If you are a low-volume electronics manufacturer or a hobbyist stepping up from hand assembly, you might be overlooking how efficient you can get in production by continuing to do hand assembly. A lot of people doing just through-hole soldering might be nervous about surface mount. They might also be tweezing their way through work, which is not the most efficient way to do things. There are many things that you can do to get more efficient.
There are different flavours of benchtop or desktop printed circuit board (PCB) assembly solutions available. “Desktop SMT equipment should be compact, yet flexible enough to cover a wide spectrum of today’s manufacturing needs and in the future, too. These should also be easy to use and economical,” says Kumud Tyagi, vice president, Bergen Associates Pvt Ltd.
Are you ready to look at pick-and-place (PNP) machines? The most important point to keep in mind is that the least expensive machines will almost always be the most difficult to use. There is a new family of PNP machines coming out of China. A number of different products are being launched by companies who are just copying each other to come out with these machines. They lack important features and also suffer from support and service issues.
Let us take a look at some of the things that you need to consider while shopping for a PNP machine.
Select the right feeders. The components now come on paper or plastic tape. So if you are assembling manually, you would just need to hold on to the tape somehow. In PNP, you might get machines where there is no facility to advance the tape and so you will have to be careful so as not to spill the components all over the workbench. It will be a pain to sort out the small components, especially if these are polarised. The last thing you want is to rework the whole thing. Low-end machines, typically, do not have auto advance, and this means that you would have to babysit the machine while it does its job.
Machine vision. The least expensive PNPs do not have machine vision. Machine vision is a camera and software combo that works to ensure that the part is on the nozzle and aligned correctly before it puts down the component. There are some new machines from China that can be sourced from AliExpress, which do this, or you can work with a local distributor to get one.
We recommend that you go for it if you can afford it. So, what does it do?
1. Verifies that the part is picked up and is on the nozzle. It is easy for the machine to not pick up the part and keep going without picking up a part.
2. Aligns the board. When you start a job and put the board in the machine vision, it will look for marks on the board called fiducial markers. This becomes even more important as the parts become smaller.
3. Helps align the pickup points and identify where the feeders are. Even if you have the mechanical position of the parts correct, you could be off by a millimetre. The problem occurs when the part is just half a millimetre.
Neoden-4 has an intelligent vision system that allows edge detection of every component. It will analyse, add correction, co-ordinate and place accurately using micron high-resolution cameras for analysis and calculation.
Speed of placement per minute. This is important as it decides the productivity that you could get out of your machine. Usually, low-end machines are not going to do more than 10 or 20 pieces per minute. This should not be a problem unless you have a lot of placements to do. For systems with machine vision, switching it off should give you significant increase in the speed of placement since it now does not have to verify the placement of every component.
Other features that can be considered include the smallest size of the part that can be picked. Currently, one of the smallest is 0402 imperial, which translates to 1mm×0.5mm.
Also important is the number of heads that the machine has. Venu Narayan Vaishnav, owner, Chipmax Group, says, “NeoDen-4 can achieve accuracy with 0201 chips and it is a quad-head machine that can carry four component pick-up nozzles at a time.”
Another good example is VisionBot PNP. An interesting machine made by a maker for other makers, it is a comparatively inexpensive tool for PCB assembly that works with gerber and csv files. You can go for 24 to 96 feeders depending on the model, and it is being launched via Kickstarter.