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SMTnet Express, August 10, 2023, Subscribers: 24,982, Companies: 11,863, Users: 28,243

█ Electronics Manufacturing Technical Articles

Common Process Defect Identification of QFN Packages

The Quad Flat Pack No Leads (QFN) style of leadless packaging [also known as a Land Grid Array (LGA)] is rapidly increasing in us e for wireless, automotive, telecom and many other areas becaus e of its low cost, low stand-off height and excellent thermal and electri cal properties. With the implementation of any new package type, there is always a learning curve for its use in design and processing as well as for the Process and Quality Engineers who have to get to grips with the challenges that these packages bring. Therefore, this paper will provide examples of the common process defects that can be seen with QFNs /LGAs when using optical and x-ray inspection as part of manufacturing quality control. Results of trials conducted on four PCB finishes and using vapour phase and convection reflow will be discussed.

Credit: Nordson DAGE

A Process For Improved QFN Reliability

The process of singulating IC packages such as Quad Flat Pack No-Lead (QFNs) by either a sawing or punching operation results in exposed copper on the sidewalls. This exposed copper surface can oxidize leading to poor or no solder wetting up the sidewall during the assembly operation. The consequence of this oxidized copper surface is either incomplete or no solder fillet formation during the PCB mounting operation resulting in solder joint reliability concerns. Currently, JEDEC and IPC assembly standards do not specify a toe fillet for assembly. However, several component manufacturers have requested a toe fillet solderability process which would improve current QFN reliability by ensuring toe fillet solder coverage A process whereby tin is plated on the copper sidewall of the QFN after singulation has been developed to improve toe fillet solderability. Several assembly studies have been conducted which demonstrate improved QFN reliability due to the use of this toe fillet solderability process. The plating process, toe fillet inspection and improved QFN reliability after assembly due to the use of this toe fillet solderability is described.

Credit: Omg Electrochemicals / Macdermid Alpha

Wettable-Flanks: Enabler for the Use of Bottom-Termination Components in Mass Production of High-Reliability Electronic Control Units

Driven by miniaturization, cost reduction and tighter requirements for electrical and thermal performance, the use of lead-frame based bottom-termination components (LF-BTC) as small-outline no-leads (SON), quad-flat no leads (QFN) packages etc., is increasing. However, a major distractor for the use of such packages in high-reliability applications has been the lack of a visible solder (toe) fillet on the edge surface of the pins: because the post-package assembly singulation process typically leaves bare copper leadframe at the singulation edge, which is not protected against oxidation and thus does not easily solder-wet, a solder fillet (toe fillet) does not generally develop.

Credit: Robert Bosch LLC Automotive Electronics Division

Factors That Influence Side-Wetting Performance on IC Terminals

A designed experiment evaluated the influence of several variables on appearance and strength of Pb-free solder joints. Components, with leads finished with nickel-palladium-gold (NiPdAu), were used from Texas Instruments (TI) and two other integrated circuit suppliers. Pb-free solder paste used was tin-silver-copper (SnAgCu) alloy. Variables were printed wiring board (PWB) pad size/stencil aperture (the pad finish was consistent; electrolysis Ni/immersion Au), reflow atmosphere, reflow temperature, Pd thickness in the NiPdAu finish, and thermal aging. Height of solder wetting to component lead sides was measured for both ceramic plate and PWB soldering. A third response was solder joint strength; a "lead pull" test determined the maximum force needed to pull the component lead from the PWB. This paper presents a statistical analysis of the designed experiment. Reflow atmosphere and pad size/stencil aperture have the greatest contribution to the height of lead side wetting. Reflow temperature, palladium thickness, and preconditioning had very little impact on side-wetting height. For lead pull, variance in the data was relatively small and the factors tested had little impact.

Credit: Texas Instruments

Side Wettable Flanks for Leadless Automotive Packaging

The MicroLeadFrame® (MLF®)/Quad Flat No-Lead (QFN) packaging solution is extremely popular in the semiconductor industry. It is used in applications ranging from consumer electronics and communications to those requiring high reliability performance, such as the automotive industry. The wide acceptance of this packaging design is primarily due to its flexible form factors, size, scalability and thermal dissipation capabilities. The adaptation and acceptance of MLF/QFN packages in automotive high reliability applications has led to the development of materials and processes that have extended its capabilities to meet the performance and quality requirements. One of process developments that is enabling the success of the MLF/QFN within the automotive industry has been the innovation of side wettable flanks that provide the capability to inspect the package lead to printed circuit board (PCB) interfaces for reliable solder joints. Traditionally, through-board X-ray was the accepted method for detecting reliable solder joints for leadless packages. However, as PBC layer counts and routing complexities have increased, this method to detect well-formed solder fillets has proven ineffective and incapable of meeting the inspection requirements. To support increased reliability and more accurate inspection of the leadless package solder joints, processes to form side-wettable flanks have been developed. These processes enable the formation of solder fillets that are detectable using state-of-the-art automated optical inspection (AOI) equipment, providing increased throughput for the surface mount technology (SMT) processes and improved quality as well.

Credit: Amkor Technology, Inc.

SEE Forum results for related keywords - "side fillet" (206)

	LEARN MORE in the Technical Library...
In the past year, the number of technical papers that contributors added to the Technical Library was: 158	MAKE Your Paper More Visible...

█ Printed Circuit Board Assembly & PCB Design Forum

BTU Pyramax 150N Flux Crystals -- We are currently experiencing an issue with one of our reflow ovens producing large amounts of flux crystals in the end of zone 12 and entrance of cooling zone. This has been going on for roughly around 4 years now, we are using Senju M705 lead free paste. Things we have tried : 1)Cleaned debris out of pipes/blowers to clear any clogs. 2)Choked down water flow going to coolers to increase heat in hopes of turning liquidous. 3)Turned off nitrogen bar that is located at end of zone 12 and entrance of cooler to prevent any initial cold N2 hitting this area. 4) Flushed the entire water cooling system. 5) Changed out cooling zone blowers, etc. I found some very old threads from around 2008 regarding these things, but none ever had any solutions. Has anyone else dealt with this and had any luck with solving the issue. Thanks in advance.

Starting wave soldering machine -- I ask for advice on starting wave soldering machine. The soldering machine is not new. Are there guidelines for properly loading solder into a bath and more. I also ask you to recommend an alloy. What do you think about Alpha Sn Plus 07 or SN100C(SnCu0.7Ni)? Thank you.

	SEARCH the PCB Assembly Forum
In the past year, the number of threads opened on the FORUM seeking your help was: 274	CONTRIBUTE to the Assembly Forum...

█ SMT, PCB Electronics Assembly Manufacturing Industry News

Precision PCB Services, Inc. Opens New Office in Plano, Texas

PCB/BGA Rework and Training Facility now in Plano, Texas...

Precision PCB Services, Inc

KYZEN to Present Keynote on Strengthening E-Mobility Infrastructure at SMTA High Reliability Cleaning and Conformal Coating Conference

KYZEN is excited to announce its participation in the SMTA High Reliability Cleaning and Conformal Coating Conference. The event is scheduled to take place Aug. 29-31, 2023 at The Westin Dallas Fort Worth Airport in Texas. KYZEN's Debbie Carboni and Ram Wissel, in cooperation with Brian Chislea from Dow Chemical and Brian O'Leary from Indium Corporation, will present the keynote "Strengthening E-Mobility Infrastructure: Overcoming High-Voltage and Environmental Challenges."...

KYZEN Corporation

pictue of KYZEN’s Debbie Carboni

U.S. Economy Continues to Surpass Growth Expectations; European Outlook is Tepid

IPC Issues July Economic Outlook Report...

Association Connecting Electronics Industries (IPC)

GET more Electronics Assembly Manufacturing News...

█ SMT / PCB Products & Services

NEW SMT / PCB EQUIPMENT & SERVICES - For Sale

REFLOW OVEN

Voidless / Vacuum Reflow Soldering Oven

Heller

Dispensing

Catalina Benchtop Dispense Robots

GPD Global

Reflow

PCB Reflow Oven Machine I.C.T Lyra Series

I.C.T

SELECTIVE SLDRNG

Pillarhouse Jade Handex

Pillarhouse USA

Inspection

CameraLink High Resolution Industrial Cameras

ISVI - Industrial Sensor Vision International Corporation

PCB SOFTWARE

ProntoGERBER CONNECTION

Unisoft

PCB ASSEMBLY

PCB Fab & Assembly

Imagineering

VIEW More New Electronic Manufacturing Products...

█ SMT / PCB Assembly Equipment Auctions

AUCTION | Baja Bid Exchange Auction

AUCTIONEER | Baja Bid

TYPE | Online Auction

SCHEDULE | Mon, Aug 21 to Wed, Aug 23, 2023

FEATURED ITEMS | 2015 Juki Cube 460 Selective Solder, 2013 Aqueous Tech Trident XLT Batch Cleaner, 2013 Mydata MY100LXe—10 Pick & Place, 2008 Assembleon MG2 Pick & Place, 2005 Assembleon Opal Xii Pick & Place, Assorted Mycronic Feeders & Magazines, MPM SPM Screen Printer, FocalSpot NXR—1525 X—Ray, Yamato DKN602C Oven, Conceptronic HVA 102 Oven, [2] Thermotron Environmental Chambers

VISIT the Assembly Equipment Auctions Calendar...

█ Electronic Equipment Mart

MART - Used Electronic Assembly Machines For Sale

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

PCB PRINTING

DEK NEOHORIZON 03iX

SMTUnion - DEK NEOHORIZON 03iX

SMTUnion

PCB LABELING

Coherent Verdi V18 SOLID-STATE Diode-Pumped Laser

World Equipment Source - Coherent Diode-Pumped Laser

World Equipment Source, LLC

	VIEW More Used Equipment For Sale...
104 RFQs were forwarded to equipment suppliers in the past 365 days	SEND a RFQ to Equipment Suppliers ....

MART - Used PCB Assembly Equipment Wanted To Buy

Soldering - Wave

Several Alternatives

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

PCB TEST

Agilent 3070

KD Electronics Agilent 3070

KD Electronics

SEE Buyers' Used Assembly Equipment Wants

█ Electronics Manufacturing & Assembly Events Calendar

EVENTS

Space Coast: Microscope Setups, Getting the Best Results From Your Equipment, a Panel Discussion | August 10 to 10

SMTA

Michigan Expo and Tech Forum | August 15

SMTA

SMTA Workforce Dev. Webinar: Effectiveness of Strain Gage Methodology for Durable Board Design | September 12 to 12

SMTA

ADD Your Electronics Manufacturing and Assembly Event Now ...

█ Electronics Manufacturing Training Courses & PCB Assembly Training

FIND TRAINING FOR:

IPC Certification

Soldering & Rework

PCB Design

Electronics Assembly

Electronics Inspection

Online Training

TRAINING - Electronics Manufacturing and PCB Assembly Training Courses

IDEA-STD-1010 Essentials Online Live Training Course

Multiple dates and locations. Check the link for details

EPTAC Corporation

Idea Counterfeit Component Workshop Online Live Training

Multiple dates and locations. Check the link for details

EPTAC Corporation

Component Identification Online Live Certification

Multiple dates and locations. Check the link for details

EPTAC Corporation

TRAINING - PCB Inspection Electronics Manufacturing Training Courses

IPC-A-640 Interactive PCB Inspection Lab (CIT or CIS Option)

Multiple dates and locations. Check the link for details

EPTAC Corporation

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

Live Online Training - IPC/WHMA-A-620 Trainer (CIT) Challenge Test

ACI Technologies, Inc.

Live Online Training - IPC-A-610 Expert (CSE) Certification Training Course

ACI Technologies, Inc.

Live Online Training - IPC-A-610 (CIT)

ACI Technologies, Inc.

VISIT All Electronics Manufacturing Training Courses...

█ Electronics Manufacturing & PCB Assembly Jobs

CAREER CENTER - Job Needs & Wants

JOBS - POST your job openings now

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. )

Manufacturing Analyst/Cost Accountant

Williamsport, Pennsylvania, USA

Spartronics

Program Manager

Williamsport, Pennsylvania, USA

Spartronics

Senior Quality Engineer

Williamsport, Pennsylvania, USA

Spartronics

Product Engineer

Williamsport, Pennsylvania, USA

Spartronics

Corporate Director of Quality

Williamsport, Pennsylvania, USA

Spartronics

Purchasing Specialist

Brooksville, Florida, USA

Spartronics

Business Development Manager- High Level Assembly- Remote

Plaistow, New Hampshire, USA

Spartronics

Process Engineer

Williamsport, Pennsylvania, USA

Spartronics

RESUMES - POST your resume now

0 Electronics Manufacturing & PCB Assembly Resumes

FIND your next job now... FIND your next employee now...

█ 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.

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