Conventional SLC single layer capacitor consists of capacitive ceramic substrate, upper surface electrode and lower surface electrode. The upper surface electrode and the lower surface electrode are respectively placed on the two surfaces of the capacitive ceramic substrate. The upper surface electrode and the lower surface electrode are made of the same metal electrode, such as silver paste or gold paste. Due to the capacitive ceramic substrate, upper surface electrode and lower surface electrode of the SLC single layer capacitor are obtained by sintering at temperatures above 800℃, so the temperature resistance performance of the chip capacitor in actual use is usually determined by the temperature resistance performance of the welding material between the chip capacitor and the applied circuit module.

The bonding process of conventional chip capacitance is to stick the lower surface electrode of the chip capacitor on the circuit board with low-temperature silver glue, and connect the upper surface electrode of the chip capacitor with the welding pad on the circuit board by means of aluminum wire, copper wire or gold wire. As the curing temperature of low-temperature silver glue is about 100℃, the temperature resistance of solidified silver glue is not more than 150℃, so the temperature resistance of the existing chip capacitor is not more than 150℃, so it can not adapt to the working environment of high temperature. Solder paste reflow soldering process is often used to weld SMT circuit boards, which has the advantages of high precision, high efficiency, stability and reliability. Compared with low-temperature silver glue, the temperature resistance of solder paste reflow soldering process can up to 260℃. Therefore, solder paste reflow soldering application in chip capacitor welding process can significantly improve the heat resistance of chip capacitor.

However, the conventional single layer capacitor has the following problems in the bonding process and actual use of solder paste reflow soldering:

Silver surface electrode is suitable for wire bonding with aluminum wire, copper wire or gold wire, and the soldering effect is good, but when the silver surface electrode is soldered on the circuit board using solder paste reflow soldering technology, there is silver migration phenomenon, which will cause the loss of the electrical properties of mutation and reliability of chip. In order to solve the above technical problems, EXSENSE Electronics introduces a composite electrode SLC single layer capacitor, which is suitable for reflow welding and wire bonding, and has the advantages of great bonding effect, high temperature resistance, high reliability and high stability. The upper surface electrode of this chip capacitor is silver layer, and the lower surface electrode is titanium tungsten layer, copper layer and gold layer which are stacked on the capacitor ceramic substrate from inside out.

Composite electrode SLC single layer capacitor, the upper surface electrode is used for wire bonding, the lower surface electrode is used for circuit board bonding. The silver layer (Ag) of the upper surface electrode is the base layer bonded with the capacitor ceramic substrate, which can form a strong bond with the capacitor ceramic substrate, and the silver layer of the upper surface electrode can bond with aluminum wire, copper wire or gold wire well. The titanium tungsten layer (TiW) of the lower surface electrode is combined with the capacitor ceramic substrate, and acts as a transition layer, which mainly plays the role of transition, so that the copper layer is better combined with the capacitor ceramic substrate, and has a blocking effect. The copper layer (Cu) of the lower surface electrode is used as a barrier layer to prevent the damage of the transition layer from the outside and has welding effect. The gold layer (Au) of the lower surface electrode is not only the welding layer, but also the protective layer, its stability is high, which can prevent the oxidation, corrosion and damage resistant, prevent silver migration, and effectively block the solder penetration into the silver layer during solder reflow soldering to form a tin-silver alloy and avoid the occurrence of silver migration phenomenon, thus preventing the solder paste from destroying the silver layer.