View source for Workers' Guide to Health and Safety:Assembling the printed circuit boards

{{bctrail|segments=3|chaptitle=Chapter 4: Electronics factories}}
{{DISPLAYTITLE:Assembling the printed circuit boards}}
{{SideSupplement|bookabbreviation=wgthas|pagealt=is from pages 80 to 82 of|bookurl=Workers' Guide to Health and Safety|chapterpdf=http://hesperian.org/wp-content/uploads/pdf/en_wgthas_2015/en_wgthas_2015_04.pdf|booktitle=Workers' Guide to Health and Safety}}
{{chaptertoc|In this chapter:|
<ul>
<li>[[Workers' Guide to Health and Safety:Chapter 4: Electronics factories|Chapter 4: Electronics factories]]
  </li>
    <li>[[Workers' Guide to Health and Safety:Making and cleaning the wafer|Making and cleaning the wafer]]</li>
    <li>[[Workers' Guide to Health and Safety:Making the chip on the wafer|Making the chip on the wafer]]</li>
    <li>[[Workers' Guide to Health and Safety:Making the individual chips|Making the individual chips]]</li>
    <li>[[Workers' Guide to Health and Safety:Making the printed circuit board|Making the printed circuit board]]</li>
    <li>[[Workers' Guide to Health and Safety:Assembling the printed circuit boards|Assembling the printed circuit boards]]</li>
    <li>[[Workers' Guide to Health and Safety:Assembling electronics|Assembling electronics]]</li>
    <li>[[Workers' Guide to Health and Safety:Making electronics safer|Making electronics safer]]</li>
  </ul>}}
The components are added to the PrCBs by hand or by machines. Both workers and machines use ﬂux to prepare the metal surfaces of the parts and the board to better accept the solder which makes the electrical connection between them. Flux is a mix of chemicals, including solvents and acids (see [[Workers'_Guide_to_Health_and_Safety:Fluxes|Fluxes]]).

====Soldering====

Soldering means melting a little bit of metal to make a bridge connecting 2 diﬀerent components. [[Workers'_Guide_to_Health_and_Safety:Metals#metals|Solder]] is usually tin, a mixture of tin and lead, or a lead-free mix of copper and other metals. Soldering can be done manually or by machines.

<table width=100% cellpadding=7>

<tr valign=top>
<td style="width:50%;padding-right:25px;">'''Hand soldering'''<br>Workers who solder by hand need mounted extractors on the soldering iron, strong local extractors, and respirators. If you notice [[Workers'_Guide_to_Health_and_Safety:Exposure_to_chemicals# Signs of exposure|signs that you are breathing in chemicals]], stop working and improve your ventilation or PPE.</td>
<td>'''Machine soldering'''<br>Wave soldering machines and other machines that solder should have strong local ventilation. PrCBs should rest in a well-ventilated area after they are soldered until they stop off-gassing.</td></tr>

<tr>
<td>[[Image:wgthas_Ch4_Page_80-1.png|240px|center|alt=2 workers soldering by hand; a small fan sits on a shelf behind them.]]</td>
<td valign=top style="padding-top:25px;">[[Image:wgthas_Ch4_Page_80-2.png|240px|center|alt=a worker using a soldering machine.]]</td></tr>

</table>

<div class{{=}}speechbub style="position:relative; width:600px; height:150px; ">[[Image:wgthas_Ch4_Page_80-3.png|270px|center|alt=a man speaking; he wears a uniform with a label that reads "Inspector."]]
<div style="position:absolute; top:14px; left:174px; width:155px;">These workers need extractors, respirators, or both. Why don’t they have them?</div></div>

====Soldering can hurt workers’ health====

Flux and solder contain chemicals which can irritate your skin or lungs, immediately or later. They also contain chemicals that can cause chronic health problems. Rosin in flux and lead in solder are 2 of the chemicals that we know cause health problems in the soldering area.

<div class{{=}}page-break></div>
Heating flux and solder releases fumes. Signs you are breathing the chemicals in flux and solder are:
*headaches
*nose bleeds
*problems breathing
*feeling tired and weak
*sore throat
*red and irritated eyes
*skin rashes
<br>
If you have any of these or other problems, tell your health and safety committee and boss. Talk to a health worker about where you work, what you do, and the chemicals you are exposed to. Smoking or just being around smoke will worsen these problems.

If your boss makes no changes to the workplace and you keep breathing the chemicals in flux and solder, you are likely to develop other health problems.

<table width=55% style="margin-left:25px;">
<td>[[Image:wgthas_Ch4_Page_81-1.png|70px|center|alt=a notebook and pencil.]]</td>
<td style="padding-left:20px;line-height:110%;">''Record all health problems and changes in solders and fluxes in your [[Workers'_Guide_to_Health_and_Safety:Keep_information_about_work_and_health#notebook|health notebook]].''</td>
</table>

====Protect workers from the dangers of soldering====

Soldering is safer when flux does not contain rosin and solder does not contain lead. We know these materials are too dangerous to use.

Soldering can be made safer when workstations have good local and general ventilation (see [[Workers'_Guide_to_Health_and_Safety:Chapter_17:_Ventilation|Chapter 17: Ventilation]]) and workers have the correct, well-fitting personal protective equipment for the chemicals they use (see [[Workers'_Guide_to_Health_and_Safety:Chapter_18:_Personal_protective_equipment_(PPE)|Chapter 18]]). When workers can tell the boss and the health and safety committee about safety issues, and get them resolved, everybody is safer.

Soldering can also be made safer by:
*turning the heat down on the soldering iron, so [[Workers'_Guide_to_Health_and_Safety:Protect_workers_from_chemicals#fumes|less fume is released into the air]].
*"following the air" (see the activity [[Workers'_Guide_to_Health_and_Safety:Local_ventilation#follow|Follow the air!]]) to check your local ventilation, and organizing to improve ventilation for everyone.
*finding out the dangers of the chemicals in your flux and solder. Look them up in the [[Workers'_Guide_to_Health_and_Safety:Fluxes|chemical charts]], get an [[Workers'_Guide_to_Health_and_Safety:Learn_about_chemicals_used_in_your_factory#sds|SDS]], try [[Workers'_Guide_to_Health_and_Safety:APPENDIX_B:_Common_chemicals_and_materials#info|other resources]], and organize to get safer flux and solder.

{{spannote|||
====Is lead-free solder really safer?====
After the [[Workers'_Guide_to_Health_and_Safety:Making_the_chip_on_the_wafer#ban|European Union banned the use of lead]] in solder and other materials used to make electronics for Europe, some companies resisted the change. They claimed lead could be used safely, that it was "necessary" for production, and that lead-free products were not as good and were more expensive.

But they lost the argument: any electronics company that wanted to sell to Europe after 2006 had to prove they were not using lead.

Alternatives to lead solder began to appear and chemical companies produced them quickly. One uses copper, tin, and nickel instead of lead.

But as with any new process, the new solders brought new problems: lead-free solder uses more [[Workers'_Guide_to_Health_and_Safety:Fluxes|flux]], which can contain harmful chemicals, is heated to higher temperatures, and may release more particles than lead-based solders. Few of these new solders and fluxes were studied to show if they were safer for workers than lead.

Making the production of electronics safer and more sustainable should mean that dangerous chemicals are replaced by chemicals proven to be safe – not just different and hoped to be safe.}}

===Testing the PrCBs===
[[Image:wgthas_Ch4_Page_82-1.png|220px|right|alt=A person is putting a printed circuit board inside a testing machine. ]]
Workers check the boards and their components visually and electronically before they are assembled or packaged for shipping. Lifting, checking, and removing the PrCBs can lead to muscle strain and overuse injuries. Often, to prevent static electricity from damaging the boards, workers are required to wear grounding wrist cords. The wrist cords contain nickel, a chemical that can irritate the skin.
*Adjust carts, work tables, and chairs to limit the amount of lifting and twisting you must do. (See [[Workers%27_Guide_to_Health_and_Safety:Chapter_7:_Ergonomics|Chapter 7: Ergonomics]].)
*Wear gloves to protect your hands from the hard edges of the fiberglass boards.
*If you already have or develop an [[Workers'_Guide_to_Health_and_Safety:Metals#metals|allergy to nickel]], ask for a nickel-free grounding cord.



{{Previous and next sections|Making the printed circuit board|Assembling electronics}}

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[[es:Workers'_Guide_to_Health_and_Safety:Montaje_de_las_placas_de_circuitos_impresos]]
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