Innovation Over 50 Years: Focus on the 1970s

It’s hard to believe it’s been 50 years since we opened our doors – but since then we have aimed to be the global leader of innovative audio solutions.

As we celebrate our 50 years in business, we are highlighting our key innovations per decade in five blog posts, starting with the 1970s.

In 1972, Projects Unlimited founded the Audio Products Division and quickly purchased the first electrical buzzers (GA 100) for telephone test sets from Roschi Electronic AG in Switzerland. More innovation in buzzer and indicators followed during the 1970s:

  • 1973: First PCB mounted Buzzer offered
  • 1975: First low frequency panel mounted Indicator offered
  • 1976: First PCB mounted Piezo Indicator
  • 1978: First externally driven Transducer

We are proud of these early innovations and look forward to sharing more with you.

Innovation Over 50 Years: Focus on 2010s

Starting in 2010, PUI Audio embarked on a new decade of product development and growth.

During that year, a Multilayer Piezo Speaker was launched, and the organization moved into a new facility as a wholly owned PUI subsidiary and incorporated as PUI Audio.

In 2011, the world’s first Fully Programmable Indicator was developed and released to the global market.

A fully functioning demo kit was also made available to the sales channel, and the company growth necessitated an additional 3,000 square feet be added to the current facility, enabling greater warehousing and testing capabilities.

Stay tuned to next week’s post to see where PUI Audio is today and what lies ahead in the future.

Innovation Over Fifty Years: Focus on 2000s

Starting in 2003, PUI Audio embarked on a series of innovations that focused on transducers and audio applications. It was in 2003 that the smallest surface mount transducers in the world were launched by PUI Audio, measuring 5x5x2mm.

In 2004, a Mil-Spec spray coating was offered for the paper cone of speakers and production was diversified to locations all across Asia.

In 2005, PUI Audio developed a transducer able to handle reflow at 260 degrees Celsius for 6- seconds.

In 2006, PUI supplied parts for the Apple iPod and in 2007, released the industry’s first side firing washable transducer.

The company’s name was also changed from PUI Audio Products Division to PUI Audio.

The decade’s innovation rounded out with the surface mount speaker being released.

Stay tuned to next week’s post to see what was accomplished in the 2010s.

Innovation Over 50 Years: Focus on 1980s/1990s

As we celebrate our 50 years in business, we are highlighting our key innovations per decade in five blog posts, with this second post featuring innovations in the 1980s-90s.

From 1980-1985, the first washable Transducer was introduced, and the company began to offer over 95 products.

The impact of globalization occurred as well, with production moving from Japan to Taiwan in 1986.

Other highlights that occurred during the 1990s included:

  • Earning ISO-9001 Certificate
  • Developed a line of SMT Alarms and Alerts
  • Introduce electret microphones and a full line of receivers

Stay tuned to next week’s post to see what was accomplished in the 2000s.

PUI Audio makes it easier to design electronics faster with new SnapEDA experience

Engineers can now download computer-aided models (CAD) for PUI Audio’s catalog of microphones, speakers, haptics and buzzers

San Francisco, CA – (October 4, 2022) – SnapEDA, the first search engine for electronics design, and PUI Audio, an industry leader in audio and haptic components, have collaborated to launch the SnapEDA Viewer, an online experience that allows engineers to visualize and download CAD models for PUI Audio products.

To save engineers weeks of design work, SnapEDA created the first search engine focused on providing trustworthy electronics CAD (E-CAD) data. Traditionally, engineers have spent hours creating the CAD models needed for circuit board design. The process of creating and verifying each schematic symbol and footprint is time-consuming and expensive. The result saves time and reduces costly prototype iterations during the manufacturing process.

With this new collaboration focused on PUI Audio products, engineers can now download free, high-quality CAD models, including symbols, footprints, and 3D models, directly on the new PUI Audio website. Available parts include audio indicators, microphones, speakers, haptics, and ultrasonic transmitter and receivers.

The CAD models have been meticulously created and verified by SnapEDA’s Component Engineering Team, which leverages SnapEDA’s patented verification technology in their process.

“We continue to dedicate our efforts to making the job of our customers–the engineers–easier,” said Paul Spain, CEO of PUI Audio. “This viewer is a key component to our successful launch of an entirely new digital experience we’ve designed toward that effort.”

“PUI Audio understands that eliminating unnecessary steps is the key to keeping innovation flowing. We are excited to see what their customer base of engineers will create with this new resource,” said Natasha Baker, the CEO and Founder of SnapEDA.

In addition to being available on PUI Audio’s website via the SnapEDA Viewer, engineers can also find the CAD models on SnapEDA’s website and PCB plugins, and its larger ecosystem via the SnapEDA Syndication Network. Affiliated partners include Digi-Key, and Mouser.

To start downloading, engineers can simply search the part number they are looking for. Once they click on the Symbol, Footprint, and 3D model sections, a viewer will pop up, allowing engineers to preview the models and download them instantly in the format they prefer.

They are compatible with nearly all major PCB design tools, including Altium, Cadence OrCAD and Allegro, KiCad, Autodesk EAGLE and Fusion360, Proteus, and over 15 more.

These models have been created based on industry standards including IEEE-315 and IPC-7351B, as well as SnapEDA’s internal standards.

About SnapEDA

SnapEDA helps engineers design electronics faster. Over 1 million electronics engineers and PCB designers use its search engine for electronics design each year, creating everything from medical devices to electric vehicles. By providing ready-to-use building blocks for design, including schematic symbols, PCB footprints, and 3D models, SnapEDA unlocks massive design productivity and innovation, improving our world through better products. Learn more at www.snapeda.com.

About PUI Audio

Founded in 1972, we strive to provide the world with the most comprehensive line of high-quality audio components and innovative custom solutions, by applying our unique design approach and world-class customer care. Learn more at www.puiaudio.com.

Welcome to PUI Audio’s New Website

PUI launched the innovative new PUIAudio.com today, a clean, clutter-free experience centered around providing users an easy and streamlined web tool to support their everyday operations.

“Our company motto is ‘When it needs to be heard,’” said CEO Paul Spain. “So, when it came to this project, we knew it was important to base our decisions on our customers, who needed to be heard, and not create this experience in a vacuum.”

After several listening sessions with audio engineers, PUI crafted a digital experience based on what actual users wanted to see and experience on the new website. The company asked questions about what would make the job of engineers easier when designing an audio solution and how they might feel more supported by the company. The resulting revolutionary experience is built with customer requests leading the forefront of the digital navigation, leading to a streamlined experience that is focused more on the customer experience than the company’s goals.

“Our primary goal has always been to support engineers in what they are doing. We prioritized listening and built this website with our customers in mind,” Spain said.

Front and center on the new website is an industry-leading search function, leading customers to exactly whatever it is they are trying to find. The website also includes several new, clutter-free experiences, that lead users into direct communication with the PUI engineering team, so that engineers can work peer to peer to develop customized solutions and innovative product lines to support and solve the problems of the future. Customers can schedule time directly with the engineering team or chat directly with the engineers via the website.

“We’ve never just been an out-of-the-box audio component manufacturer,” Spain said. “Our mission has always been to lead the industry in global innovation. We know that our key differentiator is the engineering support that enhances our products and their ability to be customized. So, we developed this website by listening directly to the innovators, our customers, and providing them with the experience they need to innovate.”

The new website also includes features such as a resource hub, knowledge center, and dynamic product specifications and tools, providing engineers with the necessary information, tools and context they need to put all the pieces together on their next design.

“We could not be more thrilled with the launch of this project,” Spain said. “But it’s important to note that we’re not the audience we’re most eager to hear from. We are waiting on the edges of our seats to hear what the customers think.”

PUI Audio, Inc. is a Dayton-based audio component manufacturer. Founded in 1972, the company has built a strong reputation for its creative solutions and engineering expertise, helping clients in medical, industrial, security and consumer markets to, “Be heard!” no matter what the need.

For media inquiries, please contact:

Erin Ruef

Vice President of Marketing

ruef@puiaudio.com

Overcoming the Pitfalls of Poor Audio

Overcoming the Pitfalls of Poor Audio

Audio is a differentiator that can make or break user experience.

In an increasingly crowded marketplace, with more than 8 billion connected smartphones, tablets, PCs, TVs, TV boxes and other bits of audio hardware, there’s more customers than ever before demanding an instant connection with a product. When poor user experience translates into lost sales, avoid these four major pitfalls when it comes to audio.

When audio is too quiet / too loud, it means…

  • Ambient noise level was not considered

  • Wrong size acoustic component chosen

  • Wrong frequency or frequencies selected for tone

If there’s distorted sound / amplifier clipping, it means…

  • Wrong input level to the amplifier

  • Amplifier gain is set too low or high

  • Not enough amplifier power

If audio has a thin, tinny sound, it means…

  • Resonant frequency of the speaker is too high

  • Size of the speaker is too small

  • Not enough enclosure volume for the speaker

When there’s echo and feedback, it means…

  • Microphone placed too close to the speaker

  • Microphone mounted to the same PCB as speaker

  • Microphone and speaker mechanically coupled to same surface

Making Sound Decisions

Audio is a differentiator that can make or break user experience.

Taking the time to consider your product’s audio while in the conceptual phase of product design is crucial to delivering strong user experience.

HERE ARE THE 6 MAJOR CONSIDERATIONS FOR AN AUDIO PLAN

1 Consider the ambient environment in which your product will be used

2 Establish the audio component dimensional envelope early on.

3 Reference the audio component’s SPL rating and distance

4 Budget for more power than what you might use

5 Choose a larger amplifier than what you might need

6 Test your audio performance before closing the mechanical and electrical design

How to Choose the Right IEC 60601-1-8 Speaker

How to Choose the Right IEC 60601-1-8 Speaker

With the increased use of medical electronics in medicine today, the International Electrotechnical Commission (IEC) developed the IEC 60601-1-8 standard to regulate alarm signals to prevent confusion, when several instruments are sounding at the same time in the same room.

While the IEC 60601-1-8 standard covers every aspect on the alarm signals, and should be referred to as the ultimate reference with regards to the specific tones to use in your device, there are three main requirements that pertain to speaker selection:

  1. A pulsed frequency between 150 Hz and 1 kHz
  2. At minimum of four harmonics of the pulsed frequency between 300 Hz and 4 kHz
  3. The sound pressure level (SPL) of the harmonics must be within ±15 dB of the pulsed frequency

Additional pulse requirements—such as pulse duration, rise time, and fall time—are also part of this standard, but pertain more to the input signal sent to the speaker.

Below is an example of the type of waveform characteristics* that may be used to meet the IEC 60601-1-8 criteria. The flat portion of the waveform is used to create the harmonics from the fundamental pulsed frequency.

*For informational purposes only

PUI Audio has taken the performance criteria called out by IEC 60601-1-8 and performed studies on speakers to gauge which specifications stand out as most important when selecting speakers to meet the criteria.

Each test below was performed with the speaker mounted to a test baffle, and a B&K measurement microphone connected to a Listen, Inc. SoundCheck test system set to spectral analyzer mode.

AS06608PS-R with 1W, 520 Hz square wave
Microphone spaced at 10cm from test baffle
AS04508MR-3-R with 1W, 325 Hz square wave
Microphone spaced at 10cm from test baffle

AS04004PO-R with 1W, 325 Hz square wave
Microphone spaced at 10cm from test baffle

AS02808MR-R with 1W, 325 Hz square wave
Microphone spaced at 10cm from test baffle

 

 

 

From our testing, we can deduce the characteristics of a speaker that makes it an ideal candidate to use within a Medical Device that needs to meet the criteria set forth by IEC 60601-1-8.

Steps to selecting the ideal speaker for your application:

1. Reference IEC 60601-1-8 to ensure correct tone selection for your product. Below is an example of tonal requirements* for different product applications.

Cause Medium Priority High Priority Mnemonic Notes Examples of type of Alarm System
General C C C C C C – C C Fixed Pitch Other Alarm Systems that do not readily fall into one of the following categories, including but not limited to electrical or non-oxygen gas supply systems, EEG monitors, intracranial pressure monitors, laparoscopic gas insufflation systems, calf compressor systems, etc.  Optionally this sound is permitted for the Alarm System of any kind of equipment.
Cardiac c e g c e g – g C Trumpet call; Call to arms; Major chord Anesthesia workstations that include cardiac monitors, multi-parameter monitors which include cardiac monitors, heart rate monitors, invasive or non-invasive blodd pressure monitors, cardiac output monitors, peripheral perfusion monitors (plethysmographs), transesophageal echo, fetal heart rate monitors.
Ventilation c a f c a f – a f Inverted major chord; Rise and fall of the lungs Anesthesia workstations which include ventilators (but which do not include cardiac monitors); lung ventilators, spirometers, CO2 monitors, ventilator disconnect (airway pressure) monitors, etc.
Oxygen C b a C b a – g f Slowly falling pitches; Top of a major scale; Falling pitch of an oximeter Pulse oximeters, transcutaneous / tissue oxygen monitors, oxygen analyzers, oxygen concentrators, oxygen gas supply lines.
Drug or Fluid Delivery C d g C d g – C d Jazz chord (inverted 9th); Drops of an infusion falling and “splashing” back up Volumetric infusion pumps, syringe drivers, anesthetic agent delivery systems or analyzers.
Equipment or Supply Failure C c c C c c – C c Falling or dropping down Any device when it experiences loss of power or other major failure of the device.

2. Convert the tones into their respective frequency. Use this musical note to frequency conversion chart to assist you.

3. Based upon the lowest musical note’s frequency (where C4, or middle C, would be ~261 Hz), you would start filtering for speakers with a resonant frequency of 261 Hz or lower.

4. If you need to meet a target SPL—70 dB at 1 meter is a good rule-of-thumb—you would then additionally filter for speakers that can achieve that SPL while observing the speaker’s power rating.

Speaker Integration Best Practices

  • If possible, mount the speaker to the inside face of the outer housing. This maximizes the speaker’s measured output. Leave a keep-out area of at least 3mm between the speaker’s diaphragm and the surface in front of it.
  • Ensure that the speaker is mounted in such a way to create a seal along the outer edges of the speaker’s frame. This reduces cancelation that occurs if the front of the speaker’s diaphragm/cone can interact with the back of the diaphragm/cone. Cancelation can cause a reduction in output below 1 kHz.
  • As the signal to the speaker is a trapezoidal waveform, or a square wave, power handling needs to be calculated using the formula below. Do not exceed the rated power (not the maximum instantaneous power, which is meant for use with voice or music) of the speaker.
     
    Power = (Volts peak)2 / Impedance
     
    Exceeding the speaker’s rated power will cause damage over time. Typically the type of damage will be broken voice coil tinsel leads or a burned voice coil that causes open load resistance, or a deformed voice coil former which locks the voice coil in the magnetic motor.
  • Mounting the speaker within an enclosure will improve performance at and below the resonant frequency of a speaker. Please contact PUI Audio for more information regarding the correct enclosure volume for your application.
  •  If your application will be chemically cleaned in a hospital environment, choose a speaker that has been treated (our WR series speakers) or a speaker with a Mylar or aluminum diaphragm.

Recommended Speakers

PUI Audio is the go-to speaker source for medical applications. Decades of experience in assisting the world’s leading Medical Device manufacturers allows us to recommend the following speakers for IEC 60601-1-8 devices:

Hi Fidelity & Superior Frequency Response:

Part Number Dimensions (in mm) Resonant Frequency SPL @ 10cm at Rated Power SPL @ 1m at Rated Power
AS02704MS-N50-LW100-R 27L x 27W x 6.6H 350 Hz 96 dB 76 dB
AS03204MS-3-R (4 ohm)

AS03208MS-3-R (8 ohm)

32.7L x 31.7W x 16.5H 200 Hz 101 dB 81 dB
AS03604MR-N50-R 36D x 18H 200 Hz 103 dB 83 dB
AS06004PS-R (4 ohm)

AS06008PS-R (8 ohm)

66.8L x 66.8W x 26.5H 160 Hz 109 dB 89 dB
AS09208AR-R 92D x 44.6H 90 Hz 112 dB 92 dB
AS03608AS-R 36L x 36W x 16.8H 250 Hz 98 dB 78 dB
AS05308AS-R 53L x 53W x 34H 230 Hz 108 dB 88 dB
AS06504PS-X-R 65.0L x 65.0W x 36.7H 130 Hz 111 dB 91 dB

Lead-Wired and/or Enclosed for Ease of Use:

Part Number Dimensions (in mm) Resonant Frequency SPL @ 10cm at Rated Power SPL @ 1m at Rated Power
AS02008MR-LW152-R 20D x 3H 500 Hz 93 dB 73 dB
AS02808MR-LW152-R 28D x 5.2H 500 Hz 95 dB 75 dB
AS03608MR-LW100-R 36D x 4.6H 500 Hz 101 dB 81 dB
AS04004PO-2-LW152-WR-R 40L x 28.5W x 11.7H 420 Hz 100 dB 80 dB
ASE04508MR-LW150-WP-R 45L x 36W x 20H* 420 Hz 98 dB 78 dB
AS06608MR-LW152-R 66L x 66W x 12.5H 380 Hz 101 dB 81 dB
AS07104PO-LW152-R (4 ohm)

AS07108PO-LW152-R (8 ohm)

71L x 41W x 25H 250 Hz 104 dB 84 dB
ASE06008MR-LW150-R 60L x 30W x 10.3H* 300 Hz 101 dB 81 dB

*Denotes speaker with enclosure

Rugged and Durable for Element Resistance:

Part Number Dimensions (in mm) Resonant Frequency SPL @ 10cm at Rated Power SPL @ 1m at Rated Power
AS04004MR-N50-WP-R 40D x 21.5H 160 Hz 105 dB 85 dB
AS04504PS-X-R 45.4L x 43.3W x 29.2H 170 Hz 110 dB 90 dB
AS05804PS-X-R 58.3L x 55.3W x 33.8H 140 Hz 109 dB 89 dB
AS04004PO-2-WR-R 40L x 28.5W x 11.7H 420 Hz 106 dB 86 dB
AS04004PR-WR-R 40L x 40W x 17.5H 180 Hz 104 dB 84 dB
AS04008PS-4W-WR-R 40L x 28.3W x 11.5H 380 Hz 101 dB 81 dB
AS06608PS-WR-R 66.3L x 66.3W x 29H 230 Hz 115 dB 95 dB
AS07104PO-LW152-WR-R (4 ohm)

AS07108PO-LW152-WR-R (8 ohm)

71L x 41W x 25H 250 Hz 104 dB 84 dB

Custom Audio Solutions for Your Unique Applications

Custom Audio Solutions for Your Unique Applications

Every project is different, and when a standard off-the-shelf solution doesn’t quite give the results you are after, PUI Audio is here to help create a solution that fits your exact need. Form, Fit, and Function can be custom-tailored on most of our components to meet your specific needs.

Our Audio Engineers are available to consult on your project to help you make the best decisions, optimize your product design for superior results, and rapid prototype a design in as little as 24 hours using one of our 3D printers and measurement systems.

From simple value-added services such as adding lead wires and connectors to components, to full-scale audio product design and consulting, PUI Audio has 50+ years of audio expertise to solve your easiest and your most complex challenges.

How we help our customers:

  • Custom tuned-port, and acoustic suspension enclosure designs
  • Bespoke speaker design
  • Audio component integration
  • Equalization settings and sound file editing
  • Helmholtz chamber designs for piezo benders
  • Complete audio system analysis
  • Piezo-ceramic design
  • Final product testing

Wide-Band MEMS Microphones Application Guide

Wide-Band MEMS Microphones Application Guide

Microphone Placement within a Product

When designing a PUI Audio MEMS microphone into your product, careful PCB placement and sound hole position need to be considered to minimize noise. The microphone should be placed to avoid antennae, amplifiers, motors, power supplies, or any other devices that may create noise interference.

Additionally, microphones should not be placed on the same PCB as spring contact or surface mount speakers, as the vibration from the speaker is often transmitted to the microphone through the PCB, creating noise, echo, or feedback.

Microphone External Sound Hole Placement on a Product’s Housing

The external sound hole on a product should be limited in distance from, and larger in diameter than, the sound hole on the microphone.

A direct path from the microphone’s sound hole (also referred to as the Acoustic Port) to the exterior of a product’s housing is required for optimum frequency response and to minimize unwanted noise from entering the microphone.

Placing the external sound hole on a flat surface simplifies the design of a gasket between the housing and the microphone sound hole.

Microphone Sound Channel Design

When designing the sound channel that connects the external sound hole to the microphone’s sound hole, first ensure that there is no leak by gasketing the area between the external sound hole and the microphone sound hole.

Many echo and feedback problems are caused by a leaky gasket between the sound hole between a top-firing microphone and the housing or between the bottom-firing microphone’s PCB and the housing. Please ensure the gasket is fully compressed to eliminate potential problems and/or a degradation in performance.

The sound channel should be kept as short as possible and larger in diameter than the microphone sound hole for top-firing microphones or be greater than or equal to the diameter of the PCB sound hole for bottom-firing microphones.

The diameter of gasket should be as close to the same size as the external sound hole to prevent creating a Helmholtz resonating chamber.

A long, thin or short, wide sound channel can “tune” the microphone, creating a peak in response between 10 kHz to 15 kHz, followed by a steep roll-off in frequency response thereafter.

Top-Firing Microphones: The diameter of the external sound hole and channel created by the gasket should be at least 0.1mm larger in diameter than the microphone’s sound hole.

Bottom-Firing Microphones: The diameter of the sound hole on the PCB should be at least 0.5mm to prevent solder paste from melting and entering the sound hole. Additionally, the interior of the PCB sound hole should not be plated to prevent solder paste from flowing into it.

Analog MEMS Microphone Circuit Design

Slight variances in power supply voltage do not affect the sensitivity of PUI Audio’s analog MEMS microphones (designated by AMM in the PUI Audio part number). As such, a circuit designer only needs to ensure that the voltage output of the power supply is within the voltage range called out in the MEMS microphone specifications.

Unlike traditional ECM microphones, MEMS microphones do not require the use of a bias resistor between the power supply and the microphone. MEMS microphones have an independent output that is separate of the voltage input. It is recommended to decouple the noise of the power supply from the MEMS microphone by using a 0.1µF capacitor at C1 in the diagram below.

A DC-blocking/high-pass filter capacitor should be placed between the MEMS output pin and the CODEC/ADC/pre-amplifier’s input pin, C2 in the diagram below. Values between 1µF and 3µF are often used, where the larger the capacitor value, the higher the frequency at which the high-pass filter’s corner frequency is placed.

In the event of electro-magnetic interference, place a resistor that matches the microphone’s impedance between the amplifier’s unused differential input and the microphone’s ground.

Digital MEMS Microphones

PUI Audio offers digital output MEMS microphones (designated by DMM in the PUI Audio part number) with PDM and I2S data formats. Both feature a Left/Right channel select pin for stereo audio capture and data transfer over a single data input line on a DAC or CODEC.  The I2S digital MEMS (DMM-4026-B-I2S-R) microphone also offers the ability to set up microphone arrays by changing the WCLK Hold Time.

PUI Audio’s digital MEMS microphones offer a Full Power mode, a reduced sensitivity Low Power mode, and a Sleep mode for reduced current draw and battery powersavings when the microphone isn’t needed.

Modes are activated by changing the input clock frequency to the microphone.

Solder Pad and Stencil Design

Each MEMS microphone is built for reflow soldering, where the solder joints serve as the means for electrical and mechanical connection to the PCB. On bottom-firing microphones, a solder joint also acts as the acoustic seal between the microphone sound hole and the PCB.

The recommended solder pad design and stencil layout is listed within the specifications for each microphone. The PCB solder pad to microphone pad ratio is 1:1

Solder Paste

A Type 4 no-clean solder paste is recommended to be used with PUI Audio’s MEMS microphones. The stencil thickness should be between 0.1mm to 0.12mm, with the ratio of the size of the stencil to pad being between 0.8:1 to 0.9:1 to minimize tin bead content.

For bottom-firing microphones, solder pastes with low flux content (such as Indium 8.9 HF SAC305) are recommended to prevent excessive flux from entering the microphone sound hole, causing damage.

Pick-and-Place Operations

Special attention needs to be observed when programming an SMD pick-and-place machine (also known as P&Ps) to place top-firing MEMS microphones (designated with a –T within PUI Audio’s part number) due to the placement of the sound hole (referred to as the Acoustic Port or AP in the specifications) on the same surface that vacuum is applied to.

The specifications call out the recommended pickup location, and the location of the sound hole.  To avoid damaging top-firing microphones, do not allow the SMD pickup nozzle to pass over the sound hole. The inside diameter of the nozzle must only move directly to the recommended pickup location, which is pink in the PUI Audio specifications.

Programming the SMD pick-and-place machine to place bottom-firing microphones is easier as the sound hole is placed on the bottom of the part.

Reflow Soldering

PUI Audio’s MEMS microphones feature gold-plated pads for lead-free reflow soldering. Please follow the reflow process below and do not exceed a total of three cycles.  If multiple reflow cycles are required, the microphone must be allowed to return to room temperature before the start of the next reflow cycle.
Allow the microphone to rest at room temperature for a minimum of three hours before functionally testing it.

MEMS Microphone PCB Cleaning Considerations

On PCBs that contain a PUI Audio MEMS microphone, please follow these precautions to minimize potential damage to the microphone.

  • Do not wash or clean PCBs after the reflow process.
  • Do not expose the PCB to ultrasonic processing or cleaning.
  • Do not pull a vacuum over the microphone sound hole (on both top-firing and bottom-firing microphones).
  • Do not apply more than 0.3mPa of air pressure into the microphone sound hole.
  • If a dust removal system is used, please ensure that the air gun nozzle diameter is greater than or equal to 2mm, less than 0.3mPa of air pressure is used, the distance between the tip of the air gun nozzle and the PCB is greater than 50mm, and that the total cycle duration is less than five seconds.
  • To eliminate the chance of dust entering the microphone’s sound hole, it is recommended that the sound hole be covered during the dust removal process, if possible.