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February 2005

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Subject:
From:
Dale Ritzen <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dale Ritzen <[log in to unmask]>
Date:
Wed, 9 Feb 2005 07:16:16 -0600
Content-Type:
text/plain
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text/plain (140 lines)
Hi Jeff,
I think Sefika meant the ambient temp/humidity/barometric pressure that an
assembled board can be stored in over time. Previous TechNet discussions
have touched on this to some extent, especially when it comes to different
board types, i.e. FR4 vs. Polyimide, etc. Some raw board types act like
sponges and absorb water quickly, others take longer to suffer from high
humidity or corrosive contaminants in the air around them. And assembled
boards still suffer from this somewhat, but the inherent problems with raw
boards are most apparent when trying to assemble boards, i.e. shrinkage
during high reflow profiles, dewetting issues, contaminated pads, etc. Once
a board is assembled most of these 'issues' go away - especially if the
boards are conformally coated. However, I remain curious to see if anyone
will wade into this issue with some good, solid statistics on the post-build
side of the equation. Any takers?

Dale Ritzen, CQA
Quality Manager
Austin Manufacturing Services


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Jeffrey Bush
Sent: Wednesday, February 09, 2005 6:11 AM
To: [log in to unmask]
Subject: Re: [TN] storage temperature of assembled pcbs


Maximum operating temp is generally 130 C for most /21 materials.  At this
temp the board an continuously operate and function electrically and
mechanically as designed.  Beyond this performance can become flakey.  

Jeffrey Bush
Director, Quality Assurance and Technical Support

VERMONT CIRCUITS INCORPORATED
  76 Technology Drive – POB 1890
    Brattleboro, Vermont 05302
      Voice: 802.257.4571.21 Fax: 802.257.0011
           http://www.vtcircuits.com
 

-----Original Message-----
From: Sefika ÖZKAL [mailto:[log in to unmask]] 
Sent: Wednesday, February 09, 2005 6:35 AM
To: [log in to unmask]
Subject: [TN] storage temperature of assembled pcbs

Hi,

 

How can we determine the storage temperature of an assembled pcb? 

 

What is the minimum temperature value which a laminate material (fr4 – tg
135°C ) can tolerate without experiencing any distortion on its
construction? 

 

Best Regards

 

Have a good day?

 

Sefika OZKAL 

Design Engineer

 

ASELSAN INC. MGEO Division

 

Address     : Cankiri Yolu 7. Km  

              Akyurt Ankara TURKEY

E-mail      : [log in to unmask]

Tel         : +90 312 84 75 300 Ext: 4698

Fax         : +90 312 84 75 320

 

 

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