00198521-01_UM_LDU_E_EN.pdf - 第28页
3 Function description and structure 3.3 Basic process 28 User Manual SIPLACE Linear Dipping Unit E 12/2018 3.3.2 Thickness of flux layer The amount of flux on the component depends on the thickness of the flux layer in …
3 Function description and structure
3.3 Basic process
User Manual SIPLACE Linear Dipping Unit E 12/2018 27
Flux application by dipping
During dipping, the component (3) is dipped with tweezers (4) into the flux by the placement
machine (2) and is then placed onto the board (6) with the contact surfaces (5). The flux must be
made available in a suitable carrier (1), on as even a surface as possible. The component is picked
up from the feeder module and is dipped into the flux. The leads or contact surfaces of the compo-
nent are coated with this flux (7). After this, the component is placed on the board. Thicker flux
types or solder pastes can be used for dipping.
3 Function description and structure
3.3 Basic process
28 User Manual SIPLACE Linear Dipping Unit E 12/2018
3.3.2 Thickness of flux layer
The amount of flux on the component depends on the thickness of the flux layer in the cavity. The
layer thickness depends both on the cavity depth and the coating effect of the fluid used. The cavity
depth is engraved on the top of the dip plate.
Influence of cavity depth on the layer thickness
In the following diagram, the same component is dipped into various different dip plates. The dip
plate cavity in (1) is deeper than in (2). This means that more flux adheres to the component be-
cause the layer of flux is thicker here.
Influence of coating fluid on the layer thickness
The capillary effect describes the behavior of fluid as shown during the contact between solids and
capillaries e.g. narrow tubes, gaps or hollow spaces.
Example: if one dips a glass tube vertically into water, the water will rise up a little in the narrow
glass tube against the force of gravity. This effect is caused by the surface tension of the fluid itself
and the interfacial tension of the fluids with the solid surface.
1. Dip plate
2. Flux
3. Hollow
4. Cavity depth in the dip plate
5. Remaining flux height
Multiple measurements lead to a value for reduction of the layer thickness. This value shows that
the flux layer thickness is roughly 2/3 of the cavity depth i.e. the layer thickness is reduced by about
1/3. Since the value of 2/3 is a rough estimate, the exact amount of flux which stays on the compo-
nent must be determined in tests. In very critical processes, dip plates with a customized cavity
depth can be supplied.
3 Function description and structure
3.3 Basic process
User Manual SIPLACE Linear Dipping Unit E 12/2018 29
Influence of coating fluid on the dipping area
A hollow is formed in the flux at the edge of the cavity. This has a width of about one to two milli-
meters.
1. Dip plate
2. Flux
3. Width of hollow
This means that the dip plate area which can be used is smaller than the cavity itself.
1. Dip plate
2. Cavity
3. Hollow
4. Dipping area, determined by the hollow
5. Edge area, determined by the hollow
This effect is taken into account in the station software. The placement machine automatically
keeps an edge of 3 mm when dipping components. The dipping area is therefore 6 mm smaller
than the cavity itself. The cavity has a size of 75 mm x 55 mm, the available dipping area only a
size of 69 mm x 49 mm.
1. Dip plate
2. Cavity
3. Print of dipped component in the flux
4. Dipping area, determined by the software
5. 3 mm edge area, determined by the soft-
ware