Smart Factory: Particle Monitoring Part II

“A Better Turnkey Solution for Particle Monitoring!”

In the previous article, Smart Factory: Particle Monitoring Part I, we described the importance of particle monitoring in a cleanroom environment and how critical it is for the manufacturing environments of automotive, display panel, pharmaceutical and semiconductor industries. And this article is going to explain you why MtM+’s cost effective PSN device and particle monitoring solution is especially designed for this manufacturing application scenario.

The following Figure-1 table summarizes the features of MtM+’s particle sensing node. MtM+’s solution supports Class 100 and higher.

Figure-1 MtM+ PSN’s Spec and Features

“Prerequisite of the Particle Sensor, Quality Matters!”

MtM+’s Smart Factory solution provides an innovative approach with cutting edge technology to remotely measure particles in various critical location spots by strategically installing particle sensing nodes (PSN) throughout the clean environment in a mesh networking style. And the quality of PSN particle sensors need to be strictly assured by following our standard screening approach in order to meet the requirement of Class100/1000 cleanroom.  

Each PSN is equipped with state-of-the-art sensors that count particles with the light scattering method.  It typically can detect particles sizes from 0.3 µm to 10 µm with a counting efficiency of 50% (+/-20%) at 0.3um.

Screening flow as Figure-2 below is applied at the sensor’s IQC stage to ensure there’s enough sensitivity for the cleanroom application requiring ISO Class 1000 & higher.

The quality of the purposed sensor parts will be first screened by the performance check in a “Isolated Chamber” to simulate the cleanroom environment. After passing the comparison between each sensor and MetOne’s high-end particle counter, then the known good parts will be sent to assembly line.

Figure-2 MtM+’s Screening Flow for the Sensitivity of PSN

“Screening of the particle sensor’s sensing capability!”

Sensing capability is the most important part for the particle count sensor in cleanroom applications. We conduct group test to preliminarily exclude these sensors with inadequate sensing capability for sensing 0.3 μm or 0.5μm particles in the experimental chamber.

Figure-3 is a comparison a group of particle sensors that will be used for MtM+ mesh PSNs after screening test.

Figure-3 Comparison among a group of particle sensors

“On-site Calibration for Better Accuracy!”

On-site calibration procedure will be followed to reach better accuracy after finishing the assembly of our Mesh PSN device. Figure-4 below shows our standard operation procedure flow after screening stage. The specific environment and calibration methods will be further explained next.

Figure-4 On-site Calibration Procedure

“Regression Analysis – A Powerful Method for Modeling Data.”

In order to reach better accuracy, we adopt the egression analysis in our calibration method to eliminate systematic difference between manual monitoring (standard approach) and automatic monitoring (MtM+’s approach) and thus to reach better data consistency.

Our data calibration principle for automatic particle monitoring is made with reference to US Environmental Protection Agency (EPA) in according to US Code of Federal Regulation (CFR). CFR provides   the calibration method which establish the linear regression in the non-federal reference method monitoring

And Taiwan’s government department, EPA (Environmental Protection Administration, Executive Yuan), has also defined a calibration principle of automatic particle monitoring according to US Federal Regulations from EPA.         

Figure-5 shows one example of our sensor test result using regression analysis based on this calibration method mentioned above.

Figure-5 Upper: Comparing METONE’s test result with our sensor’s calibrated one
Bottom: Linear Regression Formula and the curve result between METONE and our sensor

“Performance Benchmark!”

We use calibration tool to find out the gain and offset used in regression analysis and the estimated RMSE (root-mean-square-error). The final result of the calibration method applied needs to pass the 1-min mode and 10-mins mode in both given stable and unstable environment. Figure-6 below shows the UI of this tool. 

Figure-6 UI of Particle Sensor Calibration Tool

The Figure-7 and Figure-8 below are examples of test results of our sensors in unstable and stable environments before/after the calibration. The black curve is the measurement result of a standard lab meter, and the red curve in the plot is the result of our sensor. The RMSE value in each mode needs to be lower than the upper limit in order to pass our calibration procedure.

Figure-7 Sensor’s Particle Test Result in an Unstable Environment
Figure-8 Sensor’s Particle Test Result in a Stable Environment

“Benchmarks of Systematic Error…”

Deviation between particle counters is investigated and PSN’s numeric calibration tolerance is defined accordingly. If the staff takes the particle number in 1min to forecast that in 10 mins, the cumulative deviation between different meters can be obtained. The systematic errors between MetOne devices and PSNs can be found in the Figure-9 below.

Figure-9 Benchmarks of Systematic Errors.
Upper Plot: MetOne1 VS MetOne2. Bottom Plot: MetOne VS PSN

“A More Reliable Inspection Method.”

It’s hardly to obtain the overall picture of a cleanroom’s cleanliness level by using manual sampling measurement. However, MtM+’s mesh PSN network can help you monitor the cleanliness per minute within 24 hours with multiple PSN nodes deployed in scattered locations to eliminate blind spots.

The pass ratio of a cleanroom is not always 100%, few samples per day could lead to wrong perception and misleading conclusion. Figure-10 below shows the particle counting results of 4 different devices and one can see the overall data and trend curve for each day and even zoom in to investigate the data details on a minute-to-minute basis.

Figure-10 24/7 Historical Data Analysis in a mesh PSN way

“Fast Deployment is the Key!”

Wireless mesh PSN network provides customers more advantages than you think. Fast deployment is the key for users to proceed with PoC (Proof of Concept) and more efficiently to estimate the ROI of this turnkey solution without spending too much cost on wiring and too much time on scheduling for stopping the production line and breaking the wall for installation. Figure-11 is an example of our floor plan for the PoC of MtM+ PSNs Installation. Customer can quickly experiment with this turnkey solution and evaluate its performance in the production line with 15 pcs of PSN devices only.

Figure-11 Example of a real floor plan for PSN deployment

MtM+’s smart factory solution on particle monitoring has been deployed in a semiconductor manufacturing company with great results. Big data generated with these PSN boxes are vital for analysis in improving factory flow, floorplan and process. The keys to success are strategic placement of each sensors along with MtM+’s calibration algorithm.

“We need your Feedback!”

Real-time data are also essential to prevent possible disasters before it’s too late.  For more information on this technology and MtM+’s offerings, please email sales@mtmtech.com.tw.

Smart Factory: Particle Monitoring Part I

“Every particle counts! Size really matters!”

The manufacturing environments of pharmaceutical and semiconductor have strict requirements for minimizing dust, airborne organisms or vaporized particles.  These isolated areas or rooms are referred to as a “Clean Room”.  A Class 1,000 clean room is equivalent to an ISO 6, which contains 102,000 particles that are bigger than 0.3 µm in size for each cubic meter.  However, a Class 100 clean room is often requirement for the manufacturing environment which can only contain 10,200 particles that are 0.3 µm in size or smaller per cubic meter!

There are several clean room standards, typically ISO 14644-1 and FED STD 209E.  The following Figure-1 table summarizes these standards and their equivalence.  MtM+’s solution supports Class 100 and higher.

Figure-1 Cleanroom classification and standardization
(source: https://www.cleanairtechnology.com/cleanroom-classifications-class.php)

The existing industry solution to ensure a clean environment is to manually measure the number of particles in air using a portable meter (ie. MetONE HHPC3).  Typically, this can only be done once a day and only in few specific areas.  One can see that, such manufacturing environment can not react to contamination quick enough which result in defects and fallouts. 

“A Better Turnkey Solution for Particle Monitoring!”

MtM+’s Smart Factory solution provides an innovative approach with cutting edge technology to remotely measure particles in various critical location spots by strategically installing particle sensing nodes (PSN) throughout the clean environment in a mesh networking style.  A Bluetooth Low Power (BLE) Mesh network is used to transmit data from the sensors back to a local backend server as shown in the Figure-2 below.  Real-time data are collected with the options to either be analyzed locally or through a cloud network.

Figure-2 MtM+’s Mesh PSN Solution

Each PSN is equipped with state-of-the-art sensors that count particles with the light scattering method.  It typically can detect particles sizes from 0.3 µm to 10 µm with a counting efficiency of 50% (+/-20%) at 0.3um.  The size of the PSN box is 75mm by 72mm by 42mm (see below figure), which is small enough to be effectively placed in most environments. 

“Every labor counts! Time really matters!”

Utilizing the Mesh PSN technology can not only help reduce the labor cost and time, but also provide a much better and efficient way to help you analyze and collect the data precisely and further improve the quality of the manufacturing.  Figure-3 is a comparison between manual measurement and measurement using mesh PSNs.

Figure-3 Comparison between MtM+ solution and manual measurement

“Actual Deployment at the Customer’s Cleanroom.”

On-site deployment is never an easy task. However, MtM+’s dedicated special solution team will find out the best locations for particle monitoring and quickly deploy our wireless mesh nodes without rewiring or opening a big hole and re-bury tubes or wires in the wall. The figure-4 below is a real case of our on-site PSN deployment at one of our semiconductor customer’s factory floor. 8 cleanroom monitoring segments have been pre-defined by our customer and we decided to place our 15 pcs of PSNs at those selected critical area after our inspection and discussion with customer. Only one server is needed to collect those scattered sensor nodes due to the advantage of MtM+’s Mesh PSN technology.

Figure-4 Customer Factory Floor Layout & Deployment

As one can see in the figures-5 below, our solution will help visualize the data collected to help user better monitor the fluctuation of particle changes (one frame per 10mins, 144 frames per day) more frequently at the whole area within the whole day, comparing to manually measuring approach at much fewer spots and mostly 2~3 times per day in the past.

Our customer actually got notified by more alarms and thus captured an issue on the manufacturing floor, and later resolve the problem that could potentially harm it’s process by replacing the floor pieces with ventilated ones.

Figure-5 Left: 24-hours Space distribution of particle numbers.
Right: 24-hours Accumulative alarm events counts by clean room segments

The figure-6 below are the standard features of our server-based dashboard GUI that can further help users perform device management and data analysis etc.

Figure-6 MtM+ Smart Factory Dashboard Features

“More Applications on The Way”

Beside measuring air quality in a clean room, due to the small size of these PSN nodes, it can reside inside the manufacturing equipment itself (see figure-7 below).  This takes particle measurement to another level and ensuring maxim µm yield in any manufacturing environment.

Figure-7 Particle Sensing Nodes Reside Inside Main Equipment

“We need your Feedback!”

MtM+’s smart factory solution on particle monitoring has been deployed in a semiconductor manufacturing company with great results. Big data generated with these PSN boxes are vital for analysis in improving factory flow, floorplan and process. The keys to success are strategic placement of each sensors along with MtM+’s calibration algorithm, and we will cover more about our calibration process and benchmark details in the next article, Smart Factory: Particle Monitoring PartII.

Real-time data are also essential to prevent possible disasters before it’s too late.  For more information on this technology and MtM+’s offerings, please email sales@mtmtech.com.tw.