Archive for March, 2016

Parts Shortage

Written by Rush PCB Inc on . Posted in PCB, PCB Manufacturing

While assembling SMT PCBs for a customer, the line unexpectedly ran out of 01005 package size resistors during the production run. This was due to an error on the customer’s part; they simply did not provide us with enough. But the customer still expected the finished product in-hand by the due date, and we did not want to disappoint him.

This, of course, created a dilemma. Should we halt production while additional parts were ordered, or simply continue? We placed a replenishment order immediately, and learned that we could not get them until the next day. We asked, “Is it possible to assemble these boards now, and add the part later when they arrive?” We also had to quickly assess the feasibility adding the part later on. How accessible is the site for this tiny part? Can it be done by a skilled soldering technician? We decided that it could.

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An 01005 parts shortage didn’t stop production.

We proceeded to build the order with the exception of that single 01005 component. The site was accessible, we decided, so that the part could indeed be added individually to each PCB. Sure, it would take some time and hand soldering, but it would not cost us nearly as much time as if we had put the entire build on hold to wait for the parts.

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Once the needed parts arrived, they were hand soldered onto each assembly by a skilled operator using slender soldering iron tips.

When the parts arrived the next day, we were able to employ our best hand soldering people with soldering irons equipped with special slender tips. The job went quickly and easily, and we were able to minimize downtime on the SMT line due to the unexpected component shortage, and keep this job on schedule, much to the relief of our customer. We came through for them despite their mistake, and they appreciated that.

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The 01005 parts were easily and quickly added, and the entire job shipped by the required due date since the rest of the assembly had already been finished.

Efficient use of time, getting whatever can be done while minimizing down time, pays dividends when one is living by tight delivery schedules and expected ship dates. The more that can be achieved without unnecessary delays, the better the chances that a ship date can be honored.

 

Cool Facts about PCBs That You Probably Didn’t Know

Written by Rush PCB Inc on . Posted in PCB

pcb facts

PCBs – Interesting Facts

PCBs are older than you’d think: The concept of a PCB is 80 years old! The first PCB was designed by an Austrian (Paul Eisler) inventor in 1936. He used the board in a radio set. The boards only became common from the 1950s, when mass production of electronics such as radios and television sets changed the world.

They’re a part of our lives, everywhere, everyday:  We’re always aware of PCBs being present in computers. But they are in almost every device we now use. For most people, there is be a PCB within  reach at most times of the day – in your phone, your car… everywhere.

There are basic designs: Almost all PCBs can be specified within the parameters of 14 standard services. The use of standard specifications reduces manufacturing costs.

They are fully customizable: Circuit boards can be made to meet anyone’s specific requirements (although this is an expensive option).

There are many different components: batteries, LEDs, diodes, inductors, resistors, transistors, transformers, relays, capacitators,potentiometers, fuses and switches.

They are green! Original PCBs were green due to the solder mask resins. While the technology has changed, the color hasn’t. It has been suggested that green is a good color, as it allows electrical engineers to easily see faults in the traces.

They don’t use wires:  Wires take up too much space. In their place, PCBs use copper ‘traces’. This allows PCBs to be much smaller.

Change is Constant: Circuit boards have clearly changed since Paul Eisler first designed one. The technology over the years has been a steady reduction in size, corresponding to an increase in speed. Surface Mount Technology (SMT) has allowed for a reduction in size by an order of magnitude over through-hole mounting.

Graphene technology is likely to make considerable change:  Graphene is a two-dimensional array of atomic-scale carbon atoms. The use of graphene is likely to considerably reduce the size and increase the performance of future PCBs.

They can be built in layers: Original PCBs had all circuits on one side. As SMT doesn’t affect both sides of the board, both sides can be used to host components. In addition to double-sided PCBs, layers can be laid on top of each other on the same side, increasing capacity.

Another layer is the silkscreen: These are the white etchings Not etched screen printed (readable text) that sit on top of the solder mask. The silkscreen has letters and numbers drawn onto it to allow for more simple assembly.  Historically, the text was printed with a silk screen printing process. Today, it is more likely that the printing is done by ink-jet printers.

They are made twice: The first time a PCB is made, it is developed in a Computer Aided Design (CAD) program. The software will test the layout to ensure that the connections all work and perform as intended. Once the engineer is sure that the PCB is operating correctly, the physical board is made.

New technology means that PCBs may in future be biodegradable!

Mirror Mirror

Written by Rush PCB Inc on . Posted in PCB Assembly and component

A mirror can bring bad luck, it is said. In this PCB assembly challenge, it certainly did when a mirrored pad layout for a transformer made it impossible to mount the component to its intended location on the top side of a PCB in its usual orientation.

Design error: A mirrored pad layout creates orientation problems between pads and component pins; layout is for bottom-side rather than top-side mounting.

Design error: A mirrored pad layout creates orientation problems between pads and component pins; layout is for bottom-side rather than top-side mounting.

 

The component’s footprint, it turns out, would work fine if it were on the opposite side of the PCB, but that bottom-side installation is not possible.

Flipped upside down, the SMT transformer’s pins line up fine, except that they are facing upwards. But we can still mount the component and make a robust connection using adhesive and connecting wires.

Flipped upside down, the SMT transformer’s pins line up fine, except that they are facing upwards. But we can still mount the component and make a robust connection using adhesive and connecting wires.

 

The customer made a design mistake; although the pads for top-side SMT mounting of the component are in place, they are in mirror-image orientation; e.g., the pad layout with Pin 1 is intended to be installed from the bottom of the board. Consequently, it doesn’t match up in terms of orientation on the top side of the PCB unless the component is literally placed onto its back. But that means that the leads are sticking up into the air, pointing in the wrong direction.

 

Small dots of epoxy are applied to the PCB surface and to the component body, before it is attached, the epoxy cured, and the transformer connected pin by pin.

Small dots of epoxy are applied to the PCB surface and to the component body, before it is attached, the epoxy cured, and the transformer connected pin by pin.

 

It’s well known that a dab of epoxy can cure a host of ills, and in this case it was simply a matter of dispensing a tiny amount of epoxy onto the back of the component body, in the center, as well as onto its intended location on the SMT PCB assembly.

The component is then carefully located in place upside-down and the epoxy cured. With the component robustly mounted in this manner, small wires were then run from each lead (pin) to its corresponding pad on the board’s surface.

 

It requires skillful hand soldering once the component is in place, but the connection is robust and complete.

It requires skillful hand soldering once the component is in place, but the connection is robust and complete.