1. Sony ACF (Single Layer)

Sony developed advanced ACF technology called Microconnector, which is applied to COF and COG joints. This ACF material is a breakthrough development in the production of conductive particles. The conductive particles are generally coated with a metal layer on the surface of the plastic core, and then a 10nm thick insulating layer is coated on the surface of the metal layer, and the insulating layer is composed of extremely fine resin particles.

The resin adhesive of the development material can be a thermoplastic or thermosetting material, and then conductive particles are added to make a paste or film. When this material is attached to a flexible board substrate for the hot pressing process, the conductive particles and chip bumps and the flexible board substrate electrode will simultaneously break the insulating layer of the contact surface (that is, the Z axis direction), but the XY plane direction that is not contacted The insulating layer will not be crushed and maintain its insulation. Therefore Sony believes that the use of such conductive particles coated with an insulating layer can increase the particle density of anisotropic conductive adhesives, achieve the requirements of fine pitch and low on-resistance, and at the same time, no short circuit will occur.

2 Hitachi ACF (Double Layer)

In response to the fine-pitch requirements, Hitachi Chemical has proposed an ACF with a double layer structure. The upper layer of the double layer structure is a resin layer without conductive particles added, while the lower layer is an arrangement containing a single layer of conductive particles. Compared with the traditional single-layer ACF, the double-layer structure can increase the density of particles in the unit contact area of ​​the electrode without increasing the density of conductive particles. The density of particles in the unit contact area is higher, and it is close to the chip bump. In the region, the occurrence of short circuits is reduced due to the low local particle density.

In terms of resin adhesives, for reliability considerations, Hitachi Chemicals has chosen to use epoxy systems on its products to improve the material's adhesive strength, glass transition temperature, and moisture resistance.

3  3M ACF

4  Toshiba ACF

5  TeamChem Company ACF16, AC42

Low temperature operation of ACF16: Low temperature storage, 12 months below -15 ° C, 14 days at room temperature, hot pressing temperature of 80 degrees Celsius, can be applied to PET film with low heat resistance, ITO glass substrate

ACF16 is an anisotropic conductive adhesive film that Haizheng Industry launched in 2010. The biggest difference from the general commercial ACF products is their low temperature operation characteristics. Pre-sticking at room temperature, hot pressing can be completed at 80 ° C. And then the electrical resistance is low, high stability, can withstand high temperature, high humidity and reflow.

During operation, pre-adhere at room temperature, and then heat-press at 80 ° C x 5 seconds-10 seconds.

Please do not use gaskets during pre-adhesion and hot pressing, because gaskets will slow down the heat conduction, resulting in the adhesive film not being able to reach the hot-melt state in a short time, resulting in poor adhesion.

After hot pressing, the resin can be stored slowly at room temperature, so that the resin can slowly and continuously carry out molecular bonding reaction, and its bonding strength can be gradually increased accordingly. If necessary, post-cure reaction can also be used to improve its bonding strength. Post-cure can be used at 90 ° C x 60 minutes. If the product finally needs to be able to pass high temperature re-soldering, it is recommended to use two-stage post-baking: 90 ° C x 30 minutes to 150 ° C x 30 minutes, then the strength can be increased to more than 1.0 kg / cm, which is more durable. Harsh high temperature environment.

This product can be repaired after hot pressing, that is, if the conductivity problem is caused by excessive pulling or poor operation after hot pressing, it can be repaired simply by hot pressing at 80 C x 5 seconds. Without the need for heavy industry. If rework is required due to poor alignment, it can be removed simply by wiping with acetone.

After hot pressing, it can be stored at room temperature, so that the resin can slowly and continuously carry out molecular bonding reactions, and its bonding strength can be gradually increased with it. This product is RoHS & Halogen-free compliant and does not contain PFOS & PFOA.

6 UPAK ACF

Weifeng is the first mass-produced ACF manufacturer in China. Currently there are two types of products: FOG (FPC on GLASS) and FOB (FPC on PCB). COG (CHIP on GLASS) is already developed but the cost is not too high. Suitable for entering the market.