PCB Material Thermal/Mechanical Consideration

PCB Material Thermal and Mechanical Consideration

Microvias PCB in India

Glass Transition Temperature (Tg)

Glass Transition Temperature
  • The temperature at which the resin changes from a glass-like and relatively brittle state into a molten or rubber-like state changing its mechanical behavior, i.e. expansion rate
  • The glass transition takes place over a temperature range
  • Electrical and mechanical properties change as the material goes through the glass transition
  • The Coefficient of Thermal Expansion (CTE) increases dramatically above the glass transition temperature
TgRangeApplication
Low130-140 Deg CConsumer electronics, Instrumentation
Mid150 Deg CMemory storage, PC & Notebook, game station
High>175 Deg CAutomotive, Industrial, Aerospace, Military, Networking&communication

 

PCB Thermal Expansion

Coefficient of Thermal Expansion (CTE)

  • The CTE of a base laminate is the rate of expansion as a function of temperature change
  • In glass reinforced composite laminate the X-Y CTE is significantly lower (16-18 PPM) than the Z axis (55-60 PPM) since the glass fabric constrains primarily in the X-Y plane.  CTE increases dramatically above the glass transition point
  • Mismatched in plane X-Y CTE with respect to component package CTE can result in solder joint failure
  • Excessive Z axis expansion can result in hole barrel failure due to barrel cracks and corner cracks
Re-enforced Glass fabric

 

PCB Material Cross section

Thermal Decomposition Temperature (Td)

Thermal Decomposition Temperature
  • Thermal Decomposition Temperature Td: Measurement of the actual chemical and physical degradation of the laminate resin, based on mass loss vs. temperature.  A materials decomposition temperature is determined based on a 5 percent loss of the samples mass however, damage is occurring prior to the 5 percent weight loss !

Impact of Sequential Lamination

Sequential Lamination

Cerra Systems is one of the leading PCB manufacturing solutions providers with PCB manufacturing plants located in North America, Asia with certifications for MIL, AS, TS, ISO, & NADCAP. Our products are Rigid, Flex, Rigid-flex, HDI, RF, and hybrid PCBs addressing up to 64 layers and 2 mil technology. Cerra Systems  Major  PCB Market is Aerospace, defense, Medical, computing, cellular & Industrial. Microvias PCB in India

For more information, visit- http://cerrasystems.com/pcb-fabrication/