Test Your Know How: PCB Separation

Hi John,

Yes indeed, would love to hear any additional thoughts you might have. On the assembly flow, I think they hit the balance very well, based on the equipment they have. The one thing I liked was the high degree of protecting the board by using a pallet as a carrier.
This IMHO bodes well for the quality of the finished product. The huge advantage of the pallet is the board is ready to go. If the boards are de-paneled to begin with there is inherent quality built in. Needless to say this depends alot on the capability and agility of the SMD
placement equipment.

Good topics John !

Best Regards.

Hi Excellon1, I see you got nominated for "Meet the Champion of the Month: August 2025". Congratulations and well deserved!

After seeing this, I remembered this conversation. In follow up, I am definitely in favor of penalization. I cringe when I see operations happening on single PCBs. A major part of production time loss is the load unload cycles That's one major reason why penalization saves time and money. Why operate on one component when a pallet of 6, 8 or 10 can be operated upon before passing the job on to the next stage. Placement machines on the market can handle much larger pcb sizes than this example. (Example specs of 610 x 508mm are available) I would also argue that something is wrong when a guy is full time employed to sit there and touch up solder joints. Would you agree?

I too pass on my congratulations to Excellon1. Well deserved Paul!

I would be wary of panels longer than about 300mm these days. IPC allows for board "stretch" of up to 0.2mm and fabricators are reluctant to specify less. This isn't a problem for SMD placement machines, but can cause problems for stencil printing when using 0201s and similar, or smaller devices. I have seen a board come in with a 0.2mm "stretch" and it caused considerable problems in assembly. I'd prefer to keep panels shorter that 200mm. Of course, if your assembly house has access to jet printing capability, this is less of a problem for low volume runs.

True eDave, thanks for weighing in with good points. True that the larger panels suffer from stretch issues. For such large placement areas, it makes sense to run multiple panels at once to utilize the machine to its maximum capability. Even still we would endeavor to maximize individual panel size up to 350mm length and beyond. Some layout techniques are possible to minimize the effects of stretch. I would be interested to hear more about the jet printing. Have you used that? 

I haven't used jet printing. However I'm familiar with the benefits and disadvantages.

Pros:

• No stencils
• Reliable and predictable paste deposits
• Easy to test different paste patterns

Cons:

• Slow printing compared with stencils
• Expensive paste
• Good jet printers are expensive