How Pick and Place Manufacturers Specify Equipment
Placement speed for pick and place machines is measured in terms of “components per hour” or CPH (sometimes also referred to as PPH for “parts per hour”). This is the rate at which components are picked up, inspected and placed onto a PCB.
Many equipment manufacturers use the IPC-9850 standard to determine CPH rates for their machines. This ensures that they are using the same part mix and PCB placement arrays, making it easier for buyers to compare one machine - and one manufacturer's machine - against another's. Other manufacturers will design their own PCB for their speed rating and use more accessible pickup locations to get a “faster” rating.
To determine a more “real world” production speed of a machine, de-rate the manufacturer's started IPC-9850 CPH rating by 20%. If the manufacturer's CPH is not IPC-9850, de-rate it by 30%.
Feeder capacity means the number of 8 mm tape feeders that can be loaded onto the machine at one time. Larger components will require larger feeders. You'll need to find out from the manufacturer how many slots each of the larger tape feeder types — 12 mm, 16 mm, 24 mm and up — take up. Matrix or waffle trays and tube (or stick) feeders will also take up valuable feeder slot real estate. If you'll need to use trays or tubes, you'll need to find out the capacity of the available feeders and how many 8 mm spaces they'll require.
Feeder slots can be one of the most confusing aspects of pick and place machine. A machine that has 64 feeder slots won't necessarily hold 64 feeders. Feeder slots are designed for 8-mm tape feeders. If you have larger tape feeders and/or sticks and waffle trays, each feeder will take up two or more feeder slots.
To determine whether a machine has enough capacity for your requirements, you will need to calculate just how many 8-mm feeder slots you'll need.
To calculate your feeder slot requirements, first list how many of each tape feeder size you will need. Then multiply each of those by the number of feeder slots the pick & place manufacturer says each will require. For example, if you need 44 8-mm tape feeders and the manufacturer specifications say that each 8-mm tape feeder requires one feeder slot, you will need 44 feeder slots for your 8-mm tape feeders.
If you also need two 12-mm feeders, and the manufacturer's specs say that 12-mm tape feeders require two slots each, you will need an additional four 8-mm tape slots (2 feeders x 2 slots/feeder) for your 12-mm feeders, bringing your total slot requirement to 48. Stick feeders and matrix tray holders are treated differently. Each of the manufacturer's stick feeders will hold multiple sticks or tubes, so first figure out how many sticks you have, then figure out how many stick feeders you'll need, and then find out how many slots that feeder(s) will take up. For example, if you have 4 sticks and the available stick feeder holds 10 sticks, you would need one stick feeder. If the stick feeder requires 9 slots, your total slot requirement, building on the tape feeder example above, is now 57. Matrix tray holders are sometimes mounted in feeder slots and sometimes placed in the board area. If the tray holder for the machine you're looking at takes up feeder slots, you'll need to find out how many and add that to your requirement. If, on the other hand, the matrix tray holder goes in the placement area, this will affect the size of the PCB/panel that the machine can handle. You'll take that into consideration in the next step.
Equipment manufacturers will give you the maximum and minimum component dimensions that the machine will handle.
In many cases you'll see multiple component size specs given for a single machine. This happens when there are multiple alignment methods installed on the machine. One method may be faster or more precise, but because it only handles a narrow range of part sizes, an alternate alignment system is included to cover a wider component range. The machine's software will automatically switch methods as needed.
One thing you'll want to know is not just the largest size the machine can place, but what's the largest it can inspect? Some equipment has the ability to handle larger parts than they can inspect. You'll also need to know the maximum part height the machine can handle. On the small end of the spectrum, you'll want to know the minimum size the equipment can pick, index and place. Most machines are capable of handling 0402 or even 0201 chips. 01005 placement capability is out there, too. In any case, keep in mind that anything 0402 or smaller may require a special nozzle and/or feeder. Check with the manufacturer.
0.012" fine pitch is fairly standard for today's pick and place equipment. If fine pitch capability is required, do not be fooled by manufacturers referencing motor specification or motor accuracy. There is more to fine pitch placement than motor accuracy. It does not matter how accurate a motor is if the machine (system) cannot pick up, inspect, and place fine pitch leaded and ball grid components.
Other Important Considerations
- Maximum and Minimum PCB or panel size and thickness can be critical for some
- You'll also want to make note of placement accuracy
- If you're not looking at benchtop machines, the PCB loading method could be important
- Fiducial recognition, coordinate correction and bad mark detection should be standard for automatic pick and place machines- check to make sure the equipment you're looking at has these features.
- If you're looking at automatic machines, how are they programmed? CAD download, teaching camera, barcode readers, MIS and optimization functions and off-line programming can all make the operator's job easier and your production more efficient.
- Some machines can be optionally fitted with a dispense head for depositing adhesive on the board. If you require this feature, note what the dispense method is, along with dot size and dispense speed.