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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Alan Pestell

#16596

Any help reflow soldering Through Hole parts | 6 March, 1998

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

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Todd N

#16600

Re: Any help reflow soldering Through Hole parts | 6 March, 1998

| 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, We are currently using the paste-in-hole process on one of our high volume boards with excellent results. You do need to enlarge the stencil apertures in order to put down the correct volume of solder paste. There is an excellent article in the September 1996 issue of Circuits Assembly magazine on calculating the stencil aperture size. On a double-sided PCB, you want to print the connector once on the second side. You may want to consider a snap-in connector so the connector is guaranteed to stay in the board. Our connectors are on the bottom of the board, so we use a fixture to turn over the board after printing in order to snap-in the connectors. We then turn the boards over and run them through the SM process with the connectors upside down. Also, make sure the connectors can withstand 215 Degrees C. Good Luck. Todd

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Scott McKee

#16601

Re: Any help reflow soldering Through Hole parts | 6 March, 1998

| | 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, | We are currently using the paste-in-hole process on one of our high volume boards with excellent results. You do need to enlarge the stencil apertures in order to put down the correct volume of solder paste. There is an excellent | article in the September 1996 issue of Circuits Assembly magazine on calculating the stencil aperture size. On a double-sided PCB, you want to print the connector once on the second side. You may want to consider a snap-in connector | so the connector is guaranteed to stay in the board. Our connectors are on the bottom of the board, so we use a fixture to turn over the board after printing in order to snap-in the connectors. We then turn the boards over and run them | through the SM process with the connectors upside down. Also, make sure the connectors can withstand 215 Degrees C. | Good Luck. | Todd

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Scott Cook

#16599

Re: Any help reflow soldering Through Hole parts | 6 March, 1998

| 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 Hi Alan, I have quite a bit of experience with "paste-in-hole" process techniques, and would be glad to c

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Scott Cook

#16598

Re: Any help reflow soldering Through Hole parts | 6 March, 1998

| 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 Hi Alan, I have quite a bit of experience with "paste-in-hole" process techniques, and would be glad to chat with you about the process. You may call me at 850-580-0282 during normal biz hours EST. One of the first prerequisites for your applications is to ensure that your connector housing is compatible with reflow temps. Typically, the connector folks impregnate a glass resin when "shooting" the housing in the injection mold process. If you don't have a reflow capable housing, your connector will go into "meltdown". I also have numerous white papers about the process, and would be glad to share these with you if you send me your fax number. Best of Luck! Scott Cook scottc@t-com.com

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Jim McLenaghan

#16597

Re: Any help reflow soldering Through Hole parts | 9 March, 1998

| 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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