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THIS MONTH WE look at solder mask contamination on pads. FIGURE 1 is a very, very bad example that never should have made it to the customer. Solder mask residues [...]

THIS MONTH WE look at etching defects and their removal--or presence, as in the case of FIGURE 1. A customer was surprised to find a batch of bare boards with [...]

A PRINTED BOARD microsection is one of the best ways to examine the quality of boards and any faults or failures. The microsection (FIGURE 1) shows a plated through-hole that [...]

THIS MONTH WE look at printed circuit board delamination. As FIGURE 1 shows, delamination is barely visible on the surface of the board and confined to the area around through-holes [...]

THIS MONTH WE look at incomplete fill of plated through-holes. During any soldering operation a balance of flux and solder/paste chemistry and soldering temperatures creates good and reliable joints. In [...]

THIS MONTH WE look at cracks in plated through-holes around the knee of the hole. FIGURE 1 shows very small via holes that were subjected to multiple lead-free soldering steps, [...]

THIS MONTH WE look at ball grid array (BGA) opens and solder compression. Intermittent joints and shorts can be caused by package warpage at elevated temperatures. Hence the interest in [...]

THIS MONTH WE look at etching faults on PCBs. This is no ordinary set of pads. They are for an 01005 chip capacitor, the second-smallest chip component available. (Yes, there [...]

THIS MONTH WE look at solder spotting, which is often seen after first- or double-sided reflow, most commonly on gold boards. The two examples below illustrate what happens. FIGURE 1A [...]

THIS MONTH WE look at solder toe fillets. A solder toe fillet is part of the solder joint visible on most gull-wing terminations. These are typically seen on SOIC, QFP [...]

OPEN CONNECTIONS ON area array packages can be difficult to spot, particularly if they are intermittent electrical failures like the examples in FIGURE 1. One or more open joints can [...]

THIS MONTH WE we look at through-hole connectors and component pin float. All connector pins should be held in place by the body molding and not move during soldering. The [...]

PCB DELAMINATION CAN be subtle or obvious. It is caused by expansion of moisture in the PCB laminate, but that may not be the root cause. Eliminating moisture often prevents [...]

THIS MONTH WE illustrate dendrites and corrosion on board assemblies. The example in FIGURE 1 is straightforward. Saltwater was found on the surface of the metal board. It caused intermittent [...]

SUBTLE COMPONENT LIFTING can be an issue to find during inspection. Most modern AOI systems should be able to detect drawbridging on small passive and active parts. Old systems may [...]

THIS MONTH WE illustrate an example of what appears at first glance to be poor lead solderability. When examined, however, it is a combination of component and pad design. FIGURE [...]

THIS MONTH WE illustrate solder balling and incomplete reflow when reflowing through-hole components with pin-in-paste. Solder balling pin-in-hole reflow (PIHR) close to the body of the connector suggests poor design [...]

THIS MONTH WE illustrate solderability testing using simulation. This is basically conducting simple on-the-shop-floor solderability testing to decide whether to use old components. I use paste printed onto glass slides [...]

THIS MONTH WE show examples of testing BGAs with a 'dye and pry,' a simple and cost-effective way of looking at joint failure or their condition after some form of [...]

THIS MONTH WE show the ball surface on area array packages where no solder joint was formed. The joints were intermittent, but one of the surfaces --either the ball or [...]

THIS MONTH WE see a solder paste print deposit with what appears to be migration of paste particles away from the main pad. If this is just a one-off, a [...]

THIS MONTH WE show variation in the size of the solder joints on a section of a BGA. Measuring variation on solder ball size after reflow is useful. Even better [...]

THIS MONTH WE show manual conformal coating on one component. One optical example is shown under normal lighting and then under UV light, to show the tracer added in coatings [...]

THIS MONTH OUR topic is not so much a defect as something to consider when running environmental tests before any destructive analysis on solder joints. The through-hole joints shown in [...]

THIS MONTH WE show soldering of 01005 chip resistors from an early project with lead-free assembly. The microsection image in FIGURE 1 shows a few issues, but it's the circles [...]

This month we look at voids or missing conformal coating. Depending on the lack of coating and position, this condition may result in acceptance or rejection. Normally with conformal coatings, [...]

THIS MONTH WE look at crimp connections. FIGURES 1 and 2 show examples of simple compression connections. Figure 1 shows an excessive length of stripped wire within the crimp termination [...]

This month we look at solder paste slump during preheating. It is important to know how much, if any, of the paste slumps like butter on a hot day during [...]

THIS MONTH WE look at solder pad coverage. Some quality engineers still want to see solder coverage, regardless of the PCB surface finish. If they see the original surface coating, [...]

This month we illustrate what can happen when dropped chip components are permitted to remain on the board surface. In reality, parts can be dropped or misplaced, but in this [...]