1. Pre-Reflow Inspection Station (PRIS)
WSE Example
Pre-Reflow Inspection Station
(PRIS)

2. Overall SMT Process
Empty board
Dispense solder
Pick & place
To reflow

3. A Typical PCB

4. Pre-Reflow Inspection Station (PRIS)
Modern SMT process at a electronics manufacturer.
Each line consists of
1 solder dispenser
1+ pick & place machine
1 reflow oven
PRIS is to be located between Pick & Place and Reflow Oven
Excerpt from Mike Lee's thesis:
The pre-reflow inspection process starts when a populated PCB arrives on the conveyor from the last pick and place machine in the series of pick and place machines. The inspector locates the work order or OPIE (an “interactive” work instruction), identifies the model of the PCB, and loads the diagram of the PCB using a database program called [bView]. [bView] displays a diagram of the PCB on a computer monitor behind the conveyer system. There are also other sources where the inspector can obtain additional information regarding the board or the inspection process, including waivers, instructions, and upstream operators.
There are secondary tasks the inspector must perform before inspecting the PCB. An example of such a secondary task is for the inspector to determine and set a temperature profile for the reflow oven based on the board specifications.
During the inspection of the PCB, the inspector looks for four types of flaws:
Board match: The inspector checks if the populated PCB that arrived at the inspection station is the one planned on the work order.
Board population: The inspector checks the populated PCB to see if the components are placed in locations they are designed to be placed, and unpopulated where no components should be placed.
Type of component: The inspector checks the components on the PCB to make sure they are the right components.
Component orientation: The inspector checks the components on the PCB to see if they are oriented correctly. Components can be positioned slightly rotated or shifted. Another issue with certain components is the risk of the components being rotated 90 or 180 degrees.
Pick & Place Machine
Inspector
Reflow Oven
Conveyor
Solder Dispenser
Empty Boards
on Conveyor
(PRIS)

5. Inspection Process Prepare and review documents Program reflow oven
Inspect board
Check board match
Check component placement
Check component population
Check component rotation/direction
Insert manual components

6. Board “Schematic” For Inspector Reference