Hi Ramakrishnan,

Over the years I typically see these bakes during PCB fabrication at 105C 
or 125C.  I also typically see much shorter bake times after electroless 
and after oxide (typically 1 hour or less).  Typically I have not seen 
bakes after lamination or on incoming material (assuming they have been 
properly packaged and stored).  The key air bake is prior to HASL. 
Depending on material and design, these can be 4 hours or even longer 
(typically at 125C).  For solder float coupons, I have seen anywhere from 
105C to 190C with bake times anywhere from 1 hour (190C) to 24 hours 
depending on the materials in the stack up and the need for fast results.

Joel
 
Joel S. Peiffer
3M Electronic Solutions Division
3M Center, Building 201-1E-21
St. Paul, MN  55144
Tel:  (651) 575-1464
Cell:  (612) 327-1983
Fax:  (651) 737-4601
[log in to unmask]



From:   Paul Reid <[log in to unmask]>
To:     <[log in to unmask]>
Date:   10/24/2013 11:02 AM
Subject:        Re: [TN] PCB BAKING DURING FABRICATION
Sent by:        TechNet <[log in to unmask]>



Hi Ramakrishnan,

I think that your bake temperature of 140°C is too high for a DICY cured 
material. I'd drop the temperature to 105°C.

I'd drop the bake after lamination and possibly the bake after electroless 
if you can dry them without oxidation.

Sincerely, 

 

Paul Reid 

Program Coordinator 

PWB Interconnect Solutions Inc. 
235 Stafford Rd., West, Unit 103 
Nepean, Ontario Canada, K2H 9C1 

613 596 4244 ext. 229 

Skype paul_reid_pwb 
[log in to unmask] 

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ramakrishnan Saravanan
Sent: October 24, 2013 11:43 AM
To: [log in to unmask]
Subject: [TN] PCB BAKING DURING FABRICATION

We are using 170 deg C IPC 4101/24  material for making hi reliability 
PCBs. The PCB coupons are subjected to 
6X Solder Dip to access PTH integrity & laminate integrity. 5X R/W also 
carried out. 

to achieve this initial laminates(cores) are baked at 140 deg C for 4 
hours. 
after blak OXIDE  baked at 140 deg C for 4 hours
after MLB pressing baked at 140 deg C for 4 hours
after electroless copper plating baked at 140 deg C for 4 hours
prior to HASL baked at 140 deg C for 4 hours
a total of 20 hours at 140 deg C baked during fabrication.


after PCB fabrication. the coupon is separated from PCB and the coupon is 
baked for 12 hours at 120 deg C. 

The coupon is subjected to 6X solder dip & 5x R/W simulation. 

My doubts are 

Q1. These extra long hours of baking will deteriorate the chemical & 
mechanical properties of the laminates ? 
      if so , what are the properties are getting affected. The material 
dicy cured FR4. 

Q2. Whether Test coupon results will reflect the quality of PCBs ?.


R.Saravanan

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________