Analysis of patch capacitor rupture and Short Circuit

This article mainly introduces the main causes and countermeasures of chip capacitor (multilayer slice ceramic capacitor) rupture and failure.
There are three main points:
1. The main cause of problems such as rupture and short circuit is not due to the chip capacitor itself, but more factors related to the whole installation and welding process of the capacitor.
2. rupture and failure are the most common and major problems encountered in the use of SMD capacitors.
3. avx proposes solutions and corresponding products for this general situation, named flexiterm, and describes the main benefits and features of this product.
 
It should be emphasized that:
1. Although we have seen the introduction of this product in the article, we have not found this product on the market for large-scale sales.
2. When we notice this problem during line layout and strengthen process control throughout the production process using SMD capacitor, the corresponding cracking and failure situations will be improved.
 
I. Analysis and Countermeasures of MLCC rupture-avx 
Mark Stewart, Coleraine, North Ireland, avx Co., Ltd,
 
The comparison between the popularity and selectivity of MLCC capacitors is first of all their outstanding reliability record and low cost. However, in a specific environment, the ceramic part of the component may break down. When the components are welded to the circuit board, these failures are usually caused by mechanical damage. When the circuit board is maloperated or assembled under extremely harsh environment conditions, it will also lead to failure.
Fault
Just as capacitors are dominant in the number of components, multilayer ceramic capacitors (MLCC) are widely used in circuit design because of their high reliability and low cost. Even due to the characteristics of ceramic materials, MLCC itself may be cracked during assembly due to improper operations or in special environments. For this reason, the fault is broken and becomes mounted to the circuit board.
The most common failure mode of MLCC. The most common result of bending a printed circuit board with components is the cracking of the MLCC element. This kind of bending is caused by external force mechanically caused by assembly production and harsh operating conditions. In the worst case, a low resistance cracking failure may lead to extremely high temperatures, when it is directly connected to the power supply line and has sufficient current to pass through, the direct area of the circuit board will cause devastating damage.
Click to view detailed analysis

Ii. Case study of MLCC rupture and Short Circuit
Cause analysis:
This crack is not produced during the manufacturing process of the capacitor and is subject to mechanical stress or thermal stress during the use of the capacitor.
Therefore, if you do not know the production process of your company, the initial analysis may be due to the following reasons:
① During the mounting process of the capacitor, if the pressure on the suction nozzle of the stick machine is too high, bending will easily lead to deformation and crack;
② Welding pad layout and metal frame welding end welding excessive soldering tin in welding by thermal expansion force, so that the thrust will be lifted capacitor, prone to crack.
Click to view detailed analysis