9 March 1990
Removal of 5th sample – DP/16 (Crown label n°418) – solder mask scraping – solder mask test)
Williamson and Harrower visited Morton International Dynachem Limited in
Warrington, after previous telephone contact (according to Robert Linsdell’s
statement S5585). The company produced chemicals and solder masks used in the
PCB industry. They met Robert Linsdell (S5585) (it is wrongly spelt Linsdale in
some HOLMES statements), technical manager, who agreed to analyse the solder
mask on PT/35(b). A senior analyst, Steven Rawlings (S5581) removed a solder
mask scraping, designated DP/16, from the side of the fragment which did not have
the copper tracks and land, and a spectra printout, DP/17 (prod 341, the police label
for which Harrower confirmed in his CP was completed and signed by him) was
obtained after analysis on an infrared spectrometer.
According to Linsdell’s statement he compared this with a sample two-part epoxy and
a dry film solder, and concluded that PT/35(b) had a green coloured two-part epoxy solder
mask applied during manufacture. The normal way of applying this was by screen printing
and, once on, it could not be discerned who manufactured the solder mask.
Two part epoxy solder mask was the most common. Linsdell also microscopically examined PT/35(b) and DP/11 and concluded that, on the opposite side from the copper tracks, there was evidence of copper having been scraped away, indicating that originally the board had been double-sided (i.e. copper tracks on both sides) and that solder mask had been applied to the side of the fragment without the copper tracks on it. Rawlings’ defence precognition gives more details about the tests carried out.
In Rawlings’ ch10 CP he stated that he could no longer remember for sure whether
the solder mask was on one or both sides of the fragment, but he thought it most likely
that there was solder mask on only one side as he only took one scraping. He also
stated that he would be unable to say in court for certain that the solder mask coating
on PT/35(b) was not acrylete based as it was theoretically possible that, in the event of
exposure to high temperatures, the acrylete could have decomposed leaving other
materials which suggest that it was epoxy based, as acryletes burn off at much lower
temperature than other components of solder mask. He stated that this was only a
theory, and he had not conducted any tests. He gave evidence and confirmed that the
solder mask on the fragment was consistent with epoxy solder mask, and was not
acrylate-based solder mask so was not produced by his company, Morton. He made
no mention of the doubts he expressed in the CP. He confirmed in evidence that he
signed the label for DP/16.
According to Williamson’s ch 10 CP dated 17/11/99, both Linsdell and Rawlings
concluded that the sample DP/16 was a “standard sample” and they were of the strong
opinion that the solder mask had been applied to only one side of the fragment of
According to Linsdell’s ch10 CP the police were interested in distinguishing the
fragment fiom a Toshiba radio board. Linsdell’s CP states that radio cassettes are
mass-produced, constructed from cheap materials and a simple design, and the
fragment was clearly different as the material was not cheap, being a professional
base substrate widely available in the circuit board market.
It is unclear why there would be any need to distinguish the fragment from a Toshiba
circuit board. In Williamson’s memo to Henderson of 16 March 1990 he recites the
history of PT/35’s discovery and specifically states that the circuit board that
controlled the Toshiba SF16 RCR was constructed of Phenolic paper, whereas
PT/35(b) was made of fibreglass laminate, so though closely involved with the debris from the RCR, it was not part of the RCR. That conclusion is also clear from various other sources e.g. RARDE report.
Linsdell’s CP states that the officers also wanted to know if the fragment was
commercially or domestically manufactured, and Linsdell felt that domestically no
solder mask would be placed on either side and the curved edge had been
professionally routed to fit a specific container, and such a neat finish would not have
been possible if they hand cut the corner, as it was very neat and strongly suggested a
machine had been used in the process. He felt the design was constructed in a
professional shop but the design was not suitable for mass production, rather would be
used to construct 20-30 samples. [This all seems accurate when compared to the set
up at MEBO and the no. of timers they produced, but there is no record of these
opinions in Linsdell’s HOLMES statements.] He explained that Rawlings was the
expert analyst and he was not qualified to speak to the analysis carried out on DP/16.
He confirmed he had signed the label for this sample. Note however that according
to the statement of Rolf Buwert S4649U, he arranged for Linsdell to sign the label for
DP/16 on 14 January 1992.1 He could not recall examining DP/11 by microscope but
accepted that if his police statement said this, it was likely to be more accurate than
his recollection. He was asked why a board manufacturer would put solder mask on
the non-track side of a board and not the track side, and he accepted that this would be
unusual, suggesting that the solder mask gives the board a more professional look so
if the non-track side is exposed to view, that might be the reason. As noted below
(see under 17 May), at CP Linsdell was shown DP/141, Williamson’s report on the
fragment, and saw nothing wrong with the terms of it, despite it saying that the board
was solder masked on both sides, whereas Lmsdell at CP stated that it only had solder
mask on the non-track side. At the end of the CP there is another PF’s note which
indicates that the police statements overstated Linsdell’s role in the examination and
that he was not qualified to speak to the tests, which were done by Rawlings. Only
Rawlings gave evidence, Linsdell did not.
NB Linsdell examined the fragment again on 14 June 1990 at the PCB industry
convention at the SECC (below).
NB Linsdell and Rawlings were also seen by police in 1992 and asked to examine a
control sample MST-13 circuit board – see 2 March 1992 below. NB The signatures
of Linsdell and Rawlings are visible on the label for DP/16. As stated below, it seems
that Buwert arranged for Linsdell to sign the label “late”, on 14 January 1992. There
is no indication that Rawlings signed the label later, and the position of his signature
might indicate that he did not sign it late. The signatures of both do not appear to be
on the label for PT/35(b).