Brookfield DV-III Ultra Rheometer - Manual (Page 63)

Brookfield Engineering Laboratories, Inc. Page 63 Manual No. M98-211-E0912
Figure IV-51
When chocolate is used for enrobing, it must have a yield stress high enough to stay in place once
it enrobes the filling. In the case of decorating chocolate, the yield stress must be high enough so
it can keep its shape once it has been squeezed into place through a nozzle. For molding chocolate,
the plastic viscosity must be low enough to completely fill the mold.
(The NCA/CMA lists Brookfield’s HA-spring range viscometer with a Small Sample Adapter,
SC4-27 spindle and SC4-13R sample chamber as the approved apparatus.)
The IPC Paste Model
η
=kR n
The IPC Paste Model was developed for solder pastes. It calculates the viscosity of solder pastes at
10rpm. The IPC Paste Model requires that the product be tested with a Brookfield Spiral Adapter
at multiple speeds. More details can be found in the IPC-TM-650 Test Methods Manual (methods
2.4.34.2 and 2.4.3).
This model is a variation of the Power Law Model. Unlike the Power Law Model, which relates
apparent viscosity to shear rate, the IPC Paste Model relates apparent viscosity to the testing speed
(rpm).