Abstract: A package includes a substrate having a conductive layer, and the conductive layer comprises an exposed portion. A die stack is disposed over the substrate and electrically connected to the conductive layer. A high thermal conductivity material is disposed over the substrate and contacting the exposed portion of the conductive layer. The package further includes a contour ring over and contacting the high thermal conductivity material.

Abstract: A Li-ion battery pack includes a Li-ion battery, a protection circuit, and multiple plugs connectable to a power hand tool. The positive pole of the Li-ion battery and the DC supply terminal of the protection circuit are electrically connected to two contact pieces of one respective plug. The two contact pieces are short-circuited by the positive contact terminal of the power hand tool. The negative contact terminal of the power hand tool is connected to a negative-pole contact piece of one plug, so that when the potential difference between the positive and negative poles of the Li-ion battery surpasses the low voltage level defined by the protection circuit, the protection circuit switches on the connection between the negative pole of the Li-ion battery and the negative-pole contact piece for enabling the positive and negative contact terminals of the power hand tool to obtain DC power supply from the Li-ion battery.