Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Clearance between Through hole and chip component

Views: 4735

Marcin

#47994

Clearance between Through hole and chip component | 27 February, 2007

Hi All,

Anybody knows what is the minimum clearance between through hole component and chip component?

Problem description:

On bottom side of my pcb are only 0603 chip components mounted on glue. One of the component is located very close to hole of through hole component (which is mounted from top side). Bottom side is Wave soldered. But during soldering bridging effect occurs between the through hole component and one of the chip component. It seems, that distance between this two components is not big enough. Is any document which specify the minimum distance between different components?

Any additional data which may be helpful:

The pcb is 1.6 mm thick The through hole diameter is 1mm (hole) and 2 mm (whole diameter of the pad) Distance between edges of the through hole pad and chip pad is 0.5 mm.

If the clearance is ok, have anybody an idea what can be wrong with the wave process?

Thank you very much in advance for any information regarding this issue.

reply »

#48018

Clearance between Through hole and chip component | 27 February, 2007

We'll guarantee the two pads are too close together. The proper spacing depends on the orientation of the parts to the wave. * Do the pads hit the wave at the same time? * Does one pad hit the wave before the other? If so, which? * How does the 0603 hit the wave? [Both pads at once or one pad at a time]

We're aware of no formal standard the defines proper spacing between components. Some firms develop guidelines as an element of their DfM tools.

reply »

Muhammad Haris

#48026

Clearance between Through hole and chip component | 28 February, 2007

Hi, The distance between the two terminations/endings/pads of 0603 (0201)is 0.15mm i.e. lesser than than the distance between the 0603 and through hole i.e. 0.5mm My ques is that, then why its termination doesnot short as it has a minimum distance.After wave it also has to become short.INSPECT WHOLE PCB AGAIN AND FOLLOW THE ANSWERS.

ANSWERS: 1. Change the inserting position of your pcb in WAVE i.e. if u insert it in longitudinal way then put it in horizontal position . 2. Reduce the flow of your solder so that it less touches the pcb such that it doesnot deviate from the IPC 610A Rev D.

reply »

realchunks

#48043

Clearance between Through hole and chip component | 28 February, 2007

Marcin,

Think outside the box. If you are glueing the SMT part down, why not have an aperture cut in your stencil (or recut a stencil) between the SMT part and thru-hole. Wave solder hates SMT glue. This will get rid of your solder short problem without redesigning your board or twisting up your wave solder process.

reply »

#48065

Clearance between Through hole and chip component | 28 February, 2007

Very smart, Chunks.

reply »

Reflow Ovens thermal process improvement