AN-000159

CH101 and CH201 Ultrasonic Transceiver Handling and AssemblyGuidelines

CH101 and CH201 Ultrasonic Transceiver Handlingand Assembly Guidelines

Chirp Microsystems reserves the right to change
specifications and information herein without notice.

Chirp Microsystems
2560 Ninth Street, Ste 220, Berkeley, CA 94710 U.S.A+1(510) 640–8155
www.chirpmicro.com

Document Number: AN-000159
Revision: 1.0
Release Date: 11/24/2019

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1 INTRODUCTION
This document provides information and general guidelines for handling and assembling boards with CH101 and CH201 ultrasonictransceivers. The goal of the processes outlined herein is to prevent damage of ultrasonic transceivers due to mechanical, vacuum andthermal stress caused by the handling process. Any deviation from the recommendations contained in this Application Note should
be reviewed by Chirp Microsystems and thoroughly verified prior to implementation in a production environment.

Figure 1. CH101 ultrasonic transceiver

The CH101 and CH201 ultrasonic transceivers are compatible with existing industrial Surface Mount Technology (SMT) processes. An
important feature of the ultrasound transceiver is the open acoustic port hole on the top of the package. This exposes the internal
MEMS ultrasonic transducer to the external environment. Care must be taken to ensure that no particulates enter this port hole, andthere is no damage to the internal MEMS membrane contained in the device.

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TABLE OF CONTENTS
1INTRODUCTION .........................................................................................................................................................................12

MANUAL HANDLING ..................................................................................................................................................................53

AUTOMATED PICK AND PLACE ...................................................................................................................................................64

PCB DESIGN GUIDELINES ............................................................................................................................................................75

STENCIL DESIGN AND SOLDER PASTE APPLICATION ...................................................................................................................86

GENERAL GUIDELINES FOR SOLDERING......................................................................................................................................97

REVISION HISTORY ................................................................................................................................................................... 11

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LIST OF FIGURES
Figure 1. Chirp ultrasonic transceiver showing acoustic port hole .......................................................................................... 2
Figure 2. Vacuum pick up point for Pick and Place ................................................................................................................ 6
Figure 3. Recommended trace layout ..................................................................................................................................... 7
Figure 4. Recommended land and solder mask design ......................................................................................................... 7
Figure 5. Solder reflow profile ................................................................................................................................................. 9

LIST OF TABLES
Table 1. Typical soldering recommendations ......................................................................................................................... 8
Table 2. Recommended solder profile parameters ............................................................................................................... 10

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2 MANUAL HANDLINGPCB rework, prototyping, manual assembly and manual handling processes:••••••••••

Manual soldering should be avoided if possible, as it is difficult to ensure accurate temperature control. It is recommended
to start from lowest temperature possible, and the maximum temperature should typically not exceed 230°C.
All manual processes should be carried out on ESD grounded work stations.
Sharp objects of any type should not be used to pierce into the transceiver acoustic port hole. In general, the transceivershould only be handled from the side.
Use static shield bags or ESD bags for transceiver handling and storage. Avoid conductive IC boxes for transceiver storage asloose foam material can get into the transceiver acoustic port hole.
Pocket-less gel packs with adhesive gel layer are ideal to hold the transceiver in position, care should be taken to remove
the dust on the gel surface before using it for transceiver handling and storage.
Do not board brush, use an air gun or hot air blower directly over the transceiver acoustic port hole during PCB repair orrework of the transceiver or other adjacent components on the board.
Do not employ chemical board wash or cleaning, as the associated cleaning agents can enter the acoustic port hole andpermanently damage the device.
Do not use physical cleaning and do not expose to ultrasonic cleaning methods or air guns.
Use of an infra-red rework station is highly recommended for any PCB rework with CH101 and CH201 transceivers as itprovides precise control of temperature profile and process repeatability.
In addition to the general guidelines for IC handing, care should be taken to avoid any vacuum, excessive mechanical stressor contamination entering the transceiver acoustic port hole.

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3 AUTOMATED PICK AND PLACEThe Pick and Place (PnP) process often uses vacuum pick up tools for accurate placement of transceivers on the PCB. Drawing a vacuum
over the transceiver acoustic port hole may cause damage to the device and so care should be taken to avoid any direct contact ormoving the nozzle over the transceiver acoustic port hole.
••Avoid using excessive force in the PnP process
As a starting point for setting up the PnP process, it is recommended that the nozzle size to handle 0603 components orsmaller can be used for CH101 and CH201 ultrasonic transceivers

Figure 2. Vacuum pick up point for Pick and PlaceDocument Number: AN-000159
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4 PCB DESIGN GUIDELINESPCB layout should adhere to the following guidelines:
••
•
•
•

PCB design should be as symmetrical as possibleo Since the transceiver has very low power consumption, large Vdd and Gnd traces are not requiredo Do not place vias or traces within the transceiver footprint (Figure 3)
PCB land and connecting traces should be symmetrical
PCB land height and width should be equal the transceiver pad height and width (Figure 4)
Solder mask opening should exceed PCB land height and width by 0.1mm (Figure 4)
Placement of the transceiver on the PCB should avoid locations close to hot spots such as microprocessors and points ofmechanical stress such as pushbuttons and screws
Package Footprint
Avoid Traces In This Area

INT

RESET_N

SCL

AVDD

SDA

VDD

PROG

VSS

Figure 3. Recommended trace layout

Figure 4. Recommended land and solder mask design

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5 STENCIL DESIGN AND SOLDER PASTE APPLICATION
The thickness and the pattern of the soldering paste are important for the proper transceiver mounting process.

Solder paste

Type 4- alloy composition – Sn/Ag
3.0/Cu 0.5, no clean solder paste

FluxUse No Clean Flux to avoid board
cleaning
Table 1. Typical soldering recommendations

••
•
•••

Stainless steel stencils are recommended for solder paste application
A stencil thickness of 90 - 150 µm (3.5 - 6 mils) is recommended for screen printing
The openings of the stencil for the signal pads should be between 70% and 90% of the PCB pad area
The final volume of soldering paste applied to each PCB land is recommended to be within 20% among (all) the PCB landpads
Optionally, for better solder paste release, the aperture walls should be trapezoidal, and the corners rounded
The fine pitch of the IC leads requires accurate alignment of the stencil to the printed circuit board. The stencil and printed
circuit assembly should be aligned to within 25 µm (1 mil) prior to application of the solder paste

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6 GENERAL GUIDELINES FOR SOLDERINGThe following best practices for PCB design and assembly should be followed when mounting CH101 and CH201 ultrasonictransceivers:••

Solder paste should be as thick as possible to minimize stress between the PCB to the transceiver and to avoid the PCB
solder mask from touching the transceiver
Solder paste thickness must be as uniform to avoid uneven stress

CH101 and CH201 are compliant to standard solder reflow processes as specified in JEDEC standard J-STD-020, as shown in Figure 5
and specified in Table 2.

Figure 5. Solder reflow profile•••••••

Maximum ramp up rate should not be exceeded to allow for uniform temperature distribution, avoid component damage andsoldering defects
Maximum peak temperature should not be exceeded to avoid changes in transceiver performance parameters
A pre-heat zone at 200 °C for 60 to 120 seconds can be added before heating to the peak temperature to enhance uniformtemperature distribution
Allocate the transceivers to the last reflow soldering operation.
Do not employ chemical board wash or cleaning, as the associated cleaning agents can enter the port hole and permanently
damage the transceiver
Do not use physical cleaning and do not expose to ultrasonic cleaning methods or air guns
Do not use Vapor Phase Re-flow process for CH101 and CH201 transceivers, as the vapor can damage the transceiver throughthe port hole

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240 +0/-5 ˚CTable 2. Recommended solder profile parameters

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7 REVISION HISTORY
Revision Date
11/24/2019

Revision1.0

Description
Release with CH101 and CH201

This information furnished by Chirp Microsystems, Inc. (“Chirp Microsystems”) is believed to be accurate and reliable. However, no responsibility is assumed by Chirp
Microsystems for its use, or for any infringements of patents or other rights of third parties that may result from its use. Specifications are subject to change without
notice. Chirp Microsystems reserves the right to make changes to this product, including its circuits and software, in order to improve its design and/or performance,
without prior notice. Chirp Microsystems makes no warranties, neither expressed nor implied, regarding the information and specifications contained in this document.
Chirp Microsystems assumes no responsibility for any claims or damages arising from information contained in this document, or from the use of products and services
detailed therein. This includes, but is not limited to, claims or damages based on the infringement of patents, copyrights, mask work and/or other intellectual property
rights.
Certain intellectual property owned by Chirp Microsystems and described in this document is patent protected. No license is granted by implication or otherwise under
any patent or patent rights of Chirp Microsystems. This publication supersedes and replaces all information previously supplied. Trademarks that are registeredtrademarks are the property of their respective companies. Chirp Microsystems sensors should not be used or sold in the development, storage, production or utilizationof any conventional or mass-destructive weapons or for any other weapons or life threatening applications, as well as in any other life critical applications such as
medical equipment, transportation, aerospace and nuclear instruments, undersea equipment, power plant equipment, disaster prevention and crime prevention
equipment.
©2019 Chirp Microsystems. All rights reserved. Chirp Microsystems and the Chirp Microsystems logo are trademarks of Chirp Microsystems, Inc. The TDK logo is atrademark of TDK Corporation. Other company and product names may be trademarks of the respective companies with which they are associated.

©2019 Chirp Microsystems. All rights reserved.

Document Number: AN-000159
Revision: 1.0

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