42 testpoint pad turn black after reflow results

IPC-7093A BTC: QFN Solder Mask Defined Thermal Pad - PCB Libraries Forum

PCB Libraries, Inc. | https://www.pcblibraries.com/forum/topic2154&OB=ASC.html

:1 scale of the thermal pad. During reflow the paste would melt and travel down the via holes. The PCB designer might have created a fabrication note to plug the holes on the Thermal Pad not knowing that it would increase cost by 10 - 15

PCB Libraries, Inc.

IPC-7093A BTC: QFN Solder Mask Defined Thermal Pad - PCB Libraries Forum

PCB Libraries, Inc. | https://www.pcblibraries.com/forum/ipc7093a-btc-qfn-solder-mask-defined-thermal-pad_topic2154_post10556.html

. The thermal pad solder mask was 1:1 scale of the thermal pad. During reflow the paste would melt and travel down the via holes. The PCB designer might have created a fabrication note to plug the holes on the Thermal Pad not knowing that it would increase cost by 10 - 15

PCB Libraries, Inc.

automated optical inspection machine -PCB magazine loader,PCB turn conveyor,pcb conformal coating ma

ASCEN Technology | https://www.ascen.ltd/Products/auto_optical_inspection/515.html

. the A500 model is very suitable for a standard PCB inspection after reflow oven . In addition, the same machine can inspect components on glue including the pad glue contamination

ASCEN Technology

Products – Page 2 – Precision PCB Services, Inc.

Precision PCB Services, Inc | https://precision-pcb-services-inc.com/collections/all?page=2

. Home Catalog Blog About us Home › Products Products Browse by All Amtech Flux Amtech LF4300 Amtech Solders BGA Balls BGA Nozzle BGA Pad Repair BGA Reballing BGA Reballing Services BGA Rework BGA Rework Machine BGA Rework Nozzle BGA

Precision PCB Services, Inc

– Sn/Pb BGA Joint SEM of solder joint after 1000 cycles. 21 #2 Conclusions  Complete reflow achieved when peak temperature reached 218 – 222oC

| https://www.eptac.com/wp-content/uploads/2021/11/webinar_eptac_12_17_08.pdf

Legend & Assembly Polarity Marking - PCB Libraries Forum

PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/topic2593&OB=DESC.html

.   The Line Polarity Marking is also popular because it takes up the least amount of PCB real estate and runs along the entire side of the pad that is visible after assembly

PCB Libraries, Inc.

Legend & Assembly Polarity Marking - PCB Libraries Forum

PCB Libraries, Inc. | https://www.pcblibraries.com/forum/topic2593&OB=ASC.html

.   The Line Polarity Marking is also popular because it takes up the least amount of PCB real estate and runs along the entire side of the pad that is visible after assembly

PCB Libraries, Inc.

Legend & Assembly Polarity Marking - PCB Libraries Forum

PCB Libraries, Inc. | https://www.pcblibraries.com/forum/topic2593&OB=DESC.html

.   The Line Polarity Marking is also popular because it takes up the least amount of PCB real estate and runs along the entire side of the pad that is visible after assembly

PCB Libraries, Inc.

The PCB Assembly Process: How Does It Work?

Imagineering, Inc. | https://www.pcbnet.com/blog/pcb-assembly-how-does-it-work/

. The Reflow Oven After the components are all in place, the PCB is moved to the conveyor belt for the reflow oven. This step is where the actual connection will take place

Imagineering, Inc.

Beginners’ Guide To Surface Mount Soldering - Blackfox

Blackfox Training Institute, LLC | https://www.blackfox.com/beginners-guide-to-surface-mount-soldering/

.  Then, grab the component with tweezers and carefully align its pins with the soldered pads. While keeping the pins correctly aligned, use the soldering iron with your other hand to heat one of the pins, and reflow the solder onto the pad to tack the component into place

Blackfox Training Institute, LLC