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Is there any specific time frame (production time control) defined for a PCB assembly process completed SMT? How long need to co

Is there any specific time frame (production time control) defined for a PCB assembly process completed SMT? How long need to co

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Hello! Anyone here knows is there any specific time frame (... - Apr 14, 2022 by Evelyn

depends on board finish and PCB substrate materials. If you ... - Apr 14, 2022 by cbart

Thank you for sharing the helpful information. Let's say th... - Apr 15, 2022 by Evelyn

Bake a board. Measure weight. Measure board weight that have... - Apr 15, 2022 by Evtimov

So you run one side, and leave the boards sit in temperature... - Apr 18, 2022 by ProcEng1

Be aware that some "water soluble" fluxes can be c... - Apr 18, 2022 by charliem

Be careful of MSL level 4 or higher devices on the first sid... - Apr 19, 2022 by DWL

Alright. Thank you Evtimov :) ... - Apr 20, 2022 by Evelyn

@ProcEng1 Yea. Mostly is ENIG surface finished PCB. Sometime... - Apr 20, 2022 by Evelyn

@charliem, For the clean process board using "water... - Apr 20, 2022 by Evelyn

@DWL, Roger that. Thank you for your advice :) ... - Apr 20, 2022 by Evelyn

Evelyn

#87833

PCBA Production Manufacturing Time Control | 14 April, 2022

Hello! Anyone here knows is there any specific time frame (production time control) defined for a PCB assembly process completed SMT? How long need to complete the SMT process if double-sided SMD boards are assembled?

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cbart

#87839

PCBA Production Manufacturing Time Control | 14 April, 2022

depends on board finish and PCB substrate materials. If you were using OSP or silver finished bare boards the time to process is less than an ENIG or HASL finished. certain substrate material absorb more moisture than others or at a quicker rate. so this too would drive this determination. in general if you store them properly and keep the solderable surfaces free of oxidation you can waits months between processing each side. you can always bake prior to processing as well if moisture if the main concern, note this can cause oxidation as well so limit the number of times baked. hope I understoon your question or concern.

reply »

Evelyn

#87841

PCBA Production Manufacturing Time Control | 15 April, 2022

Thank you for sharing the helpful information. Let's say the PCB is a double-side assemble process and this PCB has completed the first reflowing SMT assembly process, is there any concern if the board is kept on the production floor with temperature control of 20~24deg C and resumes the second side of the reflow SMT assembly process after 3days? Is there any method to measure the moisture content in the PCB/PCBA?

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Evtimov

#87843

PCBA Production Manufacturing Time Control | 15 April, 2022

Bake a board. Measure weight. Measure board weight that haven't been baked.

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ProcEng1

#87850

PCBA Production Manufacturing Time Control | 18 April, 2022

So you run one side, and leave the boards sit in temperature controlled environment for 3 days before running the other side? Are they ENIG coated? If so, they are probably ok. You could always keep the boards in your hot room. I assume this is due to waiting on a part shortage or stencil or something?

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charliem

#87853

PCBA Production Manufacturing Time Control | 18 April, 2022

Be aware that some "water soluble" fluxes can be corrosive if left on PCB more than 48hrs.

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DWL

#87859

PCBA Production Manufacturing Time Control | 19 April, 2022

Be careful of MSL level 4 or higher devices on the first side. if they sit out 3 days, they will need to be baked before second side reflow or you risk component damage.

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Evelyn

#87861

PCBA Production Manufacturing Time Control | 20 April, 2022

Alright. Thank you Evtimov :)

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Evelyn

#87862

PCBA Production Manufacturing Time Control | 20 April, 2022

@ProcEng1 Yea. Mostly is ENIG surface finished PCB. Sometimes there is OSP board faces issues like part shortages and is forced to hold the production and resume the second process after a few days. So, would like to know any special control on keeping those boards to avoid the PCB delamination issue that induced by moisture in PCB.

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Evelyn

#87863

PCBA Production Manufacturing Time Control | 20 April, 2022

@charliem, For the clean process board using "water-soluble" fluxes, we will send the board to aqueous wash with DI water first if not able to manage to proceed with the second process within 24hours. Then, keep the board under room temperature. Should we prebake the board before resuming the second reflow soldering process?

reply »

Evelyn

#87864

PCBA Production Manufacturing Time Control | 20 April, 2022

@DWL, Roger that. Thank you for your advice :)

reply »

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Is there any specific time frame (production time control) defined for a PCB assembly process completed SMT? How long need to co

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