00193407-02 HWWS SIPLACE Machine Accuracy EN.pdf - 第5页

SIPLACE

Placement Systems

Machine Capability

SIPLACE

Placement Systems

Capability Indices

Indices are used to assess the quality of machines, steps in a process and complete processes.

A single index does not provide sufficient information for the complete characterization of a

process. A comprehensive overview of the qualification status of the process under examination

can only be achieved by studying a combination of several indices.

Placement accuracy takes the deviation from the actual position and the target position of the

components into account.

This contains positioning errors for the linear axis, rotational errors at the placement head,

twisting of the gantry system, errors at the vision modules, .....

More and more fine pitch components are being placed and an increasing number of very small

passive components, size 0402, 0201 and more smaller. Consequently, higher and higher

placement accuracy is a demand of placement machines.

Many natural and technical processes which occur randomly (stochastically) can be described by

a normal distribution.

The deviation of the placement position from the target value consists of a reproducible

component and a random component. The reproducible component can be kept relatively low

through calibration measures. The random component is close to normal distribution (this has

been experimentally confirmed). The normal distribution provides an exact mathematical model

for describing placement accuracy.

Machine Capability