Adhesives Overview

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Adhesives Overview

• By JoAnne Moody
• Adhesives Consultant

Zeta Scientific LLC
April 25, 2007
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Overview Topics

• Market
• Adhesion Terminology
• Applications
• Design Considerations
• Case Studies
• The Future

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(Est. 2004)
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Whats an Adhesive?
Adhesive - a substance capable of holding
materials together by surface attachment.
(Reference ASTM)
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Reference Adhesive Sealant Council Inc (ASC)
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ReferenceAdhesive Sealant Council Inc (ASC)
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Applications

• Consumer
• Electronics
• Medical and surgical
• Construction
• Transportation
• Telecommunications

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Adhesive Advantages

• Quick, easy, cheap and convenient
• Join dissimilar materials
• Fills gaps and voids
• Thin bond lines
• Invisible means of attachment
• May provide conductive or insulation properties

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Adhesive Limitations

• Must insure that substrate and adhesive are
  compatible
• Aging and shelf-life considerations
• Incoming material controls
• Surface preparation is critical
• May require mixing and curing time
• Parts need to be held in place during curing

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Adhesive Families

• Structural (epoxies, polyurethanes,
  cyanoacrylates)
• Water-based (natural rubber, acrylics, silicones)
• Pressure Sensitive Adhesives (acrylics, rubber,
  silicone)
• Hot Melts (Ethylene vinyl acetate, polyethylene)
• UV and E-beam Cured (acrylate, urethane,
  polyesters)
• Note This list is not all inclusive of the
  chemical families.

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Conditions

• Environmental (temperature, humidity, etc.)
• Safety factors (such as shear loads, etc.)
• Product-specific requirement
• Surface preparation
• Shelf life and aging

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Failure Modes

• All adhesive bonds should be tested to failure to
  understand the potential failure mode
• Adhesive failure The bond breaks between the
  substrate and adhesive
• Cohesive failure The bond does not break
  between the substrate and adhesive instead, the
  internal strength of the adhesive causes it to
  split. This is the preferred failure mode in
  most cases.

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Adhesive Selection

• Identify requirements.
• Determine assembly process.
• Select adhesive type and match the chemistry.
• Test bond in actual and simulated (aging) tests
  of different adhesives. Understand failure mode.
• Design production process and in-line monitoring.
• Setup quality for incoming material and
  shelf-life controls.

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Poster Mounting Adhesive Case Study

• Requirements Bond paper poster to a wall.
  Removal should not damage the poster or wall, and
  no staining.
• Assembly process Use hands only, no tools.
• Adhesives Various mouning adhesives
• Tests Simulate condition with adhesive, paper
  with a weight, and test board. Test shear, peel,
  and staining.
• Design production process and in-line monitoring.
• Setup quality for incoming material and
  shelf-life controls.

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Poster Mounting Adhesive - Case Study
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Medical Device -Intravascular Ultrasound (IVUS)
Catheter Case Study

• Flip chip bonding (indium solder bumps)
• Die underfill (cyanoacrylate)
• Encapsulation (UV cured adhesive)
• Adhesive bonding piezoelectric film to
  encapsulated device (cyanoacrylate)
• Welding wire to substrate (resistance welding))
• Conductive adhesive (silver-filled epoxy)

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Medical Device - IVUS Test Case
Flip chip bonding die underfill
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Medical Device - IVUS Test Case
Encapsulation
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Medical Device - IVUS Case Study
Adhesive bonding of piezoelectric film to
encapsulated device
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Medical Device - IVUS Test Case
Wire welding conductive adhesive bond
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Trends

• Adhesive growth in structural applications
• Raw material price increases impact growth
• Manufacturing expansion in Asia and Eastern
  Europe to reduce costs
• Demand rising in dental medical adhesives
  (Global Info 2005)
• Replacing mechanical fasteners in electronic
  components, transportation, and aerospace
  (Freedonia 2007)

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Adhesive Consultant
JoAnne Moody Principal Zeta Scientific LLC PO
Box 2935 Livermore CA 94551 Tel [phone] Fax
888.657.6506 joanne_at_zetascientific.com http//www.
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