INTA Technologies Corporation 2281 Calle de Luna, Santa Clara, CA 95054 || Tel: 408-748-9955 || Fax: 408-727-3027

 

Hermetic Brazing

 

 

Table of Contents

 

 

 

 

What does the term ‘hermetic brazing’ mean?

Hermetic brazing indicates forming a leak tight seal by means of a braze alloy. Typically, INTA Technologies Corporation performs furnace hermetic brazing in atmospheres such as hydrogen, vacuum or air.

 

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Why is hermetic brazing important?

Many applications require leak tight joints. Such applications include aerospace, medical, diagnostic equipment, etc.

 

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What materials are generally used for hermetic brazing?

Ceramic, metal (stainless steel, kovar, molybdenum, tungsten, CuW, etc), sapphire, zirconia, and more.

 

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Is hermetic brazing and expensive process?

No, it can be cost-effective. Pricing depends on various factors including size of items, complexity of project and volume.

 

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Does INTA Technologies Corp. supply materials to be brazed?

Yes.

 

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Does INTA braze customer supplied material?

Yes. When sending a request for quotation (RFQ) please indicate if the material will be customer supplied or INTA supplied.

 

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What is the typical lead time for hermetic brazing?

Lead times depend on several factors, such as material lead times and amount of fixturing and/or tooling required. If the customer supplies the material, the lead time is often 1-2 weeks unless extensive tooling needs to be designed and manufactured. If INTA Technologies supplies the materials, it will likely add three weeks to the lead time. Tooling and fixtures for proper hermetic brazing are often required, the lead time for these items can range from one to several weeks.

 

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What is a typical bond strength achieved by hermetic brazing?

Strengths can be as high as 4500 psi.

 

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How many types of hermetic braze options are available?

There are many options depending on the application and design restrictions/requirements. CuSil (copper silver) is the most popular braze. Other popular braze/solders include gold-tin, silver, copper, etc.

 

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What is the smallest part INTA can braze?

INTA Technologies can braze very small parts including .2” or 5mm diameter. INTA can braze parts much thinner than 1mm [.040”]. Each project is unique, contact us for a free design review and quote.

 

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What is the largest part INTA can braze?

INTA Technologies is limited in terms of maximum size. Typically, items larger than 12” in diameter and/or longer than 16” may be currently too large for INTA to braze.

 

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Does INTA do all the hermetic brazing and testing in-house or is it outsourced?

Yes, nothing is outsourced currently.

 

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If I need hermetic brazing services ASAP, can I speed up my order by paying extra?

In many cases, yes. The service is called expedite, call for details.

 

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What type of ceramic should I use for hermetic brazing?

The answer depends on the application. In most cases, specifying 96% min purity alumina on the drawing is adequate. HIP or iso-pressed ceramic should be used. Technical data is available at http://ceramics.net/materials/alumina.shtml

 

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Does INTA braze Si-N?

Yes, INTA Technologies currently brazes silicon nitride.

 

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What types of materials does INTA braze?

INTA metallizes ceramic before it can be brazed in some cases. For the most part, INTA Technologies brazes Al-O (aluminum oxide or Al203), copper, Cu101, Cu102, kovar (iron-nickel-cobalt), molybdenum, copper tungsten (CuW), zirconia, beryllium oxide (Be-O) and many other materials. INTA does not braze MACOR. For details, please contact our sales office at 408-748-9955 x113 or sales@intatech.com

 

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What type of joints are common?

The configuration and geometry of the joint vary according to application. Some common types of joints include:

Lap joints

Butt joints

Single lap shear joint (ASTM D-1002)

Double lap shear joint (ASTM D-3528)

Clevis and web joint (ASTM D-3528)

Pi joint (ASTM D-3528)

Socket joint (ASTM D-3528)

Tube-in-tube joint

Rod-in-tube joint

 

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Is there a specification for single lap shear joints?

Yes, see the previous answer.

 

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What is a tube-in-tube joint?

This type of joint is formed when a single lap joint is turned on its long axis.

 

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What is a rod-in-tube joint?

A rod-in-tube joint is a round single lap joint.

 

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Why is a double lap shear joint effective?

Double lap shear joints reduce peel by promoting c.l. thrust. The surface area is doubled which also promotes a stronger bond. This configuration is used primarily for critical bonding applications because it is more expensive and complicated to implement due to factors such as surface preparation, increased amount of material and complex fixturing is often required.

 

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How can side-to-side peel be reduced?

Side-to-side peel can be reduced by effectively increasing the insertion depth on tube-in-tube or rod-in-tube joints.

 

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Does INTA offer Mil-B-7883 brazing?

Yes, INTA offers brazing services which meet the requirements defined by MIL-B-7883B.

 

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What is Mil-B-7883 Type I and II?

Type I is torch brazing and Type II is furnace brazing.

 

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What is Mil-B-7883 Grade A and B?

Grade A refers to joints for critical fittings and structural applications. Grade B defines joints for non-critical fittings and non-critical structural applications.

 

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Are there any resources relating to assembly or public information to review?

Assembly Magazine is an excellent resource. www.assemblymag.com

 

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What factors can help improve adhesion?

Surface preparation, braze or solder alloy selection, testing, process/method, design, other. Contact INTA Technologies for design assistance contact@intatech.com

 

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Last revised: 03 DEC 2009