formic acid soldering processes€¦ · 3s perfects your soldering process • formic acid...

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Formic Acid Soldering Processes

Conventional

soldering process

Formic acid

soldering process

3S enables 3 Free

soldering solutions:

• Flux Free

• Void Free

• Solder Splash Free

1


• Assembly solution provider for high power devices

• 20 years experience in Die Attach, Clip Attach and Reflow process

• Over 500 installed bases for power devices with clip process all over

the world.

3S Silicon tech., Inc.

• 100 employees

• Worldwide technical support and

service

• Contact our representative or visit

www.sss-tech.com.tw

2

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Residue Free & Low Void — Formic Acid Vacuum Reflow Oven

Kuo-Liang, Yeh

Sept. 19th 2019 11:00-11:30

Location: 4F TechXPOT

Booth no: I2320

Email: [email protected]

3S Silicon Tech We are different and better


Today

• Why is the formic acid process essential?

• How can soldering problems be solved by formic

acid?

• What breakthrough has 3S Silicon tech made?

4


Why is the formic acid

process essential?

5


Package Void rate Solder Reflow Oven Application Power Devices

Stereo

package >30% Preforms

Convection reflow

oven

Consumer

electronics

Flattened

design (SMT) 10-30%

High flux

contained

solder

paste

convection reflow

oven/ 2008 3S

launched snap

oven

Household

appliances

charger

Mobile phone power

management

Flattened and

matrix design 2-5%

Low

residue

solder

paste

2015 3S launched

vacuum reflow

oven

Vehicle electronics

Server

Smart Appliances

Flattened and

matrix design <2%

Flux free

solder

paste

2019 3S launches

formic acid

vacuum reflow

oven

High-end automotive

electronics

High-end IC

Military and aviation

diodes

Evolution of Power Devices

6


Power Device Packaging Process

Below

Dispensing Die Bond

Upper

Dispensing Reflow Oven Clip Bond

Top view Side view

Assembly of components

TO lead frame TO appearance

7


Drawbacks of Voids

As a result of voids:

• Increase resistance

• Decrease thermal conductivity

• Corrosion solder joint

• Lower reliability

• Shorter lifetime

Chip

Lead Frame

Solder

Joint Macro-voids

Planar micro-voids

8


How can soldering problems

be solved by formic acid?

9


Formic Acid Soldering Process

Metal Metal

oxide

RCOOH

R’4NX

+ M(COOR)

Metal

HCOOH

+ H2O + CO2

Ideal formic acid soldering solution :

Traditional soldering process

Formic acid soldering process

Solder Paste

Flux Solder alloy

Rosin Tackifier Activator Rheology

Modifiers Solvent

R’4NX RCOOH

• Flux Free

• Void Free

• Solder splash Free

Metal Metal

oxide

10


Applications of Formic Acid Soldering Process

Copper Pillar Bumping

Formic

Acid

DBC to baseplate

A. Wafer bumping B. Flux free preforms

Bump size: 50um Preform size: 55mm

Commercialized applications

Metal oxide

Clip

FA (formic acid)

C. Flux free Solder Paste

Not yet commercialized application

11


Key Issues

Challenges of solder paste:

a. Larger surface area, more metal oxide

b. Penetration depth of FA

c. Slow reaction rate of formic acid

r r/2

Surface area

6r2 Double Surface area

[ 6(r/2)2 ] * 8 = 12r2

a

FA

Metal oxide

Clip

Melting solder

FA

Temperature

Reaction time

b

c

12


What breakthrough has

3S Silicon tech made?

13


3S’ Novel Formic Acid Reflow Oven

A. Formic Acid

Gas Supply

System

D. Plasma

Assisted

Exhaust Gas

Treatment

B. Double- Chamber Formic

Acid Design

C. Smart

Machine

Performance

EHS Policy

Features:

• Shorter cycle time

• Higher throughput

• Lower void rate

• Stronger bonding strength

• Safer FA supplied system

14


Operation of Formic Acid Reflow Oven

Double-Chamber Formic Acid Reflow Oven (patented by 3S)

Zone 1

2 3

4 5

Cycle time 45 - 90 sec

15

Formic

Acid

FA Gas

Vacuum

/Plasma

1 2 3 4 5 6 7 8 9 10 11

Evaporator


Profile of Formic Acid Chamber

Zone

3

Zone

4

Zone

5

Zone

6

Zone

7

Zone

8

Zone

9

Atmosphere

(760torr)

(1 torr)

Cycle time 45-90s

(700 torr)

N2

FA

℃


Double-Chamber Formic Acid Reflow Oven

“Double-Chamber” design is required

1. Each chamber provides optimized

conditions for different metal oxides

2. Shorten cycle time

Standard Electrode Potentials

Sn2+(aq) + 2e- Sn -0.14

Cu2+(aq) + 2e- Cu 0.34

E0/V

Chamber no. Function

1-4 Preheat zones

5 Copper oxide reduction

6 Heating zone

7 Tin oxide reduction

8 Precooling

9-11 Cooling zones

17

Reduction of

CuO SnO


FA FA

FA

FA

N2

N2

N2

N2 N2

N2 FA

FA FA

FA

N2

Formic

Acid

N2 /FA

Metal oxide

Clip

Metal oxide

Clip

Under vacuum

Deeper penetration Under 1 atm

Poor penetration

Passive

diffuse

Active

drive in

N2

N2

N2 N2

N2

Penetration Depth

Slow Faster

3S pure FA gas Traditional FA/N2 mix gas

N2 N2

N2

N2

18


Top view

FA

FA

Penetration

depth: ca. 2mm

Penetration Depth Between Pure FA Gas and FA/N2 Mix Gas

Side view

Depth: 100um

glass

vacuum

PFA: 40 torr

10 sec

Normal pressure

PFA:PN2 = 40 : 720 torr

10 sec

Penetration

depth: ca. 11mm

Before reflow

3S Pure FA gas Conventional

FA/N2 Mix gas

19

tape

340℃ 340℃ FA FA

Solder

powder


• Improve penetration

• Enhance reactivity

Pure FA Gas

(patented by 3S) FA/N2 Mix Gas

Poor reactivity Higher reactivity

Metal oxide

FA FA

FA

FA

N2

N2

N2

N2 N2

N2

FA

FA FA FA

Metal oxide

N2

Formic

Acid

N2 /FA

20

Reactivity Between Pure FA Gas and FA/N2 Mix Gas


Reactivity Between Pure FA Gas and FA/N2 Mix Gas

Reaction time:

PFA: 40 torr@ 340℃ PFA:PN2 = 40 : 720 torr @ 340℃

1000 msec 1000 msec 5000 msec

Metal oxide

FA FA

FA

FA

N2

N2

N2

N2 N2

N2 FA

FA FA FA

Metal oxide

3S pure FA gas supply system is 5 times faster than FA/N2 mix gas.

Pure FA Gas

(patented by 3S)

FA/N2 Mix Gas

Each FA is surrounded

by 18 N2.

21


EHS Policy

Healthy Safety

EHS

• Closed FA supplied system no CO, FA leakage

• Plasma enhances FA decomposition

• Smart safety control

2HCOOH + O2 2CO2 + 2H2O

2CO + O2 2CO2

Plasma oxidation

Environment

22

HCOOH + heat CO + H2O

Formic acid decomposition


3S Perfects Your Soldering Process

• Formic acid soldering process is a non-clean process with Flux Free, Void

Free , Solder Splash Free.

• 3S enhances FA penetration depth up to 5 times deeper.

• 3S enhances FA reaction rate by 5 times faster.

• 3S provides safer, non-toxic gas leakage and environment-friendly soldering

process.

• 3S provides an open innovation platform lab for product verification.

Formic Acid / Vacuum

Reflow Oven

Die/Clip Bonder Dispenser Screen Printer

23


Thank you for Your Kind Attention

3S Silicon Tech We are different and better

24


Contact information:

•Booth no: I2320 • Tel: 886-3-5577-668

• Mail: [email protected]

• 3F, 169-2, Sec. 1, Kang-Le Road, Hsin-Feng Shiang, Hsin-Chu County, Taiwan

304440

Q & A

25

formic acid soldering processes€¦ · 3s perfects your soldering process • formic acid...

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