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Solder Paste for Thermal Cycling application (-40 to 150 Degree Celcius)

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#79372

Solder Paste for Thermal Cycling application (-40 to 150 Degree Celcius) | 23 November, 2017

Hi to all experts, Can anyone advice us what solder alloy to use for thermal cycling products. We are facing a lot of issues using normal solder paste SAC305. After thermal cycling the solder is cracking. Any suggestion is welcome. Thanks in advance.

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#79440

Solder Paste for Thermal Cycling application (-40 to 150 Degree Celcius) | 7 December, 2017

Help me understand your issue better ... Are you looking to:

* Improve your products that are used for thermal cycling testing of products of other companies?

* Change your production materials so that you pass thermal cycling testing of your product?

For some background on thermal cycling testing of LF solder connections, look here:

LEAD-FREE SOLDERS (SAC305 AND SN3.5AG) FOR HIGH TEMPERATURE APPLICATIONS [https://drum.lib.umd.edu/bitstream/handle/1903/11272/George_umd_0117N_11847.pdf?sequence=1&isAllowed=y] George_umd_0117N_11847.pdf (13.65Mb) No. of downloads: 2810

Date 2010 Author George, Elviz Advisor Pecht, Michael G Metadata Show full item record Eutectic tin lead was the most widely used solder interconnect in the electronics industry before the adoption of lead-free legislation. But eutectic tin lead solder has a low melting point (183oC) and was not suited for some high temperature applications, such as oil and gas exploration, automotive, and defense. Hence, for these applications, the electronics industry had to rely on specialized solders. In this study, ball grid arrays (BGAs), quad flat packages (QFPs), and surface mount resistors assembled with SAC305 and Sn3.5Ag solder pastes were subjected to thermal cycling from -40oC to 185oC. Commercially available electroless nickel immersion gold (ENIG) board finish was compared to proprietary Sn-based board finish designed for high temperatures. The data analysis showed that the type of solder paste and board finish used did not have an impact on the reliability of BGAs. The failure site was on the package side of the solder joint. The morphology of intermetallic compounds (IMCs) formed after thermal cycling was analyzed.

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#79443

Solder Paste for Thermal Cycling application (-40 to 150 Degree Celcius) | 10 December, 2017

Hi Dave, thanks for the response.

* Improve your products that are used for thermal cycling testing of products of other companies? Yes we want to improve our products to pass thermal cycling and prolong the lifespan of the baord. * Change your production materials so that you pass thermal cycling testing of your product? We are looking for a solder paste to improve the thermal cycling capability of our product. We are using SAC305 but then after a few thermal cycling application or -40 to 150 Deg C, after 1 to 2 year the solder degrades/cracks. Hopefully can help to suggest any solder we can use to prolong the lifespan of our board.

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