User Manual SIPLACE Linear Dipping Unit 2 X - 第34页
3 Function description and structure 3.3 Basic process 34 User Manual SIPLACE Linear Dipping Unit 2 X 05/2020 Flux application by dipping During dipping, the component (3) is dipped with nozzle (4) into the flux by the p…
3 Function description and structure
3.3 Basic process
User Manual SIPLACE Linear Dipping Unit 2 X 05/2020 33
3.3 Basic process
The following section describes the dipping process and the parameters which influence this pro-
cess.
3.3.1 Usage of flux
To improve the solderability of corrosive components or components with complex structures, the
contact surfaces of these components should be coated with additional flux during production. This
increases the quality of the soldered connection. The flux is applied to the relevant contact surfaces
of the component or board during the placement procedure. The two most common procedures are
dispensing
and dipping. In addition, there are other procedures such as printing, stamping, spray-
ing, brush application etc.
Flux application by dispensing
During dispensing, the flux is applied directly onto the board (1). A needle (3) is positioned exactly
over the soldered connection or the contact surfaces (2)
and a defined amount of flux (4) is applied
to the soldered connection. A film forms on the soldered connection, in which the component (5)
is
placed with the tweezers (6)
. Only thin flux types are suitable for dispensing.
3 Function description and structure
3.3 Basic process
34 User Manual SIPLACE Linear Dipping Unit 2 X 05/2020
Flux application by dipping
During dipping, the component (3) is dipped with nozzle (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 a surface that is flat as possible. The component is picked up
from the feeder module and is dipped into the flux. The leads or contact surfaces of the component
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.
3.3.2 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 dipping plate.
Influence of cavity depth on the layer thickness
In the following diagram, the same component is dipped into various different dipping plates. The
dipping plate cavity in (1)
is deeper than in (2). This means that more flux adheres to the compo-
nent because the layer of flux is thicker here.
3 Function description and structure
3.3 Basic process
User Manual SIPLACE Linear Dipping Unit 2 X 05/2020 35
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. Dipping plate
2. Flux
3. Hollow
4. Cavity depth in the dipping 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, dipping plates with a customized cavity
depth can be supplied.
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. Dipping plate
2. Flux
3. Width of hollow
This means that the dipping plate area which can be used is smaller than the cavity itself.