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Method for a chip capacitor with coated paste on the terminal electrodes

IP.com Disclosure Number: IPCOM000083110D
Publication Date: 2005-Feb-28
Document File: 4 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a chip capacitor with coated paste on the terminal electrodes. Benefits include improved functionality, improved reliability, improved throughput time, improved process simplification, and improved cost effectiveness.

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Method for a chip capacitor with coated paste on the terminal electrodes

Disclosed is a method for a chip capacitor with coated paste on the terminal electrodes. Benefits include improved functionality, improved reliability, improved throughput time, improved process simplification, and improved cost effectiveness.

Background

              Conventional chip capacitor terminal electrodes have a very thin layer of electro-plated tin (see Figure 1). It does not melt during reflow because the melting temperature of plated tin is higher than the solder reflow temperature. Pure tin melts at 232°C and eutectic and lead-free solder have lower melting temperatures. After reflow, conventional capacitors only have solder between the joint capacitor and the substrate pad (see Figure 2).

      The conventional flux printing process on a substrate controlled collapse chip collect (C4) bump area requires an additional module for paste printing on the pad. As a result, two different printing machines are required.

              The conventional solution has several drawbacks, including:

•             Slow throughput time (TPT) due to an additional solder paste printing module in the assembly process, including solder paste replacement and cleaning the solder-paste stencil, and required equipment maintenance

•             Long substrate supplier lead time due to performing the presolder process at the substrate supplier’s site

•             Space constraint in production floor due to the paste printing machines occupying space

•             High equipment maintenance and raw materials cost due to the cost required for extra machines parts, direct/indirect materials (such as solder paste stencils, solder paste, and paper rolls), and maintaining the paste-printing equipment

•             Capacitor issues, such as tombstoning, shifting, and skewing due to paste offset and/or uneven solder paste volume on substrate pads during the paste printing process

 

      Capacitor defects could reach 1%. Additional production time is required to perform rework on the defective units.

General description

      The disclosed method is direct chip capacitor attachment to substrates without solder printing or a presolder procedure. The terminal electrodes of the capacitor have a substantial amount of solder on the substrate pad to form interconnection between the chip capacitor and substrate after reflow.

 


Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to providing direct chip capacitor attachment to substrates without solder p...