The surface mount technology process makes use of automated machines to place components. This machine is the pick and place machine. Pick and place machines play significant roles in any PCB assembly line. Also, these machines make the PCB assembly process easier and faster. They enable machine operators to place components automatically on a printed circuit board.
PCB SMT assembly has been much easier and faster since the advent of these machines. Also, they make surface mount technology a more accurate assembly process. Surface mount technology process replaced through hole technology.
What is a Pick and Place Machine?
A pick and place machine is an automated machine used for assembling components on bare boards. Also, this machine picks components and places them on the circuit board. Surface mount devices (SMDs) are usually small. Therefore, these components require accurate placement. The use of manual processes in placing these components is not usually accurate.
Also, it isn’t a feasible idea to manually place electronic components. Therefore, pick and place machines place thousands of SMDs accurately. In most PCB assemblies, the assembler solders the PCB using infra-red reflow. Before, component placements, the printed circuit boards already have solder paste at the relevant areas.
Furthermore, the pick and place machine loads up SMT components. The machine has several feeds on either side. Also, the pick and place machine features a head on an arm. This head can get to all the reels and tubes. Also, it picks them and mounts them on the board. The head makes use of a small vacuum to pick and place the component on the board.
A software controls the head and uses the accurate positioning of the PCB. This helps to ensure that all components are in the right position. Also, accurate positioning is important since there are small components and very narrow track widths.
Pick and place machines are already pre-programmed with the details about the component positions. This helps the machine to know the exact area to place the components. A pick and place machine uses vacuum to move a component from a piece of tape. After that, it rotates it and places it on the printed circuit board. There are pick and place machines. These are manual, automatic, and semi-automatic.
Methods of Pick and Place Centering
The pnp machine uses four methods for picking and placing components which are:
Mechanical centering jaws
This method involves picking the component and moving in its center position in the Y and X axes on the head. Also, this is an easy method that is repeatable within +/-0.01 inch accuracy. This centering method is common in low to middle range machines. However, it touches the component physically and this isn’t ideal for some types of parts.
Vision centering involves two types which are look-up and look-down. Look down vision often views the component’s top before picking it up for its location. After this, it calculates the center and compares it to the photo file from the stored database. The look-down vision systems can handle delicate and odd-shaped components.
The look-up vision method is very accurate. In this method, the machine picks up the surface mount components from the pickup location and then moves them to a camera station. This camera station checks the component’s bottom and calculates the center position.
No centering mechanism
This method doesn’t depend on the pick-up point for placement of the component. This means that after the tool head picks up the component, the part isn’t physically centered. Therefore, this method is not accurate for placing components since there is no tolerance. Also, this method is commonly used by instructors or hobbyists.
Laser centering involves picking the component up inline with a laser beam. This laser beam identifies the center position on the tool head of the component. Then, it recalculates the zero point of the part based on its position in the Y, X axes.
Factors to Consider when Selecting a Pick and Place Machine
There are different pick and place machines available. Some pick and place machines are fully automatic while some are semi automatic.
Accuracy and repeatability
It is advisable to check out for the accuracy and reliability of the machine you are opting for. A machine that offers accuracy of +/-.001” is advisable for production machines. Less expensive machines don’t often meet this requirement. Low-cost machines won’t come with software.
Fluid/solder paste dispensing
A pick and place machine should be able to provide a fluid dispensing system. The commonly used liquids are lubricants, solder paste, and more. This is very important when designing one-off PCB assemblies or prototypes.
This is an important consideration for selecting pick and place machines. Also, the software interface is of great importance. The software should be very easy to use and flexible. The Universal CAD Translator (UCT) enables users to import the pick and place information to the database of the machine.
Component position systems
After the machine has picked up the component and centered it. The assembler has to position it accurately on the printed circuit board in an X and Y position. The three methods used for positioning are rotary encoders, linear encoders, and positioning without feedback system.
If the pick and place machine is for a small number of components, you can easily identify the type and number of feeders. Therefore, it is important to consider a pick and place machine with more feeder positions. The types of component feeders include cut strip holders, tube feeders, matrix tray holders, and reel feeders. Your production will determine the choice of your feeders. The best thing is to purchase a machine with the most feeders.
Benefits of Pick and Place Machine
The greatest benefits of the component placement machines are consistency and speed. Also, assemblers can customize these machines to meet some production requirements. They are easy to program. Therefore, they serve multiple purposes. Below are more benefits of a pick and place machine.
This machine works at high speed. Over time, PCB designers have used several heads and gantry features. Also, pick and place machines can handle various parts. This machine can handle about 200,000 components per hour.
Ease of use
Pick and place machines are very easy to use. The automatic pick and place machine has the most intuitive interfaces that guide the operators through important steps. Also, this machine is very easy to program according to the specification of the application.
Precision and accuracy
A pick and place machine delivers precise results. Also, the key to the accuracy of this machine is its optical sensor. This sensor locks onto a feature on a part prior to registering it. The precision and accuracy of this machine offer better performance of the final barePCB.
Precision and accuracy help to prevent errors. This machine offers accuracy and precision to achieve reliable and consistent performance. The programming of this machine ensures the mechanisms and nozzles provide the same performance. Therefore, companies can get good results.
Here comes the end of our article on pick and place machines. If you have any questions, reach out to us here.