caLogo

A study of the behavior of flux-stencil interactions.

Understencil wiping has gained increased interest over the past several years. Changes in circuit design due to miniaturized components and highly dense interconnects have increased the importance of stencil cleanliness, both inside the aperture wall and on the seating surface of the stencil. A technology that wets the understencil wipe with a solvent-based cleaning agent is being studied to improve print performance and better understand the behavior of flux-stencil interactions. The cleaning agent dissolves the flux component of the solder paste to improve solder ball release from the stencil’s bottom side and aperture walls.

Kyzen and Indium performed a study to characterize the relationship between wipe processes and bottom-side stencil flux/paste flow. A highly dense circuit board and a stencil with nanocoating was used to study the effects of the understencil wiping process. After each print, the stencil was removed from the stencil printer. The apertures were examined to inspect buildup in both the apertures and bottom side of the stencil. FIGURE 1 shows the flux vehicle and some trace solder balls following the first print.

To continue reading, please log in or register using the link in the upper right corner of the page.

Read more ...

Realizing advanced electronics with the world’s smallest packages. 

Is it worthwhile to design printed circuit boards with the smallest component package available today: the 008004? And how do you do it correctly?

Several months ago, a hardware engineer in a high-tech company that is developing virtual reality headsets approached me. “These are special glasses that can integrate into game consoles in hundreds of millions of homes worldwide,” he said with excitement. “This is innovative technology that will enable a totally different viewing and gaming experience than what’s available at present.”

To continue reading, please log in or register using the link in the upper right corner of the page.


A decade in, IPC-2581 Consortium members say the pursuit toward widespread adoption of the vendor-neutral standard was well worth the rigorous effort.

Few engineers working in electronics manufacturing today predate the first efforts to develop and implement an industry-wide standard for intelligent electronics data transfer.

As early CAD tools were introduced in the late 1960s and early 1970s, IPC launched a vendor-neutral effort to describe electronics design data from schematic through test.

To continue reading, please log in or register using the link in the upper right corner of the page.

Read more ...

The annual Women’s Leadership Program at SMTA International features two leading engineers.

SMTA International returns to an in-person format this year, with a virtual option, and the Women’s Leadership Program is in-person on Tuesday, Nov. 2! The past 18 months have been a time of reflection and transition for many of us. Many professionals are reassessing their career goals and career paths. In keeping with this trend, our 2021 WLP theme, “It’s good we are not all the same,” was chosen to encourage attendees to explore career transition options.

The WLP this year will focus on the success stories of women who have created varied career paths, applying core technical strengths to a variety of areas and succeeding consistently. Hear how their diverse career experiences have contributed to their long-term success. Our two distinguished speakers have blazed unique career paths and will share their stories with the audience.

To continue reading, please log in or register using the link in the upper right corner of the page.

Read more ...

A connected factory automates the AOI validation process.

Automated optical inspection (AOI) is typically used after solder reflow to detect missing components and defects. Performing a successful inspection of a panel is not enough, however. Manufacturing execution systems (MES) are used for process control and AOI data collection to ensure the following are accomplished:

  • All prior routing operations passed.
  • Valid test program is loaded on the machine.
  • Test start- and end-times and test results are captured.
  • Failed printed circuit boards (PCB) cannot advance in the production routing and must enter rework loop.

To continue reading, please log in or register using the link in the upper right corner of the page.

Read more ...

SAC 305 shows faster shear strength degradation than Innolot, while the surface finish has no effect.

When a solder joint is exposed to cyclic stresses, thermally activated diffusion in the bulk solder, metallization and initial intermetallic (IMC) may take place. The growth of the interfacial IMC helps relieve the residual stress induced in the solder joint, and the growth rate corresponds to the magnitude of stress induced.1 Solder joint strength also decreases during exposure to temperature variations. Therefore, shear testing is a useful method to assess solder joint strength degradation caused by thermal cycling.2

In part one3 of this series we showed the voiding, solder spread and thickness of the high-reliability Innolot alloy compared with SAC 305 alloy solder pastes using five different surface finishes. Part two discusses thermal cycling effects on the growth in IMC thickness and solder joint strength. This study included two commonly used solder alloys in paste form:

  1. SAC 305 (96.5%Sn, 3%Ag, 0.5%Cu) powder size distribution (PSD) type 4 with novel “CVP-390” paste flux
  2. Innolot (91.95%Sn, 3.8%Ag, 0.7%Cu, 3.0%Bi, 1.4%Sb, 0.15%Ni) PSD type 4 with the novel paste flux and five variations of surface finishes, including
    • Organic solderability preservative (OSP) (MacDermid Enthone Entek Plus HT) using two thickness levels
    • Immersion tin (Ormecon CSN)
    • Immersion silver (MacDermid Enthone Sterling)
    • Electroless nickel/immersion gold (ENIG) (MacDermid Enthone Affinity).

To continue reading, please log in or register using the link in the upper right corner of the page.

Read more ...

Page 5 of 70

Don't have an account yet? Register Now!

Sign in to your account