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© 2011 Underwriters Laboratories Inc.
UL UpdatesPWB Testing & Certification
INEMI Update
April 3, 2014
Objectives
Demand Driver for PWB Certification
UL PWB Services
LTTA Theory
2000 hour LTTA Program
2
At UL, our mission of working for a safer world
since 1894 is at the core of everything we do.
- Advancing safety through
research and investigation
- Preventing or reducing
loss of life and property
- Promoting safe living and working
environments for people
UL offers an extensive array of services to our
diverse customers that support every stage of
the product life cycle, from the testing of new
technologies to market access.
PROVIDING SERVICES FOR
A SAFER WORLD
3
Global Electronics PWB Migration
Industry wants PWBs to be
• Smaller
• Cheaper
• Environmentally friendly
• Lead-free and halogen-free
OEMs turning to
• Unique rigid PWB constructions
• Flexible PWBs
Are the new constructions safe?
4
UL’s PWB Program
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• Driven by end product safety concerns:• Fire
• Electric Shock
• Characterize the behavior of the PWBs:• Physical, electrical, flammability, thermal
• Used as guidance for end product safety:• Material manufacturer, PWB fabricator, end product manufacturer
Requirements & Standards
Components End Product Requirements
Plastics Laminates PCBs
IEC 60950
IEC 60065
IEC 62368
IEC 60601
IEC 60335
IEC 61010
Information Technology
Equipment
Audio & Video Equipment
ITE and Audio/Video
Equipment
Medical Equipment
Appliances
Equipment for Laboratory
Use
UL 94
UL 746A
QMFZ2
UL 94
UL 746E
QMTS2,
QMJU2
UL 796
UL 796F
ZPMV2
ZPXK2
ZPVI2
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Benefits of UL PWB
Recognition
• PWBs covered by UL’s
Component Recognition Program
• Type Testing
• Confident that PWB complies
• Pre-selection allows for less
testing
• UL Recognized PWBs used
Globally
• On-going compliance FUS
• Audit during production
• Ongoing confidence the
component complies
7
UL PWB Services
• Basic Service for PWBs is Safety certification
• UL Mark demonstrates PWB certification
• UL PWB program accepted internationally
• PWB Certification Options
• Full Recognition – MOT, Flame rating and DSR
• Flame only – Flame rating only
• Materials (QMTS2) ≠ PWBs (ZPMV2)
• UL iQ for PWBs
• Intended for end-product, PWB mfrs, and EMS (Electronic Manufacturing
Services)
• Database includes Rigid and Flexible PWBs, Laminates and Coatings
• Allows searching by UL ratings, company name, type designation and UL File
Number
8
Long Term Thermal Aging (LTTA) Theory
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Purpose of Long Term Thermal Analysis
(LTTA)
Exposure to heat and weathering is a
major cause of polymeric material
degradation
• Degradation rate usually increases
with temperature
• Even at room temperature, given
enough time, polymeric materials will
degrade
Degradation characteristics for the following properties are important• Mechanical Properties – Tensile Strength and Delamination
• Electrical Properties – Dielectric Breakdown
• Flammability Properties - Ignition
Thermal Endurance Aging Theory
IEEE
• 1: Recommended Practice - General Principles for Temperature Limits
in the Rating of Electrical Equipment and for the Evaluation of
Electrical Insulation
• 98: Standard for the Preparation of Test Procedures for the Thermal
Evaluation of Solid Electrical Insulating Materials
• 101: Guide for the Statistical Analysis of Thermal Life Test Data
A comparison of the thermal-aging characteristics of one
material of proven field service at a particular temperature
level with the thermal-aging characteristics of another
material with no field service history provides a means for
estimating the relative thermal index level at which the
second material might also provide acceptable field
service.
Thermal Endurance or RTI
(746B, 6.1)
A relative thermal index of a material is an indication of the material’s
ability to retain a particular property (physical, electrical, etc.) when
exposed to elevated temperatures for an extended period of time. It is a
measure of the material’s thermal endurance. For each material, a
number of relative thermal indices can be established, each index
related to a specific property and a specific thickness of the material.
•Not a “Maximum Operating Temperature” but a maximum temperature
below which a material maintains its characteristics over a reasonable
period.
•The international community has endorsed the RTI concept from
UL746B under the alternate designation of the Relative Thermal
Endurance (RTE) in IEC 60216-5.
Basis for Thermal Aging (746B, 8.3)
The thermal-aging characteristics of a material can be determined by
measuring the changes in its properties to a predetermined level by
aging at each of several elevated temperatures; plotting log of time to
end-of-life against the reciprocal of absolute temperature; and plotting
the best-fit straight line by regression analysis. The plotted line is often
referred to as the life-line of a material.
The Arrhenius Equation
With proper application of chemical kinetic theory and subject to the
limitations imposed by necessary underlying assumptions, then the log
of these end-point times should be a linear function of the reciprocal of
the absolute end-point temperatures.
RT
E
AeK
K = Specific Reaction Rate T = Absolute Temperature
E = Degradation Reaction Activation Energy
R = Gas Constant A = Constant
Specialized Analysis of Polymer
Variations: The “2000hr LTTA Program”
WHY POLYMER VARIATIONS
- Product developers are frustrated with the time it
takes to validate the performance of a laminate
modification
- Laminate customers do not understand why it
takes so long to get a product modified and
approved
- Industry programs in more critical applications
(e.g. automotive) accept shorter programs to
validate similar performance for modifications
- Laminate manufacturers stand by their product
performance even without an RTI, but their
customers demand RTI value!
15
DEVELOPMENT OF PROGRAM
Development began with a few basic questions:
- What if we could consider customer generated
data?
- What if we could conduct more analytical testing
to confirm material properties?
- What if we could conduct a high temperature
verification per industry standards to determine
similar performance?
16
CRD:
Certification
Requirement
Decision
DEVELOPMENT OF THE CRD
The following CRD was finalized for UL 746A
17
OPPORTUNITIES
- Any polymer variation
- A versus A’
- Addition, Deletion, Replacement, Change in
Level in UL 746A, Table 9.1
LIMITATIONS
- Validate the same RTI only
- Not for an increase in RTI
- Not for an evaluation of a reduced thickness
18
DEVELOPMENT OF THE CRD
DEVELOPMENT OF THE CRD
CLAUSE (a)
The most important clause in the CRD!
- Customer information is considered
- Analytical testing is conducted
- A and A’ are considered equivalent through
analytical testing and customer supplied data
19
DEVELOPMENT OF THE CRD
CLAUSE (b)
Confirmation of statistically similar high
temperature performance
20
- How about Provisional Ratings?
• Provisional RTI Ratings on ingredient variations can be
provided if
- The analysis of the data per (a) of the CRD shows comparable
results between control and candidate
- Basic analytical testing is conducted at UL (IR, TGA, DSC, DMA,
PDSC) to determine comparable analytical profiles
- The short-term side-by-side testing per UL 746A, Table 9.1 is
completed
• Same grade – same or better side-by-side performance
• New grade – lower short-term side-by-side performance, but with
similar long-term degradation profile expected
• Final ratings will be provided with completion of the 2000 hour
elevated temperature confirmatory testing
21
Paragraph
9.9.2
PROPOSED REVISIONS
FUTURE WORK
22
130°C
115°C
130°C
125°C
140°C
120°C
130°C
140°C
RTI Banding/Cloud
105°C
140°C
Contact UL
North America
Engineering: Andrea Cote [email protected] (408) 754-6662
Engineering: Peter DeWeese [email protected] (714) 223-3676
Engineering: Michelle Courier Ross [email protected]
(408) 754-6591
Principal Engineer: Crystal Vanderpan [email protected]
(408) 754-6584
Europe
Engineering: Stephen Street [email protected] +441483402005
Asia
Engineering: Amy Chen [email protected] +886277373272
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THANK YOU.
