By Mer-Mar Electronics | Date posted: | Last updated: August 6, 2022
Wire harness design

Wire harnesses refer to wires that are bundled together to suit specific applications. They come in a wide range of complexities from individual wires to a complex harness that comprises of hundreds of individual wires. The good thing about wire harnesses is that they can be highly customized to transmit power as well as data. Additionally in terms of location they can conform to a wide variety of space constraints. Some of the aspects that need to be considered when it comes to wire harness design so that it functions safely and as per specifications include:

  • Environmental considerations
  • Power Demand
  • Lengths

Taking these details into account at the design stage means that costly errors can be avoided later & that the results are more effective. Let us look at some of the aspects that you need to consider while manufacturing a wire harness.

Wire harness design: Things to keep in mind

Environmental considerations

It is imperative to consider the demands of the environment in which the harness must function. Some of the environmental hazards that cable harness assembly must face include:

  • Extremes of temperature
  • Exposure to water
  • Exposure to chemicals
  • Exposure to vibration leading to abrasion

It is important, therefore, to choose the right wire depending on the environmental factors. The wrong choice of wire can lead to issues including but not limited to breakdown of insulation, safety issues, compliance failures, costly accidents, and more.

Parts Considerations

It is extremely important that when you share the list of parts with a contract manufacturer, you make sure that the partner can cross reference these parts to a manufacturer. In case your requirements do not pertain to a specific manufacturer or brand, a mention of “or equivalent” can go a long way for the contract manufacturer to be able to substitute the parts in a way it optimizes quality as well as costs.

In case there are internal specifications for production, you need to make sure that the same is shared with the partner so that the harness meets your bespoke specifications.

1. Lengths and Tolerances

You need to know the exact dimensions as well as the acceptable tolerances for the lengths.

2. Covering

Some of the covers available include:

  • Braided Loom
  • Split Sleeve
  • Conduit
  • Tape

Each of them has their own distinct set of advantages. Understanding them in detail will ensure that you are able to determine which one will work best for your bespoke application. In choosing the covering (or not), ensure that you keep the following aspects in mind:

  • Flexibility
  • Serviceability
  • Troubleshooting, and more.

3. Splicing and splice locations

Do remember to review the kind of splicing you need before you reach out to the wire harness manufacturer.

4. Wire color and labeling

To help identify circuit names, wire colors as well as any text that you want printed is to be determined early.

5. Type

Ensure that you choose the type of wire with care. Wire that is used for automotives, for example, is quite different from those used in electrical control panels. Some of the aspects to keep in mind include:

  • Voltage Ratings
  • Insulation Material
  • Bare or plated copper, and more.

6. Terminals, seals, and connectors

There are a wide variety of terminals in wire harness, seals as well as connectors. In fact, connectors cater to several types of terminals and seals. Additionally, some connectors require additional accessories. It is important therefore to identify such accessories in advance.

7. Labeling

In case you need certain connectors to be labeled, it is imperative that a note be placed on your drawing that informs the contract manufacturer of your requirements.

8. Testing

Depending on your bespoke requirements & where the harness needs to be used, you may have specific testing requirements. In some cases, a continuity test may be in order while in others a high voltage test may be imperative.

Work closely with the PCB contract manufacturer

It is important to recognize that a drawing can seldom be perfect. There could be occasions where in your bid to offer too many details on the drawings you have rendered it extremely cluttered. On the other hand, in a bid to avoid clutter, you could end up giving information that is too unsure for the contract manufacturer. It is therefore advisable to work closely with the contract manufacturer to ensure that you give the right level of details as well as choose a convenient way to handle any deviations and/or revisions.

Choice of the right PCB contract manufacturer can go a long way in ensuring that the process is streamlined & your wire harness is created to meet your exact specifications.

When it comes to the right PCB manufacturer you can consider Mer-Mar Electronics which provides cable harnessing assembly service without any hassle. We specialize in assembling simple wire cable harness assemblies through to complex custom-build cable and wire harnesses using combinations of single-core or multicore cables.

Get a quote to know more details.

By Mer-Mar Electronics | Date posted: | Last updated: July 9, 2022
PCB Components Assembly

When it comes to the assembly process of PCB components, there are both automated as well as manual steps involved depending on the complexity of the board. Of course, the assembly process also has a lot to do with the fact whether the assembly is being done for through-hole components, surface mount components or whether they are mixed PCB components.


Typically, these are components with long leads and are a generation behind surface mount components. These components involve that leads be inserted into holes and then soldering them. Typically such components are only mounted on the top end of the board.


While designing PCBs with through-hole components, it is important to place the holes at distances that are specified by the component manufacturer. When dealing with multi layered printed circuit boards What is also important are plated through-holes. These holes also act as vias for connecting circuits on the outer layers.

For such boards since drilling of holes is a key requirement, the area that is available for routing of traces is limited. That typically means that you have to use a board with a large area that may not be conducive to the trend of miniaturization that is prevalent. Alternately, you can use a board with multiple layers.


Whether you choose to use manual or automated component mounting, it is important that the component leads are pre-processed so that insertion becomes seamless.


Largely, through hole components are soldered by a process of wave soldering. The machine throws up molten solder through a nozzle. As the components assembly passes over this wave, the components are soldered in place.


For such components, the exercise of drilling need not be undertaken. In fact these are smaller components that can be packed together and they work particularly well in dense assemblies. Also surface mount components can be mounted on both sides of the board.


Since space does not need to be allocated for the holes, a high component density is a given. High density is also achieved by using small vias or tented vias in pads when it comes to fine pitch components such as BGAs (Ball Grid Array packages).


The use of a stencil to deposit solder pads at the right areas is important. Solder paste deposition may be manual or automated.


Typically pick-and-place machines are used to mount small components. This ensures that each component is mounted in the right location with solder paste on the pads.


Since solder paste is already present all that is required is to melt the solder so that the component is held in place. For this purpose, a reflow soldering machine comes in handy. It has infrared heaters that generate heat that melts the solder paste & fixes the components.


Some applications make use of a mixed technology & hence use both surface mount as well as through-hole components.


In such cases the surface mount components are typically placed on the underside of the board. This is advantageous as the wave soldering process ensures that they are soldered along with the through-hole components.


For the surface mount components it is important to use a glue deposition process. Essentially a dispenser places glue between the pads. The pick-and-place machine next mounts the surface mount components. Pro tip – It is important for the board to go through a curing process so that the glues is sufficiently hardened & the component is held in place.


It is now safe to turn over the board & insert the through-hole components. After this follows the wave soldering process.

To sum up

While PCB assembly of through-hole components seems simpler, the fact remains that there could be opportunities for failure. For example, if component leads are close there are chances of shorts. Also, a big disadvantage with through-hole components is that they do not lend themselves to high density assembly.

Surface mount components on the other hand can take care of many of these issues. The components can be packed densely. Also, with the reflow soldering process the quality of soldering is far higher.

Mer-Mar Electronics is one of the leading PCB manufacturing companies, providing all-in-one PCB assembly solutions. Our consistent quality & quick turnaround endear itself to our customers, who look on us as a one-stop shop for all PCB manufacturing requirements.

If you have any queries regarding our surface mount assembly or through-hole PCB assembly services, or need urgent assistance, then please do not hesitate to contact our team of skilled personnel. Send us an email with your queries at or call us at (760) 244-6149.

By Mer-Mar Electronics | Date posted: | Last updated: March 17, 2022
Flex Circuit Assembly

While for the most part we are used to circuit boards in their traditional formats, the growth of ergonomic product designs, as well as the evolution of wearable tech, necessitates a different kind of circuit board. You sure need boards to fit in miniature spaces as also for them to be resistant to vibration, mechanical wear and tear, and more.

All of these objectives can be achieved with a flexible circuit board. While earlier assembling flex circuits was prohibitively expensive both in terms of material and man-hours, flex assembly costs have been dropping, making it convenient to use them in everyday products.

Some of the many benefits that flex circuit board offer, include:

Ability to take different shapes

This of course is the most obvious advantage, as such boards can be bent and folded. It also allows components to be placed in optimal positions within the product. Essentially it lends itself to miniaturization of products, which is a growing trend.

Weight Reduction

Space, Weight and Packaging remain important issues when it comes to PCB design. With flexible circuits bulky wire and solder connections can be avoided. In turn, this leads to a significant reduction in weight and space and also in packaging size.

Reduced assembly costs

With bulky wire and cables being significantly reduced in flex circuits what is also reduced is the cost of wire as also the labor cost.

Helps with dynamic flexing

Flexible circuits can withstand flexing. Examples of this include disk drives, laptop hinges and more

Thermal management

Flexible circuits are frequently seen in high power, high frequency designs as polyimide materials can withstand high heat applications. Laos thin polyimide dissipates heat quickly.

Great for aesthetics

Flexible circuits work well in terms of product aesthetics, which is major draw for consumers. It lends itself to sleekness and rates high on consumer confidence.


Polyimide materials are known for their bio-compatibility and hence find high application in medical as well as wearable applications.

High on Reliability

As opposed to a rigid board, a flex board can simplify the system design by reducing the number of interconnections required. This also takes away the possibility of human error and increases reliability.

Aspects to be kept in mind when it comes to flex circuit assembly, some of these include:


As opposed to rigid PCBs that can work with standardized dimensions and conveyor belt-style processes, flex circuits may need to be assessed individually. Some of the areas to pay importance to, include:

  • The pallet needs to fit its unique shape
  • The pallet needs to accommodate both the top and bottom circuit configuration
  • The flexible circuit assembly needs to lay flat on the pallet otherwise an air cushion beneath the circuit can cause mechanical resistance during solder paste screening as well as pick-and place. The air cushion also can cause components to bounce off the PCB assembly.
  • It requires special tooling and backup fixtures for unique designs
  • The pallet geometry needs to be customized so that the circuit remains flat.
  • Also with pick-and-place machines working at high speed and small margin of error, there can be issues if there is any difference between circuit dimensions and actual flex circuit geometry.

Heat Sensitivity

The other issue that needs due importance is that of heat sensitivity. Essentially, flex circuits are far thinner than rigid boards. On account of this, the heat that is applied in soldering cannot be dissipated. What is important is also that there should be precise soldering tools as well as extremely experienced technicians. It is only with the investment in the state-of-the-art tools as well as trained technicians that productivity can be improved.


Flex circuits require appropriate backing during the testing process. For example, in case of Flying Probe testing, there needs to be a special custom fixture to offer support to the PCBA. In case of in-circuit testing, a rigid backing is designed into the clamshell fixture.

With flex circuits increasingly solving the constraints, their use is likely to become even more ubiquitous.

Mer-Mar Electronics is one of the leading PCB assembly manufacturers, providing all in one PCB assembly and fabrication solutions. Whether you are looking for flexible PCBs, flexible PCBs fabrication or flexible circuit board assembly, we have you covered. Send us an email with your queries at or call us at (760) 244-6149 related to our flexible PCB manufacturing and assembly.

By Mer-Mar Electronics | Date posted: | Last updated: March 14, 2022
PCB Soldering Process

Soldering is an essential process that helps fasten components onto a PCB. The right soldering can make a huge impact on the quality as well as the performance of the custom printed circuit boards. In this article, we have explained what the PCB soldering process is, the types of soldering process; and how it can be done.

There are different types of soldering techniques as well as solders, the choice of which is critical to the success of your project. Here is a detailed overview:

Types of PCB Soldering Process

Reflow Soldering

This involves using a solder paste to temporarily attach components to their respective contact pads. Post this, the assembly is subject to controlled heat. The process of reflow soldering involves the following steps:

  • Application of the solder paste.
  • Preheating the board to bring it to the required temperature.
  • Thermal Soak so that areas that weren’t adequately heated come to the required temperature.
  • Reflow process to create the necessary solder joints and remove volatiles.
  • Cooling to prevent thermal shock and excessive intermetallic formation on the board.

Wave soldering

This is a large-scale soldering process wherein electronic components are soldered to create an electronic assembly. This process involves passing the PCB over a pan that contains molten solder. It is important to maintain the right temperature during wave soldering. There also needs to be adequate pre-heating as otherwise, the board is susceptible to stress.

The steps involved in wave soldering include:

  • Melting the solder
  • Cleaning of Components
  • Placement of components
  • Application of solder
  • Cleaning of the board

The ideal temperature during wave soldering ranges between 240-250°C.


The type of soldering you go with depends on a wide variety of factors including but not limited to:

  • Shape of the pads
  • The available time
  • Component orientations
  • Type of PCB, and more.

In some ways, wave soldering is more complex as its success depends upon creating the right environment. Board temperature and the time the board spends in the solder wave need to be monitored. However, wave soldering is also faster and more cost-effective as opposed to reflow soldering. Reflow soldering is however more suited to be used in small-scale manufacturing while wave soldering is suited for large scale production.

Explore the reflow soldering v/s wave soldering in detail.

Types of solder

Other than the soldering process, what is also critical is the choice of solder. Some of the solder types that are increasingly used include:

Lead alloy solder – It is a mixture of 60 percent tin and 40 percent lead.

Lead-free solder – Given the impact of lead on the environment, the use of lead-free solder has been growing. In fact, the EU has restricted the use of lead in consumer goods.

Silver alloy solder – These emerged as alternatives to lead solder and contain between 3-5 percent of silver.

Some Common Problems in PCB soldering process

Some common problems that one needs to watch out for in the soldering process, include:

Interfered joints

These joints result on account of movement during solder solidification. As a result, the joint appears crystalline and rough.

Cold joint/overheated joints

These result if the optimal temperature isn’t maintained or if the duration of heating isn’t long enough.

Excessive solder

If there is application of too much solder it results in bubble-like solder balls. In turn, they impact the functionality of the board.

Insufficient wetting

A badly wet joint results in poor connections and impairs the overall performance of the circuit.

Solder hunger

This refers to a situation where insufficient solder is used. In turn, it leads to poor electrical contact between the parts of the circuit

Untrimmed leads

If the leads aren’t trimmed to the required lengths, there can be the risk of short circuit as the leads can come in contact with the rest of the charges.

Points to be kept in mind during PCB soldering process

#1. Heat dissipation during assembly

It is important to effectively monitor heat dissipation during assembly and to ensure that the circuit’s components remain below the required temperature limits.


If the soldering iron tip isn’t kept clean, you can run into a number of issues including low heat transfer leading to soldering issues.

#3. The sequence of welding parts

It is important for designers to understand the right sequence of affixing the various components.

#4. Removal of residue

Once the soldering process is complete, you are left with the flux. This needs to be thoroughly cleaned as otherwise it can lead to low voltage insulation short.

#5. Soldering SMT resistors and capacitors

Soldering resistors and capacitors is a challenging task. Experienced PCB designers can make a great deal of difference in this process.

#6. Continuity and Sensor Output

It is imperative to undertake testing for continuity and sensor output to ensure that there are no malfunctions.

To Sum Up

The right soldering is a matter of precision and having enough experience and access to soldering best practices. It is important, therefore, to go with the right partner who can make a difference to the project.

Mer-Mar Electronics is one of the leading PCB manufacturing companies, providing all in one PCB assembly and fabrication solutions. Our consistent quality & quick turnaround endear itself to our customers, who look on us as a one-stop shop for all their PCB manufacturing requirements. In case you have any questions or require more information about our PCB manufacturing services, contact us via email at or call us on (760) 244-6149.

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