Hand Soldering Electronics

Electronics

Published

April 1, 2023

Modified

April 6, 2023

Why Learn Hand Soldering?

Hand soldering skills required for many DIY (do-it-yourself) projects with electronics, for example…

…building quad copters and other RC (remote control) airplanes, cars or boats
…home-automation and IoT (internet of things)
…custom PC builds including peripheral devices (like keyboards)
…assembly of home-scale maker devices (for example 3D printers)

Hand soldering uses a solder iron and solder wire to connect component leads one-by-one.

Electronics projects often involve to…

…solder components onto a PCB (printed circuit board)
…solder connection wires to sensors or motors
…desolder to repair/replace components, connectors or even small microcontrollers (MCUs)

How Does it work? …solder creates a permanent bond between metal work peaces…

…solder melted to each part of a joint (usually between a component and a PCB)
…after cooling the joint forms an electrical connection
…soldering creates a metallurgical bond …it chemically reacts with the metal surfaces at the joints
…solder typical melts above 180°C, however solder irons operate above 300°C to sustains enough heat

Basic tools to solder electronic components. On the bottom you can see a solder pen powered via USB, a desolding pump and a flux pen. The top row from left to right shows a small portable iron stand, a brass sponge, solder wire and solder wick.

Solder Irons

For soldering electronics is is recommended to use a temperature regulated solder iron…

…electronics control how fast it heats up …and how accurate operation temperature maintained during use
…20 to 50 watts power rating (more is not necessarily better)
- …higher-wattage soldering irons can maintain a stable temperature longer
- …some pen style irons have a battery and/or USB-C support for portability
…replaceable tip …different shapes (depending on the project)
- …conical tip …very fine …precision electronics soldering
- …chisel tip …soldering wires or other larger components
…soldering iron stand (usually included with soldering stations)
- …prevents contact of the solder iron with flammable materials or accidental injury to your hand
- …brass sponge to keep the soldering iron tip clean

Some prominent options for solder irons typically recommended…

…solder pens – Pinecil – Miniware TS
…solder stations – Toolcraft ST-80D – Hakko FX-888D – Weller WE1010

How Do I Solder?

The process is rather simple, but requires practice…

Turn the solder iron on (a temperature of 330℃ recommended for beginners)
Hold the iron tip to the contact point for a few seconds
Touch the solder wire to the contact point until it flows to the surface.
Remove the solder iron when the contact area is completely covered

Not that applying to much heat can damage a component or a PCB surface contact plate.

Soldering requires a little bit of experience, therefore it is recommended to work on some practice kits beforehand. This is particular advisable for SMD (surface mounted device) components. The picture shows a selection of SMD components in different sizes together with precision tweezers and the tip of a solder iron. This work greatly benefits from magnification glasses or a microscope.

Tinning The Tip

…improves the heat transfer from the solder iron to the components

Prepare your soldering iron by tinning the tip with solder:

Clean the tip of the solder iron with the brass sponge
Touch the solder to the tip of the iron and make sure the solder flows evenly around the tip

Desoldering

Remove components or make a correction to an electronic circuit…

Desolder a joint with solder wick (desoldering braid) [Entlötlitze]…

Cut a small piece of braid and use a pincer to hold it (less heat-resistance)
Place a piece of the desoldering braid on top of the joint
Touch the tip to the top of the braid …wait until the braid absorbs the solder

Solder sucker [Entlötsaugpumpe] …handheld mechanical vacuum that sucks up hot solder with a press of a button

Press the plunger down at the end of the solder sucker
Heat the joint …place the tip of the solder sucker over the hot solder
Release button to suck up the liquid solder

Solder Wire

EU regulation requires lead-free solders…

…container mostly tin and copper (traces of other metals)
…melting point about 30°C then normal solder …more activated (corrosive)

A 0.5mm diameter is recommend as solder wire for electronics components…

…most suitable for electronics soldering …in particular SMD components
…does include a very small amount of flux …recommend to use additional flux on the PCB

Recommended solder wire available in Germany… Lötzinn Felder ISO-Core “clear” 0.5mm (100g)

Why Use Flux?

Flux reduces metal oxides at the point of contact…

…helps soldering and desoldering components…
…improves electrical connection and mechanical strength
…prevent toxic fumes from forming while soldering
…chemically cleans metal surfaces
…assist with the heat transfer …helps with flow-ability of the materials
…protective barrier between the metal and the soldering heat

Types of flux…

Rosin flux (r-type) used for electronics
- …can leave behind chloride ions and other corrosive residues
- …requires to remove leftovers of rosin flux agents from a PCB
- …to prevent long term corrosion related failures
- …typically done by means of 99% alcohol …or special PCB cleaner solution
No-clean flux
- …leave less residue behind than the conventional R type flux
- …remains after soldering are non-corrosive and non-conductive
- …however residues left may be sticky and attract dust
Water soluble flux …cleaned with deionized water and detergents

Multiple solutions to apply flux …flux found in paste form and semi-liquid gel

…flux paste …use a paintbrush or cotton swab to apply
…flux pen …very little excess and targeted application potential
…flux paste with a syringe dispenser

Recommend flux pen available in Germany… Stannol Flussmittelstift FLUX X32-10i

Additional Tools

Depending on the amount of soldering work, the type of components used and the requirements on quality…

Accessible tools from the price point of view..

Workmat usually from silicon with a heat resistance up to 500℃ …some include small compartments for components and screws
Helping hands (or third hands) us adjustable clamps and a stable base to hold components and PCBs
Precision Tweezers for small components (especially SMD)

Next Level

On the more expensive side …highly depending on the use-case:

Hot Air Rework Station aka heat guns…
- …improves the capabilities to rework small SMT components on PCBs
- …this includs small packaged ICs (integrated circuits)
Desoldering guns improve control during disassembly of components from PCBs…
- …combines a heating tip with a vacuum pump to remove solder from a joint
- …relatively expensive and usually not a useful investment for hobbyists
Hot Plate for hot plate soldering of SMD components
- …solder paste used to place all SMD components on the PCB
- …hot plates heats the PCB from the bottom to melt the solder paste
- …this is a cheaper solution compared to a reflow oven

Small-scale Manufacturing

PCBA (printed circuit board assembly) at small to mid-scale manufacturing with PNP (pick and place) machines…

…used to place surface-mount devices (SMDs) onto a printed circuit board (PCB)
…remove manual labor …improve speed and placing of a broad range of electronic components
Components…
- …components temporarily adhered to the PCB using a wet solder paste
  - …solder paste dispensed on the PCB with an SMD stencils…
  - …an SMD stencil is a laser cut stainless steel sheet masking the PCB only exposing parts requiring solder paste
- …vacuum-based parts picker (pneumatic suction cups)…
  - …attached to a plotter-like device with a visual system for aligning…
  - …to pick up and correctly place the components onto the PCB
- …component feeds aka feeders to supply components from tape reels
- …after component placement is finished the PCB is heated in a reflow oven
  - …temperature follows a heating and cooling profiles according to solder material and component datasheet

Related open software and hardware – OpenPNP – Opulo (@stephen_hawes)

--- title: Hand Soldering Electronics categories: - Electronics date: 2023/04/01 date-modified: 2023/04/06 --- # Why Learn Hand Soldering? Hand soldering skills required for many DIY (do-it-yourself) projects with electronics, for example... - ...building quad copters and other RC (remote control) airplanes, cars or boats - ...home-automation and IoT (internet of things) - ...custom PC builds including peripheral devices (like keyboards) - ...assembly of home-scale maker devices (for example 3D printers) Hand soldering uses a **solder iron** and **solder wire** to connect component leads one-by-one. Electronics projects often involve to... - ...**solder components onto a PCB** (printed circuit board) - ...**solder connection wires to sensors or motors** - ...**desolder to repair/replace components**, connectors or even small microcontrollers (MCUs) How Does it work? ...solder creates a permanent bond between metal work peaces... - ...solder melted to each part of a joint (usually between a component and a PCB) - ...after cooling the joint forms an electrical connection - ...soldering creates a metallurgical bond ...it chemically reacts with the metal surfaces at the joints - ...solder typical melts above 180°C, however solder irons operate above 300°C to sustains enough heat ![Basic tools to solder electronic components. On the bottom you can see a solder pen powered via USB, a desolding pump and a flux pen. The top row from left to right shows a small portable iron stand, a brass sponge, solder wire and solder wick.](images/solder-tools.jpg) ## Solder Irons For soldering electronics is is recommended to use a **temperature regulated** solder iron... - ...electronics control how fast it heats up ...and how accurate operation temperature maintained during use - ...**20 to 50 watts** power rating (more is not necessarily better) - ...higher-wattage soldering irons can maintain a stable temperature longer - ...some pen style irons have a **battery and/or USB-C support for portability** - ...**replaceable tip** ...different shapes (depending on the project) - ...conical tip ...very fine ...precision electronics soldering - ...chisel tip ...soldering wires or other larger components - ...**soldering iron stand** (usually included with soldering stations) - ...prevents contact of the solder iron with flammable materials or accidental injury to your hand - ...**brass sponge** to keep the soldering iron tip clean Some prominent options for solder irons typically recommended... - ...solder pens -- [Pinecil](https://www.pine64.org/pinecil) -- [Miniware TS](https://www.miniware.com.cn/product-category/soldering-pen) - ...solder stations -- [Toolcraft ST-80D](https://www.conrad.de/de/p/toolcraft-st-80d-loetstation-digital-80-w-150-450-c-inkl-loetspitze-1561695.html) -- [Hakko FX-888D](https://hakkousa.com/fx-888d) -- [Weller WE1010](https://www.weller-tools.com/we1010na) ### How Do I Solder? The process is rather simple, but requires practice... 1. Turn the solder iron on (a temperature of 330℃ recommended for beginners) 2. Hold the iron tip to the contact point for a few seconds 3. Touch the solder wire to the contact point until it flows to the surface. 4. Remove the solder iron when the contact area is completely covered Not that applying to much heat can damage a component or a PCB surface contact plate. ![Soldering requires a little bit of experience, therefore it is recommended to work on some practice kits beforehand. This is particular advisable for SMD (surface mounted device) components. The picture shows a selection of SMD components in different sizes together with precision tweezers and the tip of a solder iron. This work greatly benefits from magnification glasses or a microscope.](images/solder-pratice.jpg) ### Tinning The Tip ...improves the heat transfer from the solder iron to the components Prepare your soldering iron by tinning the tip with solder: 1. Clean the tip of the solder iron with the brass sponge 2. Touch the solder to the tip of the iron and make sure the solder flows evenly around the tip ### Desoldering Remove components or make a correction to an electronic circuit... Desolder a joint with **solder wick** (desoldering braid) [Entlötlitze]... 0. Cut a small piece of braid and use a pincer to hold it (less heat-resistance) 1. Place a piece of the desoldering braid on top of the joint 2. Touch the tip to the top of the braid ...wait until the braid absorbs the solder **Solder sucker** [Entlötsaugpumpe] ...handheld mechanical vacuum that sucks up hot solder with a press of a button 1. Press the plunger down at the end of the solder sucker 2. Heat the joint ...place the tip of the solder sucker over the hot solder 3. Release button to suck up the liquid solder ## Solder Wire EU regulation requires **lead-free solders**... - ...container mostly tin and copper (traces of other metals) - ...melting point about 30°C then normal solder ...more activated (corrosive) A **0.5mm diameter** is recommend as solder wire for electronics components... - ...most suitable for electronics soldering ...in particular SMD components - ...does include a very small amount of flux ...recommend to use additional flux on the PCB Recommended solder wire available in Germany... Lötzinn Felder ISO-Core "clear" 0.5mm (100g) ## Why Use Flux? Flux reduces metal oxides at the point of contact... - ...helps soldering and desoldering components... - ...improves electrical connection and mechanical strength - ...prevent toxic fumes from forming while soldering - ...chemically cleans metal surfaces - ...assist with the heat transfer ...helps with flow-ability of the materials - ...protective barrier between the metal and the soldering heat Types of flux... - Rosin flux (r-type) used for electronics - ...can leave behind chloride ions and other corrosive residues - ...requires to remove leftovers of rosin flux agents from a PCB - ...to prevent long term corrosion related failures - ...typically done by means of 99% alcohol ...or special PCB cleaner solution - **No-clean flux** - ...leave less residue behind than the conventional R type flux - ...remains after soldering are non-corrosive and non-conductive - ...however residues left may be sticky and attract dust - Water soluble flux ...cleaned with deionized water and detergents Multiple solutions to apply flux ...flux found in paste form and semi-liquid gel - ...flux paste ...use a paintbrush or cotton swab to apply - ...**flux pen** ...very little excess and targeted application potential - ...flux paste with a syringe dispenser Recommend flux pen available in Germany... Stannol Flussmittelstift FLUX X32-10i # Additional Tools Depending on the amount of soldering work, the type of components used and the requirements on quality... Accessible tools from the price point of view.. - **Workmat** usually from silicon with a heat resistance up to 500℃ ...some include small compartments for components and screws - **Helping hands** (or third hands) us adjustable clamps and a stable base to hold components and PCBs - **Precision Tweezers** for small components (especially SMD) ## Next Level On the more expensive side ...highly depending on the use-case: - **Hot Air Rework Station** aka heat guns... - ...improves the capabilities to rework small SMT components on PCBs - ...this includs small packaged ICs (integrated circuits) - **Desoldering guns** improve control during disassembly of components from PCBs... - ...combines a heating tip with a vacuum pump to remove solder from a joint - ...relatively expensive and usually not a useful investment for hobbyists - **Hot Plate** for hot plate soldering of SMD components - ...solder paste used to place all SMD components on the PCB - ...hot plates heats the PCB from the bottom to melt the solder paste - ...this is a cheaper solution compared to a reflow oven ## Small-scale Manufacturing PCBA (printed circuit board assembly) at small to mid-scale manufacturing with PNP (pick and place) machines... - ...used to place surface-mount devices (SMDs) onto a printed circuit board (PCB) - ...remove manual labor ...improve speed and placing of a broad range of electronic components - Components... - ...components temporarily adhered to the PCB using a wet **solder paste** - ...solder paste dispensed on the PCB with an **SMD stencils**... - ...an SMD stencil is a laser cut stainless steel sheet masking the PCB only exposing parts requiring solder paste - ...vacuum-based **parts picker** (pneumatic suction cups)... - ...attached to a plotter-like device with a visual system for aligning... - ...to pick up and correctly place the components onto the PCB - ...component feeds aka **feeders** to supply components from **tape reels** - ...after component placement is finished the PCB is heated in a **reflow oven** - ...temperature follows a heating and cooling profiles according to solder material and component datasheet Related open software and hardware -- [OpenPNP](https://openpnp.org) -- [Opulo](https://opulo.io) ([\@stephen_hawes](https://www.youtube.com/@stephen_hawes))