PCBA Tech - How to improve the efficiency of SMT processing

Today, let’s talk about the efficiency of the placement machine in placement processing? The core of this problem is the delivery date. Assuming that the materials are available, the delivery date after the on-line production is determined by the machine's SMT chip processing speed and efficiency. The core point is back to the placement machine, the placement speed of the placement machine. The placement speed determines the production capacity of the placement machine and the placement processing plant, and is an important limiting factor for the production capacity of the entire placement processing line.

1. Placement cycle.

The placement cycle is the most basic parameter that marks the placement speed. It refers to the time taken from the time of picking up the component, after testing, placing it on the PCB, and returning to the picking component position. Each time such a stroke is performed,

a placement operation is completed, that is, a placement cycle is completed. The placement cycle of general high-speed machine placement of Chip components is within 02s, and the current maximum placement cycle is 0.06-0.03; the placement cycle of general general-purpose machine placement QFP is 1-25, and the placement cycle of chip components is 0.3～0.6.

2. The placement rate.

The placement rate refers to the number of components placed in 1h, and the unit is ch. It is the placement speed measured by the placement machine manufacturer under ideal conditions. The calculation of the theoretical speed does not consider the PCB loading and unloading time, the placement distance is the closest, and only a small number of components (about 150 chip components) are attached, and then the time used to mount a component is calculated, and the 1h placement quantity is calculated based on this .

However, the following auxiliary time should be considered in the actual SMT chip processing and production.

a. PCB loading overhead time, usually 5-10s for the placement machine.

b. The components on the large (rectangular) PCB are far apart, so the placement time will be prolonged.

c. Refueling time.

d. Machine maintenance time (days, weeks and months).

e. Unpredictable downtime.

In short, the actual placement speed is much lower than the theoretical placement speed, usually 65%-70% of the theoretical placement speed. This is a question that should be considered when choosing a placement machine or calculating the production capacity of the placement machine.

Methods to improve the production efficiency of SMT patch processing

The efficiency of SMT chip processing has many aspects. For example, if the overall production volume is constant and the number of smt chip production lines is large, the production speed can also be increased. However, the operating costs are also increasing. Nowadays, the fierce competition in the electronics industry is unimaginable. In the case of the existing placement production line, it is essential to increase the placement rate and win customer satisfaction. The following briefly introduces the placement rate factors and improvement measures:

The placement production line mainly consists of a screen printing machine, a high-speed placement machine, a multi-function placement machine, a reflow soldering machine and an AOI automatic detector. If the two placement machines complete a placement process (hereinafter referred to as the placement time) When they are equal, the patch rate will be affected. The specific methods are as follows:

1. Balanced load distribution. Reasonably allocate the number of two placement components to achieve a balanced load distribution so that the placement time of the two placement machines is equal;

2. The smt placementmachine itself. The placement machine itself has a maximum placement speed value, but it is generally not easy to achieve this value. This has a certain relationship with the placement machine's own structure. For example, the placement machine of the X/Y structure adopts The measure is to make the placement head pick up components at the same time as much as possible. On the other hand, when arranging the placement program, arrange the same types of components together to reduce the number of nozzle changes when the placement head picks up components and save placement time.