Introduction

This unit deals with a new method of fixing electronic components to a circuit board. In the conventional (usuaJ) method, components are fixed through holes in the board. In the new method (surface mounting) the components are fixed directly onto the board without any holes.

1 Listening

A consultant engineer is answering questions about a new method of assembling electronic components on a circuit board — 'surface mounting'. As you listen, tick ( ) if the feature of the surface mounted board is an advantage; put a cross (X) if the feature of the surface mounted board is a disadvantage.

2 Presentation

The consultant engineer compared the two processes from many points of view. In making comparisons, he followed these rules:

A. 1 syllable adjectives: add 'er

e.g. SMALL — SM components are much smaller than conventional components

B. 2 syllable adjectives ending in: 'ow', 'le and y' — add: 'er

e.g. GENTLE — The SM assembly process is much gentler

EASY — The SM assembly process is easier (note change 'y' to 'i')

Other 2 syllable and 3/4/5 syllable adjectives: use 'more'

e.g. ROBUST — Old components had to be more robust

EXPENSIVE — New components are more expensive to produce

3 Controlled Practice

A. Complete the table

B. Complete the sentences:

1. Size: Conventional components are__________than SM components.

2. Weight: SM components are considerably__________than conventional

components.

3. Cost of production: Conventional components are a little__________to produce.

4. Speed of assembly: SM assembly is much__________than conventional assembly.

5. Cost of assembly: Conventional assembly is_____________________than SM

assembly.

6. Reliability: SM components are considerably_____________________

7. Accuracy of placement: The SM assembly process is_____________________than

conventional.

8. Autotesting: At the moment, autotesting is__________with conventional

components.

9. Width of pcb: SM pcbs are__________than conventional boards.

10. Strength of components: Conventional components must be__________than SM

components because the assembly process is not so gentle.

4 Transfer

PAIRWOK

Student A: Below are some specifications for a particular SM board. Student В has the specifications for a conventional board. Ask him/her for these specifications.

Student B: Look in the Key Section for your specifications. Then ask Student A for his/her specs.

After you have completed the table, make comparisons between the SM and conventional boards.

5 Word Check

PROCESS VERBS

to assemble — to fix pre-manufactured parts to the main structure

to drill (holes) — to make a hole in a surface

to push through — to insert in or through a hole

to solder — to join using a metal alloy (Sn + Pb)

to autoinsert — to push components through the holes automatically

tо vibrate — to move from side to side or up and down; to shake continuously

to autotest — to test components automatically

to tolerate — to be able to work under stress (e.g. vibration)

QUALITIES

robust - strong, well-built

gentle (process) - not needing to be strong

reliable ^— can be trusted, doesn't break down often

unit 16. Energy Sources

(question formation)