1. Flux shouldn't be flux leaking into the wave pallet if the flux setup is correct and if the circuit board is clamped to the pallet correctly. 

 a.) For wide thin boards the best method is to have a pem nut pressed into the pallet in one or two places along the center-line where ever there are some available holes for 4-40" or 6-32" pems . A thumb screw or hex standoff is used to clamp the board to the pallet. 

b.) The other design where there are no holes along the center-line is to use an over-arm bar with spring loaded plungers to hold the board down to the pallet. The clamps along the edge should be no more than three inches apart on .062" or thinner boards and the spring tension must be adequate. 

2. The activation temperature of some of the fluxes for Tin/lead No-clean is 200C (392F) after that is starts to burn off. The total deactivation depends on the type and amount of flux. 

 - The last preheat zone is going to activate the flux and the solder for Tin/lead is 249C - 260C (480F-500F) is much hotter than the activation temperature will burn off the activators and heat the pallet and should burn-off small amounts of flux that may leak in. Again the key is the type and amount flux in the pallet.  A temperature profile measuring the bottom side of the board inside the wave pallet will show provide the data to analyze the situation.   


----- Original Message ----- 
From: "Tom Burek " <Tom. Burek @ AMETEK .COM> 
To: TechNet @ IPC .ORG 
Sent: Wednesday, December 15, 2010 4:55:43 PM 
Subject: Re: [TN] No-Clean flux with a Wave pallet 

Thanks Rex, 
Your response raises the question, What happens to the No-clean Flux that 
is trapped between the PCB and the carrier and does not get activated? 
How do you clean it off or what steps do you take to de-activated the 
flux?  Does this un activated flux lead to contamination (i.e electro 
migration) problems later on? 
Once again this is a No-clean flux. 

Thanks again for the response and thank you to the others who responded 
also. 

Tom Burek , CID+ 
Ametek / VIS 



From:   "Rex Waygood " <Rex. Waygood @ hansatechems .com> 
To:     " TechNet E-Mail Forum" < TechNet @ IPC .ORG>, "Tom Burek " 
<Tom. Burek @ AMETEK .COM> 
Date:   12/15/2010 07:56 AM 
Subject:        RE: [TN] No-Clean flux with a Wave pallet 



We use a No Clean VOC free flux with selective carriers. 
An area of concern is that this requirement demands a good preheat 
system. 
The selective carriers produce regions where liquid flux can be trapped 
between the pcb and the carrier. 
Failure to adequately preheat produces problems where the entrapped 
liquid flux hits the wave. 

We use a Miele industrial dishwasher to keep the carriers clean. The 
carriers are cleaned to avoid H&S issues where flux residue builds up on 
the carriers and comes into contact with operator's skin. The carriers 
just go through the machine periodically, not every time they are used. 

Regards 
Rex 

Rex Waygood 
Technical Manager 
  
Hansatech EMS provides value manufacturing through engineering and 
quality 
  
Hansatech EMS Limited 
Benson Road 
Nuffield Industrial Estate 
Poole 
Dorset 
BH17 0RY 
  
+44 (0)1202 338200 





-----Original Message----- 
From: TechNet [ mailto : TechNet @ ipc .org] On Behalf Of Tom Burek 
Sent: 14 December 2010 17:07 
To: TechNet @ IPC .ORG 
Subject: [TN] No-Clean flux with a Wave pallet 

Season Greetings All, 
In the opinion of all the experts out there, are there any issues I need 
to be aware of in using a No-Clean flux while using a wave pallet? 
I am trying to wave solder some through hole pins on a SMT assembly 
(populated 2 sides). 
Are there flux spray heads that can limit the flux to the exposed pins 
in the wave pallet? 
How often do the wave pallets need to be cleaned between each run? 
I would be most interested in any stories of disaster or success on this 
issue. 

Thank you in advance and Best wishes to all for a prosperous New Year. 


Tom Burek , CID+ 
Ametek / VIS 





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