If there is something else to add, I would appreciate that very much.
Thanks in advance
Inge
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