This article is focused on measurement of temperature gradients in different locations on test-boards during Vapor Phase Soldering (VPS) with different materials as PCB substrates. VPS is usually applied in electronics assembly technologies due to its ability to heat the board fast and uniformly during reflow soldering. The heating rate differs significantly even on a moderate size PCB. The measurements were performed on different substrates, particularly on FR4, FR4 with aluminum core, ceramic, and polyimide flexible board samples. The temperature gradients were uniform with low heat capacity boards, contrary, the high heat capacity aluminum based PCB showed significant non-uniformity in heating, where observed temperature differences reached up to 20 °C.