I have seen this too often when US web sites do not allow people from EU to view their sites.

One alternative is hot plate. Place all the surface mount components and placed the Board on the Hot Plate. Turn On the hot plate and wait until the Solder paste melts and take out the board immediately after melt-down of solder paste. The Solder paste melts somewhere around 180 degree Celsius to 220 degree Celsius. Because it can take up to around three minutes to complete the soldering and there is no temperature, control this can be problematic to some components. Hare is a video of hotplate soldering:

The best way to solder surface mount devices (SMDs) onto printed circuit boards (PCBs) is with a reflow oven, but when that’s not possible, a hot-air station can be successfully used. Hot Air Re-flow Soldering Station is a reliable tool and is not very expensive compared to Re-flow ovens. After thoroughly cleaning the bare PCB with alcohol, the next step is solder application. For the hobbyist, there are two primary methods of applying solder paste to a PCB for surface mount devices: by hand with a syringe or a very small spatula (think wooden toothpick) and by hand with a stencil. After placing the components on the Circuit Board, set the rework station to required temperature and Air Speed. Bring the Nozzle of Blower close to the Circuit board and wait until the Solder paste melts and fuses with the IC Pins.

The challenge is that there are more variables in play when using a hot-air station. In addition to time and temperature, a handheld hot-air gun involves several other factors, including the size of the nozzle, how far the nozzle is held from the solder, the angle of the airflow from the nozzle to the solder, the speed of the air coming from the nozzle, the speed at which the nozzle is moved around over the areas to be soldered. Ideally, the hot-air gun should be held so that the nozzle opening is perpendicular to the surface of the PCB and approximately 12mm (0.5″) above it. Care should be taken to aim the nozzle toward the pins/pads being soldered while avoiding the bodies of the components as much as possible. With a little practice, hot-air soldering is not particularly difficult, but each person must find the balance of temperature, air flow, nozzle size, and gun movement that works for them. As a result of all these variables, hot-air soldering becomes very personalized—each person develops their own “style” of working. Here are some videos:

SMD soldering by hot air

SMD soldering by hot air (solder paste)

SMD Soldering – Manual Pick And Place – PCB Microscope

Then there is the selection of soldering paste. Solder paste is available in a variety of mixtures of metal. The easiest to use is approximately 60% tin and 40% lead. Alloys commonly used for electrical soldering are 60/40 Sn-Pb, which melts at 188 °C (370 °F), and 63/37 Sn-Pb used principally in electrical/electronic work. This mixture is a eutectic alloy of these metals, which: has the lowest melting point (183 °C or 361 °F) of all the tin-lead alloys. The typical peak re-flow temperatures used for lead solders are in 210 – 220 °C range.

As electronics industry is trying to get rid of lead and moving to lead free solders in may countries. There are many lead-free soldering pastes, but the downside of many of them is that lead-free solder alloys have high melting points as compared to leaded solder and usually somewhat harder to work with. The process temperatures required to solder with tin-based lead-free alloys are challenging for some assemblies. Certain assemblies cannot handle the temperatures used for lead-free soldering which typically reaches 240 – 250 °C. Sensitive components might be damaged by these high temperatures.

For this reasons there are nowadays also special low temperature lead-free solders. Indium and bismuth can be used to lower the melting points of tin-based solders. For example tin/indium 52% and tin/bismuth 58% are lead free solders that have substantially lower melting points than tin / lead 37% solder. The re-flow process temperature for tin / bismuth alloys are low (160 – 170 °C). These low peak temperatures allow for soldering of thermally sensitive assemblies. The temperatures are still high enough, that those solders do not start to melt on most normal electronics applications.

Tin / bismuth solder pastes are readily available from many sources. Generally they are good to use in many applications, but there are few thing to note when working with tin/bismuth alloys. The advantages seem obvious, but somehow the marketing literature does not mention any drawbacks to this type of solder paste. The 42/58 Tin / Bismuth is not unknown as a low temperature solder but has issues. It has reasonable shear strength and fatigue properties, but can be very brittle. Alloys with more than 47% Bi expand upon cooling, which may be used to offset thermal expansion mismatch stresses. The most important thing to note is that combination with lead-tin solder may dramatically lower melting point and lead to joint failure. It is dangerous to mix tin / bismuth with lead containing alloys, because tin, bismuth, and lead can form a very low melting combination that melts around 95 °C. This could potentially lead to solder joint failure due to natural heating of the assembly during use. The good thing is that tin / bismuth alloys are safe to use in combination with other lead free tin-based alloys.

For testing with soldering using low temperature solder flux, I ordered BEST BST-706 10cc 138℃ Syringe DIY Solder Soldering Paste Flux Chips Computer Phone BGA SMD PGA PCB Repair Tool product from Banggood(5.27 Euros). The idea is that with lower process temperature solder I can more easily do DIY SMD soldering without damaging the components.

The product page has this data on this product:

Component Sn42/Bi588

Available in syringes

Here is my picture of the product:

This eutectic Sn42 Bi58 solder alloy with a low melting point has been developed for low temperature soldering. With a melting point of 138°C and a peak reflow temperature of approximately 173°C the 670 tin bismuth paste is suitable for soldering of temperature sensitive surface mount components.

The markings on the syringe seems to be somewhat different story than the product page. But it seems that what is said on product page are truthful on the melting temperature. I used an adjustable traditional soldering iron to test the melting temperature, and it was low (melted well at slightly over 150 degrees on test).

To test how well it works in practice I manually put some soldering paste to the SMD soldering practice board and added component:

Then I used my soldering heat gun to solder. I used heat temperature of 240-260 degrees Celsius at almost maximum air flow.

With those settings at the way I hold the hot air source it took around 20-30 seconds to melt the tin paste to turn from grey to bright tin color. When I removed the hot air and let it cool, a quite nice soldering joint was made.

This soldering paste seems to work OK as promised.

If you are interested on the product, go to BEST BST-706 10cc 138℃ Syringe DIY Solder Soldering Paste Flux Chips Computer Phone BGA SMD PGA PCB Repair Tool product page or try some other similar product.

This article presents one practical alternative to PCB for high-frequency circuits.

The general approach is to start with a standard raw board with its copper layer untouched. Instead of using etched traces, you interconnect components with lead wires while leaving a large ground. You can easily check if your high-frequency circuit is working as designed.

Everything was packages to this small plastic bag.

After installing eight screws and protective films from the plastic parts, everything was ready. I must admit that it takes some time and work to do this all. If I were mass producing something with this, I would look for some quicker to build case… Anyway after the work everything worked well even though my Arduino was not exact match (case was designed for Arduino UNO R3, but I got an older original Arduino UNO R2). I added some “rubber feet” myself to the case (not included in the packet) so that the bottom of case becomes less prone to cause scratches to the table the case it on.

Also shield fits. In this case the shield is left around 1.5 mm higher than t would be without the case because solder joints on the bottom of the shield hitting the plastic case first.

Need for a custom camera module. Check out this intetesting looking project.

uCameraCube is a parametric camera module build using OpenSCAD uCube library. It is build with Raspberry Pi and Raspberry Pi camera and comes in three versions, which vary in the type of optics used.

Thin Lens version
M12 Lens version
T-Mount version

As the name implies, the purpose of a proof-of-concept (POC) prototype is to prove your product concept. A POC answers if a product is feasible.

In most cases a POC prototype is only used internally to determine the practicality of a new product. Customers will rarely see a POC prototype.

So do you need a POC prototype for your product? The simple answer is it depends, since there are multiple reasons to create a proof-of-concept prototype.

If you a maker with experience creating DIY projects using development kits such as an Arduino or Raspberry Pi, you are usually in a good place to create a POC prototype for your product.

Excellway CH2 Quick Wire Connector Terminal Block Spring Connector LED Strip Light Wire Connector

Screwless wire spring clamp terminal block connectors.

Excellway – Quick Wire Connector – Banggood SKU290726

The Specifications looked OK:
Brand: Excellway
Model: CH2
Voltage: <250V
Electricity:<10A
Size: 20.16*17.06*12.23mm/ 0.79′*0.71*0.3 inch (L*W*T)
Insulation material: PE (fire-retardant insulation)
Wire range: -3.5 ~ 0.5mm2
Temperature: -40℃ ~ 150℃
Line pressing  frame material: Rolled steel

Apply for: motor, electrical control, power, household appliances, lighting, machinery and wire joints

I received the connector and everything looked good:

I tested the connector with several different wires, and I can agree that they seem to work pretty well and are easy to use.

But there were few details that make me wonder if they really match the specifications they have. One thing was that the construction was such that there was just a small metal spring and plastic case. It seems that this might not hold the high currents on real life situations, because cable connectors that really handle 10A usually have much more metal in them to carry currents and hold wires.

So I decided to test the connector if they really could keep the promises on specifications. I first decided to test the current handling of connector. So if they say less than 10A current recommended, the I expect connector should be able to handle 10A at least for short times with some heating. So I wired 10A AC current source (connected wires 1.5mm2 solid copper wires) to the connector. The end result was that the connector melted at 10A current in around one minute when I was trying to measure with IR thermometer how hot it gets.

View to bottom: He spring melted through.

Other thing that I noticed… On one side the metal part was pretty well isolated, but on the other side they are visible that can be touched with finger without too much trying. As such those do not feel very safe to be used on mains voltage installations.

Maybe the real current rating is much less than 10A.  Also tested at 5A current. The result was that in few minutes the connector heated up very much. My IR thermometer showed 68 degrees Celsius.

The product page mentioned for less than maximum 1500W load I tried that 1500W load (1500W/230V = 6.5A). At that current the connector melted in few minutes. Sorry Banggood but pressing the cable against end of steel spring and plastics can’t end with a low contact resistance! The resistance causes heating that starts melting plastic, that again increases resistance as contact force is reduced.

The product page said temperature range -40℃ ~ 150℃. I tested the high temperature with temperature controlled soldering iron set to 15o℃ (temperature verified with soldering iron thermometer).  Soldering iron at 150℃ melted the plastic quite easily. According to Wikipedia polyethylene melting point is typically in the range 120 to 180 °C.

Verdict:

According to my tests those connectors do not seem to be suitable or safe for high currents and mains voltage. They are potential fire danger because they are expected to melt before the mains panel fuse blows in on overload or short circuit situation.

For low voltage low current bench testing those could be useful. Currents up to 3A did not seem to cause too much heating, but there was already around 200 mV voltage loss over connector.

The low voltage low currents is no problem, but please don’t use them with high current and mains voltages.

This is a learning that don’t always trust the given specifications or CE mark stamped to product.

In is the circuit in use. Much more convient than loose parts on table.

“Dead bug style” circuit wiring is the cute name for soldering together components without a printed circuit board. The “dead bug” is the integrated circuit flipped upside down with its “legs” sticking up. The chips can be glued to almost any surface, but most often the surface material is circuit board with copper (the copper is usually used as ground plane in circuit). Dead-bug construction is very straightforward and requires no special tools.

Dead bug construction is one form of Free-form construction suitable for a small number of components.In “dead bug” style the ICs flipped upside-down with their pins sticking up into the air like a dead insect. This form of construction is used by amateurs for one-off circuits for circuits with few components. Dead-bug construction generally becomes impractical once the IC pin count exceeds 20 pins or if there are more than two or three ICs.

This construction is often used for RF circuits where component leads must be kept short. For high-frequency work a grounded solderable metallic base such as the copper side of an unetched printed circuit board can be used as base and ground plane.To make the connections, components are mostly soldered directly together, lead to lead. The dead-bug style helps to eliminate capacitive coupling between traces by building the traces in the air to maximize the distance and minimize the parallel runs that various leads travel with one another.

Linear Technology application note 47 gives introduction to this construction method for quite high frequency. Dead Bug Prototyping for Effects shows how to build audio circuits. The following video shows how to do dead bug with SMD components:

Originally it was literally a bread board, a polished piece of wood used for slicing bread: when electronics were big and bulky, people would grab their mom’s breadboard, a few nails or thumbtacks, and start connecting wires onto the board.

In the 1970s the solderless breadboard (AKA plugboard, a terminal array board) became available and nowadays the term “breadboard” is commonly used to refer to these. Because the solderless breadboard does not require soldering, you don’t need soldering iron to build circuits and all parts including the board are reusable. This makes it easy to use for creating temporary prototypes and experimenting with circuit design.

A modern solderless breadboard socket consists of a perforated block of plastic with numerous tin plated phosphor bronze or nickel silver alloy spring clips under the perforations. The clips are often called tie points or contact points. The spacing between the clips (lead pitch) is typically 0.1 in (2.54 mm). Integrated circuits (ICs) in dual in-line packages (DIPs) can be inserted to straddle the centerline of the block. Interconnecting wires and the leads of discrete components (such as capacitors, resistors, and inductors) can be inserted into the remaining free holes to complete the circuit.

Solderless breadboards are available from several different manufacturers. Jump wires (also called jumper wires) for solderless breadboarding can be obtained in ready-to-use jump wire sets or you can use any suitable solid conductor wire as jumper wire.

How to Use a Breadboard

Prototyping is the process of testing out an idea by creating a preliminary model from which other forms are developed or copied, and it is one of the most common uses for breadboards. If you aren’t sure how a circuit will react under a given set of parameters, it’s best to build a prototype and test it out. The real beauty of breadboards is that they can house both the simplest circuit as well as very complex circuits.

Terminal strips metal rows have little clips that hide under the plastic holes. These clips allow you to stick a wire or the leg of a component into the exposed holes on a breadboard, which then hold it in place and make electrical contact. Once inserted that component will be electrically connected to anything else placed in that row. There is a ravine that isolates the two sides of a breadboard. This ravine serves a very important purpose allowing to connect ICs in DIP package to board – we can connect components to each side of the IC without interfering with the functionality of the leg on the opposite side.

You make the connections between metal rows with wired components and jumper wires. Typical board boards use 22AWG wire as jumpers. You can use solid 22 AWG wire pieces dirctly. Or you can buy ready made jumper wire set with connectors that plug nicely to board on their ends.

Links to some tutorials:

How to Use a Breadboard at Sparkfun

How to Use a Breadboard at Instructables

There are numerous options for powering breadboards. Some breadboards have binding posts that allow you to connect external power sources. The first step to using the binding posts is to connect them to the breadboard using some jumper wires. There are also special power supplies that plug to breadboard, like 3.3V / 5V Power Module for Breadboard I tested some years ago.

When IS it ok to use a breadboard? I’d say if the following cases are true it’s probably ok to use a breadboard.

1. Rapid prototyping (not built to last)
2. Few connections external to the breadboard
3. Mostly thru-hole components
4. Low voltage <= 12VDC
5. Low frequency <= 10Mhz

Don’t try running lots of jumper wires from the breadboard to other devices or you will spend lots of time checking for broken connections.

Examples of interesting projects built to breadboard:

http://hackaday.com/2013/06/21/building-a-synth-on-a-breadboard/

http://hackaday.com/2013/09/26/breadboard-sequencer-does-a-lot-with-very-little-hardware/

http://hackaday.com/2013/09/28/breadboard-tetris-is-wire-artwork/

http://hackaday.com/2014/11/08/breadboarding-a-68000-computer-in-under-a-week/

http://hackaday.com/2016/03/07/breadboard-colecovision/

http://hackaday.com/2017/04/10/8-bit-breadboard-computer-is-up-to-8-hours/

Accessories and tips:

8 Breadboard Hacks

http://hackaday.com/2015/08/14/panel-mounted-breadboard-accessories/

http://hackaday.com/2011/09/27/diy-breadboard-modules-for-easy-prototyping/

http://embedded-lab.com/blog/diy-plug-in-modules-to-make-microcontroller-breadboarding-easier/

Electromechanical limitations

Breadboards cannot accommodate components with multiple rows of connectors if these connectors do not match the dual in-line layout—it is impossible to provide the correct electrical connectivity. Sometimes small PCB adapters called “breakout adapters” can be used to fit the component to the board.

http://hackaday.com/2012/11/13/make-dual-pin-header-footprints-into-breadboard-friendly-dip/

http://hackaday.com/2015/08/18/literal-breadboard-hack-forces-it-to-accept-dual-pin-headers/

Solderless breadboards usually cannot accommodate surface-mount technology devices (SMD) or components with grid spacing other than 0.1 in (2.54 mm). You typically need some adapter to connect SMD components to breadboard. Many SMD -> thru-hole adaptor boards are available online that will allow you to use SMD parts with a breadboard. SMD is easily handled with breakouts – SM discretes can be easily soldered to 0.1″ pin headers. The following web pages give tips for making and using such adapters:

http://hackaday.com/2014/07/25/using-surface-mount-devices-on-a-breadboard/

http://hackaday.com/2016/02/04/a-better-way-to-plug-a-cpld-into-a-breadboard/

http://hackaday.com/2016/04/20/make-your-own-esp8266-breadboard-adapter/

Electrical limitations

There are some limitations on breadboard performance for protyping that should be taken into account. Typically the spring clips are rated for 1 ampere at 5 volts and 0.333 amperes at 15 volts (5 watts). There are board with higher ratings, like for example 36V @ 2 Amps – if you plan to go to this powe range make sure that the board can handle it. General advice (unless you know for sure that it is OK) is never go above 1A since there is no restore button after you melted it. Breadboards are certainly not suited for mains voltage.

One thing that can also cause problems with these is the quality of the contacts. Some of those breadboards have quite weak mating points, so there are a lot of resistance variance. The relatively high and somewhat variable contact resistance can already be a problem for some circuits.

There is also a relatively large parasitic capacitance compared to a properly laid out PCB (approx 2pF between adjacent contact columns), high inductance of some connections and a relatively high and not very reproducible contact resistance. Because of those limitations solderless breadboards are limited to operation at relatively low frequencies, usually less than 10 MHz, depending on the nature of the circuit. Hackaday has article on Solderless Breadboard Parasitics. Heree are two videos on breadboard parasitic capacitance. First video shows capacitance measurements:

Second video tells about parasitics and shows what’s inside breadboard:

The inductance of the traces/wires also cannot be ignored especially for higher frequencies. This is another reason why breadboards are usually only suited for simple circuits well under 1Mhz, with higher frequencies may be possible if very carefully used). It’s one of those “it depends” things. For say TTL level digital stuff you can probably get away with running 10MHz on a breadboard if done carefully. On sensitive circuits even 100KHz is going to cause trouble due to the loop inductances, capacitance, and general dickiness. 2.5pF at 1MHz is about 63k ohms. If you have a circuit where stray 63k impedances are a problem then 1MHz is too high. A lot of digital circuits wouldn’t care about a stray 1k. Advice from eevblog discussion board: “In my experience, anything TTL that is readily available in DIL packages (say 74F/HCT/HC) is slow enough so stray capacitance of breadboard does not make much of a difference, you get effects of insufficient decoupling (which is not exactly trivial on breadboard) or even problems with correct probing much sooner than anything related to stray capacitance.”

Keep in mind that there is some capacitance between a contact and the ground plane formed by the metal plate that the board and binding posts are mounted on. Breadboard mounted on a metal plate can have ~2.5pF between contacts at 100kHz. If you are looking for a worst case scenario and add everything up: signal and ground on both sides (2*2pF) + power rail (1pF) + across center gap (1pF).

When to avoid using a breadboard

What are the cases where one should avoid using a breadboard? e.g. high frequency, noise prone circuits etc.

One thing you really shouldn’t try to use them for is any sort of switching regulator.

Particularly I’m almost not using more breadboard. It’s rare. – Daniel Grillo

Be warned that with any complicated circuit on breadboard you will end up spending lotsof the time troubleshooting the breadboard. The probability of dodgy connections means that larger designs are more prone to problems and should probably be avoided.

If you are building something that has may components, consider if it would make sense to hardwire the circuitry. It does not take too much longer with right tools. You can something like Veroboard or make PCB at home if I need a prototype quickly.