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Opens at MiniMELF

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Description:
Open at a resistor in MiniMelf shape. Since the adhesive was not applied in the correct position the wave soldering process could not produce a solder joint (adhesive is on the contact pad). The component should be removed completely and a new one mounted. Excess adhesive is to be removed as well.

Causes/Remedy:
  • positioning fault in adhesive application
  • smearing of adhesive because of manual contact
  • unsuitable properties of adhesive (temperature, viscosity)

Source: SEM
Open at a MiniMELF

Description:
Open at a MiniMelf component after reflow soldering. The contact area (right) of the component is simply lying on the unmolten solder depot without forming an electrical and mechanical contact. This can already be classified as a tombstone effect. Simple rework through renewed soldering.

Causes/Remedy:
  • uneven application of solder paste (quantity)
  • inhomogeneous heat distribution
  • layout faults (heat flow)

Source: SEM
Open at a MiniMELF

Description:
Open at a MiniMelf resistor after wave soldering. It can be clearly seen where the solder fillet between component and contact pad is missing. Rework through renewed soldering is easy. Observe soldering tip temperature.

Causes/Remedy:
  • Shadowing effect during wave soldering
  • poor wettability of components
  • contamination of llanding pads and/or components

Source: visual, optical inspection - general view
Open at a MiniMELF

Description:
Open at a resistor after wave soldering. Non-qualified residues on the right landing pad prevented soldering This shows the effect which even the slightest contamination has on the formation of acceptable soldering joints. Rework is necessary, and it should also be analysed how the contamination was possible.

Causes/Remedy:
  • residues on the landing pads impairing wettability
  • contact pads partly missing metal
  • residues from adhesive application (Fädenbildung)

Source: SEM
Open at a MiniMELF
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