2.8 Program Creation & Tuning

A pick-and-place machine's performance is governed by the program that drives it. From the moment CAD data is imported, decisions regarding rotations, vision teaching, feeder layout, and placement sequence determine whether the line achieves maximum throughput or suffers from constant stoppages. Disciplined program creation ensures consistency across shifts, minimizes setup time, and maintains the maximum theoretical Components Per Hour (CPH).

2.2.8.1 Data Integrity: Standardized Inputs

Before placing the first part, the foundation must be built on clean, consistent data. Errors here force time-consuming manual fixes later.

• Input Standardization: All data imports must use consistent units (mm), a single origin for top and bottom sides, and CCW rotation convention.
• Part Library Match: All imported package names and Z-heights must strictly match the PnP machine library names. Avoid using one-off aliases that require translation.
• Fiducials: Global and local fiducials must be clearly defined in the data package and used consistently for board alignment and large component correction.
• Golden Data Pack: The final, verified set of placement data, machine offsets, and rotation tables must be archived as the single source of truth for the entire run.

Audit Tell: If a program requires bulk rotation or coordinate offsets after import, the library conventions or the CAD output are misaligned. This must be fixed at the source, not in the program.

2.2.8.2 Vision and Component Definition

Component recognition must be robust and instantaneous to prevent vision retries and slowdowns.

• Teaching and Locking: Define and lock one golden image per package family in the machine library. This image must feature clear pin-1/polarity markers and body edges.
• Pick Point Consistency: The nozzle pick-up point must be centered on the flattest, most repeatable surface of the component. Areas with embossed logos or irregular domes must be avoided.
• Algorithm Selection: Choose the simplest vision algorithm that achieves stable recognition. Stability and speed are prioritized over high-fancy recognition algorithms that may be sensitive to slight component variation.

2.2.8.3 Feeder Optimization: Minimizing Travel

The physical arrangement of feeders is the primary driver of machine speed. Feeder optimization aims to minimize the travel distance of the placement head.

• Permanent Banks: High-runner components (01005 – 0603 passives) should be assigned to fixed feeder slots across all product programs. This massively reduces changeover time.
• Shortest Paths: The highest-hit parts must be placed in feeder slots closest to the head's home position (or the center of the placement area).
• Nozzle Grouping: Feeders should be clustered by the required nozzle size/type. This minimizes the number of required tool changes during the placement sequence, improving efficiency.
• Tray Management: Large BGAs, QFNs, and odd-form parts (sourced from trays) require more time and head travel. Sequence them last to ensure the high-speed placement of chips is not interrupted.

2.2.8.4 Path Sequencing and Load Balancing

The sequence of placement determines the cycle time and whether parallel machines operate efficiently.

• Placement Order: The general rule is to place chips first (dense field moves), then ICs, and finally tall/odd-form components that might interfere with head travel.
• Load Balancing in Tandem: If running tandem mounters (Chapter 2.1),mounters, the placement program must be split to ensure the cycle times of both machines are balanced (within ±10%). The split must be by effort (e.g., fast chips on PnP A, slow ICs on PnP B) to avoid bottlenecks.

2.2.8.5 First Article (FA) and Program Freeze

The First Article procedure is a short, scripted audit used to prove the program's integrity before production release.

1. Alignment Check: Teach three fiducials and verify the global X/Y/θ alignment.
2. Witness Placement: Place witness parts for each package family near a board edge. Inspect these parts under a microscope to confirm orientation, polarity, height, and offset are correct.
3. Log Audit: Review machine pickup logs. Any high rate of misses/retries indicates a vision or nozzle parameter issue that must be fixed.
4. Recipe Freeze: After successful verification, the machine recipe and program must be locked and a Golden Board photo set captured. This freeze prevents unauthorized changes that could compromise production.

2.2.8.6 Key Performance Metrics

These metrics must be monitored on the machine dashboard to track efficiency and flag drift.

• Placement Time Per Board: The time consumed for the placement routine (excluding conveyor/buffer travel). This is the key measure of program efficiency.
• Miss/Retry Rates: The count of vision failures or pickup errors, tracked by part family. This directly indicates a feeder or vision library problem.
• Nozzle Swaps Per Board: Measures the efficiency of the feeder grouping. Higher numbers indicate poor clustering and wasted time.
• CPH vs. Theoretical: The achieved Components Per Hour must be tracked against the machine's maximum theoretical CPH to calculate overall utilization.

Program Setup Checklist

Phase	Non-Negotiable Item
Data & Library	Program based on Golden Data Pack; component library names match the PnP system.
Vision & Rotation	One Golden Image per package; Rotation Sanity Check performed on bottom-side mirroring.
Feeder Optimization	High-runner parts assigned to Permanent Feeder Banks; feeders clustered by Nozzle Type.
Sequencing	Chips first, trays last; tandem program cycle times balanced ±10%
First Article	Witness Parts verified for polarity/offset; machine logs confirmed clean; program frozen.