Solder Flux & Flux Removers « Concorde Electronics

Archive for the ‘Solder Flux & Flux Removers’ Category

Flux Test Kits, what do they do?

Thursday, August 27th, 2015

Test kits are acid titration kits. As solvent evaporates, the acids in the flux become more and more concentrated. The kit is used to determine the acid number of the flux. The test is a simple drop test with an indicator for the endpoint (similar to a swimming pool test). You count the drops and then go to a chart. From the chart you determine how much thinner to add to bring the acid number back down to spec. Traditionally flux control is maintained by measuring the density of the flux and adding thinner as the flux thickens. This is a good method for fluxes with high solids contents. A slight change in density corresponds to a small change in the flux. The no-clean fluxes have low solids percents (typically 2 or 3 %) so a small change in the flux density could reflect the change in solids of 25-30%. This would put the acid level unacceptably high. The test kits are more accurate than using density measurements as a way to monitor the flux.

Source: Kester Solder Co.

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Are Kester “44” rosin residues harmful to an assembly?

Thursday, August 27th, 2015

The “44” flux residues are non-conductive and non-corrosive. Residue removal would normally be for cosmetic reasons. If the assembly is in a heated environment and sees temperatures of over 160°F the flux residues will re-melt. When liquid (at high temperatures) the residues are conductive.

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Do rosin flux residues need to be removed?

Thursday, August 27th, 2015

Rosin flux residues are non-conductive and non-corrosive. Under normal circumstances they do not have to be removed from a printed circuit assembly. Rosin residue removal would be for cosmetic considerations. In an environment where the working temperature of the assembly will exceed 200°F the rosin residues will melt and become conductive, in these situations flux removal is required.

Source: Kester Solder

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Electronics Assembly

Friday, August 21st, 2015

Electronics Assembly

From diagnostic and imaging equipment to hand-held monitoring devices, printed circuit boards are in almost all of the equipment used by doctors, hospitals and clinics.

Smaller components in smaller devices require solder materials that provide good electrical contacts with no bridging, excellent wetting and good throughput.
In order to achieve maximum functionality in increasingly smaller spaces, the use of flexible circuit boards is increasing, providing new challenges for electronic assembly.
Connectors need to be securely soldered to the circuit board to withstand constant use.

Product Characteristics

Paste

Spherical, low-oxide powder available in various mesh sizes
Pb-free, Pb-containing, AuSn and indium-containing alloys
No-clean, water or solvent cleanable flux vehicles
Flexible packaging and quantities to support manufacturing requirements

Wire

Diameters available in SnAg and AuSn down to 0.001″
Pb-free, Pb-containing, AuSn and indium-containing alloys
Solid core and flux core

Fluxes

Flux #2 and #3 for removing tenacious oxides from metals such as Nininol and stainless steel
No-clean and water soluble Tacflux

Preforms

A large die library of washers, squares, discs, frames and special shapes
InTEGRATED™ Preforms used for fast placement of multiple washers at once
Pb-free, Pb-containing, AuSn and indium-containing alloys
Flux coatings
Small sizes, variable thicknesses to achieve optimum volume
Flexible packaging and quantities to support manufacturing requirements

Spheres

Alloys: SAC and Pb-contained alloys as well as indium-contained
Standard sizes are 300 to 1270 microns. Other sizes may be available on request.
Tolerances as tight as ±5 microns for uniform alignment

Soldering Process	Description	Challenges	Our Recommended Products
Surface Mount Reflow	Standard process for PCB assembly	Flexible circuits and smaller boards and components require no bridging and excellent wetting	Indium8.9 Series Solder Paste for the higher reflow temperatures of SnAg and SnAgCu alloys NC-SMQ92H for Sn63 and SN62 Solder Fortification™ Preforms
Laser Soldering	Non-contact; highly controlled heating	Identifying the proper power and timing to reduce voiding and flux spatter and optimize wetting	NC-SMQ75 Solder Paste Solder Preforms especially washers for pin soldering Solder Spheres
IR Soldering	Can be used for smaller packages such as chip resistors, capacitors and SOICs and high temperature soldering	Larger components may impede heating of smaller components due to shadowing effect	Solder Preforms Solder Spheres Indium8.9 Series Solder Paste SnAg, SnSb, and SnAgCu alloys NC-SMQ92H for Sn63
Induction Soldering	Localized, uniform heating	Requires proper set up and design with a repeatable process to introduce the parts being soldered	Solder Preforms Solder Spheres Solder Wire Solder Ribbon
Vacuum Soldering	Reduction in pressure allows voids in solder to escape prior to reflow, creating much lower voiding in finished solder joint	Batch process may be too slow for high volume manufacturing. Requires proper set up, design and material selection	Solder Preforms (especially AuSn) Solder Spheres Indium8.9 Series Solder Paste SnAg, SnSb, and SnAgCu alloys NC-SMQ92H for Sn63
Vapor Phase Soldering	Vapor chamber allows for uniform heating across the entire assembly	Fast wetting forces may cause tombstoning with common chip and resistors, which can be minimized with preheat	InTEGRATED™ Preforms Standard Solder Preforms NC-SMQ230 Solder Paste Indium8.9 Series Solder Paste
Manual Soldering	Using a heat gun, soldering iron or other hand-held heat source to reflow the solder	Operator-to-operator solder volume variance	Flux-Cored Wire Solid Core Wire Solder Preforms

Source: Indium Corporation, Clinton, NY

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Rework and Touch-Up

Friday, August 21st, 2015

Indium Corporation manufactures a variety of materials for PCB rework, repair, and touch up, including flux-cored wire, liquid rework fluxes, and TACFluxes^®.

Flux Cored Wire

Indium Corporation has developed a range of flux-cored wire solutions to meet the needs of virtually every electronic assembly and rework operation from no-clean flux-cored wire for circuit board assembly to activated flux-cored wire for non-sensitive electronics and electrical applications.

No-clean fluxes include:

CW-807 halogen free for high reliability assemblies
CW-807M, which has a small addition of halogen activator for more difficult to solder assemblies
CW-807H for high temperature alloys
CW-501 is rosin (colophony) free and shows exceptional soldering on a wide range of assemblies
CW-802 is recommended only when no halogen is a must and the process is well-controlled

Activated fluxes include:

CW-201, a traditional RA type flux as defined by the legacy Mil-Spec QQ-S-571
CW-207 formulated using a blend of heat stable clear rosins
CW-209, which has twice the amount of halogen activator as CW-207
CW-501, rosin (colophony) free and has exceptionally effective soldering on a wide range of assemblies

Liquid Rework Fluxes

Liquid rework fluxes are packaged in convenient pen dispensers, providing the optimal fluxing with no waste. Flux pens utilize a spring-loaded applicator tip to deliver a controlled amount of flux to the work surface. The user friendly pin-point application is deal for touch-up and light assembly work. Liquid fluxes include:

FP-500, a halogen-free flux that is compatible with both SnPb and Pb-free assemblies
NC-771, a halogen-free, low-residue, all-purpose flux that passes the SIR test in the un-reflowed state
FP-300, a water-soluble flux that is compatible with both SnPb and Pb-free assemblies

TACFluxes^®

TACFluxes^® have a variety of uses including rework and repair of various electronics assemblies and components, SMT component attach (including BGAs and flip-chips), BGA ball attach, preform soldering, and virtually any application where flux is required. Indium Corporation manufactures a complete line of TACFlux^®, which include no-clean, water-wash, and RMA-based fluxes.

Some of the most common TACFluxes^® include:

TacFlux 089: no-clean flux for Pb-free alloys
TacFlux 089HF: a halogen-free, no-clean flux for Pb-free alloys
TacFlux 025: a water-soluble flux for Pb-free and SnPb alloys
TacFlux 020B: a halogen-free, no-clean flux for Pb-free alloy

Source: Indium Corporation, Clinton, NY

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CircuitWorks Epoxy Overcoat CW2500

Wednesday, August 19th, 2015

Frequently Asked Questions
Circuitworks® Epoxy Overcoat, CW2500

1. What is an Epoxy Overcoat?
Circuitworks® Epoxy Overcoat is a permanent green coating formulated to protect circuit traces before being exposed to reflow conditions. It is a two component, 100% solids epoxy that is engineered specifically for high temperature resistance, used for electronic circuit and component protection. When properly cured the insulator forms a chemically inert coating that seals out moisture and environmental contaminants, minimizes thermal shock and prevents corrosion, oxidation, and abrasion. The Epoxy Overcoat easily withstands brief exposure to high temperatures found in normal wave and reflow applications.

2. What is the difference between Circuitworks® Overcoat Pen (CW3300G) and Circuitworks® Epoxy Overcoat?
Circuitworks® Overcoat Pen is a one component, acrylic-based system with fair heat resistance and satisfactory chemical
resistance. When subject to reflow conditions this material will quickly degrade. However it does have excellent electrical insulation and good abrasion resistance. Circuitworks® Overcoat Pen is primarily designed for protecting and electrically insulating circuit board traces and components, with an easy to use one component system.

Circuitworks® Epoxy Overcoat is a two component system with outstanding high temperature and chemical resistance. Abrasion
resistance is also excellent for this epoxy system. It’s the best choice for repairing the permanent solder mask/solder resist when the boards will be subject to reflow conditions. It also has outstanding dielectric properties as permanent coating for use on bare metal.

3. What is the mixing ratio?
The mixing ration is the volume of part A needed to mix with part B. This can be critical with some epoxy systems, and can be
difficult to get the exact quantities in the right ratios as 0.96:1.32 is not unusual. This epoxy system was developed to provide
easy mixing ratios, with a very forgiving cure system. The mixing ratio for the Epoxy Overcoat is 1:1, but this ratio is not critical to obtain the best electrical and protective capabilities.

4. What are the features and benefits of the Circuitworks® Epoxy

Features

• High temperature resistance
• Provides a hard, durable protective coating
• Excellent dielectric properties
• Solvent resistant
• Service temperature -55ºF/-48ºC to 600ºF/315ºC
• Meets IPC-7721.2.4.1 requirements

Benefits
• Ideal for pre-reflow solder resist repair
• Prevents corrosion, corrosion, oxidation, degradation and thermal shock
• Electrically insulative coating helps prevent electrical discharge
• Will not be removed by solvent cleaners
• Can be used in many environments
• Perfect as solder resist board repair

5. How is the Circuitworks® Epoxy Overcoat packaged?
The Epoxy Overcoat is packaged in two (one part A and one part B) easy to use syringes that hold approximately six (6) grams of
material. One syringe contains the epoxy, while the other contains the hardener. This allows you to use as little or as much material as you need.

6. What type of customers would use the Circuitworks® Epoxy Overcoat?
Customers involved in the manufacture and the rework/repair of printed circuit boards would use the Circuitworks® Epoxy Overcoat.
This would include those involved in:
• Circuit board manufacturing
• Data communications
• Aerospace industry
• Instrumentation and control manufacturing
• General maintenance repair

7. Can the Circuitworks® Epoxy Overcoat be used as an encapsulant?
Circuitworks® Epoxy Overcoat’s physical properties are very similar to epoxy encapsulants; it will work to encapsulate leads, traces
and small areas that need insulation and protection. However, the small quantity contained in each syringe does not make it an
ideal candidate for encapsulation.

8. Can the Circuitworks® Epoxy Overcoat be used as a conformal coating?
Conformal coatings are applied in thin layers onto printed circuit boards to provide environmental and mechanical protection to
components and circuitry. Even though the Circuitworks® Epoxy Overcoat can provide protection, the higher viscosity and small
quantity contained in each syringe does not make an ideal candidate for performing as a conformal coating.

9. What’s the shelf life of the Epoxy Overcoat?
The shelf life is twelve (12) months from the manufacturing date.

Posted in Repair and Prototying Tools, Solder Flux & Flux Removers | Comments Closed

No Clean Solder Paste. What is it?

Tuesday, August 18th, 2015

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Method of determining the deposition rate of spray fluxers

Tuesday, August 18th, 2015

Procedure

1. Take a sheet of transparency film for copy machines.
2. Roll up the film and put a rubber band around it.
3. Weigh the paper on an analytical balance. Weigh to the nearest 0.0001 grams.
4. Unroll the film and affix it to the bottom of a board using paper clips.
5. Run the board through the fluxer and remove to dry.
6. After drying (15-30 min.) look at the paper. Look for anomalies in the spray pattern.
7. Reweigh the paper and rubber band (1,000,000 micrograms per gram).
8. Calculate the weight of flux in micrograms per in2 (remember to subtract the weight of the
paper and rubber band).
Wt of flux in micrograms = X micrograms/in2
Paper is 88 in2
9. Minimum value is 700 micrograms/in2
10. Recommended value is 1000 micrograms/in2

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How much no-clan flux should be applied to a pcb and how does one determine the deposition?

Tuesday, August 18th, 2015

Procedure

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Kester VOC-Free Wave Soldering Profile Chart

Tuesday, August 18th, 2015

kester-voc-free-wave-soldering-profile-chart

Posted in Process, Solder Flux & Flux Removers | Comments Closed

Concorde Electronics

Archive for the ‘Solder Flux & Flux Removers’ Category

Flux Test Kits, what do they do?

Are Kester “44” rosin residues harmful to an assembly?

Do rosin flux residues need to be removed?

Electronics Assembly

Electronics Assembly