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SMTnet Express, April 20, 2023, Subscribers: 24,681, Companies: 11,759, Users: 27,899

█ Electronics Manufacturing Technical Articles

Residues present on circuit boards can cause leakage currents if not controlled and monitored. How "Clean is Clean" is neither easy nor cheap to determine. Most OEMs use analytical methods to assess the risk of harmful residues. The levels that can be associated with clean or dirty are typically determined based on the exposed environment where the part will be deployed. What is acceptably clean for one segment of the industry may be unacceptable for more demanding segments. As circuit assemblies increase in density, understanding cleanliness data becomes more challenging. The risk of premature failure or improper function is typically site specific. The problem is that most do not know how to measure or define cleanliness nor can they recognize process problems related to residues. A new site specific method has been designed to run performance qualifications on boards built with specific soldering materials, reflow settings and cleaning methods. High impedance measurements are performed on break off coupons designed with components geometries used to build the assembly. The test method provides a gauge of potential contamination sources coming from the assembly process that can contribute to electrochemical migration.

Credit: KYZEN Corporation

Reactivity Of No-Clean Flux Residues Trapped Under Bottom Terminated Components

As electronic devices increase functionality in smaller form factors, there will be limitations, obstacles and challenges to overcome. Advances in component technology can create issues that may have time delayed effects. One such effect is device failure due to soldering residues trapped under bottom terminated components. If the residues trapped under the component termination are active and can be mobilized with moisture, there is the potential for ion mobilization causing current leakage.

Credit: Kester

Cleaning No-Clean Fluxes Prior to Conformal Coating

A customer called the Helpline seeking advice for cleaning no-clean fluxes prior to applying a conformal coating. The customer's assemblies were manufactured with a no-clean rosin based solder paste (ROL0) and were cleaned with an isopropyl alcohol (IPA) wash. After cleaning, a white residue was sometimes found in areas with high paste concentrations and was interfering with the adhesion of the conformal coating (Figure 1). For conformal coatings to adhere properly, the printed circuit board (PCB) surface must be clean of fluxes and other residues. In addition, ionic contamination left by flux residues can lead to corrosion and dendrite growth, two common causes of electronic opens and shorts. Other residues can lead to unwanted impedance and physical interference with moving parts.

Credit: ACI Technologies, Inc.

Evaluation of No-Clean Flux Residues Remaining After Secondary Process Operations

In an ideal world, manufacturing devices would work all of the time, however, every company receives customer returns for a variety of reasons. If these returned parts contributed to a fail, most companies will perform failure analysis (FA) on the returned parts to determine the root cause of the failure. Failure can occur for a multitude of reasons, for example: wear out, fatigue, design issues, manufacturing flaw or defect. This information is then used to improve the overall quality of the product and prevent reoccurrence. If no defect is found, it is possible that in fact the product has no defect. On the other hand, the defect could be elusive and the FA techniques insufficient to detect said deficiency. No-clean flux residues can cause intermittent or elusive, hard to find defects. In an attempt to understand the effects of no-clean flux residues from the secondary soldering and cleaning processes, a matrix of varying process and cleaning operation was investigated. Of special interest, traveling flux residues and entrapped residues were examined, as well as localized and batch cleaning processes. Various techniques were employed to test the remaining residues in order to assess their propensity to cause a latent failure. These techniques include Surface Insulation Resistance1 (SIR) testing at 40°C/90% RH, 5 VDC bias along with C32 testing and Ion Exchange Chromatography (IC). These techniques facilitate the assessment of the capillary effect the tight spacing these component structures have when flux residues are present. It is expected that dendritic shorting and measurable current leakage will occur, indicating a failing SIR test. However, since the residue resides under the discrete components, there will be no visual evidence of dendritic growth or metal migration.

Credit: Foresite Inc.

SEE Forum results for related keywords - clean no-clean -- 1283

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█ Printed Circuit Board Assembly & PCB Design Forum

Any ideas what this is? -- Anyone know what this is?

Know of anyone using Screen Printer (opposed to Stencil Printer) in SMTA? -- Have heard there is some renewed interest in (micro) screen printing

SEARCH the PCB Assembly Forum VISIT the PCB Assembly Forum...

█ SMT, PCB Electronics Assembly Manufacturing Industry News

HELLER Shanghai 2023 New Plant - Grand Opening

As spring blossoms arrive and everything comes to life, HELLER Shanghai continues to grow and expand its capabilities in R&D, manufacturing, and customer support. In order to better serve its customers in China and around the world, and to meet future challenges and opportunities, HELLER China has moved to a new location after 21 years at their previous facilities in Shanghai....

Heller Industries Inc.

Heller - Shanghai Plant Grand Opening

I.C.T at Russia Expo Electronica.

I.C.T at Russia Expo Electronica.We will continue our work in the Russian market and look forward to cooperating with you!...

I.C.T

I.C.T - Russia Expo Electronica

SMTA Recognizes Achievements of Local Chapters

The SMTA is proud to congratulate several chapters on achieving notable scores through the Chapter Leadership Excellence Achievement Review (CLEAR) program for the prior year. The CLEAR program was developed by SMTA as a tool to help volunteer chapter officer teams set goals and track their progress toward success....

Surface Mount Technology Association (SMTA)

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█ SMT / PCB Products & Services

NEW SMT / PCB EQUIPMENT & SERVICES - For Sale

Reflow

PCB Reflow Oven Machine I.C.T Lyra Series

I.C.T

SELECTIVE SOLDERING

Pillarhouse Jade Handex

Pillarhouse USA

PCB INSPECTION

MV 7 OMNI 2D/3D In-Line AOI System

Inspection

Mirtec

Software

Unisoft ProntoAOI - AOI Machines Programming Software

UNISOFT Corporation

PCB ASSEMBLY

PCB Fab & Assembly

Imagineering

REFLOW OVEN

Voidless / Vacuum Reflow Soldering Oven

Heller

Dispensing

Catalina Benchtop Dispense Robots

GPD Global

VIEW More New Electronic Manufacturing Products...

█ SMT / PCB Assembly Equipment Auctions

AUCTION | Benchmark Electronics - Advanced California EMS Facility Closure

AUCTIONEER | Baja Bid

TYPE | Online Auction

FEATURING | (5) SMT Lines - Universal & Hitachi Pick & Place DEK, Yestech, Heller & Vitronics Soltec Equipment Nitrogen Generators, Air Compressors & More!

SCHEDULE | Wed, May 3 to Wed, May 10, 2023

Opens: May 3 [9:00am PST]

Closes: May 10 [9:00am PST]

INSPECTION | Available by Appointment Only on Monday, May 8th from 9:00 AM to 4:00 PM (PST)

LOCATION | Moorpark, CA USA

Click Here To Register To Bid

█ Electronic Equipment Mart

MART - Used Electronic Assembly Machines For Sale

Gen'l Purpose T&M

Zeiss LSM-880 Laser Scanning Microscope

World Equipment Source, LLC

P&P / FEEDERS

Panasonic NPM-W P&P

AllSurplus Panasonic NPM-W P&P

AllSurplus

P&P / Feeders

Assembleon AX201

KD Electronics - Assembleon AX201

KD Electronics

AOI INSPECTION

Viscom S3088 Ultra Chrome 3D AOI

Lewis & Clark Viscom S3088 AOI

Lewis & Clark

Soldering - Reflow

Heller 1809 MKIII

Baja Bid

PCB PRINTING

DEK NEOHORIZON 03iX

SMTUnion - DEK NEOHORIZON 03iX

SMTUnion

VIEW More Used Equipment For Sale... SEND a RFQ to Equipment Suppliers ....

MART - Used PCB Assembly Equipment Wanted To Buy

PCB TEST

Agilent 3070

Lewis & Clark Agilent 3070

Lewis & Clark

PCB TEST

Agilent 3070

KD Electronics Agilent 3070

KD Electronics

WIRE STRIPPERS

Autosplice SAS/2

Baja Bid - Autosplice SAS/2

Baja Bid

P&P / FEEDERS

Assembleon MG-1R

World Equipment Source Assembleon MG-1R

World Equipment Source, LLC

SEE Buyers' Used Assembly Equipment Wants

█ Electronics Manufacturing & Assembly Events Calendar

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█ Electronics Manufacturing Training Courses & PCB Assembly Training

FIND TRAINING FOR:

IPC Certification

Soldering & Rework

PCB Design

Electronics Assembly

Electronics Inspection

Online Training