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how clean is clean?

Sm Rookies

#34541

how clean is clean? | 26 May, 2005

what test methods can be use to verify that the cleaning process for SMAs with water soluble paste is sufficient?

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Mike Konrad

#34552

how clean is clean? | 26 May, 2005

Three popular methods:

Resistivity of Solvent Extract (ROSE) Test Method IPC-TM-650 2.3.25:

The ROSE test method is used as a process control tool to detect the presence of bulk ionics. The IPC upper limit is set at 10.0 *g/NaCl/in2. This test is performed using a Zero-Ion or similar style ionic testing unit that detects total ionic contamination, but does not identify specific ions present. This process draws the ions present on the PCB into the solvent solution. The results are reported as bulk ions present on the PCB per square inch.

Modified Resistivity of Solvent Extract (Modified ROSE):

The modified ROSE test method involves a thermal extraction. The PCB is exposed in a solvent solution at an elevated temperature for a specified time period. This process draws the ions present on the PCB into the solvent solution. The solution is tested using an Ionograph-style test unit. The results are reported as bulk ions present on the PCB per square inch.

Ion Chromatography IPC-TM-650 2.3.28:

This test method involves a thermal extraction similar to the modified ROSE test. After thermal extraction, the solution is tested using various standards in an ion chromatograph test unit. The results indicate the individual ionic species present and the level of each ion species per square inch.

Most common test is R.O.S.E. Equipment sells from $ 12,000.00 - $ 30,000.00. Equipment available from Aqueous Technologies (Zero-Ion) and Specialty Coatings (OmegaMeter and Ionagraph).

If ion chromatograph is your choice, recommended labs are:

Foresite http://www.residues.com

ACI http://www.aciusa.org

Hope this helps

Mike Konrad Aqueous Technologies Corporation www.aqueoustech.com konrad@aqueoustech.com

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Sarag

#34589

how clean is clean? | 27 May, 2005

There is also a new cleanliness tester that looks at localized areas to provide a cleanliness reading and can extract a sample to use in ion chromatography testing. You can find out about it here: http://www.residues.com/C3.html

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#34605

how clean is clean? | 27 May, 2005

Dear SM Rookies,

Another acceptable test method is visual inspection. IPC-A-610 details what to look for with different contaminants, providing magnified pictures of the possible visual residues.

With an existing cleaning process, magnification is not always required, though fine pitch and high density components may require magnification. Magnfication may be from 1.5X to 40X depending on Land Width's.

If you can't see underneath a device, take a sample product and rip off the component to see what you can see. If the product is expensive, consider using dummy boards simulating actual product.

Shean...always a rookie in life,

Austin American Technology www.aat-corp.com (+1) 512-335-6400

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Sm Rookies

#34606

how clean is clean? | 27 May, 2005

Thanks for your replies.

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