The Intermetallic Compound (IMC) layer grows in the interface between Cu-based, Ni-based and Sn-solder is the certain result of the chemical reaction that forming the soldering joint. But the IMC layer is also the weakest location of the solder bonding-force.
As mentioned last page, the bonding strength of PCBA shall include a minimum of 5 defect positions. Identifying the growth of IMC is crucial in determining the quality of soldering. If there is no IMC layer grows between the solder alloy and Cu or Ni substrate, the electronic component and PCB will not be joined. However, the IMC layers are also the weakest point in the whole soldering strength structure. Why?
The IMC is the abbreviation of Inter-Metallic Compounds in the electronics manufacturing industry. The IMC layer is the certain result of the chemical reaction to form the soldering joint. WorkingBear likens the IMC layer just like a child born from the marriage of a girl and a boy.