The document describes LPKF's laser direct structuring system for 3D electronics fabrication. Key steps include: 3D part and conductor design, part coating with epoxy, laser etching of conductive traces, copper plating of traces, and post-processing like soldering or wire bonding. The system allows electrical functionalization of 3D structures for applications like antennas on housings or chemical sensors with flip-chip die on plastic substrates.

1. Speciality Products and Services Group
LPKF Laser Direct Structuring System
LPKF – Laser Direct Structuring
of 3D devices.
 Electrical functionalisation of non conductive 3D
Structures
 Electrical tracks produced on 3D structures -
allowing SMT assembly, die attach, wire bonding
etc.
Metallised Fingers for
Robotic Hand

2. LPKF Laser Direct Structuring System
Tyndall Fabrication Process
• 3D Design and drawing.
• 3D part fabrication.
• Conductive layer design and drawing.
• Part Coating – ProtoPaint epoxy layer.
• Laser Direct structuring as per design.
• Copper plating
• Post processing – NiAu plating, Flip chip bonding,
SMT, wire bonding etc.

3. LPKF Laser Direct Structuring System
Fabrication Principle
LPKF Laser Direct Structuring System

4. LPKF Laser Direct Structuring System
3D Design
• In-house 3D design of parts
• Autocad used to produce .step files which can be
imported to LPKF system.
• Autocad used to produce .dwg files for fabrication
in mechanical workshop.

5. LPKF Laser Direct Structuring System
3D Part Fabrication
• In-house mechanical workshop fabrication from 3D
designs.
• Parts fabricated from metals or plastic materials.
• 3D designs can be used to fabricate parts using
standard 3D printers

6. LPKF Laser Direct Structuring System
Conductive layer design
• Autocad produces .stp files with both the 3D part
and associated conductive layer.
• LPKF system used .stp file to laser write the
conductive layer on a ProtoPaint epoxy layer which
is applied to 3D part surface.

7. LPKF Laser Direct Structuring System
Part Coating – ProtoPaint epoxy layer.
• Spray coating of 3D part surface.
• Multiple layer build up to produce a
smooth surface finish.
• Low temperature oven bake to cure
epoxy.
• Coating on conductive and non
conductive materials.
• Possible materials include metals,
plastics, glass, FR4 etc.

8. LPKF Laser Direct Structuring System
Laser Direct Structuring – Laser writing
• LPKF system laser etches the conductor design in
the top surface of the ProtoPaint epoxy.
• The laser removes some of the epoxy material
exposing metal particles in the ProtoPaint layer.
• These metal particles can act as a seed layer for
deposition of Cu layer.

9. LPKF Laser Direct Structuring System
Laser Direct Structuring – Protopaint
• Metal particles exposed by the laser
• Copper, palladium, Chromium and Magnesium Seed Layer

10. LPKF Laser Direct Structuring System
Copper plating
• Electroless copper plating of seed layer exposed by
laser etching of the ProtoPaint top surface.
• Layer thickness is a time-temperature dependent
build up of copper.

11. LPKF Laser Direct Structuring System
Copper plating

12. LPKF Laser Direct Structuring System
Copper plating
• Test coupons used to check track resistance and
isolation between tracks.
• Different track and gap widths were designed to
look at the effect of this on electrical
measurements.
• Typical track resistance of <1 ohm
• Typical isolation of > 2K ohm
Part Type Plating Thickness Track Resistance Ω Fingers Resistance Ω
200 µm TG 9 µm 0.8 0.8 Open Circuit >2000
200 µm TG 9 µm 0.9 1.0 Open Circuit >2000
500 µm TG 5 µm 0.8 1.0 Open Circuit >2000
500 µm TG 9 µm 0.5 0.5 Open Circuit >2000
100 µm TG 6 µm 0.5 0.6 Open Circuit >2000
200 µm TG 3 µm 1.4 1.4 Open Circuit >2000

13. LPKF Laser Direct Structuring System
Post Processing - Solder
• Copper plating provides a solderable finish
• Allowing post process SMT assembly, solder
flip chip etc.
Solder ball Placement
Element ID
size x
(um)
size y
(um)
SIZE X
(inch) SIZE Y (inch)
Area 10-4 (inch
square)
Mil-883-J Requirement
(Kg)
Measured Shear Force
(Kg)
SMT 1 1200 500 0.0472 0.0197 9.30 0.37 3.12
SMT 2 1200 500 0.0472 0.0197 9.30 0.37 2.72
SMT 3 1200 500 0.0472 0.0197 9.30 0.37 4.12
SMT 4 1200 500 0.0472 0.0197 9.30 0.37 3.08

14. LPKF Laser Direct Structuring System
Post Processing - Solder
• Solderable finish allows for in house Laser
Assisted Solder Jetting (SB²)

15. LPKF Laser Direct Structuring System
Post Processing - NiAu Plating
• NiAu Plating on the copper surface
• Increased solderability
• Wire bondable finish
Bond
No.
Strength
(gf)
Military
Standard (gf)
(1) 5.35 3.00
(2) 6.45 3.00
(3) 8.30 3.00
(4) 4.55 3.00
(5) 5.90 3.00
(6) 5.65 3.00
(7) 9.10 3.00
(8) 4.95 3.00
(9) 5.15 3.00
(10) 6.20 3.00

16. LPKF Laser Direct Structuring System
Post Processing - NiAu Plating

17. LPKF Laser Direct Structuring System
• Post Processing - NiAu Plating – Assisted Solder Jetting (SB²)

18. Demonstrator 1 – Antenna on housing
 Antenna fabricated directly on
surface of 3D printed component
housing.
LPKF Laser Direct Structuring System

19. Demonstrator 2 – Chemical Sensor
 Flip chip over hole based micro electrode chemical sensor
 3D substrate Demonstrator
 Silicon based Micro electrode arrays.
 Complete Design and Fabrication in Tyndall
 Machined plastic substrate
LPKF Laser Direct Structuring System
PCB Equivalents
Silicon Sensor die

20. Demonstrator 2 – Chemical Sensor
Electrodes
Machined plastic substrate
Protopaint application
Laser Patterning
Copper plating
Solder flip chip
Underfill sealing of
sensor
LPKF Laser Direct Structuring System

21. Contact Information
Ken Rodgers
Phone: +353 21 2346898
Email: ken.rodgers@tyndall.ie
Finbarr Waldron
Phone: +353 21 2346093
Email: finbarr.waldron@tyndall.ie
LPKF Laser Direct Structuring System