soldering problem?

Question

i have tested a timing circuit in a project board and working fine. but when soldered the components in PCB its not working. help me. is thr any problem due to soldering and if how give some tips to soldering.

Answer 1

One big problem in PCB joint soldering is *heat*. Some components, especially diodes and transistors, are very heat sensitive and can get fried during soldering. Use a heat sink when soldering these components and use a powerful enough soldering iron so that one quick touch makes the joint.

Answer 2

It could be a cold joint (as in that the soldering iron wasn't hot enough to melt the solder enough to both the lead on the component and the trace on the PCB. What I would do is take a digital multimeter and test for continuity between the component leads and the other end of the trace that they are soldered to. Hope that helps. Good luck.

Answer 3

I recommend a breadboard kit to wire up the circuit before you solder anything. Also, you should be using a rosin core or solder with flux so you have clean solder joint. By not using flux, you could have a cold solder joint which would act like a high impedance in part of your circuit where the joint is. Hershey kiss is not desirable for any solder joint. Through hole or Surface Mount (SMT) should have smooth uniform surface with smooth texture. Lead free or silver may appear dull in finish, regular 60/40 lead solder should be glossy or shiny if done right. 4-5 seconds with a solder iron is all you need once the lead and the mating surface or wire is heated. Never try to melt solder onto a cold lead. Heat the surface to be soldered first, then apply solder once it starts to melt when touching the lead or surface, not the iron.

Answer 4

Are you using solid state devises? 555 chips or transistors? Sounds like you may be subjecting them to too much heat.
With the ic chips, use one of those devices that short and heat sink all of the pins to hold it in place while you quickly solder each leg - wait a few seconds between soldering the pins - this will draw the heat away from the device.
Use a (I dislike this term - but here goes) "roach clip" or similar devise to draw the heat away from the transistor when you solder each pin.
If it works on a project board, it should also work on a pc.
Note: recheck the trace each circuit path to be sure the pc is indeed the same configuration as the project board circuitry.

Answer 5

Soldering tip may have neen too hot and lifted the trace out of the board. OR you created a short between two traces.

Answer 6

Is this a through hole board or surface mount?
If it's a surface mount, what's the pitch of the IC?

Another possibility is that the PCB isn't exactly the same as your project board. Might want to double check the PCB layout to see if it's what you're expecting.