A hole in solder paste

Solder paste = Tin bead + scaling powder . Enlarge the solder paste to see the following figure .

I bought a tin of solder paste last year ,138 Degree , Once or twice , Then put it somewhere without touching it , The lid is also covered , There is no refrigerator . This year, I took it out for use , No problem was found when using steel mesh brush , After pasting components , It's wrong when you go to the heating table , When the temperature rises , The solder pad is full of small tin beads , It's not hung on the pin , A dozen seconds later , It's still like this , I feel a little strange , Under normal circumstances , More than ten seconds after melting , It will be attached to the pins and pads of components . Then until the heating is over , This situation has not improved . At first I thought the temperature was too high . Then put the temperature , Down to 170 degree .（ At first it was 210 degree ）. The result is the same , Solder pads are full of tin beads , Big and small . Half of the pins are soldered , Only one by one .

Analyze it , The solder paste should have gone bad , It is likely that the flux inside has deteriorated , Because during heating and welding , It is found that the infiltration effect is very poor ...

This kind is quite speechless , I didn't expect to be bitten by solder paste , No wonder old drivers put solder paste in the refrigerator .