panelizing and cutting pcb's

Community PCB Design
21

Philba:
I wouldn’t try to cut a populated board at all. best to get it v-scored before populating.

That is not a good view on cutting boards when you are assembling them for other people. When a person sends 100 boards, the time it takes to unload and reload the Pick and Place is wasted time. Also reflowing is more difficult. It would be easy to loose track of a board, when you have 100-10,000 separate boards in a job. Also if the boards are 0.5 x 2 inches…the chances of dropping one are greater.

All SMT assembly services attempt to populate panels (arrays) before they are cut. It saves time and labor cost.

As long as the panel is not flexed when separating, no harm can come of the components. Even v-scored boards are separated after population unless a component over hangs the cut. Most of the time it will be the last thing to be placed on the board (after separation). The separation method is by a “Depanelizer” which uses the v-score as a squeeze line. It breaks the remaining fibers holding the boards together. It is almost a shear, but uses two wheels that come together.

Population after separation increases the turn around time of a job about 40%. This is due to time taken loading and unloading the machinery.

This is the standard in the industry. You can ask any assembly house (that is doing it with automated machinery) and they will tell you it would cost much more to populate the boards independently. This does of course depend on the board size. If the board is 10 inches x 13 inches, they are not likely to be in an array (or panelized).

Separation after population is the industry norm,

James L

EDIT: Just for information, I included this website for a depaneler. It tells how close to a component it can cut. https://www.manncorp.com/depanelers/sdm … ?auto=done

22

I’m confused, you say it’s not a good idea then go on to describe how Vscored boards are separated after being populated.

23

Philba:
I’m confused, you say it’s not a good idea then go on to describe how Vscored boards are separated after being populated.

Philba,

At what point did I say, “It’s not a good idea.” ??

I did say at one point, “your methods wouldn’t apply to a populated board.” I do not think a regular shear/brake will be 100% successful with populated boards. The blades are too think, and they (standard shears) tend to flex boards as they cut/shear.

I also stated, “That is not a good view on cutting boards” Meaning your view would not be a good one to have, if you are assembling a large number of boards everyday.

Also to further expand this idea (board separation): a depaneler (circular pinch type) requires a v-score to work. It will make a mess of a non-scored board. A saw on the other hand will cut any type of array board, v-scored or not. Some services do not offer v-scoring for large panels with a large number of small boards contained within.

Gold Phoenix’s special for example…they will only score 20 times. I have had over 66 boards in one panel (array).

Any type of flex separation method is subject to cause problems. Depanelers are specially designed to localize the cutting force. They are designed to minimize flexing. They are not just a shear. That is why if you go to buy one, have a think wallet, the cheapest are around $2500.00…and are the size of a small to medium printer.

But a person can build, separate, or panelize as they wish.

I’m just trying to give friendly advice that I know will work, save time, and not create problems down the road.

(Sort of like the difference of reflowing with a clothes iron or a toaster oven…there are limitations to a clothes iron, where a toaster oven can reflow just about anything you can imagine. It is all about your specific needs and application.)

James L

24

OK, you said view, not idea but I’m not sure I see the difference, even after your explanation. It seems like you are saying there are lots of ways to do it, pre or post populated.

Also, a lot depends on the volume. The OP said something like 8-10 boards. They would likely be hand assembled anyway so it doesn’t really matter when they get populated but I’d personally cut them before populating. The idea of using a saw isn’t very appetizing to me. I guess with the right setup, it could be safe and precise. I’m not sure how many people here have that kind of setup.

I don’t doubt that in even moderate volume, your approach is far superior.

25

i should update this a little.

micromark rebrands alot, there saws are just proxxon saws, proxxon sells a diamond blade for the smaller / cheaper saw. also the proxxon scroll saw can use 40tpi blades which will cut pcb’s fine and straight with the edge guide it comes with.

26

unsped:
i should update this a little.

micromark rebrands alot, there saws are just proxxon saws, proxxon sells a diamond blade for the smaller / cheaper saw. also the proxxon scroll saw can use 40tpi blades which will cut pcb’s fine and straight with the edge guide it comes with.

Yes…I agree…Micromark does re-brand alot…but they also have their own products made in China alot. This is not a Proxxon saw…although it may be a direct copy. I have compared the two…

I do not recommend using a toothed saw (circular). It would be impossible to run with a blade guard on (if components are mounted) and you could seriously hurt yourself with a toothed saw. The diamond blade works great…and it may burn you, it won’t cut you.

But as I stated before…choose what you want…I just offered my advice.

James L