Solder paste frequently asked questions and answers

Missing weld

★ Printing: offset, solder paste thickness is not uniform, the amount of tin is less

★ Patch: offset, mounting pressure, thimble positioning is poor

★ Reflow welding: the temperature setting is not appropriate, the element is not heated enough

★ Material:

a: Poor weldability of components

b: The solder paste is not very active

c: PCB and component pin are not coplanar

skew

★ There is a shift in the position of the imported components of the reflow welding furnace: check the placement machine positioning side

Method and mounting accuracy, adjust the placement machine; Check the adhesion of the solder paste; Smooth transmission process

Sex; Observe the transfer condition of substrate when entering tin furnace.

★ In the process of reflow welding occurred the component shift; Check the temperature curve and preheating time

Whether the regulations are complied with; The track operation is smooth and smooth.

★ Whether the printing amount of solder paste is too much; Adjust the printing amount of solder paste

★ Substrate welding area design is correct; Recheck according to welding zone design requirements

★ Whether the activity of solder paste is qualified; Can change the use of active solder paste

hollow

★ Printing:

a: The solder paste is too thick and the solder paste is too much

b: The ambient temperature and humidity exceed the standard, and the solder paste or PCB and BGA are damp

c: Dry solder paste does not roll

★ Reflow welding: temperature setting is not appropriate

★ PCB: The position of the PCB through hole is incorrect or the bubble is buried in the hole

★ PCB, components: not baked

★ Material: a: The quality of solder paste is not good b: There are bubbles in the BGA tin ball

Continuous tin

★ Printing: offset, bridge, uneven surface, tip, too thick, too much solder paste

★ Patch: the mounting is offset or the pressure is too large, resulting in the rear bridge connection

★ Reflow welding: temperature setting is not appropriate, uneven heating or too fast heating

★ PCB, steel mesh design: steel mesh thickness or opening discomfort

★ Material: thixotropy, collapse, viscosity change of solder paste

residue

★ Printing: a: The solder paste is too thick, the solder paste is too much b: the solder paste is not fully stirred

★ Reflow welding: temperature setting is not appropriate, preheating is not enough live temperature is too high

★ Steel mesh design: the large PAD does not do the diversion design

★ Material: solder paste quality is not good

Erection piece

★ Printing:

a: Uneven printing thickness or less tin under one end;

b: Printing offset

★ Patch: offset

★ Reflow welding:

a: Improper temperature setting;

b: component heating is not balanced;

c: The furnace △T is too large;

★ PCB:PCB pad is poorly designed

★ Material:

a: Poor weldability of one end pad or component

b: The solder paste is too active

Tin shot

★ Printing:

a: After the solder paste printing, there is too much solder paste

b: There is solder paste at the bottom of the mesh board

c: The ambient temperature exceeds the standard, and the solder paste or PCB is damp

★ Reflow welding: temperature setting is not appropriate, preheating is not enough, heating is too fast

★ PCB, steel mesh design:

a: The steel mesh does not use the "V" type or other anti-tin bead opening method

b: The openings of the steel mesh are not kept at a reasonable inner distance

★ PCB, components: not baked

★ Material:

a: The solder paste is used improperly and absorbs too much water

b: The solder paste is not of good quality