FAQ
Q.
What kinds of patterns are there among reflow profiles that can cause tombstoning?
  • Kondensatoren
  • >
  • Keramik-Vielschichtkondensatoren (MLCC)


A. There are largely two patterns. The first pattern is the case in which there is imbalance between the forces (FA and FB) applied to the electrode terminals in Figure 1. The second pattern is the case in which air trapped under the solder paste at the time of heating becomes air bubbles and pushes the chip capacitor terminals from below.

Pattern 1
Pattern 2
The phenomena that occur in each reflow profile range are summarized in Table 1.
Profile Region Soldering Effect on Component
a
b

Flux separates from paste and begins to wick up the component.
c

Some flux evaporates; the solder paste looses viscosity and runs together between PCB pads
Good Pattern 1 Pattern 2
d

175~185°C

Chip is pushed up

Unequal solder melting
e

185~195°C

Chip is pulled down

Unequal solder wetting

Flux
f

220~230°C

Foam generates and one end of the chip is lifted up
g

No Tombstoning

Tombstoning

Tombstoning


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