Ilustrovaná historie desek s plošnými spoji

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Ilustrovaná historie desek s plošnými spoji

První desku s plošnými spoji (PCB) vyvinul ve 30. letech 20. století Paul Eisler, který vystudoval strojírenství a předtím, než se začal věnovat elektrotechnice, pracoval jako redaktor časopisu. Eisler přišel s nápadem, že tisk na papír by se mohl používat nejen pro noviny. Tuto myšlenku rozvíjel v malém jednopokojovém bytě v londýnském Hampsteadu.

Moe Abramson

Historie desek s plošnými spoji byla ovlivněna mnoha technologickými trendy. Jedny z prvních desek plošných spojů vytvořil Moe Abramson, počítačový inženýr, který pomohl vyvinout proces automatické montáže. Abramson také vyvinul vzory propojení měděných fólií a techniky ponorného pájení. Jeho postup byl později zdokonalen a jeho práce vedla ke standardnímu postupu výroby desek s plošnými spoji.

Deska s plošnými spoji je obvod, který mechanicky nese a elektricky spojuje elektronické součástky. Obvykle se vyrábí ze dvou nebo více vrstev měděných plechů. Její výrobní proces umožňuje vyšší hustotu součástek. Má také pokovené průchozí otvory pro elektrické spoje. Pokročilejší desky plošných spojů obsahují také vestavěné elektronické součástky.

Stanislaus F. Danko

Historie desek s plošnými spoji sahá až do poloviny 20. století. Předtím měly elektronické součástky drátové vývody a byly připájeny přímo na stopu desky plošných spojů. První proces automatické montáže vyvinuli Moe Abramson a Stanislaus F. Danko, kteří byli členy amerického signálního sboru. Tento postup si nechali patentovat a od té doby se stal standardní metodou výroby desek s plošnými spoji.

Desky s plošnými spoji jsou důležitou součástí elektronických zařízení. Od svých skromných počátků v polovině 19. století se staly běžnou záležitostí. Jejich vývoj byl poháněn rostoucími požadavky spotřebitelů. Dnešní spotřebitelé očekávají od svých elektronických zařízení okamžitou odezvu. V roce 1925 vyvinul Charles Ducas postup zvaný "tištěný drát", který měl snížit složitost zapojení. Dr. Paul Eisler sestrojil první funkční desku plošných spojů v Rakousku v roce 1943.

Harry W. Rubinstein

Historii desek s plošnými spoji do značné míry ovlivnil muž jménem Harry W. Rubinstein, který v letech 1927 až 1946 pracoval jako vědecký pracovník a vedoucí pracovník divize Centralab společnosti Globe-Union. Rubinstein byl v Centralabu zodpovědný za několik inovací, včetně vylepšených kolečkových bruslí, zapalovacích svíček a akumulátorů. Jeho nejslavnějším vynálezem však byl tištěný elektronický obvod.

Historie desek s plošnými spoji začíná na počátku 20. století, kdy se elektronické součástky pájely na desky plošných spojů. Deska plošných spojů měla otvory pro vodiče, které se skrz tyto otvory zasunuly a poté připájely k měděným stopám na desce. V roce 1949 však Moe Abramson a Stanislaus F. Danko vyvinuli techniku, která spočívala ve vkládání vodičů součástek do propojovacího vzoru z měděné fólie a jejich ponorném pájení. Tento postup později převzala americká armáda U.S. Signal Corps a nakonec se stal standardním způsobem výroby desek s plošnými spoji.

Komponenty pro povrchovou montáž (SMT)

SMT je technologie, která umožňuje aplikovat elektronické součástky přímo na povrch desky s plošnými spoji (PCB). To umožňuje efektivnější výrobu a kompaktnější design. Snižuje také počet vrtaných otvorů, což může vést ke snížení výrobních nákladů. Součástky SMT jsou také robustnější a vydrží vyšší úroveň vibrací a nárazů.

Hlavní výhodou technologie povrchové montáže oproti průchozím součástkám je vysoká míra automatizace a snížení počtu poruch během procesu svařování. Kromě toho je balení součástek SMT mnohem levnější než balení jejich protějšků THT, což znamená nižší prodejní cenu. To je obrovská výhoda pro ty zákazníky, kteří hledají velkoobjemové desky s plošnými spoji.

Více vrstev mědi

DPS s více vrstvami mědi jsou vyrobeny z více vrstev měděné fólie a izolačního materiálu. Vrstvy mědi mohou představovat souvislou měděnou plochu nebo mohou představovat samostatné stopy. Vodivé měděné vrstvy jsou vzájemně propojeny pomocí průchodek, což jsou tenké kanálky, které mohou vést proud. Tyto vodivé vrstvy se často používají ke snížení elektromagnetického rušení a k zajištění jasné cesty zpětného proudu. Níže jsou uvedeny některé výhody použití mědi na deskách s plošnými spoji.

Vícevrstvé desky plošných spojů jsou nákladnější než jednovrstvé. Jejich výroba je také složitější a vyžaduje složitější výrobní proces. Navzdory vysokým nákladům jsou oblíbené v profesionálních elektronických zařízeních.

Elektromagnetická kompatibilita

Elektromagnetická kompatibilita (EMC) je důležitým aspektem návrhu výrobku. Normy EMC jsou předpokladem pro zajištění bezpečného provozu výrobků. Návrh desky plošných spojů musí být elektromagneticky kompatibilní s jejími součástmi a okolím. Desky s plošnými spoji obvykle nesplňují normy EMC při prvním průchodu. Proto by se proces návrhu měl od počátku soustředit na splnění norem EMC.

Existuje několik běžných technik pro dosažení elektromagnetické kompatibility. Jedna z metod zahrnuje umístění zemnící vrstvy na desku plošných spojů. Další metoda zahrnuje použití zemnících mřížek, které zajišťují nízkou impedanci. Velikost prostoru mezi mřížkami je důležitá pro určení zemní indukčnosti desky plošných spojů. Dalším způsobem, jak snížit elektromagnetické rušení, jsou Faradayovy klece. Tento postup zahrnuje nahození země kolem desky plošných spojů, což zabraňuje signálům, aby se šířily za hranici uzemnění. To pomáhá snížit emise a rušení produkované deskami plošných spojů.

What is the Impact of Galvanic Corrosion on the PCB?

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What is the Impact of Galvanic Corrosion on the PCB?

If you’ve ever wondered what is the impact of galvanic corrosion to a PCB, you’re not alone. This type of corrosion causes neighboring traces to become contaminated by a solution or ionic liquid, and small slivers grow between the traces. These slivers can cause short circuits or even disable a functional block on the PCB. If the corrosion affects the power lines on the PCB, you could experience a whole device malfunction.

Examples of galvanic corrosion on a PCB

Galvanic corrosion is an electrochemical process whereby the surface of one metal reacts with the surface of another metal. This reaction takes place in the presence of an electrolyte, and it usually occurs between dissimilar metals. In primary cells, this process is exploited to create useful voltage.

The corrosion process begins when moisture, or ionic liquid, contacts an exposed metal part. Upon contact, metal oxides begin to grow and cause the surface to corrode. This process can also affect adjacent circuit boards, causing short circuits and deterioration of the entire board.

One way to minimize galvanic corrosion is to use corrosion inhibitors. These are effective at reducing galvanic potential, but require constant monitoring. They also increase the conductivity of water. So, it’s important to properly maintain the PCB when working with it.

Another method for preventing galvanic corrosion is to use antioxidant paste between copper and aluminum electrical connections. This paste consists of metal with a lower electro potential than copper. This will help to ensure that metals do not come into contact with each other and minimize the chance of galvanic corrosion.

Galvanic corrosion is often a result of dissimilar metals used in soldering joints. Because of this, it’s crucial to choose the right material for mating connectors. Materials with the same ionic potential are more likely to resist corrosion than those with dissimilar metals.

Process for reducing galvanic corrosion degree on a PCB

The degree of galvanic corrosion on a PCB board can be reduced in various ways. The first technique involves analyzing the network and finding the causes of galvanic corrosion, and the second technique involves increasing the area of the organic coating process (OSP) disk in the network.

The copper pads on a PCB are protected by a surface finish, but moisture can enter under the finish. Once inside, moisture reacts with the copper and starts a corrosion process. This process can then spread along the trace. In many cases, galvanic corrosion occurs due to contact between two dissimilar metals, such as copper on a PCB and the metal of a component. The presence of a corrosive electrolyte also increases the chance of galvanic corrosion.

Galvanic corrosion is a common problem in electronics, particularly in high-speed applications. It happens when two dissimilar metals are in contact with an electrolyte. When two dissimilar metals are in electrical contact, the more reactive metal atoms lose electrons and cause oxidation. This leads to a short circuit.

Keeping PCBs clean is critical to their longevity and ensure the longevity of the devices. The prevention of corrosion starts with keeping them dry and free of liquids. As a result, PCB manufacturers and designers must carefully protect their boards against moisture beading on exposed conductors.

Typical corrosion failure types in electronics

Typical galvanic corrosion failure types in electronic devices occur due to different types of processes. One of them is the formation of a water film on the PCBA, which can lead to leakage currents and a wrong output signal from the electronic device. Another type of corrosion failure is caused by a defect in the manufacturing process. This corrosion type often results in a short circuit in the switch.

The rate of corrosion depends on several factors, including temperature and the surrounding environment. The presence of moisture, dew, or condensation will accelerate the process. The presence of dust particles will also increase the corrosion rate because they retain moisture. Dust particles come from a variety of sources, including soil/sand, smoke, soot particles, and salts.

Stainless steel and zinc are examples of noble and active materials. The higher the relative difference between the two metals, the greater the amount of force that will be exerted during galvanic corrosion. A cathode with a large surface area will corrode at a high rate due to the high current.

Galvanic corrosion is a major concern in industrial design. Magnesium is a highly active structural metal. It is used in the aerospace and auto industries. The area ratio of the cathode and anode will also affect the amount of current produced by galvanic corrosion. Insulation spacers between two metals may also reduce the risk of galvanic corrosion by changing the distance between them.

Solder Ball Issues of BGA Components and Their Remedies

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Solder Ball Issues of BGA Components and Their Remedies

Solder ball issues of BGA components are common problems that can lead to deterioration of the components. These problems are caused by solder ball delamination or oxidation. Fortunately, the remedies are simple and do not require any complex technical knowledge. These solutions will help you prevent further damage to your components.

Solder ball delamination

BGA components are prone to problems related to solder balls, commonly referred to as “head-in-pillow defects”. The problem occurs when two metal surfaces are mechanically connected, often by a solder ball. The amount of contact between the ball and solder varies depending on the soldering process and the heat and pressure applied to the parts. Several studies have been conducted to understand the cause of this defect and the remedies for preventing it.

A faulty BGA can have serious effects on the functionality of the product. A typical remedy is to replace the affected component with a new one. However, this solution can be problematic and expensive. The better alternative is to reball the BGA component. It requires a technician to remove the affected components and install new solder in the bare areas.

In order to prevent solder ball issues, it is important to use the correct test socket. There are two types of test sockets: claw-shaped sockets and needle-point sockets. The former causes the solder ball to expand and become deformed, while the latter causes bumping and abrasion to the solder ball.

Solder ball oxidation

Solder ball oxidation issues of BGA components are a growing problem in electronics manufacturing. These defects are caused by incomplete merging of BGA/CSP component solder spheres with molten solder paste during the solder reflow process. These defects affect both lead-free and tin-lead soldered assemblies. However, there are ways to mitigate these problems.

One way to avoid this problem is to use solder paste that is semi-liquid. This will ensure that the ball does not short-circuit when heated. To ensure a solid solder joint, the solder alloy used is carefully chosen. This alloy is also semi-liquid, allowing individual balls to remain separate from their neighboring balls.

Another way to prevent solder ball oxidation is to protect your BGA components during handling. When transporting or shipping, make sure that your BGA components are placed in a non-static foam pallet. This will delay the oxidation process of the solder balls and sockets.

Solder ball removal

Solder ball removal for BGA components is a critical process. If the solder ball is not properly removed, the BGA component can be damaged and result in a messy product. Luckily, there are several ways to remove the ball from BGA components. The first way is to use a vacuum to remove any residual solder. A second way is to use a water-soluble paste flux.

In many cases, the most cost-effective method is reballing. This process replaces lead-free solder balls with leaded ones. This method ensures that the BGA component retains its functionality. The process is much more efficient than replacing the entire board, especially if the component is regularly used.

Before starting the process, a technician should research BGA components. Before touching the device, he or she needs to assess the size and shape of the solder balls. Besides, he or she must determine the type of solder paste and stencil to use. Other factors to consider are the type of solder and the chemistry of the components.

Solder ball reballing

Solder ball reballing of BGA components is a process that involves reworking electronic assemblies. This process requires reflow soldering and a stencil. The stencil has holes for solder balls to fit into. To achieve the best results, the stencil is made from high-quality steel. The stencil can be heated with a hot air gun or a BGA machine. The stencil is necessary for the BGA reballing process and helps to ensure that the solder balls fit into their correct locations.

Before reballing a BGA component, it is important to prepare the PCB for the process. This will prevent damage to the components. First, the PCB is preheated. This will allow the solder balls to become molten. Next, the robotic de-ball system picks up a row of components from a matrix tray. It applies flux to the solder balls. It then runs through a programmed preheat stage. After that, a dynamic solder wave removes the unwanted balls from the board.

In many cases, reballing a BGA component is more economical than replacing the entire board. Replacing an entire board can be costly, especially if it is used in regularly-operating machinery. In such cases, reballing is the best option. By replacing the solder balls with new ones, the board can withstand higher temperatures, which improves board longevity.

Methods For Detecting PCB Failures

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Methods For Detecting PCB Failures

There are several ways to detect PCB failures. Among these methods are X-rays, Slice analysis, and Optical microscopy. Each of these methods is useful for identifying and assessing the extent of PCB damage. However, not all of these methods are suitable for every PCB failure. For example, electrostatic discharge damage is difficult to detect. It affects components by softening the solder and causing multiple shorts. In order to avoid this problem, the manufacturing process must be monitored minutely.

Rentgenové snímky

PCB X-rays are a useful tool for detecting PCB failures. These images can reveal problems such as voids and solder traces. These problems can occur due to escaping gases or overheating of solder.

Slice analysis

Slice analysis is a method used to analyze the microstructure of PCBs. It can help detect a wide variety of PCB failures. Slice analysis involves cutting the PCB into vertical and horizontal sections and examining their cross-sectional characteristics. It can identify many different PCB failures, such as delamination, bursting, and poor wetting. This information can be useful for quality control in the future.

Optical microscopy

Optical microscopy can be an effective method for detecting PCB failures. It provides detailed images of the failure sites, and it can be used to detect nonconformities and identify contamination sources. The method is also useful in documenting samples as they are received.

ALT

The ALT method for PCB failure detection is a more direct approach to measuring solder joints and solder paste deposition. This technology uses a laser beam to scan a PCB assembly and measure reflectivity of various components. The measured value is then compared to a board’s standard specifications to determine if there are any faults.

Micro-infrared analysis

PCB failures are typically caused by defects on the solder joints. By determining the cause of the defect, manufacturers can take necessary steps to prevent recurrence. These measures may include eliminating solder paste contamination, making sure that the PCB has the correct aspect ratio, and minimizing PCB reflow time. There are a variety of methods used to analyze PCB failures, ranging from simple electrical measurements to analyzing sample cross-sections under a microscope.

ALT measures solder joint deposition

ALT (Aligned Light Transmitter) is a newer technology for measuring the height and shape of solder joints and solder paste deposition on PCBs. This technology is more precise and allows for a fast measurement. The ALT system uses multiple light sources, such as cameras or programmable LEDs, to illuminate the solder joint components. The amount of light reflected from each component is measured using the power of the beam. However, secondary reflection can cause an error in measurement, since the beam may reflect from more than one position.

Elektrostatický výboj

The Electrostatic Discharge (ESD) method is used to detect PCB failures. An ESD is the result of extreme electrical stress, which can cause catastrophic failure and hidden damage. It can occur for a variety of reasons, including high current density, an increased electric field gradient, and localized heat formation. The resulting damage is hard to detect and can cause major product failures. PCB assemblies are most susceptible to ESD when they are in contact with other charge-carrying objects.