| We have a double sided pcb that is surface mount on both sides. Now a Through Hole connector has been added. Appart from hand soldering does anyone have info. on reflow soldering the part. The connector is 0.1mm pitch, square legs. | 1) Do you need to change the hole pad, shape. | 2) Do you apply paste from both sides of the pcb, at each printing stage. | 3) Do you need to use solder pre-forms | 4) Do you need to use jigs to prevent the solder being pushed out when the connector is inserted. | Many thanks, Alan
Alan, If your connector is single or double row you should have little problem configuring your stencil apertures for obtaining the correct solder paste volume (usually approximately 2X of solid solder volume). This is done by overprinting outside of the pad area using a rectangular or oval aperture. Be sure that the connector has a standoff higher than the thickness of your print. This will help eliminate distortion of the printed solder paste pattern which may cause solder balls, shorts, and adjacent solder thieving. The height of the solder will increase as the printed solder paste pattern reflows and coalesces. This may contact the underside of the connector which may cause "lifting" of the connector. Also connector contact may cause separation of the solder bead before solder joint formation and thus cause extraneous solder balls and starved solder joints. The generally the solder paste from extended overprint should coalesce with minimal extraneous solder balls provided that you have good print quality and no solder paste/solder mask compatibility issues. If you have a 3rd or more contact rows you will be limited as far as overprint aperture geometries. You can also use a "print print" process to force more paste in the hole provided you have good enough gasketing between the bottom of the stencil and the surface of the printed circuit board to prevent solder paste "bleeding" in the areas of the other surface mount devices. Other print options are available. Of course you can always dispense solder paste in the area of the connector if you have capability in your manufacturing line. If you would like to discuss further please feel free to e-mail me with your phone #.
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