SEM Lab, Inc.

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 2 days ago

New blog articles detected

  • FPGA ECM short

    Ionic contamination, moisture, and electrical bias can combine to create electro-chemical migration (ECM) shorts under an IC device as shown in this example. This is an optical image showing residue on the bottom surface of the FPGA package. This is a BSE SEM image of the same corner location. The residue bridges several signals at […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 3 weeks ago

New blog articles detected

  • Tin Whiskers

    A client provided a flex cable sample to SEM Lab, Inc. for SEM/EDS analysis of the crimp contact plating. EDS of the contact plating revealed that the plating was pure tin, which explains in part the many tin whiskers associated with the crimped region of the flex cable. The longest whisker in this image is […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 1 month ago

New blog articles detected

  • LED Lamp Flickers

    An LED lamp assembly reportedly “flickered”, meaning there was likely an intermittent high resistance in the LED circuit. Here are summaries of the destructive physical analysis of three suspect LEDs. The analysis results for all three samples were similar. Thermal-mechanical damage was found including (1) thermal decomposition of the lens material mid-span on the anode […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 2 months ago

New blog articles detected

  • Gold Embrittlement

    Gold embrittlement of solder joints still appears as a problem from time to time even though the issue has been understood for many decades. We diagnose this problem by using SEM/EDS to estimate the amount of gold in the solder joint. If the gold level exceeds about 3 wt% in the bulk solder joint then […]

  • MLCC manufacturing flaw

    This is a microsection of an MLCC as mounted on a PCBA. There is a fracture in the top of the MLCC, which is unusual. The fracture was clearly associated with some type of damage introduced while the ceramic dielectric was in the “green” state, i.e. prior to firing during fabrication of the multilayered ceramic […]

  • Diode Short

    The image below is a “stud diode” that had failed shorted. The diode was chemically decapsulated and the device die was examined in the SEM. A breakdown site was found near one corner of the die. Below is a higher magnification image of the breakdown site… … which shows a striking resemblance to the “Face […]

  • ESD Damage in Zener Diode

    Sometimes we’re lucky and stumble into something like this ESD damage in a Zener diode. The diode was short circuited, but it was micro sectioned in order to determine the die thickness (not something we would normally do on a shorted diode). A damage site was found directly under the ball bond. The damage was […]

  • Severe corrosion on PCBA

    Activated solder flux residues left on a PCBA can cause severe corrosion problems. The leads on the component shown below are severely corroded. The elemental spectrum suggests that the needle like corrosion product is lead chloride & lead bromide. Conclusion – avoid inadequate cleaning of PCBAs. Check out SEM Lab, Inc.  to learn more.

  • PCBA Corrosion

    Corrosion due to residual solder flux and cleaning process chemistries left on PCBAs can be a real problem for reliability. The corrosion can cause both open circuits as it eats through metal runs and short circuits due to electro-chemical migration. This (above) is the elemental spectrum of the end of a through-hole connector solder joint. […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 7 months ago

New blog articles detected

  • Shorted FET

    Electrical continuity tests suggested that the gate was shorted to the drain and the source was intact. SEM analysis revealed a suspected damage site at the end of a gate finger (see below). An elemental dot map at the breakdown site showed some slight disturbance of the aluminum metallization at the site. Voltage contrast imaging […]

  • Dendritic Growth – Shorts on PCBA

    Here is another example of electro-chemical migration that resulted in shorted signals on a printed circuit board assembly. These ECM residues can often be hard to see under an optical microscope because there are optically transparent metal oxides present with very small metallic dendrites. Backscattered electron SEM images show contrast related to atomic number, so […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 7 months ago

New blog articles detected

  • ECM of PWB Battery Contacts

    ECM (electro-chemical migration) can occur when moisture, voltage bias, and ionic contamination come together, such as was the case for the PWB battery contacts shown in the BSE SEM image below. Elemental analysis suggested that the ECM residues were primarily copper, but also zinc (from brass?) and nickel (from ENIG finish or nickel under-plate on […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 7 months ago

New blog articles detected

  • Bad Board Design

    Design rules suggest that MLCCs should be placed away from board edges and panel break out zones for reasons illustrated in this example. The MLCC was placed far too close to the breakout feature during the design phase for this product. This is a higher magnification image of the flexure fracture that caused the MLCC […]

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 7 months ago

SEM Lab, Inc.

Category: Content
Type: Blog Article

Generated 8 months ago

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