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福英达
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What are the Competitiveness of Anisotropic Conductive Adhesive (ACA)?

2022-09-22

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What are the Competitiveness of Anisotropic Conductive Adhesive (ACA)?

 

Semiconductor packaging is now moving towards miniaturization, with increasing packaging densities. The new mini-LED display has developed rapidly in recent years. There are tens of thousands of chips on a mini-LED screen. Besides, the chip soldering temperature range of mini-LED is large, and the P-N pole spacing on the flip-chip pad is only 40-50μm. The soldering temperature is normally controlled at 100 to more than 200℃, and the regular solder paste is not suitable due to the large particle size. The materials currently used for mini-LED soldering are ultra-fine solder paste, ultra-fine epoxy solder paste (solder adhesive), and solder flux. Fitech’s flagship products, Fitech mLEDTM1370 and Fitech mLEDTM1550 series T8 ultra-fine solder pastes can meet the needs of mini-LED packaging. In addition, the anisotropic conductive adhesive also has excellent effects on mini-LED packaging and can also be used in LED die-bond packaging, FPC flexible products, camera modules, liquid crystal display modules, liquid crystal drive modules, and other ultra-fine-pitch components. This article briefly discusses the ACA.
 

Excellent properties of ACA

Low-temperature ultra-fine-pitch soldering: ACA is an epoxy solder paste that can be used for ultra-fine-pitch soldering. T8-T10 Sn42Bi57.6Ag0.4 alloy powders are the solid components of ACA. ACA has great advantages for scenarios with high soldering density, fine pad size, and ultra-fine pitch. Moreover, the melting point of Sn42Bi57.6Ag0.4 is only 139 °C, which can be applied to low-temperature soldering requirements.

 

Anisotropic properties: Anisotropic conduction means that the conduction is inconsistent in different directions. When using ACA for soldering, the solder joints are vertically conductive and horizontally non-conductive. The ACA is made of Sn42Bi57.6Ag0.4 alloy, which has an excellent conductive effect.


ACA soldering mechanism
Figure 1. ACA soldering mechanism.

 

Solder joint strengthening: The ACA can be deposited on the pads by dispensing. After the soldering process is completed, the epoxy resin will be cured into a thermosetting adhesive, which can enhance the mechanical strength of the solder joints. Meanwhile, the cleaning step is omitted, and the production efficiency is improved.

 

Good adhesion: When the LED chip falls on the substrate, the ACA can play the role of buffering and bonding, which can reduce the positional deviation of the tiny chips due to the excessively fast falling speed.

 

Fitech can provide soldering materials for mini-LED packages. Self-developed products Fitech mLEDTM1370, Fitech mLEDTM1550, and anisotropic conductive adhesive products can all be used for mini-LED soldering. The die-bond effect is excellent, and the reliability after soldering is high. Welcome to consult.

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