Why is "panelization" done in PCB production?

Why is "panelization" done in PCB production? After soldering SMT and Wave To de-panel again? What is the break-away/coupon of a PCB? Isn't it cheaper to use less sheet metal? How is plate utilization rate one and the same?

Why does PCB production need to do panelization?

Common circuit board manufacturing is called "panelization," which is intended to increase the efficiency of SMT or wave soldering lines.

PCBS usually have so-called "several in one" boards, such as 2-in 1, 4-in 1, 6-in 1... And so on.

If you have a chance to visit the SMT production line, you will find that the biggest bottleneck of the SMT production line is actually in the process of Solder paste printing. No matter how big the PCB is, the printing time is almost less than 25 seconds. That is to say, if the time spent by the rapid patch beater with higher unit price and the general patch beater is less than that of the solder paste printer, it will be idle, which is a waste from the point of view of economic benefits.

Actually, SMT machine speed is very fast, fast to a second can play several parts, some of the placement machine and even several suction nozzle can play at the same time, to now phone PCBA above parts number, if only a single piece of board, and should take less than ten seconds to complete all the patch work, so the PCB to make makeup to increase patch on the number of parts, Can increase the utilization rate of the patch machine, improve efficiency. Of course, it is best to achieve a "Line Balance" so that each device is fully functional.

PCB board also has another advantage, it can save time when taking and placing PCBA, because multiple boards can be taken and placed at the same time at one time. If the subsequent step test can be done with the board test, it can also greatly save the time wasted when taking and placing the boards in the fixture.

Finally, some time will present a irregular shape of PCB design, such as the "L" shape of the board, if make it "solution 1", its place in the upper left corner will be a waste, if can be designed into upper and lower reverse makeup, waste, can greatly reduce, this is the PCB board utilization rate of the concept of ascension.

Disadvantages and limitations of PCB (panelization)

Although PCB board has many advantages, after all the PCBA assembly is completed, it still has to be de-panel into a single board, one more process, also more time, but also increase the risk of collision parts during delivery.

If there are too small parts such as thin pins and 0201 on some boards, the number of boards can not be too many pieces together, because there is a tolerance between the boards, if there are too many boards, it may cause the tolerance is too large to meet the accuracy requirements of the solder paste printing, and finally the solder paste printing deviation, solder will go wrong.

For some PCB that is too thin, it is not recommended to have too many pieces, because the thinner the PCB is, the greater the deformation will be, and the more pieces, the wider the board will be. Patch making and back welding furnace are both a test. Of course, this aspect can be overcome by using carrier or full carrier, but the cost of carrier and increased labor costs have to be considered.

What is the purpose of PCB making "break-away"?

PCB break-away, which is also called coupon by some foreigners, can be opened directly, but based on quality considerations, working bear really does not suggest breaking the excess edge by hand. Machine (Scoring or Router) should be used to remove the edge. In order to reduce the stress produced when folding plate edge, in order to avoid the influence of tin crack or parts fracture caused by the board and parts.

PCB edge design is mainly used to assist PCBA assembly and production. The CURRENT SMT production line is actually very highly automated, and the board is delivered by the belt and chain, smart you should have thought of the board edge is the main purpose of these belts and chains to transport the board.

Of course, if you are willing, you can also around the board to set aside a certain space don't put any electronic parts, general requirements to keep at least more than 5.0 mm, because the welding furnace chain need more deep edge position, so that you will have the opportunity to can not design edge, otherwise it might damage the belt and chain around the electronic parts.

In addition, PCB edges have other uses:

The "Tooling Hole" can be placed to locate the board during ICT or FVT testing after SMT process to avoid deviation between the needle bed and the test point.

Used for SMT line sensor to detect PCB position. Generally, each machine on the SMT line has a sensor to detect the arrival of subsequent boards to ensure that only one piece of the board is working. Otherwise, the machine will be confused and not know which board to hit before the previous piece of board is finished. And some of the appearance of the board may just be in the SMT production line sensor detection place basket empty, generally in the upper left edge of the board, at this time you can use the board edge place to achieve solid sensor detection.

Some of the board because of space constraints and can not set too many positioning optical points (Fiducial mark), can also be placed in the position of the board edge, but it is recommended that there should be a fixed point in the board near the thin foot parts plate, can increase the accuracy of the patch.