This document discusses bonding in automotive brakes over time. It provides definitions of bond and de-bond. It then shows how brake pad design and bonding materials have evolved from the 1980s to present. Specifically, it notes that older designs from the 1980s-1990s used phenolic adhesives and had simpler pads without features. Modern designs from 2000 onward use pressure sensitive adhesives and have more complex pads with features but rely more on noise damping than bond integrity. The document suggests recent customer expectations for quieter brakes may be leaving investigators puzzled about minor noise issues.

1. Connecting the dots between the past,
present & future of bonding
Ryan French & Haroon Mohmand, 2013.08.29

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bond
/bänd/
verb
joined securely to another thing, esp. by an adhesive, a
heat process, or pressure

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de·bond
/de-bänd/
verb
occurs when an adhesive stops sticking (adhering) to an
adherend or substrate material

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bond (re-defined)
/bänd/
verb
joined securely to another thing, esp. by an adhesive, a
heat process, or pressure
passes the newly developed tap test (audible feedback
must be in such a way as to not allow dead space sound in
pre-defined areas outside of backplate features)
passes adhesive coverage (or disturbance?) test where
the shim is removed and an approximated surface area
determined by overlaying a circle dot matrix and counting
the area that shows no visual adherence

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10. Rubber
(noise damping)
TRELLEBORG GROUP10
Shim With Phenolic (1980’s – 1990’s)
Steel
(structural integrity)
Phenolic Adhesive
(Structural Bond)
2013-08-29

11. Rubber
(noise damping)
TRELLEBORG GROUP11
Shim With PSA (2000- present)
Steel
(structural integrity)
Pressure Sensitive
Adhesive
(noise damping, not dependent on bond
integrity)
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12. Temperature Effects on PSA’s
TRELLEBORG GROUP12
Adhesive Temperature
+-
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Daily Operating Temperatures
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0%
1%
2%
3%
4%
5%
6%
1980 - 2000 2000 - 2008 2008 - present
Acceptable Noise Percentage
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Simple pad design
• No insulator retention features
• No insulator stress relief cuts
• No bond surface area concerns
• No pad/insulator shape concerns
Bonding substrate (backplate)
• Sandblasted
• Zinc coated
• Liquid paint
Complex pad design
• Large / multiple insulator retention features
• Added insulator stress relief cuts
• Bond surface area maximized
• Shapes evaluated for bond integrity
Bonding substrate (backplate)
• Liquid paint
• Some powder paint
(1980’s – 1990’s) (2000 – present)
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Complex pad design
• Limited insulator retention features
• Very few insulators with relief cuts
• Bond surface area?????
• Pad/Insulator shapes evaluated for bond integrity?????
Bonding Substrate (Backing Plate)
• 100% powder paint
(today)
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Today’s end customers expect quieter brakes?
• Which is leading to warranty claims for even minor noise or
potential noise.
• Is this leaving the investigation team puzzled, so they report
all potential causes?
Lazy pad/insulator designs?
• Tighter packaging
• Limited and/or poor retention features
• Not utilizing relief slots
• Limited bonding surface area
• Poor pad/insulator shape
2013-08-29

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