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PCB Assembly What Are The Ways
Nov 03, 2017

Electronic product assembly because of its large number of components, variety of complex and short life cycle of electronic products such as the characteristics of production operation has brought huge challenges, many varieties, small batches, variable batches has become the main stream of electronic production methods. In this way, the switching time between many varieties occupies an increasing proportion in the whole assembling time.

It is composed of high speed SMT machine and multifunction Mounter. In fact, the entire PCB assembly line also includes the pallet feeder, screen printing presses, dispensing machine, reflow soldering and curing furnace, and other equipment, these devices together to form a PCB assembly line, but these auxiliary equipment does not constitute the whole pipeline bottleneck process, so in the modeling to be omitted. Each patch machine can hold 20 feed slots, each of which occupies a feeding slot on the Mounter. In general, a single variety of PCB circuit board requirements of the number of components can not exceed the capacity of the feeder, but many varieties of PCB required by the total number of components generally exceed the capacity of the feeder.

In the process of the installation of different types of PCB circuit board requirements of the components are organized in these feeding slots, take the equipment from the feeding trough to remove components affixed to the PCB on the designated position. According to the inquiry data of the empirical research policy, the time for the high speed Mounter to mount a component evenly is 0.06s, the time to switch a feeding slot evenly is 180s. Multi-function Mounter has two operating units, but as long as a job station, the other one is only used for placing large or special-shaped components, each operating table to accommodate 10 of the feeding trough, uniform placement of a component demand 0.18s, evenly switch a feeder time of 220s. In the different varieties of PCB switching, mounter requirements must be ready to switch time, generally to switch a component feed slot time of about 6 times times, that is, 1200s. This shows that the switching time in the electronic product assembly process has a irrelevant position.

In many varieties of small batch environment, the general PCB is grouped first, will have similar characteristics of the PCB into a group, so that in the same group, different types of PCB assembly between the need to replace the feeder, also do not need to switch time, but when the two sets of PCB between the need to replace the feeder, the need to consider their switching time between. Accordingly, PCB production scheduling problem is divided into two levels: the first level scheduling problem is called "board-level" scheduling problem, that is to determine the PCB group in the production sequence between the PCB; the second level scheduling problem is called "group-level" scheduling problem, that is to determine the production sequence between PCB organization.