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Figure 6-5
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 AMETEK Brookfield's HA-spring range viscometer with a Small Sample Adapter, SC4-27 spindle
and SC4-13R sample chamber as the approved apparatus.)
6.6 The IPC Paste Model
η
=kR
n
The IPC Paste Model was developed for solder pastes. It calculates the viscosity of solder pastes at 10 RPM. The
IPC Paste Model requires that the product be tested with a AMETEK 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).
M19-2101 REVISION 2.0
D V N E X T R H E O M E T E R - O P E R AT I O N A L M A N U A L
85
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