# Presentation: 732295

## 2005 Micro/Nano Breakthrough Conference 
Portland, Oregon
 July 25- 28th, 2005 

Direct-Write Laser Micropatterning Techniques for Polymer Circuits, MEMS Interconnects and Ceramic Thick-Film Devices

**Portland, Oregon**
** ****July 25- 28th, 2005**** **
**Direct-Write Laser Micropatterning Techniques for Polymer Circuits, MEMS Interconnects and Ceramic Thick-Film Devices**

- *Scott Corbett, *Jeff Strole, *Kyle Johnston,
- **Wilson Lu, **Edward Swenson
- *MicroConnex, Inc.
- **ElectroScientific Industries, Inc.

## What is UV Laser Direct Write Patterning?

- “Using a vector-translated single laser beam
- to create a pattern”
- 		 Exposure
-           (Lower Fluence)
-             Ablation
- 	       (Higher Fluence)

- Photodefinable Dielectric or Conductor
- (Additive or subtractive)

- Non-photodefinable Dielectric or Conductor
- (Subtractive)

## Why Use Direct-write?

**Why Use Direct-write?**

- Fine-line patterning without expensive photolithography equipment
- “Virtual” pattern can be scaled to match part geometry based on fiducial alignment
- Direct transfer from “software” to “hardware” without intervening process steps
- Can be used in combination with or to replace conventional patterning methods
- Deep aspect ratio patterning

## Applications for Direct Write Processing:

- Exposure:
- Patterning positive and negative resists
- Patterning photosensitive thick film conductive inks
- Additive patterning of UV sensitive epoxies (desktop manufacturing)
- Ablation:
- Patterning positive and negative resists
- Patterning non-photosensitive dielectrics (solder masks, etc.)
- Patterning metals, ceramics, glass, polymers and other materials (subtractive)
- Via drilling of dielectrics

## Direct Write Exposure Tool:

- Pulsed UV-laser drill used as direct write imager
- ESI 5330 UV laser machining station

- 355 nm wavelength (tripled-YAG)
- Vector control of beam position
- Automatic control of laser fluence down to 30mJ/cm2 (1-5 mW average power) in range required for ink exposure or ablation
- Serves dual purpose of drilling and patterning
- Alternative beam geometries available

## Pulsed Laser Exposure Parameters (Time)

- Time

- Power

- T=1/PRF

- Average Power

- Peak Fluence

## Beam/Exposure Parameters (Spatial)Gaussian Beam

## Scanned Gaussian Beam (Produces tapered cumulative flux pattern) 

**Scanned Gaussian Beam ****(****Produces tapered cumulative flux pattern) **

**Cumulative Flux after scan**

**Integration Line**

## Shaped Beam Optics“Top Hat” Beams

- UV Laser

- Collimator

- Galvos

- Scan Lens

- Sample

**Imaging Optics**

- Round Top Hat

- Square Top Hat

**Shaped Beam Optics****“Top Hat” Beams**

## Round versus Square Shaped Beam (Line-Scan Cumulative Fluence) 

## Fluence Comparison (Line Scan)(Gaussian, Round Top Hat Round, Square Top Hat)

**Fluence Comparison (Line Scan)****(Gaussian, Round Top Hat Round, Square Top Hat)**

## Deep Aspect Via Drilling using Shaped Optics Laser Beam

**Deep Aspect Via Drilling using Shaped Optics Laser Beam**

## UV Laser-machined PZT Ceramic Die

## Laser machining of PZN PT Sensor Array

## Laser Exposure/Ablation of Resist(Negative Resist/Subtractive Process Example)

_**Laser Exposure**_
**(Pattern traces)**

**Laser**

_**Laser Ablation**_
**(Pattern spaces)**

**Resist**
**Metalization**
**Dielectric**

## Laser Exposure versus Ablation(Positive Resist/Additive Process Example)

_**Laser Exposure**_
**(Pattern traces)**

**Laser**

_**Laser Ablation**_
**(Pattern spaces)**

**Resist**
**Metalization**
**Dielectric**

## Laser Exposure or Ablation of Resist for Etch Mask(Positive Resist)

- Exposure

- Ablation

## Example of Patterned Flex Circuit(Combining Mask Photolithography with Laser-exposure of Resist)

**Direct-Write Region**

## SEM of Fine Line Inductor Pattern 

**SEM of Fine Line Inductor Pattern **
**in Resist**

- 10μ Lines, 20μ Pitch, 15μ Thick Resist

## Fine Line Inductor Pattern (Detail) 

**Fine Line Inductor Pattern (Detail)**

**10μ Lines, 20μ Pitch, 15μ Thick Resist**

## Photoimagable Thick-Film Paste Example(i.e Fodel® 6778)

_**Laser Exposure**_
**(Pattern traces)**

**Laser**

_**Laser Ablation**_
**(Pattern spaces)**

**Metal paste**
**Dielectric**

- Screen

- Expose

- Develop

- Ablate

- Fire

- Fire

## Laser Imaging Fodel® 6778

- 100 μm
- pitch

- 50 μm
- pitch

- 75 μm
- pitch

- 40 μm
- pitch

## Small Inductor Pattern in Fodel®(Ablation Process)

## Inductor Pattern Detail

**20 μm line pitch**

## Etchable Thick-Film Ink Example(Positive Resist/Subtractive Process (i.e. Heraeus KQ500 )

_**Laser Exposure**_
**(Pattern spaces)**

**Laser**

_**Laser Ablation**_
**(Pattern spaces)**

- Resist

- Fired Ink

- Ceramic

## Laser Ablation of Fired Ink (Heraeus KQ500)

- 40 μm pitch

## SEM of Unfired Heraeus KQ500 Gold Conductor (Ablation Process)

**10μ Square Spot Ablation, 20μ Pitch**

## SEM Picture of Fired Heraeus KQ500 Gold Conductor

**10μ Square Spot Ablation, 20μ Pitch, 8****μ Thick**

## Conclusions

- Vector UV laser direct write is a versatile tool for a variety of patterning requirements.
- Applications include:
-  Trace patterning of circuit boards, flex circuits, thick-film ceramic circuits
- Machining of a wide variety of materials including metals and dielectrics
- The process can be additive (exposure) or subtractive (ablation)
- Shaped beam optics improve the aspect ratio of the machining process
- We have demonstrated circuit features as small as 10 μm
- Key advantage of direct conversion from file to patterned circuit