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

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