HTD Group explain Gold Finger PCB technology

HTD Group is professional gold finger PCB manufacturer from China.
This paper will discuss gold plate technology.
If you want to learn more, please mail to info@htdcircuits.com

Gold contact surfaces are often used on circuit boards with membrane switches which are a technology of choice for industrial, commercial and consumer products. When PCBs will be repeatedly installed and removed electroplated gold is used for edge-connector contacts or as they are more commonly known: Gold fingers.
It is difficult to hear the term Gold finger without remembering the villain Auric Goldfinger from the James Bond film of 1964.
However, the gold fingers (gold-plated contact pins) found on PCBs are quite unlike Auric’s stubby, fat digits.
To begin with, the plating thickness of a PCB gold finger is typically a mere 300 micro-inch. At this thickness the hard gold is expected to survive 1,000 cycles before wear through.

HTD PCB manufacturer expert: Consider the component factor during impedance design

HTD PCB manufacturer expert: Consider the component factor during impedance design

Match component impedance:
This information should be found in the component data sheet.

Once you have this information you now know the required impedance value of the track you need to connect these two components.

Track characteristics: track length, width and thickness, its proximity to other tracks, ground planes, laminate thickness and dielectric constant (Er) are all important factors to consider.

For tracks located on outer layers the thickness of the solder mask must also be taken into consideration.

Use a Microstrip: This is a trace on one layer separated from a plane on another layer by a material (such as the substrate).

Remember the antenna example?

A substrate acts like the cable insulator and the plane acts like a shield.

Microstrip configurations are popular because you can use impedance calculators or field solver software to give you recommended trace dimensions based on the impedance you require and the parameters\configuration you are using.

Different configurations and combinations of these Microstrips can be used:

Surface:
Trace on one side and a copper plane on the other.

Coupled:
Where you have more than one trace on one side and a copper plane on the other.

Embedded:
Where the trace(s) are sandwiched between the substrate with a copper plane on one side.

Stripline:
Where the trace(s) are sandwiched between the substrate with a copper plane on both sides.

Using these methods, where you calculate all the parameters in order to control the impedance is often referred to as “Controlled Dielectric”.

This is sufficient for a lot of designs, as long as you specify the parameters to your manufacturer and they stick to the specifications.

You can calculate your impedance for free here.

From a HTD PCB manufacturer to discuss impedance control.

From a HTD PCB manufacturer to discuss impedance control.

If you want to learn more impedance control solution for big brand customers, please contact to us.

Let’s take the cable connecting your TV to your antenna\satellite dish and look at it through the lens of impedance.

The purpose of this cable is to transfer the signal from one device (in this case your satellite dish) to another (in this case your TV).

To obtain the best possible signal, the impedance of the satellite dish must match that of the cable and the impedance of the cable must match that of the TV.

If the impedances don’t match, then only a portion of the signal gets transferred down the line to the TV.

The rest of the signal gets sent back along the line to the antenna where it gets resent and another portion of it may now get to the TV but obviously later than the original signal.

This impedance mismatch causes interference in the signal resulting in a blurred picture on our TV or even some double imaging if the mismatch is particularly bad.

Now transfer this scenario to PCBs and imagine the consequences if the correct signals were not

reaching their destination at the required time due to a mismatch in impedance.

Basically nothing would work as well as it should. Controlling impedance then sounds like a pretty good idea, but how do you go about it?

How to consider a used machine for a small PCB manufacturer?

Used SMT assembly equipment can be found all over the Internet.
In most cases it’s “buyer beware,” but there are some cases where you can get a good deal and save some money over a new machine.
This chapter will help guide you in your search and give you some tips to avoid getting a raw deal or actually spending more than new by the time you get that bargain acquisition in good working order.

The “re” words—rebuilt, reconditioned, recycled, recertified, remanufactured, or refurbished—are intended to describe the various conditions you can expect to find in the used market; however, you really need to look deeper. Many times the wording is used interchangeably to mean the same thing.
The kind of description you want to avoid is simply “used” or “as-is,” because you have no idea how much work (and dollars) it will take to get it in good working order and registered by the manufacturer.
The best situation, if you can find it, is to buy a factory reconditioned machine from a respectable manufacturer.
Here’s the distinction I make between “factory reconditioned” and “refurbished”:
A refurbished machine is one that may have been damaged and repaired, while a factory reconditioned unit has had all its worn parts replaced, outdated components updated with new, everything tested to be in good working order, and a factory warranty applied by the manufacturer.

There are quite a few resellers who say they recondition used machines, but it’s always a risk.
Here’s why: Most SMT assembly equipment is initially licensed and registered with the OEM, similar to a title on a car. So, to get instructions, support and access to spare parts, you’ll need to register your used machine with the OEM PCB Manufacturer, and that can cost between $2,000 and $5,000, depending on the manufacturer.
Not doing so would be taking a big financial and implementation risk, and if you bought from someone other than the manufacturer you could be paying for support they might not be able to deliver. Source: PCB007

PCB expectors: The History of Flex PCBs

The History of Flex PCBs

At the beginning of the 20th century, early researchers in the burgeoning telephone industry saw the need to alternate layers of conductors and insulators to produce standardized, flexible electric circuits.

An English patent from 1903 describes coating paper with paraffin and laying flat metal conductors to provide the circuits. Around the same time, Thomas Edison’s notebooks suggested coating linen paper with cellulose gum, then tracing circuits on the gum with graphite powder.

The late 1940s brought in mass production techniques, resulting in a number of patents for photo-etching circuits on flexible substrate as a way of replacing wiring harnesses.

More recently, the addition of active as well as passive components to flexible circuits has introduced the term “flexible silicon technology,” referring to the ability to integrate semiconductors (using technologies that include thin-film transistors) onto the flexible substrate.

The combination of traditional advantages found within flexible circuit construction combined with onboard computing and sensing capability has led to exciting developments in several areas, most especially in applications in the aerospace, medical, and consumer-electronics fields.

Modern PCB manufacturers often face contradictory requirements when integrating complex circuits into a finished application.

The product needs to be light in weight, yet durable enough to survive in environments where heat, vibration and moving parts would tax traditional connections.

Additionally, manufacturing cost means that circuit integration cannot involve a lot of expensive, error-prone human assembly: it requires the repeatability and quality levels of IC design.

Finally, product lifecycles demand rapid prototyping and implementation, as time to market can make or break a product line. Flexible printed circuit boards (flex PCBs) offer advantages in all of these areas and can be used in a wide range of applications, from medical and aerospace to consumer electronics.

The Space, Weight, and Cost Savings of Flex

Redesigning a product to use flex PCBs rather than rigid PCBs deliver immediate benefits in weight. Customers commonly see weight reductions of up to 75% when compared to traditional designs.

This comes from using incredibly thin substrates made of polyester or polyimide material—films that can be as thin as 12-120 microns thick.

Conductive material traces are etched on the flex PCB, in as many layers as the PCB design requires. Typically, a coverlay is then applied to protect the layers from moisture, dirt and damage.

One important use of flex PCB design is the replacement of wiring harnesses and ribbon connectors once used to link together different boards—for example, to connect the engine control unit in an automobile to the dashboard or lighting components.

The standardization and economy of scale that goes along with this also reduces assembly cost by reducing the number of components and interconnections, and allowing for high-quality mass production.

Many flex PCB users find that they can reduce the cost of connections by up to 70% versus traditional wiring harness construction.

And with the reduction in connection cost comes a reduction in costs associated with inconsistent quality—flex PCB’s standardized construction also eliminates the source of potential errors from hand-built harnesses.

HTD PCB manufacturer experts: how to handle Flux residues during assembly

This paper HTD PCB manufacturer experts will introduce how to handle Flux residues during assembly.
If you have any questions about the PCB manufacturing, please contact us.

Flux residues have been the bane of reliability of PCB assemblies (PCBAs) from the first time they were used.
However, it is necessary to use some sort of compound to reduce the oxides that form on the copper surface before soldering.
Historically, activated rosin based fluxes were used to provide a surface for the solder to wet with.
The problem with these fluxes is that they contained chlorine or bromine and remained corrosive after the soldering operation and would cause corrosion of the surface during operation of the product.
Many cleaning and testing methods were developed to clean the surfaces and to test to insure the surfaces were noncorrosive afterwards.
The majority of these test methods involved checking for ionic contamination after the cleaning was performed.
A passing product would have a low level of ionic contamination.

During the changeover to RoHS compliant solders low solids fluxes were introduced as “no-clean” fluxes.
These fluxes were composed of organic acids such as adipic acid or citric acids.
These organic acids are decomposed by the temperatures reached during soldering, and were marketed as fluxes that did not need to be rinsed from the PCBAs after reflow.
This is not normally an issue with reflow soldering as the entire PCBA reaches the required temperature for degradation of the flux.

However, these fluxes may not reach the required temperature during a wave soldering operation if they are shielded from the molten solder.
Because assembly houses believe these fluxes do not need to be cleaned from the PCBA, they make no attempt to clean any flux residue that remains after reflow or wave soldering. Many assembly houses will argue that they are using “no-clean” flux which does not need cleaning.

There are areas that flux residues can be trapped and not experience enough heating during a wave soldering operation.
One of these areas is between the printed wiring board (PWB) and the pallet used to transport it across the solder wave.
Flux trapped between the wave soldering pallet and the PWB will not be exposed to the molten solder because the pallet provides a thermal barrier to the wave.
This flux can lead to corrosion because it is still acidic in nature.
It is also hygroscopic, which means it will pull water from the air and dissolve. Figure 1 shows active flux remaining on a PCBA after wave soldering.
Low solids fluxes often cause a whitish material on the PWB that is not active and will not cause issues in reliability.
This material is very resistant to removal by water or isopropyl alcohol (2-propanol).
However active fluxes are readily dissolved by either water or isopropyl alcohol.
This can be used to distinguish the active flux from decomposed flux films.
A visible difference in appearance after swabbing a suspected area with an isopropyl saturated cotton swab indicates that the swab removed a significant amount of flux, and indicates that the flux is still active.

It is important that the wave solder pallets be cleaned often to remove the flux residues that build up on them from the fluxing operation.
Cleaning should be performed using the same solvent that is used to dilute the flux.
Fiber-free cloths should be used to perform this operation so that future product is not contaminated with debris from the cleaning process.