Direct Dispensing – An Overview

Direct dispensing is a dispensing method for applying liquid and jellylike substances directly to the workpiece’s underside. The principle is similar to that of a stamping or pin transfer process. The difference is that here the workpiece forms its own reference for the substance application. This means that the workpiece itself is used as a stamping tool for the substance transfer. The entire workpiece or an individual area, such as connection pads, is used as a reference surface for wetting. The substance is provided on a foil that is formed by means of a vacuum structure. Respective process requirements are realized by arranging and exchanging of several structures as well as providing different substance thicknesses.
General workflow of the direct dispensing process:
The workpiece is immersed in the substance. There is wetting on the underside and, under certain circumstances, also slightly on the lower lateral surfaces of the workpiece.
The foil with the substance is structured according to the process requirements before or after the workpiece is immersed.
The workpiece is lifted out of the substance again.
If the workpiece is lifted out far enough, the substance will tear off, with parts of the substance remaining on the workpiece.
The workpiece with the substance is now ready for further processing, e.g. for assembly on a carrier substrate.
Direct dispensing is usually used in the following process steps:
  • Partial or full surface wetting of the workpieces‘ underside
  • The substance is applied directly to the workpiece to be assembled
  • Chip gluing with chip-on-board
  • Time-critical processes between substance application and workpiece placing
  • special forms of the dispensing material or the connection point
References
[1] Offenlegungsschrift DE000010145396A1
[2] Patent DE000010145396B4
[3] International patent application WO002002022278A2
[4] International patent application WO002002022278A3

Fig. 1 Direct dispensing unit with prepared dispensing material (blue)

3. February 2021

Leave a reply