How many times can a component go through reflow oven?| 18 August, 2009
Is there a limit to how many times a pcb with components can be run through a reflow oven before the components start to degrade?
Example: We load the SMT components on the bottom side of the pcb and run it through the reflow oven. Next we load the top side and reflow. Then we place pins (that have solder built into the pin) on the edges of the pcb and run it through reflow again. Finally, this newly created SMT module is placed on another pcb and again run through a reflow oven. That makes it a total of 4 passes through a reflow oven for the bottom side and 3 times through for the top side. The assembly is lead-free so the reflow oven is running at the elevated temperatures needed for that.
Would the multiple reflow temperature cycles cause the components to start to degrade? I would assume so but at what point or how many cycles before this happens? Would long term reliability be compromised with the 4 cycles described above? We are using IC packages SOT-23 and uSOIC-8 along with 0402 Rs and Cs. Any thoughts would be appreciated. Thanks!
How many times can a component go through reflow oven?| 21 August, 2009
Manufacturers of non hermetic SMT components have to test their devices as per IPC JEDEC 20C to check their reflow and moisture sensitivity. In this spec they pass them through reflow 3 times, then check them for damage and retest their performance. Providing you store your non hermetic components as per IPC JEDEC 33 before assembly and they don't go over their open floor time between reflow profiles then they should be okay for 3 passes. 4 passes is probably unknown territory but the device manufacturers should be able to advise.
How many times can a component go through reflow oven?| 2 September, 2009
Also consider electroltyics as some brands can only cope with one pass through reflow, 2 max. In Vapor phase 1 pass max is typical. Although depends on makers specs and what they say the device can withstand. main issue is Dielectrics get damaged , can cause failure right away or and can cause in field early failure etc.