Board Mounted Power Supply evaluation
Power bricks are one of few “hold-out” components still demanding wave solder. The conversion to SMT bricks would allow the elimination of wave processing for many printed circuit assemblies. Currently 1/16th and 1/8th brick types have wide adoption in SMT with a variety pin/leg styles, this is not the case for the 1/4 brick and above sizes.
This project focuses on the impact of DC/DC module (bricks) features on soldered PTH hole-fill and the module-PWB attachment reliability of SMT bricks. The project will measure the impact of various brick pin and footprint feature variants such as, gas vents, hole size, and thermal plane connections on the hole-fill of a pin through hole soldered joint. Besides the PTH configuration, SMT attach variants to be studied are “Pure Post”, “PIP/SMT hybrid”, and “Pedestal and ball”. Figure 18 shows a Pedestal and Ball configuration. Different brick styles will be studied in a 1/4 brick package to assess comparative thermal cycling and vibration reliability with the bricks carrying full current.
System integrators want to have well defined Lead Free requirements on Board Mount Power Supply (BMPS), Pin compatibility between functionally compliant BMPS, and industry standards for function compatibility of BMPS. They also want to eliminate the need for modules to be attached using "press fit technology" or manual soldering.
Systems Integrators and Power Module Suppliers need a common communication vehicle that will define options for pin and function compatibility, reliable interconnection techniques, and "best practices" for design, manufacturing, and assembly of BMPS. The objective of the project is to:
- Identify the key design/manufacturability issues with a focus on assembly
- Issue guidelines on PWB layout for BMPS that will aid in assembly
- Pad configurations, etc.
- Issue guidelines for automated handling of BMPSDemonstrate the feasibility/applicability (and reliability) of module - PWB interconnections
- Pick and place nozzles, grippers, etc.
Evaluate the impact of various DCDC Brick pin and footprint feature variants on hole-fill of pin through soldered joint.
Understand the impact of various DCDC Brick pin feature variants on attach reliability of SMT DCDC bricks.
Vibe/Hole Fill portion
Gas Vent vs NonGas Vent
Standard vs Large
Lead Protrusion Length
Standard vs Long
Spoke vs Via2Plane
Cookson 330 vs Cookson EF-6850HF
Pin to Paste PTH Factors
Standard vs Large
Pure Post vs Pedestal&Ball vs PIP Hybrid
Hole Fill Evaluation
Dye & Pry (T0, ATC intervals of 500)
X-sections (T0, ATC intervals of 500)
Vibration to Failure
Attach Method – SMT, PTH
Brick Design – Pure Post, Pedestal & Ball, Std Pin
6000 Cycles Total
IPC-9701 Profile (0 to 100C, 10C/min)
Continuous Monitoring of Resistance
At 250 Cycles Increments – Resistance Checks
(low temp, ambient, high temp)
Failure Analysis – Non-destructive review, Dye&Pry, X-section