This really depends on your assembly and flux. Using old fashioned RMA flux on a double sided board of moderate complexity with no unusually sensitive components we like to see 210°F to 220°F (100°C to 105°C). For multi-layer boards it may be necessary to increase the topside preheat a little to see say 235°F (115°C).

Got BGAs on board? Make sure you don't reflow them on the wave. I have seen capacitors, controls, plastic hardware, crystals, and exotic ICs that cannot take preheats as high as you are seeing. I have used fluxes that would be rendered useless at 254°F (125°C) temperatures as well.

On the other hand, there may be fluxes that require the preheat you are seeing, and your application may require this unusual (IMHO) preheat temperature.

Guy Ramsey
American Competitiveness Institute
Senior Lab Technician / Instructor
610 362-1200 ext 107

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Bob Arciolla
Sent: Friday, February 23, 2001 2:09 PM
To: [log in to unmask]
Subject: [TN] temperature

Good Afternoon,

I am looking for some input as far as what is the highest the top side temperature can be on a pcb going over the wave solder before there is damage (bonding) to components (ex: transistors, IC's etc). Any help would be appreciated. We are seeing around 254 degrees F

Thanks in advance,

Bob Arciolla [log in to unmask]