Burnthrough

Burnthrough is a failure mode in which heat, flame, or other process energy causes a material to burn or melt through its own thickness, creating a hole or compromising a barrier. It can occur during manufacturing, processing, or service when heat input exceeds what the material and its surroundings can safely tolerate. The term is used in welding, electronics, and fire safety contexts, among others, and its implications range from cosmetic damage to structural failure or loss of fire resistance.

In welding and metalworking, burnthrough describes unintended penetration of the base metal or joints due to excessive heat input, long dwell times, or inadequate shielding. It creates through-holes and can weaken joints. Preventive measures include adjusting welding parameters (current, voltage, travel speed), using appropriate shielding gas, employing backing materials, and controlling heat input with proper technique and interpass temperature management.

In electronics and printed circuit boards, burnthrough refers to damage where excessive heat or current causes insulation breakdown or substrate scorching, potentially delaminating layers or severing connections. Prevention focuses on appropriate trace widths and spacings, adequate copper weight, effective thermal management, proper soldering procedures, and using materials with suitable thermal resistance.

In fire safety, burnthrough or burn-through time describes a barrier’s vulnerability to fire penetration, where flames or hot gases breach a compartment boundary. This concept underpins fire-rated constructions and testing standards that assess the integrity and insulation of walls, floors, and doors to slow the spread of fire.

Common across contexts is the aim to prevent burnthrough by controlling heat input, cooling, materials selection, and appropriate design margins.