Noise study method of soldering joints

Formerly we have studied the noise of different electronic components (e.g. thick film resistors, polymer conductive layers, compound semiconductors, thin film layers). Now we concentrate on soldering technology. The contacts should have low resistance, low noise and high stability in time. Recently we try to find a noise measurement method to qualify the soldering joints. The measurement of noise is not very easy. We need an appropriate setup, a low-noise amplifier, separated source of energy for the circuit, isolation of other interfering signals from the environment. Since the noise of a contact is typically low, we also have to separate the contact noise from other noise sources in the circuits. Because the contact noise is still low, it is recommended to use several contacts in a serial line of connection. We also have to use multi-contacts, instead of a long soldering tube, since we want to investigate the contacts, not only the soldering materials. Basically we want to study three kinds of joints: carefully made, careless made, and damaged.