APPLICATION SPECIFIC REBALLING

As the name suggests, when our customers have specific requirements, Retronix’s expert experience and capabilities allow us to provide innovative and unique application specific solutions.

LCC Solder Joint Fracture - CTE

CLCC - Thermal Expansion Issues

Major differences in temperature between the CLCC body and the PCB substrate stresses the joint leading to cracks, solder is a fairly weak alloy which cannot withstand cyclic stresses easily. This leads to poor reliability and low cycles to failure.

Solder Joint Failure

CROSS SECTION - SOLDER JOINT FRACTURE

The cross-section shows solder joint failure travelling through the bulk of solder. Note the low solder thickness under the component.

Solder sphere attached to bottom of LCC

application specific solution

Solder spheres are attached to the bottom of the ceramic CLCC

Application Specific Reballing

Problem solved

Balled CLCC attached to the PCB using standard solder paste print and reflow techniques. This solution solves the problem of CTE, cleaning and voids.

LCC - sphere attach solution

process adapted by customer as standard for all future assemblies

Cross-section of assembled, balled CLCC. Note the increase in joint thickness under the device. Dark areas are remaining HMP (High Melting Point) spheres. During assembly some of the HMP spheres dissolve into the molten tin/lead during assembly reflow.

CYCLES TO FAILURE INCREASED BY A FACTOR OF AT LEAST 10

This is what we excel at - the customer service, the unique skills and the flexibility to be able to offer a service this bespoke

Case Study Source –

BAE Systems