Express Newsletter

The SMTnet Express newsletter is sent weekly to over 25,000 subscribers.

SMTnet
»
Express Newsletter

SMTnet Express, January 11, 2024, Subscribers: 25,289, Companies: 11,989, Users: 28,631

█ Electronics Manufacturing Technical Articles

Moisture Measurements in PCBs and Impact of Design on Desorption Behaviour

Moisture accumulates during storage and industry practice recommends specific levels of baking to avoid delamination. This paper will discuss the use of capacitance measurements to follow the absorption and desorption behaviour of moisture. The PCB design used in this work, focused on the issue of baking out moisture trapped between copper planes. The PCB was designed with different densities of plated through holes and drilled holes in external copper planes, with capacitance sensors located on the inner layers. For trapped volumes between copper planes, the distance between holes proved to be critical in affecting the desorption rate. For fully saturated PCBs, the desorption time at elevated temperatures was observed to be in the order of hundreds of hours. Finite difference diffusion modelling was carried out for moisture desorption behaviour for plated through holes and drilled holes in copper planes. A meshed copper plane was also modelled evaluating its effectiveness for assisting moisture removal and decreasing bake times. Results also showed, that in certain circumstances, regions of the PCB under copper planes initially increase in moisture during baking.

Credit: National Physical Laboratory

Controlling Moisture in Printed Circuit Boards

Moisture can accelerate various failure mechanisms in printed circuit board assemblies. Moisture can be initially present in the epoxy glass prepreg, absorbed during the wet processes in printed circuit board manufacturing, or diffuse into the printed circuit board during storage. Moisture can reside in the resin, resin/glass interfaces, and micro-cracks or voids due to defects. Higher reflow temperatures associated with lead-free processing increase the vapor pressure, which can lead to higher amounts of moisture uptake compared to eutectic tin-lead reflow processes. In addition to cohesive or adhesive failures within the printed circuit board that lead to cracking and delamination, moisture can also lead to the creation of low impedance paths due to metal migration, interfacial degradation resulting in conductive filament formation, and changes in dimensional stability. Studies have shown that moisture can also reduce the glass-transition temperature and increase the dielectric constant, leading to a reduction in circuit switching speeds and an increase in propagation delay times.

Credit: CALCE Center for Advanced Life Cycle Engineering

Impact of FPC Fabrication Process on SMT Reliability

The functionality of electronic devices continues to increase at an extraordinary rate. Simultaneously consumers are expecting even more and in ever smaller packages. One enabler for shrinking electronics has been the flexible circuit board that allows the circuit board to fit a wide variety of shapes. Flexible printed circuits (FPC) have the capability to be very thin and can have unpackaged components directly attached using surface mount technology (SMT) and flip chip on flex technologies. Bare die can also be thinned and attached very close to the circuit board. However one caveat of high density flexible circuit boards with thin die is that they can be very fragile. The use of back side films and underfill can protect the die making circuits more robust. For underfill to work well it requires good adhesion to the circuit board which can mean that flux residues under the die normally must be removed prior to underfilling.

Credit: Starkey Hearing Technologies

Drying printed circuit boards

The following aims lie behind the investigations described: The circuit board is an integrated structure made of metal and plastic. Like most integrated components enclosed in plastic, it absorbs water. When it is rapidly heated as, for example, in soldering technology temperature processes, it is a well known fact that the water will evaporate abruptly, leading to destruction. It is therefore essential that the circuit board be dried before these soldering processes. Circuit board manufacturers are extremely hesitant at providing instructions on drying their circuit boards. Information from the ZVEI [1] should also be regarded critically. The cardinal problem is the high temperature which is recommended for baking. If this is applied, the result is often de-lamination and distortion of the circuit boards. Corrosion and the formation of intermetallic phases of the metallic surfaces are also to be expected. The following investigates whether gentle drying at 45°C or 60°C and at low relative humidity achieves the same result as baking at high temperatures. The industry provides novel dry cabinets which are suitable for rapid drying at relative humidities below one percent.

Credit: TOTECH Canada N.A Inc

Drying and storage recommendation for printed circuit boards

Printed circuit boards, especially multilayer, flexible and rigid-flexible printed circuit boards, are extremely hygroscopic, i.e. they absorb and bind the moisture in the air. A dried polyimide film, for example, will have reached its moisture saturation level again after just a few hours.

Credit: ILFA GmbH

MOISTURE PHYSICS AND PROCESS OF DRYING OF PRINTED CIRCUIT BOARDS

The aim of this collection and interpretation is to develop an understanding of moisture in materials, especially in printed circuit boards, to know the effects on further processing and to be able to derive targeted corrective actions when moisture-related problems occur. In principle, the considerations are valid for all types of PCBs. Although these basic principles are of particular importance when working with flexible and rigid-flexible printed circuit boards; observing them can mean the difference between success or failure.

Credit: Wurth Elektronik GmbH & Co. KG

RESULTS of Searches for related keywords - "pcb drying" (278)

VIEW MORE PAPERS...

SUBMIT YOUR PAPER...

█ Printed Circuit Board Assembly & PCB Design Forum

Camtastic 2000 -- Hi does anyone know where I can download Camtastic 2000 ? Thanks

Selective Solder Recommendation -- Looking for some Recommendations for a Selective Solder machine. We currently have a KISS103 no pre heater. We are high mix low volume, so batch is most like best option. I have used Pilerhouse Jade MKII years ago. Wondering what other option people like.

SEARCH THE FORUM

ADD YOUR THOUGHTS ...

█ SMT, PCB Electronics Assembly Manufacturing Industry News

PCB Designers to Vie for Design Champion Title at IPC APEX EXPO 2024 Registration now open for virtual preliminary heat... Association Connecting Electronics Industries (IPC)
Seika Machinery Celebrates Three Decades of Excellence in Supplying Electronics Machinery & Products Seika Machinery, Inc. proudly marks its 30th anniversary. As a subsidiary of Seika Corporation, a global supplier of industrial machinery and electronics products, Seika Machinery has consistently delivered top-tier equipment and unrivaled support to its valued customers.... Seika Machinery, Inc.
Optimize Production with I.C.T's IC Burning Machine Explore I.C.T's IC Burning Machine for unmatched precision, high-speed programming, and versatile compatibility. Elevate your electronics manufacturing with our future-ready solutions.... I.C.T ( Dongguan ICT Technology Co., Ltd. )

ADD YOUR NEWS...

█ SMT / PCB Products & Services

NEW SMT / PCB EQUIPMENT & SERVICES - For Sale

PCB ASSEMBLY

PCB Fab & Assembly

Imagineering

PCB REFLOW OVEN

NEW! Mark 7 Series -
Reflow Oven

Heller

PCB DISPENSING

PCD Continuously Volumetric Dispense Pumps

GPD Global

Selective Soldering

Selective Wave Soldering Machine I.C.T-SS550

Dongguan I.C.T Technology

SELECTIVE SOLDERING

Pillarhouse Jade Handex

Pillarhouse USA

PCB INSPECTION

MV-3 FIVE CAMERA In-Line AOI System

Mirtec

Software

Unisoft ProntoAOI - AOI Machines Programming Software

UNISOFT Corporation

VIEW MORE NEW PRODUCTS...

█ SMT / PCB Assembly Equipment Auctions

Currently, no featured auctions are on SMTnet

SEE MORE AUCTIONS...

█ Electronic Equipment Market

MARKET - Used Electronic Assembly Machines For Sale

P&P / FEEDERS

Panasonic NPM-W2

SMTUnion - Panasonic NPM-W2 Chipshooter

SMTUnion

P&P / FEEDERS

Chroma Table Top Single Site Test Handler Model 3111

World Equipment Source - Chroma Table Top Single Site Test Handler Model 3111

World Equipment Source, LLC

Adhesive Dispensers

Musashi FAD2500

KD Electronics Ltd.

AOI INSPECTION

Viscom S3088 Ultra Chrome 3D AOI

Lewis & Clark Viscom S3088 AOI

Lewis & Clark

Board Cleaners

Aqueous Technologies Trident XLD

Baja Bid

MORE EQUIPMENT & PARTS...

SUBMIT YOUR RFQ ....

MARKET - Used PCB Assembly Equipment Wanted To Buy

PCB TEST

Agilent 3070

KD Electronics Agilent 3070

KD Electronics

P&P /FEEDERS

Mydata SMT P&P

Baja Bid - Mydata SMT Placement Machine

Baja Bid

P&P / FEEDERS

Assembleon MG-1R

World Equipment Source Assembleon MG-1R

World Equipment Source, LLC

PCB TEST

Agilent 3070

Lewis & Clark Agilent 3070

Lewis & Clark

SEE Buyers' Used Assembly Equipment Wants

█ Electronics Manufacturing & Assembly Events Calendar

EVENTS

Pan Pacific Strategic Electronics Symposium | January 29 to February 1, 2024

SMTA

Wafer-Level Packaging Symposium | February 14 to 16, 2024

SMTA

█ Electronics Manufacturing Training Courses & PCB Assembly Training

FIND TRAINING FOR:

IPC Certification

Soldering & Rework

PCB Design

Electronics Assembly

Electronics Inspection

Online Training

TRAINING - PCB Rework and Hand Soldering Training Courses

Customizable Basic Hand Soldering

Multiple dates and locations. Check the link for details

Blackfox Training Institute, LLC

TRAINING - Online Electronics Manufacturing and Assembly Training Courses

Reflow Soldering 101 Training Course

Surface Mount Technology Association (SMTA)

IPC/WHMA-A-620 Expert (CSE) Certification Training Course

EPTAC Corporation

IPC Certified Electronics Program Manager (CEPM) Training and Certification Program

Association Connecting Electronics Industries (IPC)

Component Placement 101 Training Course

Surface Mount Technology Association (SMTA)

ESD Control for Electronics Assembly

Association Connecting Electronics Industries (IPC)

MORE TRAINING COURSES...

█ Electronics Manufacturing & PCB Assembly Career Center

Job Needs & Wants

JOBS

YOUR job openings

Overseas SMT Engineer

All over the world, Alabama, USA

I.C.T ( Dongguan Intercontinental Technology Co., Ltd. )

SMT Engineer, Marketing Representative, Sales Representative, Business Assistant

All over the world, California, USA

I.C.T ( Dongguan Intercontinental Technology Co., Ltd. )

AOI Engineer

Hai Phong, Vietnam

Dongguan RuiHengHuaTai Electronic Co., Ltd

SMT Process Technician III

Racine, Wisconsin, USA

Cree Lighting

Experienced SAKI AOI programmer

All US, USA

AirDataIOT,LLC

Engineering Project Manager

Strongsville, Ohio, USA

Spartronics

Senior Quality Engineer

Williamsport, Pennsylvania, USA

Spartronics

Senior Systems Engineer

Strongsville, Ohio, USA

Spartronics

Procurement Specialist

Brooksville, Florida, USA

Spartronics

Buyer/Planner

Williamsport, Pennsylvania, USA

Spartronics

Corporate Director of Quality

Williamsport, Pennsylvania, USA

Spartronics

Automotive service Technician

Golden, CO, USA

Engage2excel

Program Manager

Williamsport, Pennsylvania, USA

Spartronics

RESUMES

YOUR resumes

POSITION: SMT Technician/ Engineer/ Management

JOB CATEGORY: Engineering Maintenance Management Production Technical Support

CURRENT LOCATION: Raymond, WA, USA

WILLING TO RELOCATE?: Not willing to relocate.

SUMMARY OF QUALIFICATIONS: Expert knowledge of circuit board manufacturing for the through-hole and Surface Mount Technology industry, international and national field work to manufacturers. Provided high value technical assistance and formal training to industry standards. Specialized in staff and department development.

YOUR next job ... YOUR next employee ...

█ PCB Design & Assembly Industry Associations

Surface Mount Technology Association (SMTA)

SMTA is a non-profit international association of companies and individuals (totalling 4,000) involved in all aspects of advanced electronics assembly, surface mount and related technologies.

Membership Info | SMTA Certification | Bookstore | Upcoming Events

Association Connecting Electronics Industries (IPC)

IPC is a US-based trade association dedicated to the competitive excellence and financial success of its nearly 2,600 member companies which represent all facets of the electronic interconnection industry, including design, printed wiring board manufacturing and electronics assembly.

Membership Info | Training & Certification | Online Store | Upcoming Events

Editor - Dave "davef" Fish (submit your technical articles)

SMTnet.com, 98 Elm Street, Portland, Maine 04101 USA, Tel.207-780-0887.

FEATURED SPONSORS
⇩