august 2015 - aculon tem analysis.pdfipa does not as effectively clean the treated stencil as...

CONFIDENTIAL: Aculon, Inc. @ 2015 1CONFIDENTIAL: Aculon, Inc. @ 2011

August 2015

CONFIDENTIAL: Aculon, Inc. @ 2015 2

About Aculon

Aculon conducted TEM on the following samples for TEM Analysis:

1. No nanocoating on stencil 2. Nanocoating on stencil prior to printing by Aculon3. Nanocoating on stencil after 15,000 printed: 5,000 cleaned by

auto wiper with solvent.

• Aculon NanoClear coating present after 15,000 prints. However, TEM Analysis indicates that the stencil is not clean and a buildup of solder paste/ contamination is present.


(Map contrasts are optimized to show element distributions, they are not directly proportional to actual abundances)

Sample preparation procedure

1. A thin layer of chrome is sputtered onto the surface of the stencil in order to be able to distinguish coating layer and the stencil.

2. C-based sharpie ink coating and then Pt coating – both to protect the sample from charging during sample preparation process.

3. Tool used for sample preparation: FEI Helios 450

4. Tool used for TEM Analysis: JEOL 2010


Stainless steel

Bright layer below Cr layer is intrinsic coating layer from sample itself.

Grey layer is Cr layer to distinguish intrinsic coating layer and our filling material – C based sharpie ink.

Bright layer above Cr and the dark material above it is our filling /protecting materials -C based sharpie ink and Pt layer, respectively.


• TEM micrographs with low and high mag for surface and corner of stencil with no coating

Low mag cross section of surface, corner and sidewallHigh mag cross section of surface

High mag cross section of surface High mag cross section of surface

Carbon layer

Pt layer Stencil

CONFIDENTIAL: Aculon, Inc. @ 2015 6• TEM micrographs with high mag for corner & sidewall aperture of stencil with no coating

High mag cross section of corner High mag cross section of corner

High mag cross section of sidewall High mag cross section of sidewall

Carbon layer

Pt layer

Stencil

CONFIDENTIAL: Aculon, Inc. @ 2015 7• TEM micrographs high mag for surface, corner and sidewall of stencil with nanocoating

Sidewall Sidewall Sidewall Sidewall

CornerSurface Surface

Nanocoating

Nanocoating

Chrome layer

Carbon layer

Pt layer


About Aculon

• TEM micrographs high mag for surface & of stencil with nanocoating

Surface Surface

Surface Corner

Chrome layer

Nanocoating


• TEM micrographs with high mag for sidewall of stencil with nanocoating

SidewallSidewall Sidewall Sidewall

Nanocoating


Low mag image Low mag image (indicating where high mag images were taken from)

Surface Surface

TEM micrographs with low and high mag for surface & corner of stencil after 15K printing Samsung process shows three layers – NanoCoating, Contamination and Chrome

Nanocoating

Chrome Contamination


About Aculon

Surface Surface Corner

• TEM micrographs with low and high mag for surface and corner of stencil after 15K printing Samsung process shows three layers – NanoCoating, Contamination and Chrome

Nanocoating

Contamination


About Aculon

Side Wall

TEM micrographs with low and high mag for surface & corner of stencil after 15K printing Samsung process shows three layers – NanoCoating, Contamination and Chrome

Nanocoating

Chrome Contamination


Summary

Stencil with no nanocoating: No coating was detected Stencil with nanocoating: Nanocoating was detected with thickness ranging

from 0.99nm to 4.76nm. Stencil with nanocoating after 15,000 printed (5,000 cleaned by auto wiper with

solvent): Nanocoating remained intact. However, there appears to be a buildup of solder paste/ contamination beneath the chrome layer that was not present before. Due to a lack of cleaning solder paste / contamination has essentially overwhelmed the nanocoating as material has built up on top of it.

In prior work Aculon has demonstrated that the use of just a dry wipe or using just IPA does not as effectively clean the treated stencil as engineered solvents. See Appendix pages 17 -19.


Recommendation

After 4 years of working with this technology and customers we have developed a series of best practices to improve Nanoclear durability that include the following:

1. Utilize Soft non Abrasive Understencil Wiper Paper E.g. DEK Eco Roll SC-ER3602. Utilize a Solvent Wipe Rather than a Dry Wipe – engineered solvents are even better3. Utilize pH Neutral Cleaners4. Reduce Understencil Wipe Frequency


Appendix


• Ultraviolet tracer added to flux

• Underside of stencils photographed with black light illumination after each print/wipe test

• Readily reveals flux build up and clogged apertures

Enhanced image


Wipe

Type Nano-Coating #1 No Coating Nano-Coating #2

VDV

VWV

IPA

VWV

Eng

Solv


Testing by both Kyzen and Zestron have determined NanoClear’scompatibility and the durability with their respective stencil washes.

A treated stencil was subjected to the following test procedures:

Kyzen Zestron

Treated samples submerged in 6 popular Kyzensolutions at room temperature with no agitation

Washed in Vigon SC 210 at 15% concentration

Pieces removed after 15 mins and 1, 4,8,24,48 hours

Washed for a total of 2400 minutes exposure (160 cycles at 15 minutes) each in a Systronic SYS 152/2 system

Rinsed with DI water & Dried Foil checked for compatibility after each wash cycle

Surface energy measured using dyne pen Rinsed with DI water

If surface energy < 30 dyne/CM then it was considered a pass

The stencil was inspected and tested every 20-30 cycles for delamination and discoloration and repellency

All of the solvents were compatible with NanoClear

Performance. Surface. Solutions.

august 2015 - aculon tem analysis.pdfipa does not as effectively clean the treated stencil as...

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