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36th INTERNEPCON JAPAN/23th IC & Sensor Packaging Technology EXPO/23th ELECTRONIC COMPONENTS & MATERIALS EXPO/23th Printed Wiring Boards Expo/12th FINE PROCESS TECHNOLOGY EXPO (Jan.19 - 21)


36th INTERNEPCON JAPAN/23th IC & Sensor Packaging Technology EXPO/23th ELECTRONIC COMPONENTS & MATERIALS EXPO/23th Printed Wiring Boards Expo/12th FINE PROCESS TECHNOLOGY EXPO
New proposals about deposition infrastructure were easy to notice

January 19-21, 36th INTERNEPCON JAPAN/23th IC & Sensor Packaging Technology EXPO/23th ELECTRONIC COMPONENTS & MATERIALS EXPO/23th Printed Wiring Boards Expo/12th FINE PROCESS TECHNOLOGY EXPO were held in Tokyo Big Site. In this here, main topics are picked up.


Mitsubishi Chemical mounts LEDs on an originally epoxy film


Picture 1. Mini/Micro-LED using newly epoxy film
As regards materials, Mitsubishi Chemical demonstrated an epoxy film as a new transparent plastic film. Various inks, pastes, and liquids can be directly coated and printed on this film without buffer layer because of high adhesiveness, which is essential property of epoxy resin. Furthermore, thermal resistance is superior because of Tg free. Transmittance and coefficient of thermal expansion are approximate 89 - 91% and 54 - 71ppm respectively.

The company exhibited this film firstly at The Total Solution Exhibition for Electronic Equipment 2021, which was held in Tokyo Big Site at October 27-29, 2021, and disclosed a distributed type inorganic EL using this film substrate. In this time, Mini/Micro-LED was exhibited by making use of this film. In short, LED chips were directly mounted on this film with Ag electrode without adhesive layer. As a result, it's sure to be effective for electric devices with high adhesiveness and heat resistance.

Reflection ratio is reduced by blackening of wiring using new sputtering target

In this time, new proposals about deposition infrastructure were easy to notice. With respect to material, Daido Steel proposed a sputtering target "STARMESH series" as blackening use of Cu wiring for touch-panel of automobile system. and so on. It's possible to greatly reduce reflection ratio because of blackening and suppression of corrosion of Cu wiring by depositing this film on Cu wiring.


Picture 3. Mesh pattern of 10 μm and 3 μm line width

Picture 2. Comparison of black level (left:STARMESH-β1 film, center:Cu film, right:STARMESH-α1 film)
Cu alloy (STARMESH-α1) and Ti alloy (STARMESH-β1) have been released. Reflectance of the former and the latter are approximate 19% and 16% (@400-800 nm). In the booth, deposited samples of STARMESH-α1 film, Cu film, and STARMESH-β1 film were exhibited to comparison of black level (Picture 2). By the way, Cu alloy film (STARMESH-α1) and Cu films can be wet-etched at the same time. On the other hand, it's necessary to wet-etch Ti alloy film and Cu film respectively (total 2 or 3 times).

Furthermore, as picture 3, fine patterned samples (10 μm and 3 μm line width) were exhibited, too. In short, it's possible to correspond to fine pattern such as 10 μm and under. In the present moment, the company is supplying sample to deposition makers.

Cu film is directly deposited on plastic film by use of high-speed sputtering system


Picture 4. Deposited Cu film by high-speed PVD method
On the other hand, as concerns deposition system, Shibaura Machine appealed an originally high-speed PVD system for deposition of Cu film. PVD is abbreviated name of Physical Vapor Deposition. In a word, it's a sputtering system.

In this system, it's possible to directly deposit Cu film on a plastic film without adhesion layer. It's reason why surface of resin on plastic film is modified because of environment at high density plasma and at medium vacuum area such as 0.1 - 100Pa. In short, function group is generated in surface of plastic film, and then, it's connected to Cu film by chemical reaction. In fact, deposition rate is relatively high same as 35nm/sec. By the way, film thickness uniformity is 10% and under in case of 540 × 630㎜ substrate.

Adhesive is finely patented by the screen printing method

As regards manufacturing process, Micro-tec proposed to use the screen printing method for patterning of adhesive. In the booth, printed sample with various shape pattern, such as frame, dot, square, line, entire-surface was pilot-produced by use of the screen printer "MT-650TVC (Micro-tec)" and a specific adhesive (DELO Industrial Adhesives). It's possible to print fine line same as 250 μm width.


Picture 5. Screen printed sample of adhesive
First target is Mini/Micro-LED, which is difficult to mount LED chip on the substrate. It's easy to produce Mini/Micro-LED relatively by use of this printing technology as mounting method of LED chip.

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