SMT007 Magazine

26 SMT Magazine • October 2015 fast is much worse than producing good boards slowly. The first experiment is to increase the speed of the squeegee stoke. Figure 1 shows the relationship of the squeegee speed, stroke length and the time required for the solder paste to be printed. If a slow squeegee speed is currently being used (<2 inches/second), there is a greater op- portunity for increasing throughput. When running the experiment at increasing squeegee speeds, review the CpK recorded on your SPI equipment for a gain or reduction in process capability. Some solder pastes give better print volume reproducibility at higher speeds. This results in a win-win, higher production and im- proved process yields. One important thing to look for when in- creasing the squeegee speed is paste left on the stencil (Figure 2). When a higher squeegee speed is used, it is usually necessary to increase FeATure COluMn Of the several steps in the SMT process, an effective method of increasing throughput is to reduce the cycle time of the rate-controlling process step. Depending on the type of assem- bly and equipment set used, the process step with the longest cycle time could potentially be printing, solder paste inspection (SPI), compo- nent placement or reflow oven conveyor speed. This article will discuss two simple experiments that may lead to increased throughput and in- creased profitability (assuming the selling price exceeds the marginal cost of each assembly). Print cycle time can be the bottleneck if the electronic assembly has relatively few compo- nents or if the production line used has a well equipped set of placement devices. If this is the case, there are two simple experiments that can be carried out to evaluate if a reduction in print cycle time can increase production volumes without reducing quality. Producing bad boards by Mitch holtzer and Lourenco nampo alpHa AcroSS the boArd reducing Print cycle time Figure 1: Stroke time versus speed (inches per second) and distance.

• Cover
• Feature Articles — Cycle Time Reduction
• Table of Contents
• Column — The Need for Speed
• Feature — Value Stream Mapping: Operationalizing Lean Manufacturing
• Feature Interview — Choosing the Right Component to Reduce Cycle Times
• Feature Column — Reducing Print Cycle Time
• Short — Darwin on a Chip
• Feature Interview — Cycle Time Reduction in the Eye of AOI
• EIN Market Highlights
• Feature Interview — Reducing Cycle Times with Innovative Bonding Solutions
• Feature — Technologies to Enable Quick-Turn PCB Assemblies
• Feature Interview — Process Improvements for Cycle Time Reduction
• Short — Nanostructures for Contactless Control
• Feature Column — Cycle Time Reduction with WORK, Part I
• MilAero007 Highlights
• Feature Interview — Is Automation the Answer to Cycle Time Reduction?
• Column — Gold Embrittlement Mitigation: Understanding the New J-STD-001 Requirements
• Short — A Fast Cell Sorter Shrinks to Cell Phone Size
• Supply Line Highlights
• Feature Interview — Inspection Innovations to Reduce Cycle Time
• Short — Permanent Data Storage with Light
• Column — Selecting a Reflow Oven, Part 3
• Top Ten Recent Highlights from SMT007
• Events Calendar
• Advertiser Index and Masthead