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6 Component placement
1. Manual placement of parts
2. Automatic placement of parts
Surface mount components are placed on a printed circuit board after deposition of adhesive or solder paste. Generally, the adhesive deposition is done at the placement equipment itself. Thus the main function of most placement equipment is adhesive deposition, and of course component placement. Placement equipment is commonly referred to as
“pick-and-place” equipment. The components can be placed on the board by
1. Manual placement
2. Automatic placement
Manual placement of surface mount components is not reliable and can be used only for prototyping applications. The following are some of the problems associated with manual placement of components.
1. Most passive components do not have any part markings, and therefore, the possibility of part mix-up is very high.
2. Placement of components in wrong orientations due to operator related errors
3. Placement accuracy will again depends on the operator and it is very difficult to obtain good placement accuracy with manual placement.
In component placement, there are two main functions, pickup and placement. In manual placement, the components parts are picked up either by tweezers or by a vacuum pipette. For passive components tweezers are adequate, but for multi-leaded active devices, a vacuum pipette is very helpful in dealing with component rotation and is recommended when working with manual placement of components.
The following are the benefits of using manual placement machines
1. Very low capital cost
2. Ideal for prototype development due to low turnaround time and low cost
3. For low volume production manual pick and place machines with vacuum pickup and placement are preferred.
2. Automatic placement of parts
Automatic placement machines are required for high volume production as the manual method turnsout to be very slow. It is also possible to achieve consistent quality levels with automatic placement equipment. Vision capability is required for placement of fine-pitch components and it may add to the overall cost of the equipment. The following are the important parameters while selecting an automatic placement machine.
1. Placement speed, i.e. the number of components that the machine should be able to place per minute
2. Requirement of placement of fine pitch or very fine pitch components
3. The variety of components that the machine should handle
4. Types of feeders that the machine should support
5. Other features like CAD data downloading for reduction in programming time
6. Ability to dispense adhesive
7. Need for component testing
The user has to choose the placement machine appropriately depending on the application on hand and the future needs.
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