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When people talk about AOI, they often say, “Just buy a good machine and you’re fine.”
Honestly, that’s not true.

If the AOI program is weak, even the best machine will miss defects. Or it will scream “NG” on every second board and drive your operators crazy.

In this article, we’ll walk through AOI programming tips that actually help you catch real defects on SMT boards. And we’ll tie it back to real hardware projects like cold storage room controllers and walk-in freezer control panels that sit behind your 냉장실 다층 와이어 선반 그리고 워크인 냉장 와이어 선반.

If you build those systems with QIAO, you don’t want tombstoning or missing parts on the PCB hiding inside the freezer box. AOI is one big guard rail here.

AOI Programming For SMT Assembly

AOI (Automated Optical Inspection) checks:

• missing parts
• wrong polarity
• solder bridges
• tombstoning
• skewed or twisted chips

The camera can see all of that.
But the program tells AOI what is OK 그리고 what is defect.

So your job is not only “teach the board”.
Your job is to make the AOI think the same way as your quality engineer.

That matters a lot when the board controls 냉동고 구성 요소 또는 냉장 장치 구성 요소 inside a cold room.

AOI Reference Data And Component Library

First tip: give AOI a clean, solid “truth”.

Use a golden board and CAD data

• Start from CAD + BOM: correct X/Y, rotation, designators.
• 사용 골든 보드 that’s really good. No rework, no scratch, no half-baked solder.
• Let the machine learn the good image from that board.

If your “good” reference already has a little skew or poor wetting, the AOI will learn that bad habit. Later, real defects escape because they still look “kinda similar”.

Build and maintain the component library

Create a component library that includes:

• package size and outline
• pin count
• polarity mark (dot, notch, chamfer)
• expected solder joint area

And please, don’t just copy a random library from another plant.
For critical parts (MCU, drivers for compressor, fan controller, safety relay), spend extra time:

• zoom in
• define clear pads
• define polarity region
• check a few boards from different lots

Library work is boring a bit, I know.
But it pays back every single day in less false calls.

AOI Thresholds And Defect Criteria

This is where many teams mess up.

If thresholds are too tight, AOI will call “NG” for every small variation.
If too loose, real defects run away from you.

Link thresholds to real quality rules

Use real rules, not “feeling”:

• follow IPC class: Class 2 vs Class 3 have different acceptance limits
• define what is “major defect” (safety, function) and “minor defect” (cosmetic)
• set tighter limits on safety-related parts (over-temperature protection, door sensor input, etc.)

예를 들어

• allow small position drift on a big resistor
• but be strict on polarity and offset for the compressor driver IC

Use data, not only eyeballs

You can monitor:

• false call rate (too many fake alarms = program too nervous)
• escape defects (customer or final QC finds what AOI missed)
• first pass yield (FPY) after AOI

If false call is crazy high, operators start to click “OK” without thinking.
Then even good AOI can’t save the line.

Pre-Reflow And Post-Reflow AOI Inspection

Where do you place AOI in the SMT line?
Answer: not only one place.

Pre-reflow AOI

Before reflow, AOI can catch:

• missing component
• wrong value / wrong part
• polarity mistakes
• gross skew

This is perfect for high-mix boards used in refrigeration control, where you have many part numbers. You fix placement before you “bake in” the problem.

Post-reflow AOI

After reflow, AOI checks:

• solder bridges
• insufficient solder
• open joints
• tombstoning / lifted leads

For boards that manage cold room fans, defrost heaters, and door alarms on 냉동고 와이어 선반, bad solder can mean field failure and food waste.

Simple AOI inspection strategy

You can use a combo like this:

This looks simple, but it covers most of the real world traps.

AOI Programming Checklist Table

Below is a quick cheat sheet you can even print and stick near the AOI.

No need rocket science here.
Just follow the list and update it when your line changes.

Make PCB Layout AOI Friendly

AOI programming does not live alone.
그리고 PCB layout can make AOI easy or almost impossible.

Some quick layout habits that help AOI a lot:

• add fiducial marks with clear copper pads
• keep tall parts away from tiny chips they will shadow
• align polarity marks all in one main direction, not random
• keep text readable and not under parts

QIAO can offer DFM feedback so the control PCB works well with AOI and with your freezer cabinet design at the same time, including 상업용 냉장고 와이어 선반 and other 냉장실 구성 요소.

Turn AOI Results Into Process Control

If AOI only “kicks out bad boards”, you’re wasting half of the value.

Use AOI data to tune the process:

• track where defects happen most (which feeder, which side, which product family)
• look at solder-related defects vs paste printer settings
• check if defects spike after changeover or stencil cleaning

When you see more 브릿징 on one pad design, maybe your paste aperture is off.
When missing parts always come from the same feeder, maybe that feeder needs deep maintenance, not just a quick blow of air.